# i have 2 SBC questions having to deal with HP **URL:** \ **Category:** PittSpeed Automotive\ **Created:** [January 21, 2007, 7:11pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560 "2007-01-21T19:11:54Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 21, 2007, 7:11pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/1 "2007-01-21T19:11:54Z")
hey guys, i know you wolnt be able to get a definite answer, but at least a rough estimate is what im looking for. how much HP do you think the following engine would make, im going to list EVERYTHING i know about it: SBC from a 67’ impala ss entire engine is blueprinted/balanced domed pistons engine is milled down, 12.5:1 comp ratio fullie heads (either 462 or 492 casting number) older style weiand xcellerator intake comp cams 280h (280 duration, 480 lift) 750 CFM holley carb accel HEI distrib (planning on replacing) headers sorry if i forgot something important, but im looking for a rough HP rating, sorry i cant get the exact specs, but at this time it isnt possible. for my next question… lets say you have 2 SBC’s with the exact same parts, ecept one is 9.5:1 comp and the other is 12.5:1 comp how much extra HP do you think the higher comp engine will make? Once again, i know there is no definitive answer, but an estimate. Thanks guys! ---
**Author:** ![eurodad](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/eurodad/32/5988_2.png) [@eurodad](https://forums.speedlife.net/u/eurodad)\ **Post date:** [January 22, 2007, 6:12am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/2 "2007-01-22T06:12:05Z")
ported heads or non ported? my guess is you’ll be lucky if your anywhere near 400 hp at the flywheel ---
**Author:** ![yelo69](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/yelo69/32/6023_2.png) [@yelo69](https://forums.speedlife.net/u/yelo69)\ **Post date:** [January 22, 2007, 7:16am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/3 "2007-01-22T07:16:52Z")
Your missing 1 important thing…How many cubic in…? Also 3 points of compression will make a big difference in h.p. ---
**Author:** ![eurodad](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/eurodad/32/5988_2.png) [@eurodad](https://forums.speedlife.net/u/eurodad)\ **Post date:** [January 22, 2007, 8:18am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/4 "2007-01-22T08:18:50Z")
> [@Do you know him?](https://forums.speedlife.net/t/do-you-know-him/27470/4): > > Your missing 1 important thing…How many cubic in…? your right, i was going with 350ci, but it’s probably smaller. ---
**Author:** ![MONTE\_SS](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@MONTE\_SS](https://forums.speedlife.net/u/MONTE_SS)\ **Post date:** [January 22, 2007, 9:01am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/5 "2007-01-22T09:01:01Z")
> [@cheap,fast car](https://forums.speedlife.net/t/cheap-fast-car/27471/8): > > ported heads or non ported? > > my guess is you’ll be lucky if your anywhere near 400 hp at the flywheel ---
**Author:** ![Orr89rocz](https://avatars.discourse-cdn.com/v4/letter/o/ac91a4/32.png) [@Orr89rocz](https://forums.speedlife.net/u/Orr89rocz)\ **Post date:** [January 22, 2007, 10:10am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/6 "2007-01-22T10:10:22Z")
> my guess is you’ll be lucky if your anywhere near 400 hp at the flywheel yep, this is what i was thinking…those heads kinda suck. you need something that can flow better for that motor with that compression and cam. ---
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 22, 2007, 12:25pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/7 "2007-01-22T12:25:45Z")
> [@Do you know him?](https://forums.speedlife.net/t/do-you-know-him/27470/4): > > Your missing 1 important thing…How many cubic in…? Also 3 points of compression will make a big difference in h.p. damn, i knew i was missing something. its a 355 ---
**Author:** ![yelo69](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/yelo69/32/6023_2.png) [@yelo69](https://forums.speedlife.net/u/yelo69)\ **Post date:** [January 22, 2007, 2:42pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/8 "2007-01-22T14:42:17Z")
With that compression a 355 will make better than 400 hp with camel humps. Just remember you won’t run on pump gas. Moving to a solid cam would even give you a little more. ---
**Author:** ![tom\_vito](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/tom_vito/32/6000_2.png) [@tom\_vito](https://forums.speedlife.net/u/tom_vito)\ **Post date:** [January 22, 2007, 2:44pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/9 "2007-01-22T14:44:04Z")
Running the numbers through desktop dyno, give the following results the 12.5 engine should produce about 398@5500rpm, and the 9.5 346@5400. I’m sure these numbers are just an estimate. And this was done as large tube headers, with open exhaust… ---
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 22, 2007, 3:02pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/10 "2007-01-22T15:02:45Z")
thanks guys 🙂 vito, can i get more info about this “desktop dyno”?? ---
**Author:** ![tom\_vito](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/tom_vito/32/6000_2.png) [@tom\_vito](https://forums.speedlife.net/u/tom_vito)\ **Post date:** [January 22, 2007, 3:28pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/11 "2007-01-22T15:28:47Z")
It’s a program I got years ago, (so old it’s a DOS version) that Mr. gasket sold. I think Summit has something similar listed in their catalog. If you would like I could try e-mailing it to ya. It fit on a floppy, but I tried e-mailing it to someone else and it didn’t work. not sure if it was their connection speed or something else. ---
**Author:** ![eurodad](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/eurodad/32/5988_2.png) [@eurodad](https://forums.speedlife.net/u/eurodad)\ **Post date:** [January 22, 2007, 4:03pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/12 "2007-01-22T16:03:10Z")
i had the same one years ago, then we switched computers so i lost it. wouldn’t mind fooling with it again, HINT HINT ---
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 22, 2007, 4:16pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/13 "2007-01-22T16:16:41Z")
> [@Official NHL playoffs thread](https://forums.speedlife.net/t/official-nhl-playoffs-thread/27476/14): > > It’s a program I got years ago, (so old it’s a DOS version) that Mr. gasket sold. I think Summit has something similar listed in their catalog. If you would like I could try e-mailing it to ya. It fit on a floppy, but I tried e-mailing it to someone else and it didn’t work. not sure if it was their connection speed or something else. hey thanks, my e-mail is [slvr98camaro@gmail.com](mailto:slvr98camaro@gmail.com) :bowdown: :hs: ---
**Author:** ![yelo69](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/yelo69/32/6023_2.png) [@yelo69](https://forums.speedlife.net/u/yelo69)\ **Post date:** [January 22, 2007, 4:23pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/14 "2007-01-22T16:23:13Z")
The old Desktop Dyno is great info for setting up combinations… ---
**Author:** ![Orr89rocz](https://avatars.discourse-cdn.com/v4/letter/o/ac91a4/32.png) [@Orr89rocz](https://forums.speedlife.net/u/Orr89rocz)\ **Post date:** [January 22, 2007, 4:54pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/15 "2007-01-22T16:54:52Z")
well there are some 355 crate motors making over 400 hp with less compression with cams similar to that one and some slightly bigger, but they have good heads that flow well like vortecs, or dart iron eagles. that seems like a lot of compression for that cam and heads. ---
**Author:** ![yelo69](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/yelo69/32/6023_2.png) [@yelo69](https://forums.speedlife.net/u/yelo69)\ **Post date:** [January 22, 2007, 5:07pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/16 "2007-01-22T17:07:11Z")
I run a 355 with 13:1, 291 camel humps, comp cam 294s cam, holley 300-36 intake, 750 edelbrock…The only issue is I have to run aviation fuel…but it is sure fun to drive. ---
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 22, 2007, 6:18pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/17 "2007-01-22T18:18:46Z")
> [@GTI \> lancer i believe.](https://forums.speedlife.net/t/gti-lancer-i-believe/20605/69): > > well there are some 355 crate motors making over 400 hp with less compression with cams similar to that one and some slightly bigger, but they have good heads that flow well like vortecs, or dart iron eagles. > > that seems like a lot of compression for that cam and heads. yeah, people asked me what i think the HP rating is, because i only had a guess, and i told them prolly 400, and everyone told me there was no way it was making that power, and its prolly around 260HP, i guess they forgot most stock SBC’s make 1 HP per CI, which would be 350 right there. the car came with those specs, i personally didnt do it, but i do know it has some high comp (the guy who sold the car to us used to drag race it) but anyways, i found some spark plugs laying around, they were honostly 1mm longer, and i hit the key with the ign off, and i pulled the plug and it was closed up. internally, im just going by what i was told (domed pistons) but i am 100% sure of everything else > [@Buffalo Bills 2007 Schedule !!](https://forums.speedlife.net/t/buffalo-bills-2007-schedule/27464/16): > > I run a 355 with 13:1, 291 camel humps, comp cam 294s cam, holley 300-36 intake, 750 edelbrock…The only issue is I have to run aviation fuel…but it is sure fun to drive. how much HP does it have? we have it running on 115 octane turbo blue, $5.45 a gal ☹ ---
**Author:** ![tom\_vito](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/tom_vito/32/6000_2.png) [@tom\_vito](https://forums.speedlife.net/u/tom_vito)\ **Post date:** [January 22, 2007, 6:22pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/18 "2007-01-22T18:22:05Z")
> [@Official NHL playoffs thread](https://forums.speedlife.net/t/official-nhl-playoffs-thread/27476/17): > > hey thanks, my e-mail is [slvr98camaro@gmail.com](mailto:slvr98camaro@gmail.com) > > :bowdown: :hs: e-mail sent… ---
**Author:** ![BadassNovas.com](https://avatars.discourse-cdn.com/v4/letter/b/848f3c/32.png) [@BadassNovas.com](https://forums.speedlife.net/u/BadassNovas.com)\ **Post date:** [January 22, 2007, 8:39pm UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/19 "2007-01-22T20:39:59Z")
That’s A LOT of compression for that small of a camshaft. ---
**Author:** ![slvr98camaro](https://avatars.discourse-cdn.com/v4/letter/s/7c8e57/32.png) [@slvr98camaro](https://forums.speedlife.net/u/slvr98camaro)\ **Post date:** [January 23, 2007, 7:50am UTC](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560/20 "2007-01-23T07:50:42Z")
> [@FS/TRADE 1994 Grand Prix GTP Damaged](https://forums.speedlife.net/t/fs-trade-1994-grand-prix-gtp-damaged/27274/11): > > That’s A LOT of compression for that small of a camshaft. how come? [Next page](https://forums.speedlife.net/t/i-have-2-sbc-questions-having-to-deal-with-hp/187560.md?page=2)