Another how much HP question. . .

[BRauscher]

Sorry to ask another one of those "How much will my engine make" questions. I know how much everyone loves reading and answering them, but please be kind!
Ok, here it is. 383 SBC, GM Bowtie Vortecs 215cc ported to 223cc 2.05 / 1.60 chambers opened up to bore edge & offset dowels .030" to center the valves more. Don't have them flowed yet, but hoping in the 280-290 range. Solid roller 262 /270 @ .050 on a 106 lsa cam card says install @ 102. .672/.672 lift w/ 1.6 rockers. Super Victor w/ and 830 Holley & 2" spacer. Mahle flat tops, compression comes in right @ 11.0:1. Headers are 1 3/4 stepped up to 1 7/8, 3" collector.
Thanks in advance, and like I said, please be kind!

Thanks!

[IDT-572]

597.4 hp

[mag2555]

If the heads can turn in 280 cfm @ .600" lift then 560 to 575 HP should be had.

[automotive breath]

585 hp

[BRauscher]

Thanks guys. Any estimates on where peak TQ & HP might be?

[mag2555]

I must note to you that I do not like step headers unless after the major bend area they funnel back down smooth to the original ID , which only takes place on custom ones made that way!

[user-612937456]

565 hp @7000 if you put a Holley 950 HP carb you will get 580 hp @7200

[randy331]

Sorry to ask another one of those "How much will my engine make" questions. I know how much everyone loves reading and answering them, but please be kind!
Ok, here it is. 383 SBC, GM Bowtie Vortecs 215cc ported to 223cc 2.05 / 1.60 chambers opened up to bore edge & offset dowels .030" to center the valves more. Don't have them flowed yet, but hoping in the 280-290 range. Solid roller 262 /270 @ .050 on a 106 lsa cam card says install @ 102. .672/.672 lift w/ 1.6 rockers. Super Victor w/ and 830 Holley & 2" spacer. Mahle flat tops, compression comes in right @ 11.0:1. Headers are 1 3/4 stepped up to 1 7/8, 3" collector.
Thanks in advance, and like I said, please be kind!

The nearest 383 to yours I've done would be our 383 emc engine. It had GMPP large port vortec bowties on it. They were ported then epoxied down in size to smaller than original cc volume.

4.031 bore x 3.75 stroke
It had same size carb as your 830 but was a Braswell.
We used a ported Motown intake at the competition, but tested a ported 2814 SV also and both made the same top end power but the Motown produced a bit more TQ down below peak TQ.
The GMPP vortec bowtie heads flowed 290 cfm and had 2.08"/1.55 valves with 50* seats.
Srp flat top pistons with comp at 11.4-1 so just a bit more than yours
5.7 rods
We used a Comp cam 236-248-108 lsa solid roller cam with .650 lift. ( .650 was the lift limit that year ) So considerably less duration and a little less lift than yours.
We had a deep oil pan that you probably couldn't use in whatever chassis your engine is going in.
1-3/4 x 1 7/8 step headers to 3 inch collector but weren't custom made with special taper after the bends, just a shelf header, so similar to your headers.
It made 539 Lbs a@ 5000 rpm and 606 HP @ 6500 rpm on the EMC dyno through mufflers (6500 was the limit)
Without mufflers and the cam in at 108* ICL, instead of the 103* that made best score, little tighter lash and a bit of tune up change, it would make 620 HP.

So the big differences between yours and the our emc 383 would be your considerably larger cam, the intake porting, and the big question, the unknown difference between the port work on the 2 sets of heads.

So I'd think your larger port size and larger cam should help rpm enough to make similar HP.
And the potential to make more depending on your port work, but the potential to make less too.

To give you an example of how much difference port work can make.
The shop I dyno at built a 406 dirt track engine using the GMPP large port vortec bowtie heads.
Rules said no porting, but valve/size and valve job ok.
He went to 2.08" valve no other porting.
But it was 14.4-1 comp and had a cam similar to the one you used, but was 108 LSA.
It had a SV 2 that was port matched up but no other porting.
Large Braswell carb.


It made similar power to our emc engine. 614 HP I think was best pull. It made more TQ, That cubes and comp are hard to over come on TQ.

But I thought it interesting that the intake and head porting on our 383 was able to offset more cam, more cubes, and more comp, for making HP even if not TQ. Of course we had more dyno time too, and that never hurts.

I think your combo is a good one, and I expect it to run well.
Drag race ??

Anyway thought it may be of some interest to you.

Randy

[wyrmrider]

Randy- thanks for yet another great post