Piston top designs vary greatly between high compression and 'boosted' lower compression motors, especially an engine that has a large combustion chamber. Think BBC and even worse Hemi.

You are lighting the fire before a piston comes up to tdc, and the closer the piston top comes to the top, these big domes can create some bad issues including, creating partial and then multiple combustion areas, places for fuel to hide, and etc, etc. Dome designs today are far better for making power by addressing these concerns, but will still have flame propagation and combustion issues compared to a flat top or dish.

Oh, one last other issue with N/A especially domes/large domes is during tdc in overlap, it can block the exhaust valve from the intake, cutting down on the time and quality of 'pull' your exhaust can help the intake.

So again, less dome/lack of dome/etc helps alleviate many issues for many different motor designs. However, you need compression for power.

nice pics,,I like how theres nothing coming out of the breathers,,good to see someone can plumb a dry sump oiling system.

Who doesnt? Are you saying no dry sump setups have valve cover breathing ?

nope,they can

Could you give us a complete run down of what you have currently? If I remember correctly you are not running chillers, did you ever record what IAT is on your current setup?

:hijack::offtopic::throw:

Compression test done on port engine today.

#1=150psi #2=155psi
#3=147psi #4=152psi
#5=145psi #6=150psi
#7=155psi #8=152psi

Did leakdown test. Particular leakdown tester showed 15-20% leakage on all cylinders. Not sure on the accuracy of this particular Napa tester. First gauge on leakdown tester, was set/regulated to 100psi. When hooked to cylinder, leakage would show 20%. But gauge would drop from 100, to 90psi. My old leakdown tester had two psi gauges. If you set it to 100psi on first gauge, and second gauge read 90psi, you had 10% leakdown, if second gauge read 80psi, you had 20% leakdown. I may get a new tester, and retest.

However, no leakage at all at the valves. Any leakage was past rings. Looking into cylinders with borescope, crosshatch pattern on cylinder walls, looks like the day they were honed.

PS, Matt, Dan/icdedppl's Intake air temps, are like 150ish WOT full boost if I recall.

I knew you would bite :angry-smiley-038:

Sorry, I won't derail your thread anymore.

Your engine is fine, its your leakdown tester that needs an overhaul! :cartman:

And you better not be playing with my beaker while I am gone.

wow no feedback
 

Nobody`s ever built a 555 or 565 or 572 here I guess , ok. Too bad Bob doesn`t build short blocks I`d have 7 pages of replies... wait wait no I don`t want that either.