F54 and P90

[madkaw]

Yes, I will check it if I decide to change the pistons.

Now when I have more information I've started to to think that maybe I just should keep this L28 as a turboengine, becouse it should be a nice setup as it is. As Zed Head wrote I could sell it and buy a stock NA L28 and build it instead.

I got to make a decision. I'll let you know if I start to work on this engine

Not sure you want to go ahead with a turbo with this set-up. You started down the path of a NA set-up with your head and now your compression ratio will be high for a turbo engine. Shaving 74 thous. off the head and now turbocharging might not be a good idea. Not sure what octane of fuel you have over there which will have some bearing on this issue. A higher compression turbo build would be great, but it would be tricky to tune and get right without blowing up!!You would need to run a better ECU than stock.

We all made comments regarding NA motors, but not turbocharging, so you might need to think again.

Edited October 16, 2012 by madkaw

[Kimi]

Not sure you want to go ahead with a turbo with this set-up. You started down the path of a NA set-up with your head and now your compression ratio will be high for a turbo engine. Shaving 74 thous. off the head and now turbocharging might not be a good idea. Not sure what octane of fuel you have over there which will have some bearing on this issue. A higher compression turbo build would be great, but it would be tricky to tune and get right without blowing up!!You would need to run a better ECU than stock.

We all made comments regarding NA motors, but not turbocharging, so you might need to think again.

I ment with my previous post that maybe I should let the L28ET be as it is with the turbo pistons, and get a stock NA L28 instead for the project.

The P90 was already shaved when I bought the engine, and has been used with the F54 block, turbo pistons and a turbo before I bought it. It has not been used with a stock L28ET ECU.

Don't get me wrong, I really appreciate all the help I get here

Now I just need to decide what to do with the engine.

[John Coffey]

Maybe John Coffey could clarify or give his clearance preferences. Does anyone know what the stock gasket compressed thickness is?

I defer to what Dave Rebello and other professional engine builders recommend.

[Zed Head]

You started down the path of a NA set-up with your head and now your compression ratio will be high for a turbo engine. Shaving 74 thous. off the head and now turbocharging might not be a good idea.

madkaw makes a good point. Actually, it's not clear what the intent is of the work done. I used one of the calculators and get 8.5 CR for the saved head, versus 7.3 for the stock setup. So now it's actually similar to an N42/N42 setup in CR, and with dished pistons. Plus, the calculator says that the pistons will hit the head. So you might need a thicker head gasket to get back to usable.

Flat tops come out at 10.1 CR, but pistons still hitting the head. Looks like a 2.0 mm HG might get you back to 8.4 CR with flat tops, 7.3 with dished pistons.

Here's the calculator if you want to explore options - http://www.ozdat.com/ozdatonline/enginedesign/ You can put a negative number in the HG thickness box to simulate the shaved head. Subtract the shave from the HG thickness.

[Diseazd]

Zed Head.....Am I missing something? Shaving the head doesn't put the pistons any closer to the head.....you're still .040 inches away (stock head gasket thickness). Decking the block puts your pistons closer to the head (by the amount the piston comes above the deck).

[Zed Head]

No, I got my thinking screwed up using the engine calculator and putting negative numbers in the head gasket box to simulate the head shave (the calculator reports piston head contact, probably because the equations used are adding the HG thickness to the deck height). You are right, shaving the head should not cause piston-head contact.

Sorry for that, I didn't think it through before I posted.

I think that numbers reported by the calculator are pretty close though. Of course, a .074" (1.9 mm) HG would get his head back to where it started.

[Kimi]

I'm sorry that I haven't been clear enough with my question. I should have written more about the engine in my first post, my bad

<O:pSo the P90 on the F54 had already been shaved .074" when I bought the engine. I was going to install the engine as it is, with the turbo and everything. This setup has been used before I bought it so it should work.<O:p</O:p

Then I started to look at NA setups and thought that maybe this engine could be nice as a NA too.<O:p</O:p

Now after the help and advice here I think that maybe the best solution for me is to keep this engine a turbo.<O:p</O:p

Thanks for the link Been playing with the calculator, looks like the CR should be a somewhere near 8 with this setup (if it has a stock HG).<O:p</O:p

I'll probably sell this L28ET and buy a L28 NA and start to work on it, if I don't decide to use this turboengine.<O:p</O:p

[Diseazd]

http://www.classiczcars.com/forums/thread34448.html

Kimi.....This thread may help.....I used the P79, which is the same as the P90 with liners. Sounds to me like what you're thinking about building. Believe me......it's an awesome combination. Good Luck......Guy

Edited October 17, 2012 by Diseazd

[Lazeum]

I'm running as well F54/P79 with head shaved only by 0.020", Rebello cam, 3x 40DCOE, Unilite dizzy.

I'm very happy with the build so far. Engine/car is very nice to drive.

[bacarl]

http://www.classiczcars.com/forums/thread34448.html

Kimi.....This thread may help.....I used the P79, which is the same as the P90 with liners. Sounds to me like what you're thinking about building. Believe me......it's an awesome combination. Good Luck......Guy

I know this thread is six months old, but I'm interested in Diseazd's build and this link only takes me to the forum homepage.

Diseazd, does the thread still exist?

[Diseazd]

http://www.classiczcars.com/forums/engine-drivetrain-s30/34448-new-l-28-my-72-a.html

http://www.classiczcars.com/forums/engine-drivetrain-s30/31001-new-l-28-goes-1970-a.html

http://www.classiczcars.com/forums/engine-drivetrain-s30/42488-new-engine.html

Hope these help......I used shaved and shimmed P79 heads in all 3 builds, also used Isky Stage III cams in each........Guy

Edited April 16, 2013 by Diseazd