Im running a 2.2 aluminum rod build with ported head, oversized valves, dual valve springs the works, Map Rev3 intake manifold, curt brown ported fp race manifold, and 3in ets fmic. Car will be on a FP Red mhi and or FP Zephyr on 93 and E85. I was set on some GSC R2'S but came upon some STM 650's for a hell of a deal. Ive seen numbers on R2's so they seem ideal for a stroker but havent found much on the 650's. Yes they say made for 650hp but there are always exception to the rules. Ive only talked to one person thats used both and said the 650's were the better option.They were also in the 700hp range running a 6266. So im interested in what the community has to say about this. TIA

 

Running the red or Zephyr, I would do the R2's since the small twin scroll ports on a stock frame exhaust manifold are going to coke the motor out from revving too much past 8500. If you go with a big turbo (t3 or twin scroll T4) set up, I would run S3's so the cams have the duration to run 9,500 rpm's. No experience with the STM cams, but if you're head is an English racing head, I've seen their 2.2, their head, and S3's do some magic.

 

Yea ive read plenty on the s3's S2's and R2's and the results are consistent. 650s are still a mystery since they arent as mainstream and just lack info or comparisons.R2's i think would be the safe bet but i want to see some if the 650 owners crawl out and give their input also. Ive honestly have always done things a little different and have came out on top and also paid out of my pocket. I know if i dont flow enough air these cams are worthless either way but i think it possible on E85.

 

Where are the stm 650 owners?