Cylinder compresion test. Expert Help!!

[locote]

i got 200psi at all 4 cylinders its a stock B18B.
Thats the norm for a 160 000 k motor????

[LowEk]

as long as they are all round the same not much diffrence its all good.

[newmski]

200psi is quite normal but as mentioned variation (5% or more) between cylinders is not good.

[dsp26]

^^^as above

however, if you have a lower CR in 2 adjacent cylinders its most likely a a blown HG.

but it sounds like you got perfect 200 an all 4. thats awesome for a 160k motor. at least it shows you take care of your ride.

[Slow96GSR]

200 all across is great. Up at this sea level we get 160-170's. As long as they are almost all the same then you are good. Now do a leak down test and see what you come up with there.

[ECU-MAN]

yeah dude as above

for an engine that age, your doing really well.

[SiR JDM]

Ive never had one of these done. How much roughly would it cost? How much extra is a leak down test?

[locote]

I had a mate do it.
What is a leak down test???
ill be turboing the motor in a month thats why i tested it.

[dsp26]

Ive never had one of these done. How much roughly would it cost?

goto supercheap and pay $20 for a cylinder compression tester. get one that has the extended hose with multi size screw end.

-disconnect lead that goes from dizzy to coil (either ground it or make sure its not near anything as it will spark)
-take plug out one at a time.
-screw tester in properly
-hold throttle at WOT and crank a few times
- take the reading down and repeat on the other cylinders

200 all across is great. Up at this sea level we get 160-170's

for the B18B stated above?? man i didn't realise altitude played THAt much of a diff???

[yourfather]

well, I have between 170 and 180 psi and my motor has done 170k

So doing good dude!

[CUL8R]

lol i wanted to get one of these done, but im super scared if something was wrong itll cost me a couple k for a rebuild lol! i think ill have this test done in about 2k time.

[Slow96GSR]

... for the B18B stated above?? man i didn't realise altitude played THAt much of a diff???

At this alt we lose 30% of our power. That's why we do F.I. and very little N/A/ tuning. You can't get much on a N/A motor here. For every 100 feet you lose something like 1-2 hp and at 5000 feet, that's a butt load. I'll have to check. I don't really remember exact numbers, everyone here know so I don't have to explain it much!!

The less air you have due to pressure, a.k.a. thinner air, the lower the actual compression is. Also the thinner oxygen doesn't burn as much/hot/fully/whatever you want to say, and so we run F.I. to get it up. At this alt don't even have to lower the comp ratio of the pistons to run boost unless you want to go really high. I have to have many maps for my ecu, one at each alt. It's not that bad since it takes like 30 seconds to load a new one. It's what you have to do to run a car nationally. There are a few people here with n/a cars but they don't get too high until they spend a lot of money, 10k-15k+ USD, some times less but not to often!



On the main topic, a cylinder leak down test puts compressed air in to the cylinder at TDC and checks the valves, head gasket, and rings for leaks. It measures based on a percentage. You hook it up just like a compression tester but you add the air compressor line to it. Read this! Should help you all!