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(Not*) Mediocre 242

I'm getting closer in the tune. This is what it was doing at the start of the night. The green line is MAP and the white line is boost solenoid duty cycle. It's oscillating all over the place, giving me a very inconsistent boost level.

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I changed a few things and got this:

Ogshw8ph.png


It's much better and much more consistent. Response isn't insane, but I'm seeing a couple psi below 3k rpm which is pretty good. I haven't really tuned for quick spool yet either, just trying to maintain a smooth target boost level. I probably will increase the hose diameter from the turbo to the boost solenoid to try and improve wastegate response.
 
I did some tuning last night on e85 and upped the boost to 26 psi. Everything felt pretty good, but when I got home, I noticed I had some oil seeping out of my air filter. When I took the filter off, I noticed probably an ounce of oil pooled in my intake pipe right near where my catch can outlet is.

I'm using a yoshifab catch can with 3 stainless steel scrubbing pads for baffling. It's set up to drain back to the block and takes inputs from the oil fill cap and the crank case breather. The outlet is plumbed back to the pre turbo intake. Anyone have any ideas how to reduce the amount of oil going through my ventilation system? Should I just vent the catch can to atmosphere? I really don't like that much oil going through my engine.
 
I had the same problem, to the point I thought I'd blown my turbo. I ended up putting a small piece of Scotchbrite in the Yoshi old cap to baffle it. At the same time, I also added a small vacuum line to the manifold like stock, though I know that only helps at idle.

Anyway, after doing that stuff, I don't have oil pooling in the intake anymore. Have you done a leakdown test?
 
I haven't done a leakdown test, but maybe I'll have to.

Your idea sounds great though. I think the pressure is so low in there that it just sucks oil from the sump straight through the can.

So how did you convert from a -10 to a small vacuum line? You also hooked it up to the manifold so it sees positive pressure?
 
t8fanning said:
I haven't done a leakdown test, but maybe I'll have to.

Your idea sounds great though. I think the pressure is so low in there that it just sucks oil from the sump straight through the can.

So how did you convert from a -10 to a small vacuum line? You also hooked it up to the manifold so it sees positive pressure?
Click to expand...

I still have the stock breather box, so I put a tee with a 5/16 line (with a check valve) to the manifold right near the box. The other side of the tee is the -10 rubber hose that goes over to the catch can.
 
I see. Glad to hear that works. I think I'm going to vent the can to atmosphere until I can figure out a more permanent solution. Maybe I'll have to do a restrictor in the tube to the intake.
 
Not really what I wanted to see, but I put a filter on the catch can outlet to see what would happen, and it still pushes a significant amount of oil through the whole can. It's gotta be too much blowby or something. Probably should do a leakdown. I really hope I don't need new rings.

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Some more discouraging news. I did a compression test. It was with the throttle open on a cold engine, so the numbers might be higher when the pistons heat up.

Cylinder 1:

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Cylinder 2:

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Cylinder 3:

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Cylinder 4:

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And some pictures of two pistons and bores:

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Looks like it was pinging like crazy. All of the bores looked pretty good except for those few vertical scratches. I wonder if I didn't break my engine in very well and the rings aren't seated properly. I'm not really sure what I should do. Should I pull it apart to get a better look at the pistons? Should I hone and get new rings? Maybe new pistons? I'd love any input.
 
been on e85 the whole time? You're thinking this was an existing condition before the turbo?

Seems like popping the head off is going to be on the list.
 
Last edited:
Stiggy Pop said:
been on e85 the whole time? You're thinking this was an existing condition before the turbo?

Seems like popping the head off is going to be on the list.
Click to expand...

I haven't really been on e85 at all until now. I tried before, but the clutch started slipping and the fuel pump was running out of steam.

I definitely think it's a pre turbo upgrade condition. I think I probably didn't break the rings in very well. But I guess we'll see when I pull the head.

I think I'll take a compression measurement after heating up the engine a bit and then pull the head.
 
Pull the head, but just run a fingernail over the vertical scratches. If you can't snag your nail on them, I wouldn't worry about them.

Remember that compression test is dynamic, so static compression ratio plus your cam overlap will make a difference. Those (all though a little low, but could be due to cam, which one?) they are fairly even. I'd expect one failure, not all so even like that. Or numbers all over the board.

I'd do a leak down test to get a better understanding of what's sealing and if something isn't.

Jordan
 
Tate's cam is an RSI 3, so I would expect the dynamic compression to be a little on the low side with 9:1 CR pistons. We'll see what he ends up finding.
 
Stiggy Pop said:
what'd you do for break in?
Click to expand...

Some hard break in procedure I read online. Rev high and then brake hard a bunch of times. I stayed out of boost which I think was a mistake, because it didn't really give much cylinder pressure and load the rings.

GTJordan said:
Pull the head, but just run a fingernail over the vertical scratches. If you can't snag your nail on them, I wouldn't worry about them.

Remember that compression test is dynamic, so static compression ratio plus your cam overlap will make a difference. Those (all though a little low, but could be due to cam, which one?) they are fairly even. I'd expect one failure, not all so even like that. Or numbers all over the board.

I'd do a leak down test to get a better understanding of what's sealing and if something isn't.

Jordan
Click to expand...

A leakdown would be nice, but I don't have shop air and pulling the head is faster, because I'm pretty sure it's rings.

cosbySweater said:
is this the first time you've done a compression test on the engine?
Click to expand...

Yeah. I picked up the engine rebuilt, so I didn't bother.
 
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