So i decided to do a compression test on the r, which i should of done a long time ago. Results were 120 all across. Weird part is that she put out 163whp on the dyno, which from what ive read are normal c5 numbers with basic I/H/E, granted the car does feel a bit slower since then. Does this mean low comp pistons?? Because i know for sure that the car was boosted before. Should i be concered? Any input highly appreciated

 

was the motor cold?
did you hold the tb open?
was the gauge accurate?

how much oil do you burn?

120 even cold is starting to get down there though. if you're burning a qt every 500 miles a rebuild is in your future

i had a gsr engine get to 140 all across warm, lasted about 3-4 months after that reading before an exhaust valve fragged

 

negative, motor was warm. burns quite a bit of oil, i would say about a quart every 7-800 miles, although i do have a heavy foot at times. tb was not open. oil consumption is a sign of bad piston rings, correct?

 

Those number are extremely low for a c5. When I did my test, my numbers were 190 cold and 210 warm across the broad. Does your motor smoke, burn oil, anything that makes you lack power? Even if the motor was boosted b4, you have to really be sure that there's been internal work done in the past. The best way to find out is a leak down test to determine proper internal failure. As fas as dyno #. Im sure c5 are getting more better numbers then that with bolt on and a proper tune. Yes, most of the time it is your ring that make you burn oil or your valve seal in your head. Let us know what's up and GL

 

Mine tested at 220psi hot w/ TB open and my LS1 was at 190psi after 90k miles, so yes, your numbers are low even when considering testing method and tool discrepancies.

I'm afraid that it's bad news from here on out. Your problem is likely located in worn rings, valve damage, or the headgasket. The generale rule of thumb is that if your compression is low AND constant across multiple cylinders, the headgasket is to blame. The side-effect is that you're also losing water and/or mixing it with oil, so it makes it pretty obvious. This is a very easy fix in comparison to the following...

However, when you said that you're burning a lot of oil (5qt/3500mi is a lot), one begins to immediately suspect worn piston rings or ring lands. This is bad news because the fix effectively involves a full cylinder block rebuild.

My advice to you, and I'm sure many people with echo this, is to perform a leak-down test in order to narrow down the loss of compression. The idea is that you fill up the combustion chamber with compressed air and listen/look for where it's escaping... hissing at the intake or exhaust suggests the respective valves, bubbling in the radiator suggests headgasket, and hissing at the oil cap or dipstick tube suggest piston rings (usually).

Take a look at this video:

http://www.youtube.com/watch?v=ofSiTGeLXvc

 

I bolded your problem. Redo the test at WOT.

Oil consumption can be bad rings or bad valve seals.

 

dogg is right, drive the car, shut it down, unhook the distributor and redo the test with the TB open. it's going to pop the number up some, get back to us with how much if you would like.

oddly enough how much oil you burn really seems to have a direct link to the health of the engine with these. a quart every 700-800 is starting to get up there. you might get another 20k miles from the motor before one of your oil coated exhaust valves frags

 

If you're going to redo it, it's worth suggesting to disconnect the fuel system via fuel pump fuse or at the injectors.

Also, are you turning it over several times for each cylinder? The suggested number of compression strokes will vary but I'd do it until it basically stabilizes near the peak (5-10 jumps of the needle).

 

i posted numbers on ti.net and other r owners said that those are about right. It wasnt tuned, just simply put it on the dyno to see what im putting out. Burns oil when vtecin, just like most honda's.

 

ill try to do another test tonight, and post up the numbers

 

not so much

a quart every 1500 is common. twice that is getting worn

there are smart people on ti but suggesting 120psi is normal isn't right. a lot of higher mileage b18c's are reading 160-180psi which is still a lot more than 120

 

you miss understood. Not the compression results, i posted the dyno sheet which was like at 163whp i believe, and people told me those are pretty normal numbers. Been a busy week, R has been in the garage, havent even drove it. will try to redo a comp. test this weekend

 

Did you use an OHC extension adapter? If so, remove it and run the compression tester straight to the head. An extension adapter won't allow the pressure to go across the check valve because the air in it will compress. The adapter looks like this:

 

as previously stated.. redo test with t-body fully open but also do a wet compression test. if numbers go up to around normal then most likely rings.