I'm interested in a possible group buy for a street performance piston for a Chevrolet 250. I called a couple of piston manufacturing companies this past week.

I'm interested in the following:

Normally aspirated street engine, Chevrolet 250
Tighter piston-to-wall clearance, 0.003" or less
Cast or forged, through only forged looks practical
Eutectic or hypereutectic silicon alloys prefered, 4032 alloy or similar acceptable (as used by OEM's forged pistons, Ford, BMW, Mahle)
For 6" connecting rod application (Off the shelf Crower Sportsman or Scat)
Approximate 1.365" compression height
Flat top piston
Use widely available rings, sizes and material to be determined
If single overbore size: either 0.030" or 0.040"
If two overbore sizes: 0.030" and 0.050"
Desire a piston weight under 470 grams

Manufacturers require:
Minimum run for forged pistons: 40 to 80 pistons, dependent on manufacturer
Minimum run for cast piston: 250 pistons, not appealing
Possibly may allow two different overbore sizes during single run
Manufacturing time after receiving 50% payment and signed design drawing: 4 to 6 weeks
Remainder of payment required to ship pistons


Let me know you are interested in joining in a group buy of the above mentioned type of piston in the near future. Either respond or send me a PM. The group buy will drop the price from around $100 each to possibly $50 each. I am flexible on some of the design details, but want to maintain the 6" connecting rod application, use of the tighter clearance forged silicon aluminum alloys, and flat top pistons.

Winter,
You probably remember me bringing this up earlier this last year.
https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=50182&fpart=1

Your price would certainly be better though. The pistons I was checking on would be slightly lighter (440 gms).

What about the guy's (majority) that want to run 5.7 rods? Tom

Yes, I remember the positive and productive thread.

I was hoping to find at least buyers for seven sets for my proposed configuration, including my myself. If seven sets are quickly accounted for, I will move quickly on working out the details and placing the order. Fourteen sets let me consider another manufacturer. If minimal interest is shown for my proposed pistons, then I will be glad to share the information gathered and help for another different piston group purchase.

Either way, I will help with another order. A different piston configuration requires a different CNC machining program so the minimum allotment is required for each differnet configuration.

Once the CNC program has been developed, and the forging slugs are available, then later single sets may be purchased at a reduce cost (compared to a single set custom order).

I agree the majority will probably want pistons for 5.7" rods. Concerning the piston weight, I was just giving an upper limit and not one that was actually proposed.


The possible major piston configurations for street performance:

1) Cast eutectic or hypereutectic, 5.7" or 6.0" rod
2) Chevrolet LS1 type piston, custom length rod around 6.050"
3) Forged hi silicon alloy, eutectic, 4032 alloy or similar
4) Forged low silicon alloy, 2618 alloy, 5.7" or 6.0" rod
5) Forged low silicon alloy, 2618 alloy for forced induction, 5.7" or 6.0" rod

Getting a consensus on what exact piston configuration(s) to purchase may require some work, with all the different valid justifications available.

I am not particularly interested in 250 pistons but after using a few brands of pistons I have settled on Diamonds. Reasons include tight quality control and fast turnaround time. The cost seemed reasonable too. Good luck.

If we go to 5.7 rods I may be interested in a set, just seem that the age of the engines in use that an overbore piston may be more practical. (.030?)