Small Block & Big Block Chevy Specific - Guesstimations With A Sb 408 Combo

I Have A 408 And Was Wanting Opinions On How Much Power Ya'll Think I Would Make With Sportman Ii Cylinder Heads Right Out Of The Box Which Consist Of 200cc Intake Runners With 10:1 Compression In Combination With A Comp Cams Hydraulic 274 Cam And The Performer Rpm Intake In Conjunction With Edelbrock's 800cfm Eps Carb. I Was Wanting It For A Budgeted Street/strip Motor With Stock Internals. It's Going To Be The Heart Of A 3,360 Raceweight 1987 Camaro. Any Inputs Would Be Greatly Appreciated!!!!!!!!!!!!!

Thanks, 1sicsss

87 Camaros are the best!!!!! As long as you have lts and it is a roller cam it should be in excess of 500hp, that should make for a 10 sec car with the proper drivetrain.

500 give or take, depends on the flow ability of the heads and how well it all works together, i think that is a small cam isnt it? I done feel like looking it up.

500 give or take, depends on the flow ability of the heads and how well it all works together, i think that is a small cam isnt it? I done feel like looking it up.

It is a 230/236 I believe, with 500ish lift. It is too small for his setup, it will idle like stock though. That could hurt numbers, IMO it should be stepped up to a 240+ cam w/ atleast .580 lift. With those cubes 550hp could be seen but not with that cam.
-Jeremy

Yea, with that i think it would squeeze 450ish with that tiny cam...it is not small for a 350, but for 400 cubes it is not enough.

What block, bore, and stroke?

^^My guess:


Stock 400 block, 4.165 bore and a 3.75 stroke.

It's not going to make 500 hp with those heads or that cam. The Sportsman II heads out-of-the-box flow is only 240 CFM at .600" lift.

That thing would LUCKY to make 440hp....Probably about 430hp. Those arent ANY better than vortecs when both are in stock form.

According to potential HP calculation's they could support up to 493 HP. With a bowl blend and some clean up work they should be able to support 550 HP. http://www.malcams.com/legacy/misc/headflow.htm

Now welcome to the real world. Show me a SBC with out of the box Sportsman II that is making 490 hp. And find me a head porter that can do a "bowl blend and some clean up work" to gain another 60 hp. Be realistic man.

Now welcome to the real world. Show me a SBC with out of the box Sportsman II that is making 490 hp. And find me a head porter that can do a "bowl blend and some clean up work" to gain another 60 hp. Be realistic man.

I'm sorry that you misunderstood my previous post, I said potential HP. In reality he is going to need to better optimize his components in order to get the maximum HP. These heads are not my favorite by any means, but they can support 550 HP whether you think so or not.

That's cool. I have just found from my personal experience that it takes a very good SBC combination to make more than 500 hp. I have never used Sportsman heads, so I shouldn't speak with authority on them. I would still like to see a SBC with Sportsman II heads that makes 550 hp though.

You can build many different combo's to make the 550 HP (355/383/377/406/414/421). The problem then becomes streetability, E85 would work fairly well in this situation. You are going to need compression (12.75:1 or better) in order to complete this goal. I build IMCA "Modified" motors that require cast iron heads and a flat tappet cam, these motors are 550+ HP on alcohol. I have designed a cam that works very well with the Sportsman II's. It took me countless hours on my dynomation engine building program and a full race season changing cam profiles until I found the best cam that worked well for the 383's & 406's.

:shiner: This is one of the times I stood up when I should have stayed seated. It's sometimes hard to distinguish keyboard warriors from hands-on mechanics. I'll bow to your experience building iron headed SBC.

:shiner: This is one of the times I stood up when I should have stayed seated. It's sometimes hard to distinguish keyboard warriors from hands-on mechanics. I'll bow to your experience building iron headed SBC.

No worries, I took no offence to your posts! I was just trying to help the original poster with some info.:punch:

450-475 is a more realistic number for a streetable engine

You can build many different combo's to make the 550 HP (355/383/377/406/414/421). The problem then becomes streetability, E85 would work fairly well in this situation. You are going to need compression (12.75:1 or better) in order to complete this goal. I build IMCA "Modified" motors that require cast iron heads and a flat tappet cam, these motors are 550+ HP on alcohol. I have designed a cam that works very well with the Sportsman II's. It took me countless hours on my dynomation engine building program and a full race season changing cam profiles until I found the best cam that worked well for the 383's & 406's.
Are you kidding? Ive seen plenty of 350s on pump gas making 500hp without a solid roller or a crazy setup. If a 408 cant churn out 500hp then there is something seriously wrong. All a 408 needs to reach that number is a roller cam w/230+duration and around .600 lift and a set of out of the box aluminum heads with flow #s in the 260cfm range. There have been multiple magazine builds with less cubes and sportsman heads that made 500hp, just because your alky engines only make 550hp doesnt mean you can base all sbc builds on that. I know you are probably alot more experienced than me but c'mon, cam-only ls1s make 500+hp with 10:1 cr.

Are you kidding? Ive seen plenty of 350s on pump gas making 500hp without a solid roller or a crazy setup. If a 408 cant churn out 500hp then there is something seriously wrong. All a 408 needs to reach that number is a roller cam w/230+duration and around .600 lift and a set of out of the box aluminum heads with flow #s in the 260cfm range. There have been multiple magazine builds with less cubes and sportsman heads that made 500hp, just because your alky engines only make 550hp doesnt mean you can base all sbc builds on that. I know you are probably alot more experienced than me but c'mon, cam-only ls1s make 500+hp with 10:1 cr.

Well first, I don't have the luxury of useing a SR cam, I have to use a solid flat tappet cam. I had given this info in a previous post. Your are also not going to get 500 HP with a set of out of the box Sportsman II's, the most you can make is 493 HP. With a set of bowl blended & cleaned up Sportsman II's you are only going to get around 550 HP max'd out. As for the LS1 comment, you don't seam to be able to distinguish the differances between the two motors. Also I don't think that he is useing a hyd. roller cam, it sounded like he was useing a hyd. flat tappet with the info he gave out. Will his combo of parts make the max'd out the 493 HP? I highly doubt it! He is going to be more in the range of 425 HP. Sorry to come off a little harsh, but I think that you have been reading to many magazine articles, without enough real world experiance. I love the LSx motors b/c they are easy to make HP with, not so for your old school SBC's.:barf:

Are you kidding? Ive seen plenty of 350s on pump gas making 500hp without a solid roller or a crazy setup. If a 408 cant churn out 500hp then there is something seriously wrong. All a 408 needs to reach that number is a roller cam w/230+duration and around .600 lift and a set of out of the box aluminum heads with flow #s in the 260cfm range. There have been multiple magazine builds with less cubes and sportsman heads that made 500hp, just because your alky engines only make 550hp doesnt mean you can base all sbc builds on that. I know you are probably alot more experienced than me but c'mon, cam-only ls1s make 500+hp with 10:1 cr.

i'm with 1997bird --it's not that easy to make that power on a REAL dyno with a streetable combination & those heads need work to make any power if they are anything like they used to be. I have built & dynoed lots of pump gas engines on MY dyno & they are usually 460-490hp & they will run all day on real pump gas for thousands of miles.The magazines are there to sell parts for the sponsors & the numbers tend to be high on the engines they test or my dyno reads really low.

Well first, I don't have the luxury of useing a SR cam, I have to use a solid flat tappet cam. I had given this info in a previous post. Your are also not going to get 500 HP with a set of out of the box Sportsman II's, the most you can make is 493 HP. With a set of bowl blended & cleaned up Sportsman II's you are only going to get around 550 HP max'd out. As for the LS1 comment, you don't seam to be able to distinguish the differances between the two motors. Also I don't think that he is useing a hyd. roller cam, it sounded like he was useing a hyd. flat tappet with the info he gave out. Will his combo of parts make the max'd out the 493 HP? I highly doubt it! He is going to be more in the range of 425 HP. Sorry to come off a little harsh, but I think that you have been reading to many magazine articles, without enough real world experiance. I love the LSx motors b/c they are easy to make HP with, not so for your old school SBC's.:barf:
I wasnt trying to come off rude, sorry. I have alot of real world experience with this matter, I agree with your post but 425hp from a 408? Honestly a 350 would make those numbers with those parts, I didnt notice it wasnt a hr cam. His setup will be highly restricted with those parts, I have personally seen 482hp with box stock sportsmanIIs. As for the 493 I guess theory doesnt lie, well Op I guess you have your answers. Dont build that motor without a hr and some head work.

1sicss, I would buy a different set of heads if you have not already purchased them. I would stick a set of the RHS Pro Action head(formerly ProTopline), Dart Iron Eagle Platinum heads, or the EQ (Engine Quest--aka Pro Action) 215/220cc intake runner heads. If you already have a set of heads I would bowl blend & clean up the runners for better performance. I would also stay far away from the Edlebrock carb, I would suggest a modified Holley such as Proform/Quickfuel/AED/Demon/Holley Ultra HP in a 750 cfm rating(they will flow up to 950 cfm if the motor needs more). A custom cam would be the best bet to use, if you can go with a HR cam that would be your best HP. A full body roller rocker arm is worth 20-30 HP over a stamped steel rocker and your valve guides will wear less, as long as your pushrod length is correct. A performer rpm air gap or Bodix HV1016 dual plane manifold will work better than a single plane manifold will for a street motor with your compression. Your peak numbers may not be as high, but your average HP & TQ will be higher over the rpm range.