As a follow up of this thread about cams I would very much like to hear all your opinions on cams, profiles, valve lift, cam wear, lifter shape, etc on the B18/20 pushrod engines.

I made some drawings on the way a lifter responds to cam shape:



The blue curved line shows the cam profile (as if measured with a micro meter). The red line show the actual profile the lifter would follow. It's clear that they differ.


When plotting graphs of lobe profile and actual valve lift you can again see that they differ. The blue and red line again correspond to lobe shape and valve action. They are basically the same lines as in the figure above, only plotted in a graph.



You can see that the actual valve action starts earlier then you would expect based on cam duration numbers. Naturally, with a large vale lash this effect gets smaller. With an extrem valve lash it would theoretically look like this:




What one would want for a better valve action is more lift at low duration. You want the area under the curve to be as large as possible:



So to get to this valve action, would would the lobe shape look like? You would a 'fatter' start/bottom of the lobe, so that the valves open further, more quickly, like the cam in Case B below. However, when you would use the same CAM-duration, this would yield in a very large increase in actual VALVE duration. A lot more then allready was the case with the stock cam in Case A.



To eliminate this effect of strongly increased Valve duration, one could create a lobe with less overall duration, and create something like the cam below, in Case C. This lobe would be quite good imo. One could maintain a low overall duration, but the valves would open quicker so the area under the curve would be increased. However, the side load on the lifter would be relative high, which would result in increased cam wear.



IMO, the only way to solve this is to create a new lifter shape: a lifter with a smaller bottom. That way you could use the cam of Case B, but not have the effect of increased valve duration.





So, what do you guys think if this?

Cheers, Ben

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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Hello Knutselsmurf,

First of all, I havn't read the other answers to this thread, too many to cope with.

You make some interesting statements, however, the B18/20 engines has been modifyed for over 40 years and yes, they probably would produce some extra HP/torque with additional lift.

But the big problem isn't found in lifter shape, rocker-arms or similar.

There is already an lifter with wider base-plate(mounted from underneath) available, that can cope with higer lift.

The big problem is the three-bearing camshaft, even if you create a sturdy valvetrain the cam-shaft will always bend.

BR, amazonet

We talked about the wide base plate lifter below.

What is the problem of cam shaft flexing, other then a very small decrease in lift? Will they break eventually?

Cheers, ben
--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Hello, sorry for a late reply, my work-hours doesn't allow for much i-net visit anymore.

I guessed that "mushroom"-lifters was mentioned in some earlier posts, however they were to many to read.

Well the decrease in lift isn't so small when you pass 12,5-13mm lift, it seems like around that lift-height, the bend "eats" up the added lift, of cause less at the lobes that are closest to the bearings.

I haven't seen/heard of cams that have break because of too much lift.

But, I have seen cams that are so bent, that they even have split the distributor housing in half (!).

BR

Just some quick observations without reading:

Cam A: the red contact point moves as it should, it starts in the middle, as the lobe reaches maximum acceleration the red contact point moves towards the outside edge of the lifter & then as it decelerates it moves to the centre again. This gives the best wear of cam & lifters.

Cam B: appears to start at maximum velocity, when opening it would simply try & smash eveything to bits. If you did this when closing it would cause the valve to bounce off the seat indefinately.

Cam C: isn't possible with any kind of flat lifter, but the most radical roller cams look like this.

Cam D: is trying to emulate a roller cam. It won't last very long because your red contact point doesn't move very far.

Your comments on Cam A:
I'd say this still results in relative large cam wear. This is why these engines need cam replacements so often. On a worn cam you see this pattern, which is the contact area of the lifter. Thats not would I call 'good'.



Your comments on Cam B:
Yup.

Your comments on Cam C:
Yup.

Your comments on Cam D:
I do not agree. I'd say it results in less wear compared to stock, especially since the red contact point does NOT move very far.


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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

"This is why these engines need cam replacements so often."

B20 cam wear problems got cured way back in 1973 with a new billet from CWC. The big difference is the placement & width of the lobes.

I am not sure how you have mapped out the wear pattern. You really need to put a good cam & lifters into a block with some bearing blue & turn it over.

B20 cam wear problems got cured way back in 1973 with a new billet from CWC.
What does billet mean in this context? (sorry, english is not my native language). Same or CWC. I found this using google: Canadian Wood Council, Cool Air Clustering, Chemical Weapons Convention, Cricket World Cup, Condensed Water Content, but I have a strong feelting those are not the right ones tho ;^)

The big difference is the placement & width of the lobes
I guess wider lobes?

I am not sure how you have mapped out the wear pattern.
Simple, this pattern is what ALL the worn cams look like.
--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

http://www.textron.com/textron_businesses/industrial/kautex_products.jsp
CWC-Textron make just about every iron camshaft on the planet. I don't know what CWC stands for, it could be just three guys names like TRW for all I know.

A billet is a semi finished cam, the bearing surfaces, pump encentric & snout taper/key/threads are finished, but the lobes are 'as cast' & only vaguely look like a lobe. Cam companies & car manufacturers by these billets & grind the profile on them.

When CWC improved the billet they do so by making the lobes narrower than the original & better placed relative to the lifter bore. The old lobes were so wide that once they wore down a little they would touch the lifter at both ends of the taper & then stop spinning. You can rescue an old cam by narrowing the lobes to a more sensible width.

That was going to be my next comment regarding the narrow-tipped lifters. If oyu install a cam and peer down the lifter bores you willl see that the lobe is not centered in the bore, rather it is off to the side. This is intentional, and causes the lifter to spin as it rides up and down on the cam. This distributes the wear evenly on the lifter face. A narrower tipped lifter wouldn't get as much spin, and thus is more likely to become fixed in the bore, concentrating all the wear in one spot.

Over on that turbobricks thread someone showed a picture of some roller rockers that don't need keyways machined in the block - just a sort of collar that sits on top. For Volvo application I guess you'd need:
- Collars on the proper centers, still in pairs. The center may or may not be the same as more common applications
- Custom holders for the collars - probably in pairs as we don't have a wide open gallery around the lifters like the V8's. You could fasten them through some holes in the block above the lifter gallery.
- Custom pushrods - shorter than stock and much shorter than the SBC solid lifter length
- Custom cam

Combine those with some roller rockers and you would have knocked some serious friction out of the drivetrain. Although the roller ligters probably weigh a bit more.
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I'm JohnMc, and I approved this message.

The roller lifters have never been a problem.
Its getting the cams made at a reasonable cost.

John
V-performance.com

I'd have *thought* that Isky would whip them up pretty reasonably. Of course, me thinking and them doing is entirely different. I could have sworn I've seen B20 roller cams listed somewhere or another. I checked the Isky catalog and it wasn't there that I saw it.
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I'm JohnMc, and I approved this message.

This goes back to research I did years ago, so I may have forgotten some of it.
In any case there was a definite reason why you just can't go to a cam maker like Isky, Comp Cams, etc., and have them do a cam for roller lifters on the cam core that is available. But roller lifters in a B18/B20 is something that has been done for race and rally applications.

John
V-performance.com

Perhaps it has something to do with the lobes for a regular lifter being offset to the side?

Either way, probably too much money for too little benefit. Except in an *almost* no expense spared race car.
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I'm JohnMc, and I approved this message.

Don't forget that the lobes are also tappered, half front to rear, half rear to front. .002"/1" normally.

I though about the rotation of the lifter aswell, being off centered. The size of the small lifter bottom will be too small to still rotate, but since the cam lobe is quite a bit smaller then the stock lifter I figured you could get away with a bit smaller lifter bottom.
When going to even smaller lifter bottoms (like on my figures) you need to make the cam lobe narrower, or at least grind one side of it away, so you'd still get the rotation of the lifters. Dunno wether that would still be realistic tho.

About the roller lifters, I think it will be worth looking into. They will most likely indeed be heavier then stock lifters but since there is less friction you could get away with more radical profiles without putting too much side load in the lifter. Hmm, interesting!



But how do these ones below work? Is there a slot in that connection piece to allow for the side to side movement, neccesary since both lifter dont move simultaiously?



Actually, JohnMc, maybe you are willing to try some of this? I mean, you have to take of the head of that engine in your 544 anyway... ;^)

Cheers, ben

--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Don't you think that reducing the lifter size is contrary to what some of the Swedes do? ie: fit mushroom lifters.

Yeah I thought of that aswell. But there is not a lot of room for it. I mentioned this on the same thread I opened in turbobricks aswell. I guess you could fit wider bottom lifters with some creativaty: you'd have to fit them 'from below' before placing the cam. It would be a possibility, although the weight factor would might be a problem. It would certainly reduce wear on the cam. Do you say you know/seen of some Swedes who creates mushroom lifters on the B18/20?? That would be interesting.

But there is actually no real benefit of using mushroom lifters as aposed to rollers. The cam profile would be completely different to get the same valve actions but I dont see any advantage other then that. It would absolutely be an enormous improvement compared to the stock setup.
EDIT: Actuall, when I think of it, the mushroom lifters will have FAR less side load then the roller type. Perhaps that would be an even 'better' option.

--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Oh no - not trying anything *else* new on my PV engine. Roller lifters would involve a new cam and I'm not about to take out my brand new Isky VV71 and new set of SBC lifters and my MG-TD pushrods!

Those rollers with the arms must have a slot instead of a hole in them. The length between those points will change as they go up and down independently. There probably isn't much sideways force on them, they just need a gentle point in the right direction I'd guess. Although that makes me wonder - do roller cams need to have the lobes gorund flat and centered in the bores?

KgTrimning sells mushroom lifters. I can't recall if it takes a little machining in the block or not - probably providing a little clearance on the bottom side of the lifter bores. I have a catalog at home, I could try deciphering a little of the Svedish on the mushroom lifter decription to see. They look to have just a little extension on the bottom, protruding maybe 1/8" around the bottom edge. I didn't see a picture on their website (www.kgtrimning.com) or I'd have linked it.
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I'm JohnMc, and I approved this message.

The only real issues in regards to putting roller lifters in a B20, outside of a nice theoretical discussion, are:
1) can you do a roller lifter cam on the cast billet that is currently available?
2) cost v benefit
3) whether there are those willing to pay the cost to make them available.

Otherwise its just a lot of nice talk.

David Methely in the UK did B18/B20 engines with roller lifters. Anyone interested in pursuing this could contact him. His Volvo powered Marcos cars won the European FIA historic championship for under 2 liter cars several years.

John
V-performance.com

Ah, I did see something on kgtrimning.com/kamtillb.htm: the lifter + pushrod:

- VENTILLYFTARE MUSHROOM MÅSTE användas tillsammans med vår mushroomkamaxel. Lättade. Mindre modifiering av blocket nödvändig. MR-202 275:-/st

- STÖTSTÄNGER För mushroomkamaxel. 488-3 125:-

No pics unfortunately, I might send them an email.

Apparently they also still sell a matching 'mushroomkamaxel'; might be this one:

- KG MR3 avsedd för maxeffekt gata, rally, rallycross, racing mm. Denna kamaxel ger den absolut högsta effekten och det bästa vridmomentet. Den är minst lika stark som t ex en KG6:a.
Kräver våra special ventillyftare mushroom samt en mindre modifiering av motorblocket. Mycket lämplig att använda tillsammans med våra rullvippor.
Lämplig topp från steg 3 och uppåt.
Lämpliga förgasare 2X48:or m fl.

Pretty darn radical I think:
Lift: 13.9, Lobe seperation: 103°, Duration 320°.


--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

They have pics of them in the catalogue: http://www.kgtrimning.com/KG2003katalogweb.pdf
They would just be modified Chev lifters. Profiles that require mushroom lifters are not something you would ever use in a road car.

I wonder why they left that whole front section of their catalog out, where they talk at length for pages on all the aspects of building a perfomance engine.
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I'm JohnMc, and I approved this message.

The tightarses want you to pay for that part.

I got a catalog free (TANSTAAFL!) when I got my Bilsteins for the PV. Of course technical Swedish is pretty hard to decipher, but I think I can usually get the gist of what they are saying.
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I'm JohnMc, and I approved this message.

Have you got a scanner? :)

Hmm, would they be wide enough to completely get rid of the side load on the lifters? I mean, would the cam lobe allways be pushing from underneath instead of from the side/edges? This does look good to me though. Although: why are they so short? Also, I wonder what the 'mindre modifiering' (small modifications) to the block would be?

Like you say, "profiles that require mushroom lifters are not something you would ever use in a road car" is correct. The numbers will be different. However, with mushroom lifters, the advertised duration at different liofts would be less then with the stock lifters if the base circle would be the same (since the mushroom lifters base is wider). Also, I think you might need a larger base circle on the cam to be able to get to a usable profile (Case F). If the bottom surface is still relative small, the cam will still push against the side of the lifter (Case E). To eliminate side load on the lifter, you always wnat the highest point of the cam to be right 'under' the lifter bottom surface area, and not 'outside' of it. But if the mushroom cam has a large base circle, total duration numbers can not also not be compared.





--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

'Case E' doesn't happen. The red point of contact is always inside the diameter of a standard lifter with a standard cam profile. Replacing stock lifters with mushroom lifters makes no difference to a stock cam.

The red point of contact is always inside the diameter of a standard lifter with a standard cam profile.
No way. I suggest you might need to check that. Stock lifters/cam DO act that way. It's not a lot. But I just checked on a few cams I have here, and they all do it. Some more then others. You can see the contact surface has become a single point: the edge/corner of the lifter. Only with mushroom lifter you might be able to keep the red (contact) point completely under the lifter base.
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Just a random question - but are the lifter bores centered over the camshaft center line? Or are they off set somewhat - like toward the rotation slightly to make the stress of lifting the lifter more in line with the movement they want it to make. It would add stress (theoretically) the the back side of the lobe but in reality it is greatly unwieghted at that point.
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I'm JohnMc, and I approved this message.

Yes, they are centered. There only off-centered axially for the lifter rotation. It would also require different ramps on each side of the lobe if you'd want the valve action to be 'symmetrical'.

Btw1, you say: "like toward the rotation slightly to make the stress of lifting the lifter more in line with the movement they want it to make" but its just the opposite: The more mushroom effect > the larger discrepancy between lobe shape and valve action (the further the red and blue lines im my figures will be apart). Moving the lifter TOWARDS the rotation would yield in more mushroom effect in the opening side, and less on the closing side.

Btw2, you only need very slightly larger lifters to maintain the full mushroom effect, so the KG lifters will do the job perfectly. (I figured they might still not be wide enough, but they are)

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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Again, I must add that any discrepancy between the lobe shape and the lifter movement should not be considered a problem. If the cams were designed for off center lifters then the shape would have been intentional. Any difference in the blue and red lines is intentional, not accidental. The Volvo (or was that still Pentaverken?) engineers were not that clueless. At least I'd certainly hope they weren't.
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I'm JohnMc, and I approved this message.

LOL, yeah I know. The actual valve action is the goal. From there you reverse calculate the actual lobe shape, taking the discrepancy into account. I'm just saying that the larger the mushroom effect, the larger this discreapancy will be, so you would have to take that into account in the lobe profile.
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Yes way! :) The lobes never touch the side of the lifter, if they did they wouldn't last long.

if they did they wouldn't last long.
LOL, which is my point EXACTLY! (However its more the cam that will wear rather then the lifter)
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

I'm talking instant destruction. Standard lobes never get anywhere near the edge of the standard lifter. Mushroom lifter don't alter things either, they have the same radius.

What do you mean with "they have the same radius"??

Please check how the lifter and cam interact. Trust me, at some point the cam contacts the lifter on one single point only. And also check this: if you'd have wider lifters (mushrooms), this would NOT occur.

cheers
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

The radius that the bottom of the lifter is ground on are all the same for solid lifters. If you reduce the radius, ie: swap flat for roller lifters, you slow the lifter motion.

If you have a new or reground cam & lifters laying around get some bearing blue check it out in a block. It doesn't matter how big the diameter of the lifters are, you will find that the Volvo profile will only use a 0.800" diameter circle worth in the middle.

I do not agree at all Paul, I checked this a number of times, you are wrong. :)

Check the drawing, this is what happens: The area where the lobe touches the lifter moves to the side. The red line is the contact area.



So when you look at all the contact areas you will find this: which is the picture I posted before, and which is what a worn cam looks like. THIS IS THE WEAR PATTERN. Please, do check it.



In real life this is what the lobes will look like:







Check the cam in the middle, you can see the two black spots: the lifter never touches this spot! With more radical profile this effect will get greater, which results in greater wear.

And when you look at the contact surface you can see why this happens:





So when increasing the lifters size, you are able to keep the red contact line as wide as the lobe itself, AND you can use a more radical profile without the lobe actually pushing the lifter from the side.

Have fun, cheers, ben






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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Ben, you are showing pictures of lobes that are rooted. You can't base your observations on a worn out camshaft. Get a new cam & lifters.

I strongly suggest you make a test-setup so you can see what actually happens. You'll see that the contact area (red lines) are like what I have drawn. The fact that these cam lobes are rooted increases this effect, but check a new cam, you'll see what I mean.
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Do you have a new or reground cam to look at?

Yes I have a (nearly) new C-cam. The C does exactly the same thing, but since you need to look exactly perpendicular and with the lobe and cam both beeing 100% flat, there is no use of making a pic: you cannot make it visable in a camera. When looking along side of the lifter you can see how the contact area moves to the side of the lifter, and therefore decreases in size, and thus creating the wear patterns I posted. This can also not be made visable in pictures, which is why I made some drawings.
If you say this is not true, and the contact stays in the middle of the lifter, it would result in a 1:1 valve lobe shape vs. lifter action. As is concluded before this is NOT the case.
All I can say is, please check it, and you'll see what is actually happeing down there.

Cheers, Ben

--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Is your 'new' C cam nearly as rooted as the worn cam you have posted pictues of? Post some pics of it & I tell you if it needs chucking in the bin like that one.



This picture you show with the middle of the lifter touching the middle of the lobe is very wrong. With a new or good wearing lobe the lifter doesn't touch the middle of lobe. They should only touch the front edge or rear edge of the lobe. Not the middle & not both front & rear at the same time.

Post some more pictures of lobes, perhaps you have one that is running properly.

Like I said, with a new cam, and a picture from the same angle you don not see anything special. In that case you need to make a picture form the top of the lifter (looking along side of the lifter onto the cam lobe). But on a picture you cannot see where the lifters touches the lobe: but it does this according to the red line in my drawing. Please, PLEASE, check it...



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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

What makes the B18/20 lifter setup any worse than any of the other bazillion pushrod engines? More lift? More PSI on the lifter face? More abrupt opening? Springs allowing bounce? Is it only a problem when you frequently run up past 6000 rpm?
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I'm JohnMc, and I approved this message.

Its not. I was just looking at the cam/lifter interaction, the lobe shape, and the actual valve action, and I though maybe we could improve that a bit. The real problems start when you want different/other valve actions, without snapping of lifters, have cams that only last a few hours or have extreme valve train accelerations.

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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

My point is this subject must have been beaten to *death* by very experienced engineers. Not just by a few Volvo guys (pro and am). For cams mild to wilder than we'd (probably) ever consider. If you look around at solutions done for more common types of engines (like the Chevy SBC and it's 45+ (?) years of development of performance parts) you should find directly applicable knowledge. I'm not saying that you aren't advancing the theory of cam/lifter design here, just suggesting that perhaps others have already done the same thing, and worked through the trial and error of actually building examples and seeing how they worked.
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I'm JohnMc, and I approved this message.

excellent point
Unless someone has a lot of money to spend, this kind of cam theory is not something that can easily be tested in practice. Better to beneifit from those who
have already done it.
There are other areas, such as exhaust configuration, where its comparatively easy for a car owner to work out theoretical solutions and then test them in practice.

John
V-performance.com

"Unless someone has a lot of money to spend, this kind of cam theory is not something that can easily be tested in practice. Better to beneifit from those who have already done it."

Yeah I know, but its not that I will actually be developing concepts, its just that I like to learn more about it. I now know that there actually ARE things like mushroom lifters and rollervipars, which I didn't realy knew before. Also, we have no Chevy V8's over here from where I might pick some ideas or anything. So yes, we dont have to re-invent things that allready exist. But the theory behind it is interesting though, imho...

Now, who's got some formulas for calculating exhaust configuration and lenght? :)

Cheers, Ben
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

I am thinking that there is a bunch to be done with intake manifolds. I'd like a tunnel ram manifold featuring SU's.

Spent much of last Feb. doing dyno testing and finding out what you can't do with SU's on a stock manifold. Essentially, with our street performance cam, ported head, etc., could not get the engine to produce power over 5300 rpm without modifications to the stock AL manifold. Had to do with tuned length, pulses, etc. Necassary modifications include soft mounts, spacers, reduction of the balance tube area - all things that have been done for years on pure race applications using SU's. Also happened to discover that there are at least two internal shapes of the SU AL intakes, and one flows significantly better than the other.

John
V-performance.com

It's been a lot of years since I did anything with SU's. I developed a phobia to ram tubes on SU's after I accidentally found a pair that created an extremely lean period around 5500rpm's on a welded stroker motor that busted all 4 top compression rings after one quick trip around the block. IMHO getting ram effect from ram tubes on SU's is best reserved for single SU fitment a la David Vizard single SU mini's.

For stopping bits falling off SU's & other things I found that putting a vibration damper on the front of the crank to be a good way to go.

Not happy with the SU carbs either. However a setup that racers have used allows some quick experimentation on intake length. Two adapters are made, one for the carb and the other for the intake manifold, then a piece of high quality flexible hose is hose clamped between the two. With this setup you can test changes in intake lengh very quickly just by changing the hose length.

Your example is also why we test with 02 sensors on street engines and ext temp gauges on race engines.

Seems to me that you gave us info on a vibration damper that would fit the B20 some time ago. I believe it was made in your part of word. I can't find the info. Can you give it to us again?

John
V-performance.com

I noticed in another thread that you are trying HS6 carbs! Forget it, they aren't big enough. Try a set of HIF6 carbs, they flow 15% more air than HS6's do & they would get you from 5300rpm to 6000rpm.

Romac made some balancers for us. I doubt that they would have made any in the last decade, but they would still have the plans to them floating around. The balancer was an inch smaller in diameter than the stock pulley with one V-belt groove running around the outside. We figured underdriving the water pump & alternator would be a good thing & never had a problem.

FWIW, here's my dyno sheet. This is with an internally unmodified b20b, so I wasn't expecting anything drastic. I had a stock air filter in the box I think, and then a 2" mandrel bent, perforated core exhaust. Nothing else special really. Although I was hoping to make peak power a bit beyond 5200rpms, no luck there I guess...



And John, how can one tell between the two aluminum intake manifolds? Are the part numbers different? Is it easy to tell by looking at the outside of them??? When I go to the dyno next, I'll bring along some spacers and some air horns maybe and play with them in between runs, see what I come up with...


--
Kyle E.
VP of Membership and Website Administrator
Oregon Volvo Tuners
Portland/Corvallis, OR - 1968 142 - 71b20b SUs, m40, ask me for more info...

How about starting a new thread for this.
The current one is just getting too hard to follow.

John
V-performance.com

The issue of using HS6 carbs is not one of choice, but of using what customers want to maintain a stock look. AT the time we did the testing last year we also tested the HIF6 carbs, and some other carbs as well. Without looking up the dyno data, my recollection is that the HIF6 carbs were better from 5300 - 6000 as you suggest, but that we lost power and torque in the lower rpm range. The HS6 carbs with spacers equalled the HIF6 high end while giving better low end. Eventually ran out of time on the testing, so there are still combinations that I would like to try.

Some of the reason for spending time on SU carbs and others that would mount on a stock SU manifold is due to the current cost of going to new weber sidedrafts, which is now in the $1300 range in the US, including the carbs, manifolds, linkage, soft mounts and aircleaners, but not counting the jets, etc., needed for tuning.
At those prices it has become important to have some alternatives available and we be testing at least one other this spring.

Every "romac" I can find, including one in Australia is the wrong one.
Have ATI doing adapters for their dampers here for race engines, but its very expensive. Probably more than anyone would want to pay for a street engine, so
looking for alternatives that could be made up for customers. What kind of damper did Romac do for you? Approx. price?
Can you give me contact details for Romac?

John
V-performance.com

You might want to try stiffer springs in the HIF6's. SU's develop more bottom end torque than other carbies because they atomize fuel so much better than fixed venturi carbies, loss of torque would indicate that the spring might be too soft.

Are HS8 allowed? They work well too. I got a pair from an old Rover 2000. You would find the Rover setup interesting as they use softmounts & springs.

I would guess alternate manifolds aren't allowed, I always wanted to try SU's on a Lynx 180 degree manifold but never got around to it.

Tried a whole set of springs if I remember. As I said, ran out of time before I could try everything. The HIF6s might have worked better with a different exhaust setup, etc., but just did not have time to get into that. Hope to go back and renew that testing this spring. As it was we spent over 20 hours of actual run time on the dyno over a 3 week period. A lot of time was spent with different springs, different needles, doing custom needles, different damping oil viscosities, developing better anti vibration mounts as we had a problem of fuel foaming in the float bowl at high rpm, developing spacers, then trying two different types of carbs on the same maniflod.

This was a street project so any manifolds were allowed, but the object was to develop a setup that was as close to stock appearance with as many stock parts as possible. Sticking with SU's because everyone has a set and sidedraft webers have gotten so expensive. We ended up with about 155 HP from the HS6 carbs, which was not bad for a 2 liter street motor with 9.5 CR. Not as much on the top end as I would have liked but most drivers would rather have more low end rather than top end.

John
V-performance.com

I'd like to know how much duration that cam you are using has. Too much sharing between the cylinders can be counter productive. Are you familiar with scatter pattern cams used in old mini's to counteract some of their siamese port problems?

Romac Performance Products
21 Spine St Sumner Park QLD 4074
ph: (07) 3376 7244

Would be 61 7 3376 7244 for you I think

I doubt that they have made any in the last 12 years, back then they were $350 Australian I think. They are steel/steel with a quality bit of neoprene rubber in between, pushed together with a big snap ring holding it together.

I will check with them, but I suspect at that price it might not be any less expensive then having them done here.

Thanks,
John
V-performance.com

They aren't noted for making cheap stuff. They are probably better known for their timing chain sets. (Rollmaster)

I'd think for $1300 you be darn close (or maybe under) to having a couple of DCOE throttle bodies, injectors, manifold, and a programmable fuel injection system. And then the tuning wouldn't involve swapping expensive brass bits.
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I'm JohnMc, and I approved this message.

You still can't do a complete throttle body system with manifolds, linkage, air filters and a commercial programable FI system for that. You might be able to do it with megasquirt. The problem is that the throttle bodies, as well as the manifolds, will probably have to come from Europe and anyone in the US will get killed with the current exchange rate. A lot of this stuff costs 40% more in the US than it did 2 - 3 years ago.

John
V-performance.com

What's the balance tube area? How much longer did you have to make the length? Were you just going by the general length intake length formula that's out there? Running air horns will effectively increase the length as well correct? I want to make power over 5300, and sure I don't have a SP cam or ported head, but that will be in the future... I'll want to be working with you on having one of the most powerful SU equipped engines... =D But tuning the length can still help cars that don't have ported heads and hot cams right? I've been thinking about the 2"(length) air horns specifically made for my HIF6s from TWM for a while now(or "Ram Stack 27mm" air horn from APT, both are full radius horns). And are there part numbers for the AL intakes for the ones that flow better?

Thanks for all the great info John!!!
--
Kyle E.
VP of Membership and Website Administrator
Oregon Volvo Tuners
Portland/Corvallis, OR - 1968 142 - 71b20b SUs, m40, ask me for more info...

Maybe you want something like this: (http://www.bccp.nl/nl/indexnl.htm)
It seems to work on the flow bench, dunno about real life... They claim 12-15% increased flow.











--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

The balance tube is the tube connecting the 1 & 2 port to the 3 &4 ports.
Its area - the diameter of the tube - determines how much air can go back and forth.
You have to do some work to get these things right. Too many variables to just use a stock formula. You take your application and do a series of tests and see what works best. Control the conditions, do it on a dyno if possible, or time to distance, or G tech, etc. No easy way to get it right. Or use exactly the same setup as someone else who has done the testing and you will likely come close to his results.
I can't answer the question as to wether changing the intake length would be beneficial. Have never tried it and don't want to waste time doing this sort of testing on a stock engine where the performance gains will necessarily be very limited.

John
V-performance.com

If you wrap the intakes back over the top of the engine it will make adjusting the valves a difficult task!
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I'm JohnMc, and I approved this message.

A couple of points.

1) - There is no way that the engineer who designed the original cam shape 'meant' for the valve to travel in the theoretical 'blue' curve you depicted in the first picture. That would mean they just didn't know that the lifter would interact in that way with the lobe, and I'm absolutely sure that tidbit did not escape them. They designed the lobe for the end result - at the valve tip - even including the rocker arm's contributions. If they had been using roller lifters they would have designed the shape of the lobe differently - to produce what they thought was the best end result at the valve.

2) 'Optimal' valve actuation isn't as simple as maximizing the area under the curve. Opening valves faster and farther doesn't always keep on adding HP. Air isn't electricity, it doesn't immediately stop and start, especially at the speeds at which things are happening at 6000 rpm. Snapping an exhaust valve shut abruptly at the end of an intake cyce could cause more reverberation back out the intake than would closing it more gently. Snapping an exhaust open quickly at the beginning of an exhaust cycle could yank the air in the port backwards momentarily. Valves have inertia and momentum too, snapping them open faster and farther isn't very easy on them when the valve needs to open and close again in less than a hundredth of a second.

This isn't to say that the cam lobes they developed back in the 60's are the best that can ever be done, just saying that they probably aren't *that* far off.
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I'm JohnMc, and I approved this message.

1) Offcourse volvo engineers knew that the valve would act different then the actual lobe shapes. My ponit is that the realation Lobe shape vs Valve action is far from 1:1. Which makes it harder to design a cam.

2) I know there is no optimum lobe shape, but i'm just hypothetiocal here. Just pondering if, and how the volvo lobe could be improved, and in the mean time minimizing wear. So that would also mean low valve acceleration etc.

Snapping an exhaust valve shut abruptly at the end of an intake cyce could cause more reverberation back out the intake than would closing it more gently.
Hmm, yes. Have not though of that yet. AND, this would also mean that on a more radical profile, the lenght of the intake runners would become a lot more critical.

BTW. I'm not at all saying I know anything about cam at all. Like I said in the other cam thread, I'm a newbie, but eager to learn. So keep those replys coming! :)

Cheers, Ben
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P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

Ben, those are great drawings and you raise many interesting points. It gets more complicated yet when you factor in rocker arm geometry... the rocker supposedly multiplies lift by 1.5, but it does not do so linearly -- it has more "gain" in the middle of the lifter stroke than at either end. Also, that 1.5:1 ratio changes with the position of the adjuster screw -- the further down (tight) the screw is, the lower the ratio.

The lifter in your example D is not an advantage, I don't think. With a flat lifter (they are almost flat in real life), the acceleration of the valve is faster coming off the base and slower approaching the peak of the lobe, as your curves show. This is GOOD. There is also little metal-to-metal contact area during the time the lifter is under the most load, so friction and wear is much lower than with the altered lifter shape -- on the base circle there is lash and so no load on the lifter, and at the peak the valve is decelerating and unloading the lifter (which is valve float if it unloads completely).

Modern cams that have more area under the lobes, and therefore steeper slopes / faster peak velocities, have a ramp coming off the base circle so the valve train is subject to less sudden acceleration, but nonetheless opens to substantial lift faster than with older designs. According to B20B Paul, the OE cams do not have this feature. (???)

Now let me restate what John Parker pointed out several times in the previous thread, because he's absolutely correct: the "optimum" cam is whatever works together with any particular ports, valves, intake system and exhaust system (etc.) to produce the performance characteristics desired in that individual car. A change in any one of those variables requires a change in the cam profile. There are two or three combinations that are proven to work together, and if a customer wants something different, it's a custom job.

This, in a nutshell, is why you can't build performance motors buying parts from a catalog.

Ben,
Let me add that I think its great that you spent the time to put all of that info together graphically. It really shows clearly what some of the problems and issues are that cam designers have been working on for the past 100 years. Its good for all of us to have an understanding of these issues but we have to rely on the experts for whom improving cam design is a profession. The process for them is one of extensive rounds of design, execution of prototypes, and extensive testing for each specific application. Change the exhaust system, or even the gearing and a different cam might be a better choice.

Each issue you have pointed out involves compromises where other factors such as metalurgy, lubrication, and the specific cam application are important. You can design a different lobe profile for a racecar, for example, that is going to have the cam changed frequently, as opposed to a car that is designed to go 100,000 - 200,000 miles on the same cam. The cams and lobes are designed to minimize wear, and a key factor in this is shapes that will provide for continuous rotation of the lifter and keep contact pressures within certain parameters. The actual pressure of the lifter on the cam is a key as are the materials and hardness of the components.

Another issue is the valve train and its components. The lifter has to be able to follow the cam lobe shape. In fact the actual path of the lifter may not be the actual shape of the lobe. You can see from your diagram that the only thing that prevents the lifter from flying off the end of the cam is valve spring pressure. Not enough pressure and the lifter does not follow the cam. Too much spring pressure and the cam and lifter can be overstressed resulting in high wear or premature failure. The spring pressure needed is highly related to rpm and several other factors includig the rate of acceleration of the lifter on the cam lobe. For race applications we use double or triple springs that are much larger in diameter than stock and may have almost twice the spring pressure when the valve is open. With these springs we can use a much more aggressive lobe shape, but the spring pressures necessary just would not work on a street engine.

The issue of lifter shape that you raise was first "solved" with the mushroom lifter that is larger on the bottom - the shape of an upsidedown mushroom. The better solution is the roller lifter that can be found on most modern cars with lifters. The roller on the end of the lifter allows for a completely different cam lobe profile. There have been b20 cams done for roller lifters, but to my knowledge there are none available today. If someone out there knows of someone who is or can do them, please let me know. One of the problems here is that race use would usually be the place where there would be the greatest demand,and people would be willing to pay the cost, but most if not all organizations who sanction vintage/historic races and rallies have rulled that roller cams and lifters are a non periord modification that will not be allowed. They were being used in the UK a few years ago with great affect.

So there are solutions that are out there. Applying them in an economical manner to an engine design that is coming up on being 50 years old is the real challenge, not trying to design new solutions. A lot of this boils down to economics. Those of us who are in the business of supplying performance products for your cars need your support. We can't spend a lot of money designing and testing improved cams, for example, if we are only going to sell a few a year. Every time a Volvo owner makes the decision to buy a D cam, or one of the Isky cams that was designed 30 years ago and have been sold mainly by IPD, because it is $100 - $200 cheaper than one of the new performance cams and "is almost as good", that hurts the process. If I could sell 100 cams a year the price would be $50 - $100 less per cam, my profit on cams would be be higher ( which would be easy because there isn't any now), and it would make sense to spend more time in cam development. Because of the time it takes to do the necessary testing, we usually only come out with one new cam grind per year, and that is divided amoung normally aspirated street cars, supercharged street cars, and racecars.

All of the companies that still deal in Volvo performance parts, and especially those that still do development work rather than just sell old products, need your support. The reason that there are more parts available for vintage Porsche and BMW owners, for example, is that they spend more to support companies that provide products for their cars. Its not because there are more of their cars out there. The problem for us is trying to provide performance products on a very limited budget. I know exactly what has to be done to get very significant improvements in performance for B20 engines.

I actually have an offer on the table TODAY for a product that would be unbelievable if we could do it. It could be ready and available in less than 6 months, but the estimate is that it would cost in the range of $50,000 for the basic development work, tooling and patterns, before production of each item. If this was for a Porsche it would be great as we know the market is there, but for old Volvos, at this point I have to pass.

Now back to work.

John
V-performance.com

"According to B20B Paul, the OE cams do not have this feature."

I'm not sure what you are talking about here Phil, could you please refresh my memory?

Paul, something I half remember from way back when we were discussing the effect of lash on valve train impact. Apologies if I've got it wrong.

Valve Lash: Volvos ancient profiles have clearence ramps that are constant velocity.(I'm not sure what Cam designers call this). Even thirty year old Isky profiles have ramps that accelerate.

About the rockers: I realise the rocker action is not 1:1 either, and by altering the rockers pivot point (the rocker shaft) lower or higher, you also alter this. But this effect is not near a large as the lifter-lobe mushroom effect.

About my example D: you say With a flat lifter the acceleration of the valve is faster coming off the base and slower approaching the peak of the lobe, as your curves show. This is GOOD But that is basically what I tried to do. I think that the actual valve action on Case D, is pretty simular to Case A (stock). But in Case D, I'd say, there is less wear then the stock situation, since you INcrease the metal-to-metal contact. You say little metal-to-metal contact results in little wear. How can that be true? The large contact area, the lower the froce per area, so little metal-to-metal would actually create MORE wear imo. Which is why large main / bigend bearings last longer then small bearings. Right?

About the fact there is no optimum cam, and everything has to match: I know. I just like to know more about this subject. IMO, the design of the lifter-cam lobe interaction is pretty crappy. It works ok, but not without relative much wear. (se the pic I just posted as a reply to B20Paul) A wider base on the lifter would be nice, since this wear pattern shown in the pic would be gone, but there is no room for such an alteration. Roller lifters would be ideal, but would require quite a bit of alterations to the block.
I'm just pondering about all this, and hope to learn more with the help of you guys. So like I said earlier: keep those replys coming!

Cheers, Ben

ps. Basically I was just thinking how a cam and matching lifter would look like with:
-stock duration
-stock lift
-more area under the curve
-less cam/lifter wear
-relative low peak accelerations

--
P131, '65, B20B+M47. P131, '69, B20E+AW71L+LSD. (www.tinustechniek.tk)

WOW!.................. I'm impressed. It seems to very logical and efficient to do.

Bob 1800ES

I think that's AWESOME, and we'll definitely have some fun and great learning coming from this. Thanks for laying that out there man! I had been closely following that other thread, but didn't really feel the need to say anything, just took a back seat and watched it flow. I might get a little more involved in this one, if I can keep up with it all. Thanks again for laying this out here, I'll have to finish checking it out when I have some more time....
--
Kyle E.
VP of Membership and Website Administrator
Oregon Volvo Tuners
Portland/Corvallis, OR - 1968 142 - 71b20b SUs, m40, ask me for more info...