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376shovel
10-15-2020, 12:07 PM
I built engine with 4032 flat top pistons, roadrunner rods and the stock crank.

My eaton came with a 2.76 inch pulley on it, which I do not plan to use. I bought a -2 lb lower pulley with the intent of finding a 3.4 inch upper pulley to net around the stock boost level. I'm having trouble finding a 3.4 inch pulley now, so I'm looking at other options. Anyone out there having success with a 3.1 inch pulley and -2 lb pulley, running 93 pump gas? I have a calculated 10.7:1 static compression.

I think a 3.1 and -2 lower equates to about a 3.4 upper and the stock lower pulley. Open to all your experiences to ensure I put the right pulley on this.

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dmjarosz
10-17-2020, 08:52 AM
Probably wont help but just FYI, Im running a +2lb lower and stock 3.6 upper with a Stiegemeyer Stage 6 port and Stainless Works long tubes and it makes ~11psi with a stock motor.
376shovel
10-17-2020, 08:55 AM
Probably wont help but just FYI, Im running a +2lb lower and stock 3.6 upper with a Stiegemeyer Stage 6 port and Stainless Works long tubes and it makes ~11psi with a stock motor.Great info. Are you running pump gas?

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ChiTownMaraud3r
10-17-2020, 01:28 PM
3.1 upper and stock lower yields about 11psi here, was on factory compression, but now will run a bit less after rebuild.
376shovel
10-17-2020, 01:30 PM
3.1 upper and stock lower yields about 11psi here, was on factory compression, but now will run a bit less after rebuild.Nice. I think a 3.2 sounds about right for me then considering I have the under drive lower. Trying to keep it around 8 psi

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justbob
10-17-2020, 03:38 PM
93 is good to around 19#s I’ve been told. I flirt with 19-21 on 93 almost every week it’s driven, but that’s also on a lower compression Cobra block.

I’d be more worried about over spinning that roots with a 2.anything upper. My old Trilogy set up was first stock pulleys (yawn) then a 3.2 upper, only 2 psi added but definitely better, finally a 2.8 upper and +4 lower on 93. I pegged my gauge so I upgraded to a 0-30 and saw a consistent 20#s of heat being made and only made 461 over the 3.2/stock lower that made 445 if I recall..

I’ve never heard of a -2 lower?


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