Whatcha think?

350 bored .040 over
SRP blower pistons - reverse dome -16cc
Piston .005" in hole
.039" / 4.166 head gasket (felpro-1010)
trickflow aluminum heads
Singleplane manifold
Hydraulic roller cam: 230/244 @.050, .533/.540" lift, 114 lsa installed @ 114 ica
SQ S-trim supercharger

9.73:1 compression ratio with heads milled to 58cc chambers
9.3:1 heads light polish 62cc chambers
9.14:1 heads with mirror polish 64cc chamber

The short block is done and i've light polished the chambers. Just not sure if I wanna mill them or not. I'd have to mill them about .024" to get 9.73:1 I think.

I'm thinking 9.73:1 might be fine with the alum heads. Stock l98 is 9.7:1 right? I sold my old S-trim (straight cut). I'm gonna order a new SQ. (I can't take the noise any more. It's just too much).

Perhaps I'm being liberal in this calculation, but I think with 9.73:1 c/r, the combination should be around 475hp naturally aspirated, and about 595 hp with the SQ S-trim.

-- Joe

 

How must boost?
My guess is 430FWHP, maybe up to 450FWHP, both N/A. That is a guess from a combo that I have that was on an engine dyno. How did you come up with 475HP.

Do you like those Felpro 1010 gaskets? Plan on using the "new ones"?

Stock TPI engine is either 9.3:1 or 9.5:1 depending on the year

 

According to the tech articles on this board the L98 350 had 9.3:1 compression ratio.

I guess the desired compression ratio depends on how much boost you wanna run. right? the Vortechs usually come with 6-8 psi pullies. right? Maybe the SQ is more. But that rating is for a stock motor. Your pressure would be less since the engine flows better than stock. You'd have to try different pullies to get the boost where you want it. You may already have the pulley stuff figured out.

I would not mill the heads if it were my choice, unless they're warped. I predict half a point will not lead to very noticable differences in performance, but may lead to minor tuning differences.

 

Joe,

I like the setup you are running. I have a 383 with pretty much the same setup. TFS (G1 twisted) heads, cam is a little smaller (non roller) 490,500 lift, 110lsa, TPIS mini ram. I had compression of 10:1 on hyper pistons. Had a bad turn and eventualy broke a piston. It ran quite a long time 2 years, then I started tuning & it blew. It ran 415rwhp, 485lb-ft at the time. I'm now building a better short block, hoping for 500rwhp.

New setup
500,513 lift 234/244 dur, Probe -20cc dish for 8.8 compression. I have an SQ going to run 10-12lbs. Tuning with a 749ECM. I have your BIN as a guide this time from your old motor.

I think a 350 would be capable of the same numbers. The torque may be a little different. As long as the tune is good 9.73:1 should work, watch the boost. The SQ is great, can barely hear it over the motor, only a slight whistle at idle, when I'm on it all I can hear is exhaust!

 

Stock TPI is supposed to be 9.5:1 but if you take it apart and measure them they are around 9.3:1.

Why so much compression, why not lower that some and run more boost? I'm dissapointed that my current build is going to come out as high as 8.7:1...

 

Difference between a street car and a strip only car. If 80% of the driving on the street won't be boosting, why run such low compression? Ever drive a 8:1 car with a centrifigul blower? Drives like a stone around town, compared to a car with slightly higher static compression. Sure you can run more boost, but still.

I've driven 8:1 roots cars, and it's a whole other ballgame.
With the centrifigul, it's better to have slightly higher compression.

-- Joe

 

After CCing the heads, and putting the mother together and in the car yesterday, we'll be at 9.3:1 c/r. The pin in the timing set was slightly mis-aligned, so the crank ended up being installed at 113* intake centerline. I wanted to install it at 114*, but it wasn't worth driling out the hole, and putting in a bushing for 1*.

Is your SQ and SQ-S or an SQ-SC ? I like the power my S-trim gave, but couldn't take the noise. Looking forward to getting an SQ. My Buddy's cobra mustang has an SQ-SC trim and it's nice and quiet!

To those who asked, the guestimates were based on tinking with desktop dyno. I know it's usually +/- 20hp off, but it's still a good guestimate of powerband. I think with the SQ it will be a strong mid 11 second car on street tires.

-- Joe