Hey guys,

so i finally got to do a compression test today. I have a EG Hatch with a 98
B18b1 non vtec swap, the previous owner said the engine is build with forged internals, I am running 10 PSI of boost.

Ok here are the results:

Cylinder 1: 221 PSI
Cylinder 2: 220 PSI
Cylinder 3: 197 PSI
Cylinder 4: 202 PSI

I cranked the engine at least 30 times @ WOT - these are all Dry with the engine warm. So basically I have two sets of cylinders with a similar pressure but what exactly does that mean to the health of the overall engine? Is this normal?

Also here are some pics of my spark plugs can someone tell me if my engine is ok? or am I running rich/lean or what?? Thanks! Guys!

 

your compression seem kind of high for a b18b1 turbo especially on 10 psi.Correct me if I'm wrong but isn't stock b18b1 compression suppose to sit around 180-190psi?What kind of piston are you running?

 

I am pretty sure the previous owner rebuild this engine with aftermarket pistons I just do not know the specs. The engine is running pretty strong as far as I can tell, doesnt burn much oil, doesn't smoke or anything - running just a tad rich on idle but other than that no problems. I thought the compression ratio is supposed to be lower than stock for a turbo application? Or am I getting the compression ratio and compression pressures mixed up? Anyways what could cause a high compression pressure?

 

if the previous owner built it right he should of used low compression pistons for a turbo setup and yes your numbers seem high for a boosted motor and piston 3&4 seem kinda off

 

I wonder if those numbers are that high due to me cranking it alot (30 times) I read somewhere that you have to basically crank it until the compression tester needle doesnt go up anymore and it took me about 25-30 starter cranks to get to a point. Any thoughts? Did I do it too much?

 

i usually just do it till the needle stops but i try to be consistant with every cylinder. i just count to 10 everytime i do it. works good for me all the time

 

^^^ that's what I do and I always get really consistent and repeatable ###s

Since the numbers don't make a lot of sense, you could just take a fresh start and try again. If the pattern is repeatable then you really know something's going on. NM if you've already tried that.

 

all pistons should be within 20% from each other. if not then something is up

 

Yeah actually i did and the first time I did with the throttle closed (cuz i forgot I had to floor it when testing) I got almost the same numbers but a little lower but the pattern was still there cylinder 3+4 were still a little lower than 1+2. So I am basically confused. Is my 3rd cylinder going bad or what?

 

it could be but how does the motor run?

 

Maybe this is stupid but I'm gonna throw it out there anyways b/c the worst that can happen is that I'll get publicly humiliated:

Could there be a break in the gasket between 3 & 4 that's causing them to be connected? That way every time you compress one cylinder it's leaking a little into the other cylinder, and it's leaking about the same amt each way so the compressions are similar.

 

Well if that would be true I'd be burning radiator fluid and thats not happening since my coolant level hasnt moved for a few months now. Oh and the engine seems to run fine like I mentioned before. It runs pretty strong right past EVO's and STI's at only 10 PSI.