Piston options

[Doug_RS2]

Ross Racing Pistons
JE pistons
Mahle Pistons

What others?

I am tempted to go with standard Mahle pistons(they are standard ones?) - although I need 81.5mm diameter because of reboring. I will get the raised part machined off so the piston will be flat, apart from the valve recesses. These will cost me £112+vat each, but they come with oversized rings and pins.

Anyone know where I can get these cheaper?

Cheers

[Mark Halligan]

Another factor as well as strength......and price, will be weight as well, I think that I read somewhere that JE pistons are a lot lighter than the standard ones?

Mark.

[Doug_RS2]

Have you got a weight? I can measure a standard one.

How much effect does weight actually have? Would there be a measurable difference?

[Doug_RS2]

Mahle full CDROM download - it is 22Meg - but has all the info for Mahle products:

http://www.mahle.com/obj.nsf/22BB696...56B270003A2CB/$FILE/m2000_e.zip

You need to extract to a temp folder, run the setup and you will have the full catalog installed.

And here are the pistons/rings/pins I'm probably getting:

[Mark Halligan]

Don't have a weight, but managed to find out where I read about it:

What will be the weight of the pistons ? Jeffer told me that JE-ones are allmost half the weight of the original pistons.

here .

Lightening and good balancing of the internals, flywheel etc. is supposed to make it free'er revving and more responsive, less energy is used in spooling up the engine on acceleration.


Cheers,

Mark.

[Pisobiker]

Another very important advantage of lightening alternating masses weight is inertial loads. Total mass will determine at given conrod strenght what max safe rpm the setup can manage. Lowering weight will make the engine be able to run higher rpms therefore increasing peak hp potential.

Marco

P.S. Consider inertial forces are inversally proportional to mass and proprtional to the square of rotational speed. Just to make an example, if a given conrod+piston setup is good for 7.000 rpm if total weight of alternating part of conrod + piston (complete with bearing, pin, circlips, rings) is lowerd of 15% at same inertial loads you can rev your engine up to ~7.300 rpm........

[Pisobiker]

........

[Nick Psaltakis]

try dahlback

Try dahlback racing. They have modified their site with more info and a kit of camshaft pistons and rods in order to go up to 9krpm.....they cost a bit more but you know you get what you pay ( most of the times).

[Doug_RS2]

Just waiting on feedback from Ross Racing Pistons - looks like myself and Dave(desmo) will be going with these. Luckily we are both going with 81.5mm pistons and Dave has already given them a piston for measuremts - superb prices - I had never heard of them before but the place that is doing tthe engine work recommends them.

I'll be going with some with approcx 4.2cc removed from the top of a standard one, hopefully keeping the same profile, just dropping everything 0.8mm.

Anyone else interested in a set in the next week?

[Jeffer]

Tomorrow I will weigh my JE baby's. And post a picture.

[Mark Halligan]

"These are RACING pistons. They are low silicon forgings which means they are immensely strong BUT do grow more with heat than a standard forged piston. This means greater cold clearances must be run. These greater cold clearances may cause a slight noise (piston slap) at start up."

I was thinking about getting these, does anyone know how much the clearances need to be adjusted compared to the standard size pistons in order to take up expansion. How much they rattle on start up and how long for?

Doug, how long are you looking at for delivery if ordered in the next week?

Mark.

[Audi Parts Guru]

Doug, that link doesn't seem to work

[Doug_RS2]

Paul - try this:

link to mahle

I don't think the forum likes the $ sign in the web address.

Mark - is that a quote from Ross? Maybe Dave can help us with that - I did see there where guidlines on the ross page on what clearances you need to run - I'll need another look.

Dave was saying approx 3 weeks from when we order - Dave can organise shipping for us as well. It would be nice to have 3 sets as Dave organised a group discount for 3.

[Vagsport]

Doug, just realised today that the Volvo T5 (2.3 / 2.5 20V turbo) has the same bore as the S2! The crowns are very thick, CR on the 2.3 is 8.5:1 while the 2.5 is lower still @ 8.4:1. Engine looks vaguely similar to Audi unit, will compare head gaskets to see if engine length is close. Strangely though, the cams are held down by the rocker cover, which has integral bearing caps.

Siena

[Mark Halligan]

Doug, Dave quoted that here in the group buy section.

I was thinking about getting these, does anyone know how much the clearances need to be adjusted compared to the standard size pistons in order to take up expansion.

Forget I asked that , just had a look at their site in the FAQ section and they say to just tell them what size bore you have and they make them to fit.

Mark.