I just did compression test on my built engine its running JE 9:1

I got 175-180psi across , is that acceptable for 9:1 CR ??

Thanks boys

 

per the evans tuning checklist:
8:1-8.5:1 compression: 150-170 psi per cylinder
8.5:1~9.5:1 compression: 170-210 psi per cylinder
9.5:1~11:1 compression: 210-275 psi per cylinder
11:1+ compression: 250+ per cylinder (highly depends on cams being used)

 

WOW MINE IS Low


175

 

for 9:1? No its not.....

 

I'm running 9:1 CPs. My compression was 175-180 so I'd say everything looks good. It's more about the 4 cyls being consistant then the actual number. I've seen different gauges give 5-15psi differences on the same motor.

 

x2

 

stock b16a

 

dang, mine is 138, 130, 135, 150 on my gsr with mahle 9.1

 

No bueno.

 

I have a 81mm gsr engine at my shop with eagle H beams and JE 9:1's. I've checked the compression several times since break in and its always yielded around 180psi each cylinder.

 

according to the evans chart an jdm itr would have 275psi and a b20z would have around 220 psi which both are of by almost 30-50 psi, how trust worthy is this?

 

So your saying you have more experience in Honda compression testing than Evans? Its a chart to go by its not set in stone, use it as a general guideline.

I pull 190 with my 8.8:1 motor, so I trust it.....

 

ehh every compression tester is going to be a little different. Those numbers do seem rather high but it might be according to his tester.

I've just got an actron unit and i usually show:

170 ish for 8.5:1
180 ish for 9:1
210 ish for 9.8:1

probably used this tester on about 30-35 different engines, mostly hondas. The numbers i posted are general. As stated earlier in this thread, you wanna have consistant numbers accross the cylinders, they don't have to match someone elses. Now obviously if thye are extreamly low, theres probably a probablem!

Leak down is one heck of a more valuable test tho, that can backup your compression resultz to give you something a little more precise.

Photo of tester i use:

 

And how do you use a chart off by 50 psi as a guideline when being off by 20 psi is considered time to look into whats wrong? yes Iam saying that this chart is garbage! its almost impossible to get the perfect answer to an engines psi with your compression ratio, there are wayyyy too many things to consider that vary that number! what good is a chart thats off by %20 ? you want exact answers when it comes to psi, anything else= useless info! I highly doubt that chart came from evans or atleast from someone experienced at evans, they should have atleast said this chart apply's to a completely stock b18c1,using an xxxxx gauge! get me? look even in this very thread right here there are sooo many confused and thinking is my motor ok just because of it!

 

my stock internal b20vtec gave out 160psi on all 4 cylinder.

 

lets see than according to this chart you have a 8.3 comp engine, did we guess right? LOL!

 

Keep in mind a b16 head will yield a different CR than a GSR head. Also, milled heads and decked blocks also play a role in determining the CR.

 

my f22b1 put out 160 on all cylinders is that good for 8.8:1????

 

Ive got this same tester and I got 185 across all four with a 8.5 motor

 

more important that each cylinder is within 15-20psi of each other

 

exactly its more important to have numbers close to one another or within 5-20 psi difference of each other, the psi number you read can differ off soo many things like, the tester itself,temp of the oil,oil viscosity,type of valves used, etc. plus you can not use the same chart once your motor has internal work to it, the b20z chart is useless for a b20vtec as is a gsr chart for a poormans type r!