SBC Horsepower estimate

General engine tech -- Drag Racing to Circle Track

Moderator: Team

kimosabi
Member
Member
Posts: 168
Joined: Sat Feb 22, 2014 5:01 pm

Re: SBC Horsepower estimate

Post by kimosabi » Mon Oct 23, 2017 7:07 am

wilson1970 wrote:
Sun Oct 22, 2017 1:24 pm
I decided to go with a .540 .236/.242@.050 will much power be lost in .060 in lift? Most likely will step up to a 1.6 Ratio rocker. This will give me .555 & .576 respectively
That's more cam than I have in my 10.7:1 400 and it rips my face off every time I floor it.

wilson1970
Member
Member
Posts: 55
Joined: Sun May 14, 2017 3:29 pm

Re: SBC Horsepower estimate

Post by wilson1970 » Mon Oct 23, 2017 8:37 am

I like that kind of response. =D>

kimosabi
Member
Member
Posts: 168
Joined: Sat Feb 22, 2014 5:01 pm

Re: SBC Horsepower estimate

Post by kimosabi » Mon Oct 23, 2017 9:24 am

Well it kinda depends if you want max power and fancy numbers or if you are looking for a certain behaviour. I know for sure I have more power in a cam change but I also know I'd sacrifice a little of that BANG when I slam it. God knows I have been doing ALOT of timing adjustments and curves to get there though. Most guys would probably say a 232/232 .540 108LSA cam is way too small for a 10.7:1 400 with non eliminator afr 210 heads. Well, it pulls hard to 6k so...

I gotta plug Mike Jones a little here though. I doubt a shelf cam would do.

wilson1970
Member
Member
Posts: 55
Joined: Sun May 14, 2017 3:29 pm

Re: SBC Horsepower estimate

Post by wilson1970 » Mon Oct 23, 2017 10:46 am

I am looking for a decent driver with some manners that will run strong to 6000. Hopefully on the right path.

G72Zed
New Member
New Member
Posts: 3
Joined: Fri Dec 16, 2016 12:12 pm

Re: SBC Horsepower estimate

Post by G72Zed » Wed Oct 25, 2017 10:34 pm

wilson1970 wrote:
Sun Aug 13, 2017 5:43 pm
What could I expect for power levels with ths combo? 355 SBC zero deck, 10.5 compression, .597 lift 236/242@.050. Hydraulic roller, Sportman 11 heads with some port work, stud girdle, Rpm Air Gap intake, 750 HP carb. Thanks for info.
I have a similar combo, but less ci and more dur. 333 SBC, zero deck, 10.57 cr, .510 lift 'net" 252/260@.050, solid FT, home ported iron Sportsman II, still @ 200 cc runner with 2.02/1.6 valves, stud girdle, 750HP, looked in my dyno files, I tried the RPM Air Gap, with 1.5 inch custom spacer, made 518 hp at 7000 rpm, 441 tq at 4,800.

wilson1970
Member
Member
Posts: 55
Joined: Sun May 14, 2017 3:29 pm

Re: SBC Horsepower estimate

Post by wilson1970 » Thu Oct 26, 2017 6:09 pm

Thanks. Was that 550 or 750?

G72Zed
New Member
New Member
Posts: 3
Joined: Fri Dec 16, 2016 12:12 pm

Re: SBC Horsepower estimate

Post by G72Zed » Sat Oct 28, 2017 9:20 am

wilson1970 wrote:
Thu Oct 26, 2017 6:09 pm
Thanks. Was that 550 or 750?
The "750HP" I have in my reply is the carb size used, and not the HP attained. sorry about that.

wilson1970
Member
Member
Posts: 55
Joined: Sun May 14, 2017 3:29 pm

Re: SBC Horsepower estimate

Post by wilson1970 » Sun Nov 05, 2017 6:56 am

Has anyone used the Comp Cams Ultra Magnum Xd roller rockers? Thinking about stepping up to these in a 1.6 ratio vs the 1.5 Harland Sharp that I currently have. Thoughts on increasing rocker ratio?

vortecpro
Guru
Guru
Posts: 1080
Joined: Fri Apr 24, 2009 11:10 pm

Re: SBC Horsepower estimate

Post by vortecpro » Sun Nov 05, 2017 9:33 am

Frankshaft wrote:
Thu Aug 17, 2017 9:47 am
I had a similar engine years ago for my 73 Camaro, 406, had rebuilt stock 5.565 rods with arp bolts, stock crank ground .010/.010, trw forged replacement dish pistons, it was about 9.5:1, sportsman 2's, bowl ported, elgin hyd flat tappet cam, 244/244 .510 lift on 108 lobe sep, victor jr intake for hood clearance, fit under my flat stock hood with a drop base air cleaner, nd a 3310 holley with choke horn milled off. Made just shy of 500hp and 488 ft/lbs. A perf rpm dual plane, it was a hair over 500 ft/lbs and lost about 10 peak hp, but wouldn't fit under my hood. It was a snappy, fun street engine.
71 Camaro, turbo 350, 3.73/4.10 gear, power steering, 275 drag radials, 3290 weight, always driven to the track, 406, 5.7 GM rods, Isky .520/240/108 flattappet, Edel RPM heads, Air gap intake, Hyp pistons. 10.60s @ 122.7
Racing a NA NHRA stocker should be mandatory before any posting.

Monza355
Pro
Pro
Posts: 222
Joined: Sat Dec 07, 2013 6:06 pm

Re: SBC Horsepower estimate

Post by Monza355 » Sun Nov 05, 2017 4:48 pm

vortecpro wrote:
Sun Nov 05, 2017 9:33 am
Frankshaft wrote:
Thu Aug 17, 2017 9:47 am
I had a similar engine years ago for my 73 Camaro, 406, had rebuilt stock 5.565 rods with arp bolts, stock crank ground .010/.010, trw forged replacement dish pistons, it was about 9.5:1, sportsman 2's, bowl ported, elgin hyd flat tappet cam, 244/244 .510 lift on 108 lobe sep, victor jr intake for hood clearance, fit under my flat stock hood with a drop base air cleaner, nd a 3310 holley with choke horn milled off. Made just shy of 500hp and 488 ft/lbs. A perf rpm dual plane, it was a hair over 500 ft/lbs and lost about 10 peak hp, but wouldn't fit under my hood. It was a snappy, fun street engine.
71 Camaro, turbo 350, 3.73/4.10 gear, power steering, 275 drag radials, 3290 weight, always driven to the track, 406, 5.7 GM rods, Isky .520/240/108 flattappet, Edel RPM heads, Air gap intake, Hyp pistons. 10.60s @ 122.7
Very impressive. What converter & compression ratio ?

kirkwoodken
Guru
Guru
Posts: 1501
Joined: Thu Dec 06, 2007 11:35 pm

Re: SBC Horsepower estimate

Post by kirkwoodken » Mon Nov 06, 2017 1:29 am

I worked on 4 or 5 DZ's back in 68. Rejetted with 72 or 73 jets, added 1 5/8" headers, recurved dist 18 initial and 20 advance, usually ran 38-42 total, checked for good ring seal and valve leakage, ran 1" open carb spacers, 140 cam and springs. Some heads required longer pushrods. Changed rear to 4.88's if they had 3.73's. 160* thermostats. Pin the studs. Slicks on 1955 rims. Slapper bars. CR 4 speeds with shields. They all ran mid 12's.

My first Z was a slug off the showroom floor. I bought the car as a demo. Did most of the above on that car except stayed with the 30-30 advanced 8* and didn't add a spacer under the carb. It came with 3.73 gears and would go 70 MPH in 1st gear.

30-30, 3.73, 2.2 first, retarded timing, lean front jets, AC-42-1 plugs, 195 thermostat, rocker arms hitting the edge of the valve stems, restrictive exhaust, left side mounted fan belt that always flew off, rear end that hammered when you dropped the clutch, spaghetti shift linkage, and a clutch that stuck to the floor at high revs. Not to mention the drive shafts made without the yokes aligned. What were they smoking?

Still, when everything was fixed, the 3500# car ran mid 12's. That's around the 370 HP range. Not too shabby for a streetable 302. And every one of them were capable of doing at least that. Adding a roller back then meant you had a 302 that could beat just about anything, and Herbert sold one for $100. Isky made a "Track Grind" gear drive roller cam which worked very well on the street in the little DZ. And the cowl fed cold air cleaner added a few more HP if you could afford one. Only $140 back then. The FIRST purchase for my Z was a scatter shield. I would not work on anyone's solid lifter car unless they installed a shield.
"Life is too short to not run a solid roller cam."
"Anything is possible, if you don't know what you're talking about."
I am NOT an Expert, and DEFINITELY NOT a GURU.
Kirkwoodken

User avatar
MadBill
Guru
Guru
Posts: 12706
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: SBC Horsepower estimate

Post by MadBill » Mon Nov 06, 2017 1:12 pm

kirkwoodken wrote:
Mon Nov 06, 2017 1:29 am
..Not to mention the drive shafts made without the yokes aligned. What were they smoking?
Ha, I can speak to that one! Back in the mid-seventies, tracking a driveline vibration in my buddy's '71 Z28, I discovered the yokes were misaligned ~ 20°. He had done a couple of seasons drag racing on 10" slicks, so we chalked it up to twist and had it repaired. Didn't seem to make much difference.
Many years later, I learned that GM built them that way to add some kind of preload and reduce gear rattle. #-o
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

kirkwoodken
Guru
Guru
Posts: 1501
Joined: Thu Dec 06, 2007 11:35 pm

Re: SBC Horsepower estimate

Post by kirkwoodken » Mon Nov 06, 2017 6:05 pm

SUPPOSEDLY, the yolks were off-set because the engine sat to one side of the car, not on center line with the companion flange. With 4.88 gears, the whole car shook. A short phone call to Smokey supplied the cure. I would have never thought a factory would have off-timed yolks for any reason.

I always advanced the 30-30 8* with the only street driven Z/28's, and loosened the lifters another .005". That seemed to get the cam away from its mushy
position. As noisy as the lifters were, another .005" didn't make much more noise. With the old Micky Thompson non-roller aluminum rockers, the engines sounded like they had hydraulics. I also ran the Rochester F.I. DP distributor in my own Z, was Bill Jenkin's favorite in his "Toy" series. I didn't copy that from him. It was just the best performer on the distributor machine. No point float at 8000 RPM with D112PS points. What great stuff they used to make in the Old Days.

FWIW, my first Z went 6600 in 4th gear with 3.73's. About 135 with only jet changes and timing work. Wasn't pulling hard at that speed but I was running out of space.
"Life is too short to not run a solid roller cam."
"Anything is possible, if you don't know what you're talking about."
I am NOT an Expert, and DEFINITELY NOT a GURU.
Kirkwoodken

vortecpro
Guru
Guru
Posts: 1080
Joined: Fri Apr 24, 2009 11:10 pm

Re: SBC Horsepower estimate

Post by vortecpro » Mon Nov 06, 2017 7:17 pm

Monza355 wrote:
Sun Nov 05, 2017 4:48 pm
vortecpro wrote:
Sun Nov 05, 2017 9:33 am
Frankshaft wrote:
Thu Aug 17, 2017 9:47 am
I had a similar engine years ago for my 73 Camaro, 406, had rebuilt stock 5.565 rods with arp bolts, stock crank ground .010/.010, trw forged replacement dish pistons, it was about 9.5:1, sportsman 2's, bowl ported, elgin hyd flat tappet cam, 244/244 .510 lift on 108 lobe sep, victor jr intake for hood clearance, fit under my flat stock hood with a drop base air cleaner, nd a 3310 holley with choke horn milled off. Made just shy of 500hp and 488 ft/lbs. A perf rpm dual plane, it was a hair over 500 ft/lbs and lost about 10 peak hp, but wouldn't fit under my hood. It was a snappy, fun street engine.
71 Camaro, turbo 350, 3.73/4.10 gear, power steering, 275 drag radials, 3290 weight, always driven to the track, 406, 5.7 GM rods, Isky .520/240/108 flattappet, Edel RPM heads, Air gap intake, Hyp pistons. 10.60s @ 122.7
Very impressive. What converter & compression ratio ?
Probably around 11.0, converter was a 8 inch Munsinger.
Racing a NA NHRA stocker should be mandatory before any posting.

User avatar
MadBill
Guru
Guru
Posts: 12706
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: SBC Horsepower estimate

Post by MadBill » Mon Nov 06, 2017 9:55 pm

With plenty of throttle to spare, my '70 -1/2 Z28 with 12:1, xxx140 cam, cross-ram, headers, 3" exhaust, etc. pulled 7500 in 4th with 26.5" tires and 4.10:1 gears. (144 MPH), but then... #-o
.
Broken Rod 001.JPG
You do not have the required permissions to view the files attached to this post.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

Post Reply