Most psi seen!! a 2.5 block take?
 

What is the most boost or psi, anyone has seen on a dyno run or boost guage, for a 2.5 liter block either Turbo or modified NA block?

Kevin
PCM Injection

24-25 briefly

Erick

Wolf:

Was that boost or Absolute pressure?

Kevin
PCM Injection

I've seen 20psi boost. 20-24psi absolute would be stock or less so I'm sure that means boost.

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'86 951 Graphite Metallic/Tan

I know someone in Florida that runs 22psi in a 951...he knows someone that runs 40psi + NOS....
the 22psi car had a O-ringed head and wide fire headgasket...not sure what other engine mods. The 40 psi I have no idea.

I've seen 21psi briefly with a stock block 2.5. I usually run 18psi. Currently working through the startup bugs on a new APEXi AVC-R boost controller. So far the most I've been able to get out of it is 17.
Give me another week or 2 and I'll do a writeup on it.
DanD
http://www.Boost-O-Holic.com

Since we are on the boost subject what is an safe boost to run in an 951, that is stock no new gaskets or stuff like that?

you cannot raise the boost w/o chips or the DME will cut you off. With just chips i would advise @ 15 psi. I have run 24 psi before with a wide-fire gasket and a shaved head which raises compression slightly. All internals were stock at the time.

I hit 28.6lbs (hi boost recorded on my AEM tru-boost), running a k27/6 on a turbo s with stock internals, wastegate stuck closed. Damn happy I didn't send this engine over the rainbow bridge though. But damn, that was one hairy ride for a few seconds.

someone here in colorado was running 30+psi on his old 2.5 engine

I ran 20 psi boost briefly with autothority maf, autothority chips, stock fpr and stock injectors and it was fun. I do run 15 psi with a 3 bar regulator and performance chips for everyday driving.

also what are you running? 93? 101? 118? E85??

At 15 you can get by with 91 but I don't chance it and run 93 always.

I run 1.5 bar (22 psi) daily and have been for the past 3 years. I use E85 fuel and my Vi-PEC engine management kit. Absolutely no problems and I know it will take more boost without any issues.

somewhat off topic. i personally witnessed 40psi on my fathers 2.3 liter Ford Mustang SVO. it had a cast iron block, head, and forged pistons...some multi-layer steel head gasket too.

somethings you never forget...

thank god for slicks!

pressure is a small part of the equation. Having more boost does not always mean more power (most likely less).
I make a **** ton more power now with 19psi on this engine than I ever did at 35psi on the old one. To take advantage of more air coming in you need to address quite a few things first, otherwise it is just pressure for the sake of pressure.

This has all been documented through my 1/4 mile trap speeds over the years.

I've hit 2 bar a few times by accident. Usually running E85. I like 2 bar, is very fast!!

How much stress can the rods and pistons take? I'm guessing more than the head gasket.

I just did a dyno session today with the 951. I've run 1.5 bar with E85 for a number of years and thankfully the car has been absolutely reliable.

Here's a couple of videos showing comparison runs using different timing values and just a regular run.

951 Timing Comparison
951 Dyno Run

Very impressive, Vic! I still tell people about my ride in your car. Fantastic. What a beast!

Vic has an engine management system that just completely impressed me.

Jeff