"PSI" level is not directly relative to cylinder pressures??!!!!!!!!!!

[Marceldsm]

"PSI" level is not directly relative to cylinder pressures??!!!!!!!!!!

i saw a stock 7 bolt run 32 psi on stock everyting .....made 417 fwhp


the question is ..........is that engine still alive or not
apparently they did a compression test after
the engine is OK


I WHAT MORE INFO ON CYLINDER PRESSURE AND BOOST


TANKS IN ADVACE

I REALY WHANNA UNDERSTAND THE TECHNICAL PART

stock 7-bolt block and head (even stock cams). I'm also still on the stock intake manifold and throttle body
* Acceleration from 3100 to 7100
* Absolute barometric pressure: 28.90 in. Hg.
* Vapor pressure: 0.4 in. Hg.
* Elevation: 997 ft. above sea level
* T3 50-trim @ 27.6 psi (spikes briefly at around 32 psi)
* peak timing advance: 21.4 degrees
* Injector duty cycle: 69.0% (850cc)
* Air-to-fuel ratio: 12.3:1 (on 110 octane Sunoco)
* Airflow: 47.5 lbs/min
* Peak power: 403.4 WHP
* Peak torque: 356.9 ft/lbs

 

[1995gsx20g]

your the one who wrote this.. thank you. ive read it a couple times already.

My best effort to describe this concept was in the BOOST IS GOOD section of http://www.kidzuku.com/StrokeOrNot.pdf.

this thread should be a sticky.

 

[Marceldsm]

Those stats sure do look familiar. You pulled those off of my youtube video, I take it?

Yes, that same engine lived until the following summer when I overboosted 40+ psi by accident, and then I finally bent all 4 rods. I rebuilt it after that, but I'm still rocking the same block, crank, and head. These engines can handle some crazy cylinder pressures, and will hold together fine as long as your tune is in check.


'PSI' is only relative to the turbocharger itself. The engine only cares about air mass, which is not measured in 'PSI'.

Think about this; Assume you have a T25 running at 25 psi, and a GT42r running at 20 psi. Even though the T25 is running more boost, the 42r is flowing more overall air and will allow for more cylinder pressure due to it's larger compressor wheel. This is why comparing PSI numbers between turbos is useless. It would be more appropiate to compare mass flow numbers, as that is what the engine cares about.

yes ........and still i dont belive it

 

[Lofty]

This was a good read. Thanks Knoch/99gst

 

[toofast82]

Corky Bell's "Maximum Boost" chapter 1 talks all about how forced induction engines can withstand all the power when properly set up.
Also, browsing through turboforums.com, you'd be amazed how much power some budget/stock v8s have made and lasted for thousands of miles

 

[knochgoon24]

...My best effort to describe this concept was in the BOOST IS GOOD section of http://www.kidzuku.com/StrokeOrNot.pdf.

your the one who wrote this.. thank you. ive read it a couple times already.
http://www.kidzuku.com/StrokeOrNot.pdf
this thread should be a sticky.

I don't know how many times I've read through that. I actually printed it out and used it as a reference for my SAE High Mileage Car team when they were trying to figure out connecting rod lengths for our custom motor.