Hot Rod Forum : Hotrodders Bulletin Board - Reply to Topic -- Hot Rod Forum

Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics> Small Block Chevy Top End Rebuild: How Much HP??
User Name
lost password?   |   register now

Thread: Small Block Chevy Top End Rebuild: How Much HP?? Reply to Thread
Send Trackbacks to (Separate multiple URLs with spaces) :

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Please select your insurance company (Optional)


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Additional Options
Miscellaneous Options

Topic Review (Newest First)
03-28-2004 06:38 AM
tm454 Lots of HP on good gas! Just how much HP do you want to believe it makes? How much HP is really important to you? If you have 250 Hp in that 67 your going to move that little dar pretty fast when you want anyway. This is just a guess of course but I's say 300hp for sure. Does this help??


Rat RodsRule!
03-27-2004 07:08 PM
BanditT/A 9.5:1 compression is too much for a supercharger in my opinion. Best to shoot for around 8:1. You could probably run like 3 psi with 9.5:1 and then you'll blow your heads right through your hood.
So unless you plan on swapping heads or pistons to lower your compression to go with the supercharger, I would stick with your original mods to the motor.
03-27-2004 06:28 PM
purple1967camaro thank you all for your great answers! you helped me a ton!! but ive got another question i need some help answering!

ive been researching superchargers and found that i could put a weiand 142 supercharger on my engine as it sits now and they only mods i would need is a bigger carb and a longer throttle cable. for a grand total of around $1800 with everything including intake gaskets.

the first setup i proposed with the cam/heads etc would have costed a total of around $1100.

with the supercharger ive estimated i would get about double the power that the cam/heads deal would give me.

so please tell me what you all think and which would be a better way to go!

thanks again!
03-27-2004 03:53 PM
killerformula I'm telling you guy, its not a 450 horse motor, I would be surprised if it broke the 400 mark. Torquer heads are 170 cc runners, you need about 190-200 to make an easy 450 horse. Your friend's cam is flat and is 10-20 degrees shorter on duration. Don't get me wrong, I'm sure its a potent motor, but I'm just trying to tell you 450 horse is not easy to get! BTW, as long as you know the compression ratio, we don't need to know how big the domes are. Domes are not the best way to bump compression and are probably hurting the flow of the motor rather than helping it. Unless you need some serious compression, domes are bad.

Just for giggles, I did your setup with the compression you mentioned. I have exact numbers on cams and the flow numbers for the SR heads.

HP 379@ 5000 RPM
TQ 427@ 3000 RPM

Which sounds exactly right. I put a 272 comps cam in it and used headers in the combo.

Those are great numbers man, just build the motor, you'll be happy with the results. The torque figure is VERY good, and will be a killer on the street for sure. I actually like this setup very much, just enough cam to hear, nice torque, very streetable, even daily-driver quality. Don't worry about the numbers man. Take it to the track and lay waste, most of the guys who say they have 4 or 500 horse really only have just over 300 anyway!

You'll be in the low 13's with this setup, which is really hauling *****. One other thing to mention is that your torque curve for this setup is very flat, meaning consistent power and response throughout the power band. You get your HP early so you don't have to run super low gears and can still have it on the highway. One thing to remember is that a 380 horse motor with a flat curve and early HP will probably beat a 450 horse motor that is running a huge cam "stoplight to stoplight" (not implying streetracing, just using the term for reference). Peak HP means nothing, your band and curve are what to look at. YOu can't run your motor at 6500 R's all day long, so why not have your power where you drive it?

Good motor, Build it.

03-27-2004 03:17 PM
purple1967camaro yes my friend has a 383 stroker sorry about the confusion on that. the heads he has are 76cc and they are world products torquer heads available from summit racing :

with that out of the way. the engine Killerformula posted on here is close to the same as my friends engine, except for the cam in my friends car is a 280H so has a tiny bit lower duration and is nothing compared to a roller cam, his carb is edelbrock 750, his intake is performer RPM air gap, his heads are the world industries heads shown above, and he has some big *** keith black dome pistons (ill get you the actual dome size next time i talk to him) oh and his ignition is an HEI dist with msd cap, rotor, coil, and wires. the exhaust is the same (2.5 inch piping) same forged crank and 5.7" rods and his comp ratio is somewhere abouts 10.3-10.5:1. so those dome pistons could possibly throw him up over the 450 HP mark.

can someone please give me some advise on if should really go through all this cam and head trouble or would i get more power out of a Weiand 142 c.i.d. supercharger?

03-27-2004 03:07 PM
Super Streeter Dont buy into dyno hype,tell the builder you want to know how fast the combo is going to make your car.In a 3400# camaro,450 true flywhel hp with a th350 trand and the proper convertor and gears should put you into the 12.0's or high 11's.I did this with an LT1 piston 355 with ported double hump heads and a 250 degree {at .050} solid flat tappet cam,a strip dominator intake and 750 mechanical carb with a 3500 stall convertor and 5.13:1 gears.I was spinning the engine to 7000 rpm to do it!I could have done more at a lower rpm with better heads,but this was back before good heads were readily available for smallblocks.I would say that the combo I had was making in the low to mid 400 hp range.You buddy doesnt sound like he is ready to run with that combo.So you need to know how fast you want to go and then build an engine to do the job,not build an engine to get a dyno sheet good luck.
03-27-2004 01:30 PM
Originally posted by purple1967camaro
i base my guess about my friends engine on the engine my dad had in his 82 corvette. it was a 383 stroker with flat tops and 76cc heads and a mild cam 260 or 270 and mild valve train. it had a performer manifold and a 600cfm carb and was engine dynoed at 450hp. and because my friend has that same setup but with dome pistons and a lumpier cam and a higher ratio valvetrain i would imagine his engine would make quite a bit more power.
There is no way. As far as I know there are no 76cc aftermarket heads, so I'm assuming you're referring to stock heads. With that cam and setup in a 383 you're looking at like 270-290 HP, and he's lucky to get 220 at the wheels. Unless you saw the motor go on the dyno, watched the slip print up and saw that motor dropped into the car, this guy is telling stories. Maybe he's counting the HP his stickers give him on the side of the car! Sorry, had to throw that one in.

Here's a clip from Ryan's stroker page on a 440 horse 383:

Combo 10.
Combo 10 uses Dart Iron Eagles instead of Sportsman II's. The swap produces 24 more HP and 7 more ft-lbs of torque than the Sportsman II's. The Iron Eagles also made 14 less HP and 18 less ft-lbs of torque than the Trick Flow 23 heads. We can see that the Dart heads are clearly better than the World Products heads.
Displacement: 383 cu. in.
Carburetor: Holley 750 double pumper
Heads: Dart Iron Eagle
Intake: Edelbrock Victor Jr.
Camshaft: Comp Cams hydraulic roller, with 230/236 of duration @ 0.050 in. lift, and 0.510/0.520 in. lift
Rockers: Trick Flow roller, 1.5:1
Headers: 1 3/4 in. primaries, with 3 in. exhaust and Flowmaster mufflers
Pistons: KB hypereutectic, 12 cc dish
Rods: Trick Flow forged, 5.7 in.
Crank: Trick Flow forged
Distributor: MSD Billet with 6AL ignition
Comp. Ratio: 10.0:1

MAX HP: 446 @ 5500
MAX Torque: 433 @ 4500

Notice this motor doesn't break the 450 horse mark, has $1000 dollar a set aftermarket heads, a 280-286 500 lift ROLLER cam in it, an intake that is two steps up from the performer you're using, and a HUGE set of headers on it.

You're not the first one who's had a story told to them, I wouldn't mention it to your buddy who told you it, they usually don't take it well! What's the 1/4 mile time and speed for this car? That's the true test!

03-27-2004 01:25 PM
BanditT/A So does your friend have a 383 or a 350 because that makes a world of difference. I was assumming he had a 350 as that is what this discussion was based on; a 350 build up. 450 is more believable with a 383.
03-27-2004 01:15 PM
purple1967camaro i base my guess about my friends engine on the engine my dad had in his 82 corvette. it was a 383 stroker with flat tops and 76cc heads and a mild cam 260 or 270 and mild valve train. it had a performer manifold and a 600cfm carb and was engine dynoed at 450hp. and because my friend has that same setup but with dome pistons and a lumpier cam and a higher ratio valvetrain i would imagine his engine would make quite a bit more power.
03-27-2004 12:58 PM
BanditT/A I have to agree with stepside on this one. His deskdyno numbers seem about right.
As for your friend having well over 450 horses with that set-up, I find that extremely hard to believe. I'd be willing to be he has more like 370- 380 at the flywheel if he's lucky and thats pushing it. Show me some dyno sheets for your motor and your friends and then I'll believe it. Does he have actuall sheets or is that what he thinks he has
Hope you like spending big bucks for gas as with your new setup as you will have around 10.5-11 compression. If you run aluminum heads, it won't be as bad. I'd personally stay away from iron heads with 10.5 comp for the street. I guess it all depends what you use it for.
03-27-2004 10:19 AM
purple1967camaro stepside454: the reason i said guaranteed 350 HP is because it was built at a local machine shop here called A.I.M.S. and they built what they call a 350/350 horse package. and they engine dyno all of their engines to ensure the advertised horsepower is correct. maybe your engine program calculates realworld horsepower or horsepower at the fly? and the second part about the 346HP with the new items i dont think that could be possible, because my friend has close to the same engine as what i want to get, except it has some 10.3:1 dome pistons and 76cc heads. and hes running well over 450HP. everything else on his engine is the same as what i listed above. thanks for the help!

Super Streeter: thanks for all the input! i have and HEI ignition and some hooker super comp headers, the 1 5/8's to 3 inch collectors. and i have an ok exhaust system, 2 1/4 chambered exhaust, no mufflers, with mechanical 2.5 inch exhaust cutouts that i can pull open from inside the cab. i was planning on eventually getting a new converter that had a stall speed of around 2000 since my powerband will begin around 1800rpm. and i wasnt sure whether to get 3.55 gears or 3.73. im planning on driving my car on the street a lot so im not sure which would be better for that. and as for the tires i got some T/A radials on it right now that are about 28 inches tall and 9 inches wide. and with the traction bars i hardly burn out at all!

Another question relating to this for you guys..
Do you think i would get more horsepower by putting a weiand 142 c.i.d. supercharger on my current engine than i would by putting on the new heads/cam/rollerrockers/intake/carb? thanks again!
03-27-2004 09:48 AM
Super Streeter The combo you propose isnt too bad.I should mention that while the cam company may say that the 270 cam is the biggest that will work with a stock convertor,you should know that for all around performance,any engine even a bone stock one will perform better with a slight stall speed increase.I would run about 2200 to 2500 with either the 260 or 270 cam.With a stock convertor the 270 cam will feel soft out of the hole,but it should idle OK in gear.
As for the combo,If you hav a true flat piston 355,I would top it with the 270 cam,a set of perfromer rpm heads,air gap intake,and 750 edelbrock,or 650 mechanical secondary holley carb,a good hei type ignition,and a set of 1 5/8" headers with 2.5" exhaust,and with a th350 and 2500 stall speed, and the equivelent of 3.55;s with 27 inch tall tires you will have a strong street combo that will overpower most true street tires that would fit in your stock wheelwell.You dont need much more then that.BTW,that combo will make a true 380hp in my book,and should put a 3400# street car into the mid 12's with good traction.Good luck.
03-27-2004 06:52 AM
stepside454 First off, not that it really matters, but if the engine is a 350 & its from a 78 Mailbu. thanb it wasnt the Malibus original engine. unless Im mistaken the only v8s available for 78 in Malibu were 267 & 305.
now, as far as your current engine being gauranteed 350 HP, based on what specs you gave me,n ot a chance, so punched it up in DD2000 just to see what it said.Hell maybe I was wrong LOL. heres what I came up with.
peak HP 294@4500 RPMS
peak TQ 370@3000 RPMS
after switching cam, intake carb, & heads( by the way, 76cc to 64cc gets you 10.7:1).
peak HP 346@5500 RPMs
peak TQ 382 @4000 RPMs
Those numbers are assuming you have headers & a decent exhaust system, you didnt say.
You said it has Performer intake now, & plan to change to an Air Gap, I assume you mean th RPM AIr Gap, its confusing, but you can by the AirGap in Performer & Performer RPM.
If that was the combo I was going to use, I think Id just keep the regular performer on it, & either keep the 600 cfm carb & add a 1" open spacer, or buy a Demon 625 for it. John
03-26-2004 11:36 PM
Small Block Chevy Top End Rebuild: How Much HP??

hi everyone! im 18 years old and ive got a 1967 camaro with a Small Block Chevy 350 motor in it. the block is from a 78 malibu and is bored .030 over with forged crank and rods, and forged flat tops 9.5:1 ratio pistons(cant remember the brand name).as for the valvetrain it has a 260H comp cams camshaft and 1.52 roller tip com cams rockers to match. heads are other wise stock 76cc heads that have been resurfaced and have stock sized valves. the engine is topped off with an edelbrock performer intake and an edelbrock 600cfm carb. how the engine sets now it makes a 'guaranteed' 350HP at the fly. ive got a stock torque converter and TH350 tranny out of a 76 camaro and the stock 3.08 gears out back.

now for the upgrades!

1. up the cam to a 270H comp cams (highest you can go on a stock converter)
2. 64cc heads with 2.02/1.60 valves.
3. full roller rockers, either 1.5 or 1.6 ratio (havent decided yet.. still researching)
4. edelbrock air gap intake.
5. 750cfm edelbrock carb.

please let me know how much horsepower you think this new set up will make! and i am open to any suggestions you might have, so PLEASE feel free to post whatever you want! i would also like to know if anyone could guess what my new compression ratio would be with the new parts, as it is a 9.5:1 right now! thanks a bunch everyone!

here's some pics of my car so you guys know what im workin on!

that pic was taken about a year ago. since then i dropped the front down low with 2" dropped spindles and did a front end suspension rebuild and disc brake conversion. and i put some thicker tires out back and some comp engineering traction bars on it!


Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -6. The time now is 11:00 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.