Hi all.. Well heres my first question poll..( compression check) Im running 148-155 across the board.. Too me it should be around 180. The car has 19,000 mi on it, and its an 03. I know how to break the motor in, I extended break in to 1500 mi, due to the tight bearing clearences.. I did not use regular oil.. Im going to change my oil to regular oil for 1000 mi in hopes of my rings seating in a little better.. wishful thinking.. I ran my compression check as follows: 1. motor at operating temp, 2. all plugs out, 3. throttle all the way open, open or closed same reading. i reached peak pressure on 4 revolutions, which is good.. but pressure is not high enough.. I would say this is why i have one of the slow evos.. Like many others here.. this is probly the culprete.. I do not burn oil excessively. Just the normal quart every 2500 mi. 1 downfall of synthetic oil, its to thin.. So let me know what you think.. These pressures are a little too low for a car this few of miles..

update.

 

When the idiots at Gillman checked mine, all be it reluctantly, they claimed that mine read #1-165, #2-155, #3-155, #4-165

 

See the thing is my older dsm"s were higher.. Plus a bunch of the bigger tuners say alot off the cars they check are around 180..So what should we be at.. Mitsu wont tell me..

 

mine was at 210 or so. i beat on my motor since day 1. on my tests i pull out all the plugs and have the throttle pressed full open. also done with engine at operating temp. however, i crank the engine over until the gauge stops moving... and i hear that this is not how its usually done.

 

damn thats high..

 

http://www.evolutionmr.net/forum/vie....php?p=936#936

check out my pics and test proceedure. superz commented on how i wasn't doing it correctly, and i have had my coworker say the same thing. i.e., stop at so many cranks.

however, i have done this to test "known" bad engines... and no matter how many times you crank it.... if there's an engine problem, it wont come out even or necessarily high.

 

my build honda engine with 9.5 compression puts out 225. using this same proceedure.

 

there seems to be a trend already of mr's being over 200

 

the actual pressure number isn't what really matters. Its the difference between the numbers. As long as the numbers are within 20% of each other you should be fine. You should only do 5 cranks with the throttle open spark plugs out. My regular lancer put out 180 psi across all cylindars and i think the manual called for like 200 or something but mine was fine since they were all close together. My turbo van only calls for 100psi with 25% variance and its 8:1 compression and has 140 across all the cylindars.

You can also squirt some oil in the cylindars to do a wet compression test. If the psi raises a lot then your rings might worn and leaking.

 

the actual pressure will matter some.. 145 psi, compared to 180-200, will make a diff. in horsepower ratings.. Im going to do a wet test after i run regular oil in it first.. Last step a leak down test.. If that fails mitsu will be rebuiling my bottom end.. Id rather the money ill do it my self.. but it will never happen

 

There is also some variation between compression gauges, so long as your numbers are consistent you should be okay.

Robert

 

we did my friends 03 evo (Az3ar) and his came out to be 179 180 180 180

but we were not at normal operating temp, we let it sit for about half an hour


I have not done my MR yet, but I will do it probally this weekend, been to busy installing stuff gettting ready for the vishnu dyno day in GA

 

When I did a test about 9 months ago, I came out between 169-173 across the board.

Shane

 

i put down 195 across the board on mine. I got about 1,100 miles on the engine. Its got a .020 overbore and wiseco 9:1 compression pistons.

 

bump