compression test figures
- Thread starter nsxhk
- Start date
Henry I think those are good numbers. I'm sure Larry B, or one of our other great techs on here, will be able to give a better reply. In the mean time you can do a search since I posted my compression numbers on here last year. That and others might have also, so at least you would have something to compare yours against until one of the real experts opines.
nsxhk said:
What year is your car? According to the online service manual here on Prime at 200 RPM and WOT the nominal value is 199psi, the minimum is 142psi and the maximum variation should be 28psi.
Yeah, I agree, any of those numbers may be OK if the spread was not so great. And was it done when the motor was up to operating temp? It needs to be.. If you had any range of those numbers, but they were all within about 5-10 of each other, it'd be good.
- engine on cradle and out of the car
- cold engine
- just finished reassebling the engine minus the valve covers with sos stage 3 internal mods (cams, valve springs/retainers, lma, bigbore tb)
- connect battery to starter and crank for maybe 10 rev each cylinder
- each cylinder started out at 180psi and at the end of around 10 rev, they each ended up at around 210psi.
My tech said it's all good but I just want a second opinion before the engine goes back on to the car, that's all.
Thnx in advance.
Henry.
- cold engine
- just finished reassebling the engine minus the valve covers with sos stage 3 internal mods (cams, valve springs/retainers, lma, bigbore tb)
- connect battery to starter and crank for maybe 10 rev each cylinder
- each cylinder started out at 180psi and at the end of around 10 rev, they each ended up at around 210psi.
My tech said it's all good but I just want a second opinion before the engine goes back on to the car, that's all.
Thnx in advance.
Henry.
Since the NSX is a V type engine with two banks; I believe the variation between cylinders is best evaluated by comparing the numbers obtained from the front bank and the numbers obtained from the rear bank. If the front bank are all 200-210 and the rear all 180-190 then you should be fine esp if your heads were milled.
I think the numbers are fine. Also this is a COLD engine. Typically you should do a compression test on a warm engine
.
Also as Hugh mentions, WOT is key. You cannot compress air that you do not have
.
HTH,
LarryB
.Also as Hugh mentions, WOT is key. You cannot compress air that you do not have
.HTH,
LarryB
nsxhk said:
Ah ok, we were all under the assumption that this was the range of numbers between different cylinders. You're saying they all started out near 180 and then they all ended up near 210.
Do you have the exact numbers as they correspond to each individual cylinder?
Larry Bastanza said:I think the numbers are fine. Also this is a COLD engine. Typically you should do a compression test on a warm engine
Also as Hugh mentions, WOT is key. You cannot compress air that you do not have
HTH,
LarryB
I will definitely try a lot of WOT and report back
Thnx.
Henry.
nsxhk said:Sorry, don't have that data. My tech was doing the test without the valve covers so oil was spilling everywhere every time he start the engine. I can imgaine the mess
Henry.
:biggrin: I don't know why, but that just cracked me up LOL (just shaking my head...)
