Hey first off I did search, I am wanting to know what I should expect as far as how high a compression test should be on a jdm ITR swap. I am going to buy one tomorrow and want to make sure its not a hurt motor. Also if it makes a difference the test will be done at a higher altitude about 5300 feet if that would make a difference. I would appreciate some help I am not a noob and I did search to find answers ranging between 200 and 250 which seemed a little to wide of range.

 

the number itself isn't what's really important. You'll probably get between 130-160 psi per cylinder. What's important is that there isn't a big dropoff from one cylinder to the next. If there's a difference of more than 10-15 psi on one cylinder, it could be a sign of a head gasket leak or a scored cylinder.

 

The 200-250 range you got from the search sounds right. But as mentioned, the most important thing is the consistency across all the cylinders.

 

OK thanks for the quick response. The guy is a pretty reputable seller on the forum so I would figure it to be cool, but you know how things can go especially when the internet is involved! LOL

 

yeah i have also noticed a difference between different gauges. so i always use the same gauge and compare the numbers to that.

but. like they said, more concerned that the numbers are close. be sure to hold the throttle wide open. ecu/distributor unplugged. and crank them all the same. and probably should have the motor be warm.

my JDM 97R swap was about 240psi across. at probably a couple 100ft above sea level. i can give numbers from other motors too if that may help, if you have used that gauge on other motors?

 

If you are looking to buy a used motor from a running car, you should really get a leak-down.

ITR motor can have great compression but burn oil like crazy. Leak-down will give you a better idea of the condition.

As other have said, # isn't what matters -it's consistency.

As for leakdown, it should be less than 5% on a healthy, warm motor

 

yeah this is a swap its not in a car. I know to hold the throttle open, I just wanted a better idea on what the comp should have been, Sounds like as long as there all close together it should be cool. I am most worried about the condition of the trans.

 

Well it tested an even 190-195 all the way across! So I bought it I hope the trans isn't crap... He said it is a 2000, I am gonna figure out how to read the head castings and double check.

 

Hey if someone could answer a quick question for me, I was splitting the trans and block apart to check the clutch and I noticed that the block said p72, are they the same casting or did I get screwed???!!!

 

yep, B18C1 B18C5 B18C and B16B all use a "P72" casting...

 

you don't need to hold the throttle open if the motor isn't in a car. the purpose of that is to put the ecu (or carburetor) in clear flood mode. The ecu wont deliver fuel when cranking at wot. And i guess you'll be cranking it by hand to do that compression test...kinda time consuming. If you have access to shop air and a leak down gauge, it would be much easier and a better indication of the condition of the engine to do a leak down test

 

Thanks for the good news on the block casting!! For the compression test we took a spare bat clipped a ground to the starter, clipped the positive the the positive post on the starter with a piece of wire and touch the wire to the solenoid to crank it over, So not to time consuming at all.