ALFAGTV6.COM

Does anybody have the specifications (all the measures) of the stock 3.0 12 v pistons for the 9,5:1 and 10:1CR models?

THANKS!!

One more thing, what's the diameter of the piston pins?

Thanks

Jose_76 wrote:One more thing, what's the diameter of the piston pins?

Thanks

My bet is 22mm

Thanks, Mats!

Do you know if Porsche 3.0 pistons can be fitted in Alfa's V6 12v engines?
That's whay I want the specifications of the pistons. They look to me similar, but it's important to know about the differences between domes.

My 3.0 Porsche had 104 mm pistons so they might be "biggish".
The 2.5 I had before had 100 mm pistons so they could be usable. Models were 944 S2 and S

Sorry for my lack of precision.
I mean 95 and 98mm pistons from the 911's

Jose,

Why not get JE or Venolia? I think Greg has specs on Venolia.

Jose,We have done many big bores using the Porche piston..98mm and 100mm.
In fact I have Kevins dad`s engine with me right now,98mm Porche pistons..

Also look at Bike pistons,Honda and Yamaha 100mm..Excellent quality,light weight..
American Hyperuetectics as in Kb for Chevvy v6..There are hundreds..

Cp pistoni will make custom for you at 160Euro each...This is top dog stuff..
The American forgings from je,ross etc..are solid and heavy..I found rather large clearences...Very good stuff,but live with a rattling engine when cold...again,super pistons...You cannot beat the bike stuff..its just so good...

Barry I think this piston rattling when cold is somewhat of a myth. We have built four motors using Venolias and none rattle when cold. Corvettes and many other factory cars have forged pistons and no rattling when cold.

Venolia suggests rather large clearances in thier specs as do most makers of traditional forged pistons. However, in Venolia's case and probably the others they include a spec tag that say these specs are general guidelines and to have your machinest set the clearances up for your specific appliation.

Having called Venolia to ask what the heck that means they told me that the specs they suggest are for hard core race use and are on the ultra conservative side. They don't want the pistons expanding enough to scruff up the cyliner walls in extreem applications so they suggest the most conservative possible (loosest) clearances.

We set them up for .006 of an inch and have never had a problem and definatly have not had any rattling.

Greg,Ive got 2x 3.8l 24v using JE 101.6mm forgings...Its a shortish skirt piston,probably 65mm,and they are set at 0.006" clearence..
These buggrs rattle when cold..Not loudly,granted,but audible for a while..
My 2.0l turbo ran Venolia`s(remember the old John Shankle Venolias??)Destroyed a set at the reccomended clearence,contacted John,increased clearence and had a rattling motor at cold..
Im NOT saying the U.S.forgings are crap,far from it..Ive used JE,Venolia,Arias,CP,TRW,and a few ohers..Excellent products and thank goodness for these guys,otherwise we would all drive boggo stock std. cars..

What I am saying is that for the street,if I can use a cast piston,it would be preferable..Tighter clearences,MORE POWER,longer lasting engine..
This is where I enjoy using the Japanese piston..
Hey,this is simply a personal choice..
Another S.African engine builder of note has stadardised on 100mm CP forgings.Great engines,they all rattle when cold...Also a lot of blowby compared to the castings..Blowby i.m.o,is where the mot efficiency in an enginis lost.
You have 10% blowby,its approx.7% power down the drain..A 3 or 4 % blowby engine just feels soo much better..And Ill stand by this statement ..I have experienced it first hand...

I totally agree that if you can use cast pistons they are better for a street car, especially a normally aspirated car. Cast pistons will give more power, better oil consumption etc. However on a forced induction motor the comfort factor of knowing the pistons are forged is well worth it. The Venolias we use don't rattle at .006 inch clearance so far so good.

My JEs are ok, they're the low expansion type. No rattling when cold.

My car is so noisy anyway that piston rattling is no problem whatsoever. Forged Mondials. The TS will be with forged Venolias.

Oh. Almost forgot.
I guy I know was rallying with OE pistons. Looked a bit funny when the head was removed and 3 of 4 were at TDC! One piston just broke in half and the top part stayed up.
OK, he was revving slightly more than stock

Micke,did you know theres a motorbike piston that gives up to 13:1 cr,and is good for 8500rpm on the ts???

Nope. Tell me more.