How does one check the amount of boost generated by the turbo?

Thanks in advance,

Jeff Pierce
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'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)

Any air pressure gauge would indicate boost pressure- it also needs to be capable of reading, or at least withstanding vacuum. The manifold epxeriences vacuum at idle and a lot of regular driving conditions, then pressure rises upon acceleration to a max of about 7.5- 12psi positive pressure when the turbo begins providing boost. Your peak pressure will depend on your wastegate setting and how well everything's working (includign condition of air hoses).
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Rob Bareiss, New London CT ::: 86 244DL, 87 244DL, 88 744GLE, 91 244: 808K total

I was thinking I just wanted to test what the max boost is. I assume this happens wide-open at or near redline. Is this correct?

And is there any other measurements one needs to take concerning boost?

Again, thanks in advance.

Jeff Pierce
--
'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)

this will be governed by the waste gate and doesnt really depend on engine revs or throttle position as you might expect, as the 'resistance' your driving against has an effect (which is why you cant test boost in the drive....

basically take it out, get it up to 10mph or so in 2nd and floor it...you wont accelerate much but your will (very quickly) drive the turbo to the point where the waste gate opens....and thats you maximum boost as the 'power' for the boost is then being dumped away from the turbo..

basically your looking to make the engine work hard...then boost is generated...

fit a boost guage to your dash and watch it as you drive..you will quickly become aware of how the boost curve works...

I have a boost guage on the dash -- but of course there are no incriments. So I know there's boost, and I can see where it peaks, but I have no idea what the actual pressure is.

BTW, what is the spec for max boost? I also assume that it is adjustable at the wastegate.

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'92 Mercedes 190E (my daily driver), '93 945 Turbo (a kickass family car), '53 Willys-Overland Pickup (my snow-plow truck/conversation piece)

the standard boost is speced at about 7.5 - 8 psi, turbo+ i believe upped the peak boost on this (but this is clever managment of the boost verses the power curve and worth about 30bhp) you can adjust the boost the gate opens at by adjusting the waste gate actuator rod - but this is not recomended if you dont know what your doing! - get this wrong and BANG! may be the most expensive sound you will hear!..

basically fit a calibrated boost guage as the fist stage - its easy
then check the health of your engine (compression test, leak down test etc) before even considering upping boost.....

check out www.turbobricks.com for full details of how to 'play with your brick' i think they go up to stage 4 at 400+bhp but this will NOT be cheap or possibly very reliable!

Some sort of calibrated vacuum/boost gauge teed into the gauge hose under the dash. You can install one in your car or just get a temporary one that you only occasionally use. egauges.com has several boost gauges for installation in the car. Or you can get one for a hardware store or something.

-Greg