Don Terrill’s Speed-Talk

Ok I am lost trying to figure out the static on this new build...... 3.75 stroke 4.135 bore. I have at .375" down 75 cc the head gasket at .040" and the heads 46 cc. I measured down .375 because of the domes. Thanks I have a head ache finding it out I am figuring 17:1 but making sure so I can get a good flow# for the injection set up.

Assuming ....0 deck with your .040 gasket. 75cc's at .375 down comes out to 7.4 dome volume. I get 18.3:1..unless I'm missing or not reading something correctly.

We need the Bore, stroke, deck, gasket, head ccs, and net dome volume.

Mark O'Neal wrote: ↑Tue Jan 21, 2020 8:57 pm We need the Bore, stroke, deck, gasket, head ccs, and net dome volume.

First post.

http://www.wallaceracing.com/cr_test2.php

Somewhere north of 18.5:1, depending on the deck height and the diameter of the head gasket.

CGT wrote: ↑Tue Jan 21, 2020 8:56 pm Assuming ....0 deck with your .040 gasket. 75cc's at .375 down comes out to 7.4 dome volume. I get 18.3:1..unless I'm missing or not reading something correctly.

Thats why am asking? The dome volume was to be 3 cc???? Had to cut a bunch off to limit head contact now doing the measuring I see more.. True measuring with a burrett not some back yard stuff

af2 wrote: ↑Tue Jan 21, 2020 9:16 pm

CGT wrote: ↑Tue Jan 21, 2020 8:56 pm Assuming ....0 deck with your .040 gasket. 75cc's at .375 down comes out to 7.4 dome volume. I get 18.3:1..unless I'm missing or not reading something correctly.

Thats why am asking? The dome volume was to be 3 cc???? Had to cut a bunch off to limit head contact now doing the measuring I see more.. True measuring with a burrett not some back yard stuff

Are you at 0 deck? If so...using 0 deck, 4.200 gasket bore. I get 18.3. Whoa! Lol

Elroy wrote: ↑Tue Jan 21, 2020 9:30 pm

af2 wrote: ↑Tue Jan 21, 2020 9:16 pm

CGT wrote: ↑Tue Jan 21, 2020 8:56 pm Assuming ....0 deck with your .040 gasket. 75cc's at .375 down comes out to 7.4 dome volume. I get 18.3:1..unless I'm missing or not reading something correctly.

Thats why am asking? The dome volume was to be 3 cc???? Had to cut a bunch off to limit head contact now doing the measuring I see more.. True measuring with a burrett not some back yard stuff

Are you at 0 deck? If so...using 0 deck, 4.200 gasket bore. I get 18.3. Whoa! Lol

Whoa X2 lol

What is piston to deck and gasket bore measurements?

will a leaded 110 octane fuel be enough for those kind of ratios or is that methanol territory?

More like diesel

Yes,so let me get this straight, your shooting for a 17 to 1 compression on your 403 cid motor?

I am hoping you have more then 4 head bolts per cylinder?

mag2555 wrote: ↑Wed Jan 22, 2020 6:16 am Yes,so let me get this straight, your shooting for a 17 to 1 compression on your 403 cid motor?

I am hoping you have more then 4 head bolts per cylinder?

Eh....why is this any different than running 25 psi of boost? As long as it doesn't go lean your peak firing pressure is just going to be similar to that of a boosted engine. Build it accordingly.

LoganD wrote: ↑Wed Jan 22, 2020 9:19 am Eh....why is this any different than running 25 psi of boost?

You beat me to it. I was thinking the same thing. Mag, have you failed a sbc at or because of 17:1 compression lol?...There is literally stuff out there with 15:1 and a couple atmospheres on top of it...and that just the stuff I've heard of or seen. Im sure there is way more severe stuff out there than that.

AF2, got any pics of your pistons?