Oil Inspection / Compression Results FRESH ENGINE

[NHerron]

Hey guys after a long 6 month build, I finally got her done and broken in, for the most part. (300 miles) Had very minimal leaks / problems, I was surprised I used motoman method after I set the engine up (base timing, BISS, burping coolant, checking for leaks)

I decided I would share pictures of the oil filter I tore into for close inspection, between the pleats. I also performed a compression test.

First, oil filter. I used Napa brand, part number 21381. Overall, nothing really concerned me, although I found a bunch of red particles not sure what that's from. Best I could figure is the valve cover possibly chipping.

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Good there? Okay now ponder my compression test results

The engine is fairly built.
Evo16G NEW
2.3L with forged 8.8:1 CR Wiseco pistons.
Ring end gaps were filed to .020" on top & .025" on bottom.
Piston to cylinder clearance is .0035" verifed by measuring.
Block & head were both decked, retorqued head studs after 100 miles
FP2X cams with Skunk2 adjustable gears
I degreed them to the best of my knowledge. Nothing crazy, just straight up.
Brand new Ferrea Valves, seats cut & lapped

Before I did my testing, I got the engine up to operating temperature. Pulled all the spark plugs and the 30A 'moteur' fuse in the engine bay. Held throttle WOT and cranked about 6 seconds each. Also had a trickle charger on the battery.

I got 140PSI, yes 140 +/- 2 PSI across all cylinders. What's up with that?? It's only about 200 miles on it, stock boost, no overheating, correct AFR's, 19inHG vacuum @ idle. Pulls very hard without dipstick flying out.

Here's a link from the website for the FP2X's, in case overlap is to blame (scroll to bottom)
Forced Performance Turbochargers: FP DSM Exhaust Cams


I'm at a loss here guys, any ideas?

 

[1983gsp]

Do a leak down test. Its way more accurate than a simple compression test. If i had to guess, id blame valve overlap.

 

[nickk90]

2.3l will almost make the spec. change from the stock 170psi aswell as the cams.

 

[Aproductions]

So breaking a motor in with aftermarket cams will make the compression lower than using stock cams and then switching?

 

[nickk90]

So breaking a motor in with aftermarket cams will make the compression lower than using stock cams and then switching?

A lager cam will lower compression test numbers on any engine. It dosnt mean their is a problem it is just from the overlap of the cam. A leak down test will tell you if theirs any problems.

 

[crimsondragon]

Did you paint the underside of the valve cover or something?

 

[NHerron]

Sorry guys my email didn't let me know of any responses

1983gsp: I plan on it. I meant to order one a while ago, just never made the decision what brand since I saw alot of generic leak down testers on eBay. I'm going to Napa tomorrow to see if they can lend me one. Or my machinist, he's a pretty cool guy

nickk90: I'm not fluent in strokers vs stock yet (getting there) but I thought compression would be higher than stock (assuming same CR) because it can displace more air then a 2L?

crimsondragon: Well the car came with a red valve cover. I think some 4G's came stock in red color? Not sure. It very well might have been powder coated however. Today, I took a razor to where the oil cap meets the valve cover because most VC I seen are bare aluminum there. It likes to leak oil there too

 

[nickk90]

I'm not fluent in strokers vs stock yet (getting there) but I thought compression would be higher than stock (assuming same CR) because it can displace more air

Sorry you are right on that . I was thinking the other way around for some reason when I made that response. I still would say its low because of the cams though.

 

[NHerron]

Sorry you are right on that . I was thinking the other way around for some reason when I made that response. I still would say its low because of the cams though.

No biggie, I know what you mean

Did you see the FP cams overlap vs stock overlap, in the link? I really don't know what else it could be. I mean, everything else checks out at least

 

[bryanwheat]

nickk90: I'm not fluent in strokers vs stock yet (getting there) but I thought compression would be higher than stock (assuming same CR) because it can displace more air then a 2L?

This is not the case at all. Just because there is a higher volume of air being pulled into the cylinders doesn't make the cylinder pressure higher. If that were the case than a big block v8 would have 500 psi. It's all about the volume of air taken in compared to the volume that it is compressed to.

 

[Calan]

This is not the case at all. Just because there is a higher volume of air being pulled into the cylinders doesn't make the cylinder pressure higher. If that were the case than a big block v8 would have 500 psi. It's all about the volume of air taken in compared to the volume that it is compressed to.

This ^.

OP - Are you running adjustable cam gears, and if so did you degree the cams?

How much was shaved from the head and block, and what thickness head gasket did you use?

 

[NHerron]

CALAN! I just read your compression / leak down guide and saw you had 187psi on your stroker. Good thing you dropped by!

Yes I am running Skunk2 cam gears and it took me about a month to learn how to degree. They are straight up for now (to match cam card specs), only had to adjust +/- 1 degree each cam. Brand new timing components all around

I just went looking through my notes. I couldn't find the measurement I got for the head thickness, but I remember it being a little out of spec (too thin) so that told me it was cut at least a few times. Just for good measure, I clayed the piston tops to see my valve to piston clearance. Got at least 1/4". I used Bogus's guide on head thickness.

The block was pulled from a stock car, never been rebuilt before but I had the machine shop cut the deck just for a new smooth surface anyway. (They neglected to remember how much, I was not impressed among the other things they pulled with me)

I don't know the thickness on the HG. It's an ITM HG. I can check it tomorrow because a piece sticks out near the thermostat housing that my caliper could easily reach

This is not the case at all. Just because there is a higher volume of air being pulled into the cylinders doesn't make the cylinder pressure higher. If that were the case than a big block v8 would have 500 psi. It's all about the volume of air taken in compared to the volume that it is compressed to.

I'm going to educate myself a little more tomorrow but for now, I think I know what your saying. CR in itself is the final say in compression ratio? With 8.8:1 pistons in a 88mm stroke engine, they have stroke in mind so they would adjust for a 8.8:1 compression, correct?

 

[Aproductions]

Thanks so just for clarification, if I break my car in on stock cams and then switch to the aftermarket cams it will be faster than if I just kept the aftermarket ones in? I don't really wanna switch them out since the motor is together now.

 

[Calan]

CALAN! I just read your compression / leak down guide and saw you had 187psi on your stroker.

After some head work and different ACG settings (and 30k miles), it's closer to 155-160 now. As mentioned, valve overlap has a lot to do with it.

Thanks so just for clarification, if I break my car in on stock cams and then switch to the aftermarket cams it will be faster than if I just kept the aftermarket ones in? I don't really wanna switch them out since the motor is together now.

You don't need to swap cams to break the motor in. Just break it in properly (lot's of engine decel), and run what ya brung.

 

[NHerron]

Alrighty, got the leakdown test accomplished...

I went to Harbor Freight and bought one of their leakdown testers. Came home, screwed around with getting it to work, figured out the directions were incorrect, leakage gauge was crap right out of the box, and so was the flexible hose (leaked at both swivel points).

After reading reviews (and maybe using a little common sense) I got it dialed in correctly. Just so happened I had a spare gauge around so I used that in place of the crap HB leakage gauge.

After each piston was at TDC, set my leakage gauge to 50 psi, plugged it into the cylinder and gauge went down to 47psi, each cylinder. So that would be 6% leakage. Does that sound okay? My rings were set .020" on top and .025" on bottom.

This is a picture of how I had to modify the tester. I just ignored the first gauge and set the leakage gauge (the one replaced) to 50psi, then plugged into cylinder and it dropped to 47psi.

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[1983gsp]

On a fresh rebuild, 6% doesn't seem like a bad number. Pull the dipstick and oil cap to listen for leaks while doing the test. Also pull the throttle body elbow and open up the throttle to listen for intake valve leakage. Listen to the exhaust pipe for exhaust valve leakage. If you hear leakage at the dipstick or oil cap its leakage by the rings. If its the rings, put another 3-500 on the engine and retest. Also, do the test at 100psi. It will be easier to detect leaks and whatever the drop across the gauge is will be your leak down %. Good luck.

 

[NHerron]

Thanks there Robert

Funny thing is, when I did 50 psi and saw it drop to 47, I was enthused! 3% leakage? But that's when I remembered why I went to school and did the math, 6%. Yeah, I haven't done a leakage test before

I heard air coming from oil cap so that's why I guessed it was due to my ring gaps. I think I should have set them a little less

 

[1983gsp]

Bore x (wiseco factor)

Stock bore on a 4g63 is 85mm or 3.346

To convert from mm to inches 85mm x .03937 = 3.346

3.346 bore + .020 over bore = 3.366

Wiseco recomends "street-moderate turbo" top ring factor .0050 2nd ring factor .0055

so 3.366 x .0050 = .01683 or .017 for top ring 3.366 x .0055 = .018513 or .019 for the 2nd ring

For 30psi of boost these are too tight..

Now Wiseco "Blown Race only" Top .0065 2nd .0070

3.366 bore x .0065 = .021879 or .022 3.366 bore x .0070 = .023562 or .024

The common gap I have seen used on tuners is the .020 top and .024 2nd ring

Depending on how well you can tune, should help you decide on the ring gap.

If you are a good tuner then you can run a little tighter If you are new to tuning, then run a tad looser.(copy pasta)

 

[NHerron]

I believe that's why I choose a little wider, come to think of it. I've never tuned before (no one here does either) so I gave myself a little error room to compensate in case I screw up. Next year I'm going to try and max out the 16G with meth injection so that should help keep temps down

I also just read a little more on ring end gap / leakdown results, and it seems there isn't much power to be had by running tighter gaps. Since my readings are consistent with eachother there really isn't much else to blame except gaps. The valves are brand new / fresh cut seats, HG obviously sealing well so unless I'm missing something, the primary source of leakage seems to be gaps / ring seal, correct me if I'm wrong though

I'll buy a better leakage tester and test again in a couple months probably