AND the 2002 turbo compression numbers are.......

[fiftytakedowns]

50 - 150 - 145 - 75

4 3 2 1

i wondered why the car NEVER ran right with this motor from the get go. once I bought the motor, till now. I guess I should have tested it first... whoops. but finally I got my hands on a compression testor, and this is the final numbers. I got till the end of summer to do a swap somewhere.

Im in the market...

[TobyB]

Try a leakdown next.

you might just need a valve job.

t

[fiftytakedowns]

I had the head sent to a machine shop to get pressure tested, and checked for warpage etc. I assume he would have checked all that.

but I heard if you put oil in the cyl, and then do a compression test, the numbers would skyrocket. Which I did, and the number was up to 150 from 50

Currently im debating to just slap in BRand new parts in the bottom end, or just do with some used parts. IE stock flat top CAST or custom forged for EXtra$$$$

[aa/fd]

I would suggest using forged pistons on any supercharged application, castings no matter the source, are just not up to the task.

[fiftytakedowns]

I normally would agree, but PInepig a member on this board has been running cast flat tops pistons up to 25 psi with MEth injection. Still no kaboom.

Thats whats changing my mind.

[Pinepig]

I would suggest using forged pistons on any supercharged application, castings no matter the source, are just not up to the task.

Yep, there is " I've heard " and then there is " I've done "

Stock cast pistons will take a lot more than you guys give them credit for, after 2 years of beating on an unknown mileage motor somewhere between 20-25 PSI daily I took it apart and there wasn't a damn thing wrong with the pistons.

[4x2]

So far I haven't been able to blow my stock pistons (and I did try)

I did blow 2 headgaskets, the first because it was already gone, the turbo just pushed it over the edge.

The second one because I accidentally ran 30-35 degrees of advance @ 13psi

Still took some 7000 miles before it went kaboom.

Current one seems to be holding up fine so far (though I did use a cutting ring gasket and ARP studs this time)

Anyway, to be honest I would just get a cheap E30 engine, swap everything and see how long it lasts (probably quite long if you don't make any huge tuning mistakes)

Swapping an engine is not that much work, the E30 engines are usually in much better shape than 02 engines and you won't cry for a week if it blows (like you would with an expensive engine)

[fiftytakedowns]

Hopefully I can find just an 02 Shortblock, Id like the increased displacement.

[TobyB]

I had the head sent to a machine shop to get pressure tested, and checked for warpage etc. I assume he would have checked all that.

but I heard if you put oil in the cyl, and then do a compression test, the numbers would skyrocket. Which I did, and the number was up to 150 from 50

oh.

then u need rings,which almost always means pistons...

yup shortblock.

Cast pistons are heat limited. if you keep them cool, boost makes very

little difference. Ask Corky...

t

[fiftytakedowns]

I had the head sent to a machine shop to get pressure tested, and checked for warpage etc. I assume he would have checked all that.

but I heard if you put oil in the cyl, and then do a compression test, the numbers would skyrocket. Which I did, and the number was up to 150 from 50

oh.

then u need rings,which almost always means pistons...

yup shortblock.

Cast pistons are heat limited. if you keep them cool, boost makes very

little difference. Ask Corky...

t

I got a 2002 block and crank, and I was thinking of using some 76 Flat top pistons. all would be used, but ID obvously refresh the bottom end. new bearings, a hone, new rings ETC. I already have a MLS gasket and ARP studs. So pretty much plug and play.

the 2.0 bottom end would be an improvement over the 1.8 I hwas running until the rings went out.

What would be recommended pistons/ ocmpression ratio for running around 15-20 PSI? I plan to go oil cooler or something to keep the temps down, and I WILL be getting it PRofessionally dyno tuned. so I feel like I could just use some used flat tops, and trust in the tune to prevent me from doing some damage.

What Compression ratio would Flat tops with a .071 MLS gasket plus a 1.8 320i Head have?

I know you can get some good power with higher compression pistons as long as you have a good tune.

Thanks!

[Pinepig]

About 8 to 1. Perfect.

[fiftytakedowns]

MORE BEWWWST!!!

8:1 it is. sweet.

What would normal 2002 pistons I feel like there are tons of different ones. with the 1.8 head have as far as compression ratio goes? if the flat tops are 8:1

[Pinepig]

8.2 to 1 for the short piano tops.

[fiftytakedowns]

oh damn . this 1.8 head is perfect fer tarrbos

[aa/fd]

I would suggest using forged pistons on any supercharged application, castings no matter the source, are just not up to the task.

Yep, there is " I've heard " and then there is " I've done "

Stock cast pistons will take a lot more than you guys give them credit for, after 2 years of beating on an unknown mileage motor somewhere between 20-25 PSI daily I took it apart and there wasn't a damn thing wrong with the pistons.

Well I believe I fit in the "I've done" category and I would never advocate a cast piston in any friends supercharged engine, just my opinion which is ok by me. People like me see 25lbs was good than 35lb must be better and if it lives at 35 than 45 must be better yet. There are a lot of factory turbo-ed motors with forged piston and production will not be allowed to install a more expensive part unless it can be justified to accounting. There are very talented people than can make a lot of parts survive that most can not, but I always like to error on the side of having an extra margin of safety and reliability, it is way cheaper to do it right the first time. You want to see boost come visit me at Pacific Raceways this morning.