Cosworth 57mm Pistons HAVE ARRIVED

[dx400r]

Pornographic Engineering that :)

[mruehl34]

Herye hereye, come one...come all. Let it be known, the Cosworth 57mm pistons for the NC-30/35 have arrived.

I had the majority made for our stroker (454) and stock crank racers (428) with longer Rods. I also had an extra set made for our super-long-rod engine, wich uses the HRC specs of +3.00mm. I have the following quantities available. Please note, I am selling these at my cost of $300 per piston without rings ($1,200/set of 4 with pins and clips). They're not cheap, but they are literally the best pistons money can buy. So, only serious inquiries please.

AVAILABLE FOR SALE:
2 Sets of Standard Compression Height Drop-in pistons (Bore and Go)
3 Sets of 1.25mm Shorter Compression Height
1 Set of 3.00mm Shorter Compression Height (HRC Spec)

Mike Norman
G-Force Engine Development
mngforce(at)speakeasy(dot)net

Mike i have some questions:

When i have a complete HRC-engine ( VFR 400, NC30 ) with the HRC rods and take a set of of 3.00mm Shorter Compression Height (HRC Spec) then i can bore and go? You take the frz rings for the pistons?


Michael

[g-force performance]

Mike i have some questions:

When i have a complete HRC-engine ( VFR 400, NC30 ) with the HRC rods and take a set of of 3.00mm Shorter Compression Height (HRC Spec) then i can bore and go? You take the frz rings for the pistons?

Yes, this is correct. For you, with HRC +3.00mm rods, you can bore and go.
Yes - again - the rings are directly from the Yamaha FZR400 +1mm pistons (57.00mm).

[g-force performance]

What rings do they use, Mike - obviously not stock NC30, but are they something `over the counter` or exotic/expensive?

Are both the deck height and the compression ratio stock on the `drop in` 428s or are they higher comp than the originals?

How great is the weight saving, and by extension what`s the safe rev limit likely to be with these pistons?

Thanks,
Rick

As just about everyone asked what rings they use, I apologize for not answering that clearly. As I just responded to Michael, these pistons were designed to use "overthe counter" Yamaha FZR400 +1.0mm rings. Just eliminate the second (dark grey) compression ring.

I just took a new job (now an Engineer for Kawasaki Motors Corp., USA) and have moved. All my shop equip is 400 miles away. So, I have not been able to weigh these yet. However, the CAD file estimated them as the same as the previous pistons. This would put them at around 10 grams less than stock. So, they should rev to the stock limiter, or the HRC limiter, just fine.

For those who don't know, "Compression Height" is the term for the distance from the center of the pin to the flat portion of the crown of the piston (aka: Squish Band). I have altered this from stock (even on the Standard pistons) to tighten the "Squish" by about .0039" (0.10mm). In addition, I have adjusted the Compression Height range to cover stock, stroker cranks and really long rods. All these, with a stock stroke make 428cc.

The "Compresion Ratio" has been bumped to 13.0:1 with stock heads and no stroke. Cosworth said I should be trying to push for over 14.0:1. We'll try it like this for now.

[mo haggs]

Cosworth 57mm Pistons - what size are stock pistons?

[Waza4]

I take it there good to go in CBR's too ?

[g-force performance]

I take it there good to go in CBR's too ?

I believe so, but don't hold me to that.

If I remember correctly, the CBR and VFR/RVF have the same pin size, bore size and compression height. I think (this is where I get foggy) they have the same valve angles. Where they are different is the compression ratio. Putting RVF pistons in a CBR bumps the compression up. So, putting these in a CBR REALLY bumps the compression up. Probably still to a safe limit (under 14.0:1) but I have never measured to know for sure.

Any CBR experts out there than can back me, or correct me, on this?

[g-force performance]

Now that Coswoth have made the pistons and have templates/got all the info they need; maybe future sets will be cheaper to make?

Smev

Smev:

On one hand, you're right. We have the designs and such to make more. On the other hand, Cosworth will only make 48 at a time. I really don't know who is willing to shell out another $14,400.00. So, the reality of it is.....this batch is probably the one-and only - batch of Cosworth pistons for the NCs. With that, there are only 6 sets available from that batch. So, only 6 other bikes besides ours can have 'em.

[Smev]

$14,400!!!

I didn't think of it that way!!!!

Guess I'd better start saving my pennies!!!

[g-force performance]

I just weighed the pistons. I am really excited about the findings.

The Stock VFR pistons weighed in at just under 100g. The REC pistons (our first run of pistons) weighed in at approximately 95g. The Cosworths weigh in at 87g. Much lighter than I had expected.