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Forged Pistons

After learning that I would need overbore pistons, and then learning that ISUZU Japan was all out, and every Lotus service shop only had stock bore I would need to get a set of custom forged pistons.
This is where I learned that these will single handedly cost the most out of everything I have done to the car at the time. . .
So, I called around to get some average prices:
  • Wiseco- $110 per piston with a 12 piston minimum order. Guess they are out!
  • Arias- $580 with a 5 week backlog. . .
  • Ross- $600 (with upgraded pin bridges, rings and pins)
  • JE- $600-$650 with a 14 week backlog...
  • Probe Industries- $550
I decided to go with ROSS because of the wait time (4-5 weeks at the time). I talked with George@Ross, and he also upsold me on a couple upgrades.
  • 9.35:1CR flat top with valve reliefs
  • .030" Overbore (0.762mm)
  • Ross Racing Molly rings ($75 extra)
  • 4340 Chrome Moly Tapered Pins($22each extra)
  • Reinforced pin bridge($27 extra)
  • Turnaround time in 2 weeks.
If you want to order some Forged pistons from me, check out this link. I can get them cheaper with any compression ratio and overbore you want, and my pistons have the upgrades built into them.
side geo storm isuzu forged pistons from Ross
Here is the comparison of the Ross piston on the left and the stock RS piston on the right.
The Ross piston is 19 grams lighter at 270grams, the RS pistons were 289grams.
bottom geo storm isuzu forged pistons from Ross
You can see the reinforced pin bridges. These pistons are designed to take 30+psi of boost. . .
top geo storm isuzu forged pistons from Ross
You can see in this shot that the Ross pistons are flat top with the valve reliefs. This changes the compression ratio to 9.35:1. The RS piston top is dished and yields an 8.5:1 compression ratio.

Talking with both George @ Ross and the guys down at the machine shop, both of them are pretty sure that the RS pistons are forged. The pistons didn't have the casting markings on the side like the Impulse XS and GSi pistons did.
To them, that was impressive that a car from '91 was so built up properly. All I could say was; "yea, I know. . ." ;-)
They probably said to themselves "he is a smug little bastard!" <