Forged Pistons for L28 F54 block with P90 head.

[RaGnaR_RattmuFF]

Hello!

 

I would like to buy a set of forged pistons for my engine build.

 

I don't know what compression ratio I should have?

 

Looked at Motorsport auto and they have Ross pistons for L28ET engine 81-83, but they don't write what CR I will get (maybe stock 7:4:1?)

 

Have mailed them but don't get any answers.

 

Have anyone else here used their pistons with any luck? Looking for around 300WHP.

 

Best regards

Johan

 

 

 

 

 

 

 

 

[SleeperZ]

People get 400whp with stock pistons.  Reliably, with good engine management.  And forgies will not protect you from bad engine management.

[NewZed]

 

I don't know what compression ratio I should have?

 

Looked at Motorsport auto and they have Ross pistons for L28ET engine 81-83, but they don't write what CR I will get (maybe stock 7:4:1?)

 

It would depend on the head (combustion chamber size).  The dished pistons will give ~7.4 with a P79 or P90 head, or 8.3 with a N42 or N47 head.  The flat-tops will give 8.8 or ~10, respectively (calculator results vary on the last one, others are from the FSM's).  Assuming no major machining done to the sealing surface.

 

There's only two options and the flat-top's are labeled as flat-tops.  The picture shows dished in the other link.  They're just stock design replacements.

 

Flat-tops http://www.thezstore.com/page/TZS/PROD/classic12d08/10-4080

 

Dished http://www.thezstore.com/page/TZS/PROD/classic12d08/10-4081

[RaGnaR_RattmuFF]

but you can't rev higher then 5-6000rpm with stock piston I read. Will go with Stock rods and JE pistons with 8:4:1 CR. They did cost 995$ + shipping to Sweden but then I know the piston is new and nice pins and rings.
 

I have stock pistons 86,5mm but with no rings. So I choose to go with forged pistons. Rods I suppose they will be good.

The only bad thing is they are pressed wrist pins. But my machine shop will handle that for me.

[Tony D]

How high do you intend to rev? Is it Turbocharged or N/A?

Cast Pistons handle 6,500-7,00 just fine. 

 

The Power in an L-Series has always been in the HEAD, and porting a turbo engine, camming it properly to peak at 6,500 with a 7,000 shift point with the proper turbo will have you in the 500HP range on cast L28ET pistons, under 20psi. 

 

With 300 HP at the rear wheels as a goal, a bone stock L28ET can do that will simple boost. Having a mildly ported head and proper cam that gives you another 1,000 rpms of power (from 5,500 to 6,500 rpms) which is still 300,000 miles reliable -- if you don't detonate. It will happen at a significantly lower boost pressure and that means detonation, spark blowout, etc. are all minimised compared to a "Bell Boost It" type of build making the exact same HP at higher pressures. Do it right, and this is a 10 to 12 psi proposition max... almost non-intercooled territory. In fact, I've seen 380 ftlbs of torque at 4,500 and 8 psi on one build...definitely non-intercooled territory!

This level of power is nothing extraordinary. No need for floating pins, forged pistons, metal head gaskets.

 

As Sleeper Says: what you DO need is proper fuel and spark control "Good Engine Management".... Without it, even the best Carillo Rods, MLS Head Gaskets, and JE Forged Pistons are turned to scrap metal with one good detonation incident (*That You NEVER EVEN HEARD*) --- and the costs are exponentially higher to start over!