Turbo/superchager 90mm pistols?

[hightuned]

Hi

Im looking for a set of forged pistons for my supercharged 2,7L, they need to be forged std 90mm bore with a comp ratio around 7'5-8'5:1. JE Said their forged pistons is not for supercharger use, is the piston top to thin to handle the extra heat?
I have aske Motormeister and Ross for a quote to make a custon set but they dont even bother to reply? Would be most grateful for a hint where i can find a set to suit my needs?

Fredrik

[Raceboy]

90mm RS stock Mahle pistons are forged.

[Ronnie's.930]

Originally Posted by hightuned

Hi

Im looking for a set of forged pistons for my supercharged 2,7L, they need to be forged std 90mm bore with a comp ratio around 7'5-8'5:1. JE Said their forged pistons is not for supercharger use, is the piston top to thin to handle the extra heat?
I have aske Motormeister and Ross for a quote to make a custon set but they dont even bother to reply? Would be most grateful for a hint where i can find a set to suit my needs?

Fredrik

Consider it a blessing that you have not heard from Motor Meister - do a Google search and you will see what I mean.

[hightuned]

Originally Posted by Raceboy

90mm RS stock Mahle pistons are forged.

But the rs piston gives a 10,5:1 comp ratio, right? i dont want more then the stock 8,5:1 as the engine runs 15psi boost on e85.

[hightuned]

Originally Posted by Ronnie's.930

Consider it a blessing that you have not heard from Motor Meister - do a Google search and you will see what I mean.

Right you are, ive never seen so many complaints before! And Ross pistons seems to a few dents in their armor aswell does anyone have any experience from their products? I'll have to try Carillo then, if they dont make custom sets i guess im down do designing my own piston and have a machine shop mill them for me? Thats realy something i dont wanna do as its gonna cost a fortune and making a piston takes alot of knowhow when it comes to the materials used. Im getting desperate im getting the rods and crang back from the machine shop this week and realy want put my engine back together again to get on with the supercharger build.

[Raceboy]

Originally Posted by hightuned

But the rs piston gives a 10,5:1 comp ratio, right? i dont want more then the stock 8,5:1 as the engine runs 15psi boost on e85.

No, the stock RS piston is 8,5:1 using stock 2,4/2,7 70,4mm crankshaft. With E85 the car will have great power once tuned!

I use also RS pistons on my short-stroke 2.5 turbo build but with 66mm crank. This lower CR but it really is a reasonable option. I woul love to have the pistons 8.5:1 on 66mm crank though

Good luck!

[totle]

If you are only going to run E85 and not gas, you can have higher compression piston as you would normally run on gas

Raceboy, did you finish your build? remember I read about the project

[hightuned]

Originally Posted by totle

If you are only going to run E85 and not gas, you can have higher compression piston as you would normally run on gas

Raceboy, did you finish your build? remember I read about the project

It cools better as i consumes more fuel, and as its a 2v air cooled engine with about 15psi boost 8,5:1 is all the comp ratio i dare use. Ive calculated running the engine on gas but that would force med to only run about 5-6 psi of boost cost me the loss of over 100hp. These are all ofc theoretical numbes and i will be interesting to se what the dyno sais when its all finnished, i got pleanty of experience from racebikes and v8's but this is my first Porsche

[hightuned]

Originally Posted by Raceboy

No, the stock RS piston is 8,5:1 using stock 2,4/2,7 70,4mm crankshaft. With E85 the car will have great power once tuned!

I use also RS pistons on my short-stroke 2.5 turbo build but with 66mm crank. This lower CR but it really is a reasonable option. I woul love to have the pistons 8.5:1 on 66mm crank though

Good luck!

Sry you are absoluty right, was just offerd a set and looked it up. Was thinking of the rsr 10,3:1 ratio and mixed em up. The calculations say about 400hp so im keeping my fingers crossed?

[Raceboy]

Originally Posted by totle

Raceboy, did you finish your build? remember I read about the project

No, not yet, has to finish my other project car 1st (924 with 2.5 16v turbo engine, 500+ hp).
Also at the moment last races of the season are coming and I want to race my 931.
But the heads are twin-plugged and ready to go, have to find either 7R case or early aluminium case as I sold my 2R/3R case to a friend in desperate need.