i have recently been told by one of my mecanics (not the brightest) that it is possible to run 87 pump octane through a turbo engine that we converted from a non-turbo. my question is because we used the stock high compression pistons, he says that all we have to do is advance the hell out of the timing and it wont ping. im sure that at around 5 psi of boost we will commpresing that fuel to the limmit and should run at least 93 octane fuel if not water injection

Mr. Lot is correct, as usual.

Your mechanic needs a new one. His is backwards.

My car (a 240 turbo) even pings slightly with the best gas at that low compression ratio. You will rocket a rod, (typically #1) or blow a hole in a piston if at the very least you don't run premium with an octane booster.

What year motor? You could get a B21Fti distributor or a MSD spark system with boost RETARD.

Intercooler sounds nice, too.

How did they run the oil lines?



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www.fidalgo.net/~brook4

Paul,,Who carries the..MSD spark system with boost RETARD..for my 245:Ti ?
Thanks...
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john,,1985, 245:GLTi 246k mi..so.california

The usual speed suspects. JEG's, Summit, etc I think it's called MSD-5462...it T's into a 1/8" vacuum hose...you can dial into 1°-3° retard per pound of boost...it'll retard up to something like 15 or 20° retard total....

But there is one unit that works with stock ignition and another that you use with an MSD ignition.
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http://www.fidalgo.net/~brook4/oilslubesfilters.html

Thanks Paul..
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john,,1985, 245:GLTi 246k mi..so.california

Also there is a all in one called MSD 6BTM (I think...do a search)
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http://www.fidalgo.net/~brook4/oilslubesfilters.html

You must run premium gas from now on. The stock normally aspirated pistons require 91 in the US. If you turbo the stock setup you need to run premium.
You'll still probably ping if you go above 5-6psi with the setup you are talking.
The mechanic is totally wrong about the timing. You need to retard the timing
under boost conditions to avoid pinging. The stock 240T distributor has advance
when the engine makes vacuum. When the engine makes boost the mechanism on the
distributor retards the timing. To run a setup you are talking about you must retard the timing. Retarding the timing and water injection will help but your setup really can't run high boost with so much static compression. Also a lower compression ratio makes more room for more combustion. This is why any high
boost pressure motor runs low static compression. A good idea but it does require careful setup.

Another thing you can do is to install an intercooler more efficent than the stock volvo one. You'll have to have this made for you.

Dave 82 242ti 278k mi.