This will be short as 3rd time trying.
Replaced TPIS big port TPI setup with HSRam. Now trying to fix loss of low torque and increase height to what was advertised. Installing S&P risers for their tunnel ram style manifold.
Question is do I leave runners separated in riser for a 2 1/4" (6" to 8 1/4") runner increase or machine out center to retain 6" runner lenght but increase plenum volumn?
Is plenum supposed to be sized by runner lenght and area?
420" SBC is turning to 5500 RPM and cam peak torque on engine dyno was 3750 with peak HP at 5200-5500 with 750 Holley carb and manifold.

Any thoughts or opinions appreciated.
Thanks guys.

Hope it works this time.

 

check with jay87gta over at www.fl-thirdgen.org

 

Mrr23,

Thanks. Will give it a try.

Now that I have this figured out will supply a little more info.

My thinking was that I tried a Mini Ram which was terrible with 3" runners, Big Mouth TPIS with stock lenght (14"?) which ran good but did lay down a little at 4500 RPM (only had GM 24 lb inj)and this HSR with 6" runners. Thought if went around 8-9" might be best of both. Don't know what effect would be to open up risers so had mini plenum on top of each set of 4 runners (2 1/4" high) before opening into main HSR plenum. Or do 1/2 way on risers.

I originaly wanted S&P tunnel ram set up with the 2 1/4" risers that would give me the 11 3/4" height from front block surface to top of TB. (now have 4" over TB on HSR. HSR was supposed to be 10 3/4" but came in at approx 9 1/2. I ordered an S&P last year but never received. They said a month to get this time but didn't dare gamble so got HSR. Need to take to Maine this summer with me. Been tuning VE tables from TPI to run HSR lately. Changed from 24 inj on TPI to 27-30 SYTY inj on HSR. Should have tried on TPI. Fueling sure is different and able to add more timing at lower KPAs.
Had to try this one more time to see if got a handle on posting.