Cosworth 57mm Pistons HAVE ARRIVED

[racesupplies]

What weight wrist pins are you running? Are they lighter than standard Honda,they seem over heavy,even for the size of the standard piston.

[mlohmeyer]

Thinking about the Omega pistons we were going to buy,did you get the Cosworth pistons from the UK? They are near me,and I was wondering if it was worth a visit to see if there was any chance of doing another batch.

Cosworth is happy to make more pistons, but we have to order a minumum 48 pistons (12 sets) to do it. That's the only problem.

What weight wrist pins are you running? Are they lighter than standard Honda,they seem over heavy,even for the size of the standard piston.

The Cosworth wrist pins are shorter than stock Honda NC30/35, and so I 'm pretty sure they are lighter, or maybe the same due to being a little more stout. Mike mentioned the Cosworth pistons are 13 grams lighter than stock, but I forget if that was just the piston, or the entire package (rings, wrist pin, piston).

Oh, Mike Norman just posted these elsewhere. This is for assembled pistons (piston, pin, rings & circlips)

JE 444cc: 147.6g
OE VFR: 133.4g
OE RVF: 133.3g
REC 57mm: 127.6g (our original 2mm over piston - 3 ring)
CP 57mm: 119.5g (our second piston design - 2 ring)
Cosworth: 118.0g (the new piston we are using - 2 ring)
HRC 55mm: 117.2g

[racesupplies]

Thet makes the pin 33g,I have a OE piston here its 100g complete but with no pin.Just thought I would ask as Mike says they are the best piston.I am going with the Omega pistons.Used them before in other another engine they do stuff for F1 and Moto gp,think they will be OK for what I want.I dont know if I got it wrong but were they £1250 a set,is that including VAT and shipping? Thats a lot more than the Omegas.If they have done them before would a new batch be any cheaper,thats some of the reason these are a better price,they have allready done a batch.

[mlohmeyer]

Cosworth always has been the best piston, but as always, you pay for the best. The Cosworth pistons are 100% machined from billet (or a forged billet cylinder?). This is different vs. what JE was doing, which is to forge a piston of the basic shape and size using a standard forge die they have. They have different forge sizes they can start with, and then they machine the diameter down to the final piston. The same forging is used for multiple different piston sizes and types. That's how JE keeps the cost down - how they pay for the very expensive forging dies.

One reason the JE pistons were heavier than stock is because they started with a forging that was designed for a much larger piston. Machining them down to a 57mm created compromises. It was a stretch for them to do it - because they didn't really have a small enough forged slug to start with. Also, the forging determines things like the skirt features and sides of the piston. These features are not machined after the fact. Only the diameter of the piston, the wrist pin location, the crown, and ring grooves are machined. The rest is exactly as the forge die makes it (the inside of the piston, and material thickness of the wrist pin bosses and crown). Think about it. That means the forged piston is made for a variety of bikes, with enough meat and design strength to handle the largest size piston they make with it, and our little 57mm piston, which doesn't need all that meat, suffers with excess weight.

Our REC, CP, and Cosworth pistons were all 100% machined from scratch, and that makes them much more expensive. The only way to get the price down is to do a large batch. Unfortunately, every time you do a batch, the cost is the same because it's the setup time that makes it expensive. Mike did a lot of the engineering, so we didn't have much NRE the first time, so I think the price is still the same high price. I could be wrong, but it's not much different.

This is why we are very interested to see the Omega pistons. If they have a forging that starts out small enough, that can make the difference. JE couldn't deliver on this. We even had face to face meetings to work that out to try and get a cheaper piston, but JE's forge size was the problem. We would have had to buy a couple hundred pistons to cover the NRE cost of a custom forging.

Again, that's why we are very interested to see the Omega pistons. If they have a small enough forging to start with, that can make the difference. The price is certainly right.

[racesupplies]

Have a look on their website,they will talk to you you need to know more.They have also joined with another company recently that are as far as I know are very good Accralite.I know what you mean about JE,I think some of theirs are cast.I have seen a set distort in a vintage race and pinch the wrist pin,not good as the pin was clamped at the small end of the rod.That set didnt complete 500 miles.The replacements looked better,but one had a porous crown,sort of an inclusion in the metal in the centre of the crown.The engine was smoking badly and pressurising the crankcase.I told Mike in a PM what I think of them anyway.Just saying have a look at Omega,they are a good company and have been about longer than I have.They have allready done a batch for another company,theirs are forged or bar,and I know several other types they have done without any problems.Sarah deals with enquiries,the email is on the website.Let us know how you get on,I am going to use them,just passed on the details as I thought it might be usefull.If they are OK,and I dont know why not,it would leave me a lot more money to do something else.Like the Manx.

[xeno]

Hello,

I'm also interested on these pistons. My company has an assosiate in UK, that works with Cosworth, and I believe they can order these pistons for us, and we might get them in a better price. Do you know how many sets we require at this point so I could get a price quote? We also work with accralite (very good pistons, even better from cosworth, but MUCH more expensive).

Is there a con rod set available now?

[racesupplies]

Accralite are now part of Omega,I dont get the price of the Cosworth ones because they have done other small quantity orders here in the UK for £400-£600.That why I wondered if it might be worth asking them again.They too were taken over a while ago,perhaps there is new managment.They are local to me,I thought it might be worth a go.Have a look at the Omega website,the contact details are on there.They do pistons for F1 and Moto GP. If you are interested in rods I have good contact that can make a set of four less shells for somewhere around £200 each.Same deal with pistons,more=cheaper.They need your old rod,piston weight,which I am waiting for,and revs you expect to acheive.I think they are I beam pattern.Again it would be better for you to contact them direct,they can give you expected weights etc.PM me and I will give you their contact details.Regards Carl.

[montsta56]

Mike do you still have any of these still available???I'd be keen for a set.
Cheers
Anthony

[mlohmeyer]

All the pistons are spoken for. Sorry.

[vfrman]

Sad day for me. So I guess you can't build me a motor now, huh?