I was expecting a little more - Compression on new engine

90redgst · Dec 17, 2007

I think you'll be fine. My numbers went up drastically after my first scare. Just keep breaking in the motor as you are doing and it'll turn out to be okay.

DSMscreamer · Dec 17, 2007

I've always gotten my best compression results on a fresh motor by hitting it with a couple pulls @25psi in third to 7500rpm, then heavy vacuum back down to idle. This is done immediately after initial warm up followed by an oil change. With 8.5:1 pistons this giave me 195psi across the board after 200 miles.

The_EE · Dec 18, 2007

Well, I was having a little issue with my turbo boosting to 25-30psi. Somehow the MBC was getting stuck so I took it apart and cleaned it and relocated where it was tapped to. I did a pull today and via DSMlink this is what it showed. I could not do a full pull due to traffic, just a small one but thats fine, its good numbers.

5327 RPM 317hp and 313.7 TQ at 17 psi, 11.8 AFR and no knock, 17.2 degrees of timing flowing 26.7 lbs/min

The car is holding steady boost now so I can do some pulls and really get that compression up there now.

Really need to get myself on some pump gas in the car hehe. Drove it to work today on 110. Been lazy and have not drained the tank.

flexnuts02 · Dec 18, 2007

Yeah my JE/eagle motor threw 170 across the board with 5k miles cold!! It was engine broken like a mother! Only problem I see though is that the cross hatch isn't very visible? Is this from high reving and alot of engine breaking?

K_Mans_TSI · Dec 18, 2007

DSMscreamer said:
I've always gotten my best compression results on a fresh motor by hitting it with a couple pulls @25psi in third to 7500rpm, then heavy vacuum back down to idle. This is done immediately after initial warm up followed by an oil change. With 8.5:1 pistons this giave me 195psi across the board after 200 miles.

Exactly what I saw with my 8.3:1's being 180 across after 200 or so miles.

4 Bang Her · Dec 19, 2007

What cam is in it??

Do a leak down test to give you a bigger picture.

Cams, static compression ratio, WOT testing and a leak down put everything in perspective. It's hard to compare #'s to everyone elses set ups.

Example, my FP2's and 8:1 comp netted me 130's across the board ( not WOT ) and had 3% leak down on a 12k mile daily driven rebuild.

The_EE · Dec 19, 2007

HKS 272's are currently in it, thinking about saying F it and going with some 280's.

16G_tsi_awd · Dec 19, 2007

Guys seeing better results faster are speeding up the break in process. I call it forcing break in. They will see good results but if you plan on pulling lots of miles out of it and you seat them slower than you will see more in the end. If you rebuilt your head it will take time to seat the valves as well. Oil consumption during break in is normal as well. Put 10000-15000 on it will be better. I suggest checking out AMS overstock part of their website if you need HKS 280's.

The_EE · Dec 19, 2007

16G_tsi_awd said:
Guys seeing better results faster are speeding up the break in process. I call it forcing break in. They will see good results but if you plan on pulling lots of miles out of it and you seat them slower than you will see more in the end. If you rebuilt your head it will take time to seat the valves as well. Oil consumption during break in is normal as well. Put 10000-15000 on it will be better. I suggest checking out AMS overstock part of their website if you need HKS 280's.

Well, a friend is wanting to go with HKS 272's so I am thinking of just letting him buy me 280's and I will give him my 272's.

dsmraver · Dec 19, 2007

16G_tsi_awd said:
Guys seeing better results faster are speeding up the break in process. I call it forcing break in. They will see good results but if you plan on pulling lots of miles out of it and you seat them slower than you will see more in the end.

This is not true.

The rings seat on the fresh crosshatch that's been honed into the cylinder. Many (all of the ones I've talked to) performance engine builders recommend a "hard" break-in, since that's the only way to get the rings to mate with the bore. If you don't put some power (read: cylinder pressure) to the rings, then let the motor engine brake for at least a few pulls, you're doing your brand spanking new motor a large disservice.

Have you watched the Bugatti Veyron assembly video that's floating around the net? The first thing they do is put the engine on a dyno and run it, then in the chassis under power.

http://www.youtube.com/watch?v=Di0TMV1sdkc Watch at 3:40 & 5:20 for the engine, then chassis dynos.

I'm not saying go out and beat the crap out of the car, but you *need* to make some WOT pulls at a reasonable boost level, to ~80% of redline then let it engine brake under heavy vacuum, as others have posted. This will result in a long running and strong shortblock.

fatalshock · Dec 19, 2007

^^ That mirrors everything I've ever been told.

I was expecting a little more - Compression on new engine

90redgst

DSMscreamer

The_EE

flexnuts02

K_Mans_TSI

4 Bang Her

The_EE

16G_tsi_awd

The_EE

dsmraver

fatalshock

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