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Old 12-02-2007, 11:45 AM
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Looking for horsepower for my engine

Can someone put these specs in their computer program to see what the estimated horsepower should be;

350 chevy 4 bolt main block bored .040
Scat stock cast iron crank, normal stroke
6'' rods
Crower solid cam; .504 lift exhaust, .483 lift intake
Ported and polished '78 era heads 1.94I 1.5 E 76cc chambers
I used a shim gasket to get cr at 10:1
Pistons are KB hyperutectic 11:1
Intake manifold is an RPM air gap
The carburator is a holley 750 with vacuum secondaries
I am also using Harland sharp roller rockers
dynomax headers w/ 1 5/8 diameter tubes

I am estimating around 350 - 375 but just wanted to see what the computer said.

As always, thanks for any and all responses,

rob
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Old 12-02-2007, 01:00 PM
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Even so I`m no help on a dyno figure, I will say you got a heck of a combo going, but the heads throw it off, why run all that equipment for horsepower only to be held back by the heads? If I had a combo I was building like that, I would build it around the heads, meaning I would have started with a aftermarket set of heads. You can get a set of RHS 190cc runner heads that won`t break the bank.
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Old 12-02-2007, 02:14 PM
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You've pretty well nailed it. Have you ever had it at the track? The Q/M mph and car weight are very good for indicating the engine's real power.
The heads have got to go.
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Old 12-03-2007, 07:37 AM
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we need the cam duration at 0.050" to make a good guess. LSA would also be nice to have.

but judging from the lift the cam duration should be about 225-230 on the intake and 230 to 235 on the exhaust.

365 to 375hp would be a good guess.

another 40 or 50hp with a set of afr's
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Old 12-04-2007, 04:45 AM
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More Horsepower

Put some chrome on it, everyone knows that chrome adds horsepower
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Old 12-05-2007, 07:47 PM
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Yep, I know the heads need to go. I got them cheap and in good shape, so I cleaned them up, removed the casting flash/ridges in the runners, valve bowl area/exhaust port, etc. I extimated a gain in cfm of 15 on the intake side and 30 on the exhaust side give or take a little. The idea was that a 1.94 head will have a little more velocity that a 2.02 head, the motor was not going to see more than 6500rpm, and with only a .08 difference between the two, I opted out of getting the 2.02 heads

I have since changed my mind, the January '08 issue of stock car racing magazine had an article featuring several heads that got my attention;
- Engine Quest EQ 23 heads
- Dart Platinum Iron Eagles
-RHS Pro Action Cylinder Heads

Right out of the box, either one of these heads will help make over 500 hp with some other key componets.
I am leaning toward the EQ 23 heads.

Also, the part number for the cam in my motor is 274SF from Crower.
Advertised camshaft specifications are;
Intake duration: 274 degrees .482 lift
Exhaust duration: 282 degrees .504lift

I installed the cam "dot to dot" as per OEM specs. I did not degree the cam.
If I degreed the cam the duration at .050 lift is as follows;
Intake: 242deg
Exhaust: 248deg
Intake: .321
Exhaust: .336

Hope this helps on getting a decent Hp figure using someone dyno program.

Thanks for all the responses.
Robert
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Old 12-06-2007, 07:05 AM
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242/248 is bigger than I guessed. The lift is a little low for that duration but lower lift will be better for cam wear and valve control. I would say your engine could be making a little over 400hp if the carb and ignition curve is tuned right.

A dyno program might even predict 435hp+. It all depends on the head flow which is kind of hard to get right unless the heads have been measured on a flow bench. And even with that, a dyno program will most likely over estimate.

I use the dart iron eagles 200cc and like them very much. However, I'm pretty sure I would also like afr's or edelbrock heads. My engine (362, 11;1 cr) is making about 450hp with a 292H compcam (244/244 duration, 0.501 lift) with the dart heads. I base my estimate on 120 mph trap speed in the 1/4 mile and a 2800 pound car.
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