Compression results on rebuild @ 234miles

[Bullet3]

Just want to get some opinions. I know it's early, but im a worry wort.

1:155
2:165
3:165
4:165

Wiseco 9:1's. Its an evo 3, so I dunno how different it is from NA 2g's. The reason i did it so early is that I am burning oil. I put in about a quart in roughly 125miles. No other leaks.

edit: also, im using Motoman's break in. The only thing is when i first got it running it idled for about 20 mins as i bled the cooling system.

edit again: this is my build thread if you want to see anything else. http://www.dsmtuners.com/forums/newbie-forum/382211-my-canadian-evo-iii-build.html

Im also running very rich. low 10's at WOT. But my exhaust doesnt look black like it should be.

Also, it was done with a hot engine, but not WOT. Didn't know I had to.

 

[gusu]

I'm not sure, but from what I've read lower compression on stronger pistons equals lower compression test numbers.

I'd at least google it.

 

[Boostjunki84]

That 20 minutes at idle is not going to hurt and those compression numbers look good and should improve a little over the next few hundred miles. That leaves the oil leak. Are there any leaks coming from the engine that are visible? It the car smoking on start up, idle, or while driving? How's your oil pressure?

 

[Bullet3]

That 20 minutes at idle is not going to hurt and those compression numbers look good and should improve a little over the next few hundred miles. That leaves the oil leak. Are there any leaks coming from the engine that are visible? It the car smoking on start up, idle, or while driving? How's your oil pressure?

The car is being parked in the same place overnight since start up and shows no visible leaks. No smoke from the engine bay. Oil pressure idles at ~18psi, and goes up as far as ~80psi on WOT.

My wideband tells me I'm running rich, but the black smoke that should be billowing at 10.2:1 from the exhaust has yet to be seen. I put about 90km on it last night, gonna check the oil level as it was topped up prior to this.

Oil is down to about 1/8" over halfway on the dipstick. Roughly .4qts burned.

 

[lil corb]

Was the head rebuilt too? Any sign of overheating?

 

[viperlp01]

I would do a leak down test and find out where the compression is leaking but I wouldn't be too worried. What was the ring end gap and PTW clearance?

 

[Bullet3]

Was the head rebuilt too? Any sign of overheating?

yes the head was rebuilt. No signs of over heating.

I would do a leak down test and find out where the compression is leaking but I wouldn't be too worried. What was the ring end gap and PTW clearance?

Will do a leak down this weekend, and I would have to call the shop. It was a fresh bore and hone.

 

[PieEyedPiper]

Wiseco 9:1's. Its an evo 3, so I dunno how different it is from NA 2g's.

I don't understand?

 

[slow8033]

I don't understand?

Stock pistons on a NT 420a 2g have a 9:6:1 ratio, so im assuming the original poster thinks it should yeild similar compression test results. Which on a NT stock motor can be upwards of 190-210.

 

[donniekak]

Not being wot, the test is no good. Do another test at wot. Also, what cams do you have? I run 9:1's and get 180psi, to 150psi, depending on the cams i use.

 

[PieEyedPiper]

Stock pistons on a NT 420a 2g have a 9:6:1 ratio, so im assuming the original poster thinks it should yeild similar compression test results. Which on a NT stock motor can be upwards of 190-210.

Interesting, I'd have not considered comparing compression results between different engine families/manufacturers.

 

[slow8033]

Interesting, I'd have not considered comparing compression results between different engine families.

Yeah, I'm not sure if it translates over to the 4g63 either. I'm sure there are variables. Plus with boring out that will effect it as well.

The other interesting fact is the service manual says that the NT 9:6:1 compression ratio (which is rated at 210 compression from the factory) isn't rated as "out of spec" until it drops below 135.

I wouldn't assume you could compare these 2 engines on any level really. Different beasts.

 

[Bullet3]

Uhh, I don't know where the 420a talk is from. The car is an evo 3. I just wasn't sure if there was a difference in the blocks from the NA(north american) 7bolt blocks. I will do another comp test in a few hundred more km's, at wot. Also, I'm running fp1x in/ex cams.

 

[slow8033]

all the 420a talk is from what you said in the first paragraph of your original post.

"Wiseco 9:1's. Its an evo 3, so I dunno how different it is from NA 2g's. "

^^
Is what you said. A 2g NA eclipse has a 420a engine..with 9:6:1 compression ratio. I figured you were making a comparison. If that is in fact NOT what you ment by that sentence, then I have NO idea why you even brought up 2g NA cars. WTF

AH... U used NA for North american.... Problem is NA is the common term used on here...for Naturally Aspirated.

 

[PieEyedPiper]

The other interesting fact is the service manual says that the NT 9:6:1 compression ratio (which is rated at 210 compression from the factory) isn't rated as "out of spec" until it drops below 135.

Whoa.

AH... U used NA for North american.... Problem is NA is the common term used on here...for Naturally Aspirated.

Doh!

 

[MY1GDSM]

As said above do another Compression test but WOT...
Also again what Cams are you running?

 

[larvaman]

What was the ring gap on the piston install and were the gaps set the right distance apart, oil can leak up past the rings if not set to spec.

 

[donniekak]

What was the ring gap on the piston install and were the gaps set the right distance apart, oil can leak up past the rings if not set to spec.

In all truth, you can run 2x the recommended ring gap, and not have a noticeable decrease in cranking compression. All new engines burn some oil, it sounds like he may have an improper cylinder wall finish for his ring pack with as much as the op is losing.

 

[DSM_love_GST]

im guessing bad build on bottom end

 

[e85_4g63]

it sounds like he may have an improper cylinder wall finish for his ring pack

This is what I was thinking as well.

OP: Did you do that leak down test yet?

 

[jimbob_843]

Could be loosing oil from the turbo.

 

[DSM_love_GST]

I highly doubt its from the turbo. His CT is pointing at the obvious reason

 

[jimbob_843]

Yeah but just because of his compression results not being 100% at less than 500 miles doesnt rule out that a turbo seal could be bad. If everything was rebuilt right there should be no oil loss engine wise ,atleast not this much.

 

[donniekak]

Yeah but just because of his compression results not being 100% at less than 500 miles doesnt rule out that a turbo seal could be bad. If everything was rebuilt right there should be no oil loss engine wise ,atleast not this much.

The fact that smoke isn't pouring out the tailpipe, points towards a slow, constant oil burn. When turbo seals, or valvestem seals are bad, there is usually visible smoke, under specific circumstances. An improper cylinder wall finish allows more oil than needed to remain in the surface of the cylinder wall during combustion, burning a much larger amount of oil than usual, but not enough to make a smoke stack out of the exhaust.

 

[jimbob_843]

Touche'