Question about forged pistons

Road-race engines and ancillaries - general discussion
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iceman_n
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Joined: November 27th, 2011, 9:18 pm

Question about forged pistons

Post by iceman_n » December 7th, 2011, 2:29 pm

I am reading in several forum's many different opinions about forged pistons.
I read in a Peugeot Rallye forum that someone change his Wossner forged piston with JE and it makes from 160hp with Wossner 180hp with JE. Same thing happen when change JE with Accralite, the engine makes 184hp and with his last choice of pistons was Omega, the engine makes 195hp. All this without to change anything else (same head, same camshafts etc)

I know that each company has their own design, different piston skirts, CR, weight, dome volume etc.

I want to ask if this is possible to happen ? In other words in my engine if I change the Wossner pistons with CPS is it possible to make more power ?

I have also see the CPS pistons for my engine, it is more expensive than Wosnner ones that's why I choose Wossner it was cheaper, but they have the same design. How is it possible an engine to make that much more power just changing pistons ?

Guy Croft
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Re: Question about forged pistons

Post by Guy Croft » December 7th, 2011, 3:45 pm

The only features that would make any material difference to power would be the intruder volume (ie: dome) & thus CR and the ring pack.

GC

iceman_n
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Joined: November 27th, 2011, 9:18 pm

Re: Question about forged pistons

Post by iceman_n » December 7th, 2011, 3:55 pm

why ring pack ?

As for dome volume and CR I agree but the change from piston to piston can be so impressive ? Almost 30 hp as the example that i write in the first post ?

Guy Croft
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Re: Question about forged pistons

Post by Guy Croft » December 7th, 2011, 4:28 pm

The thinner the rings (and special coatings like PVD chrome also help) the lower the outspring - this gives lower mechanical (frictional) loss.

For same dome configuration and ring type you won't get any power difference.

Don't be fooled by claims - unless the power is same engine and same (bench) dyno reading directly off the flywheel comparative results like that cannot be relied on.

G

iceman_n
Posts: 21
Joined: November 27th, 2011, 9:18 pm

Re: Question about forged pistons

Post by iceman_n » December 7th, 2011, 5:05 pm

Thank you Mr Croft

This results that I mention is a true story from the owner of this Peugeot Rallye, I do not see the dyno results that he says that he make in dyno.

But I am curious because the power increase is to high.

Guy Croft
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Re: Question about forged pistons

Post by Guy Croft » December 7th, 2011, 5:06 pm

Believe me - after 23 years in racing engines - if it was that easy to get from 180 to 196bhp I would be a very happy man.

GC

iceman_n
Posts: 21
Joined: November 27th, 2011, 9:18 pm

Re: Question about forged pistons

Post by iceman_n » December 9th, 2011, 8:06 pm

Thank you Mr Croft...I hope my engine to produce over 170bhp with the Alfa Romeo forged pistons...

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