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billonwheels 06-12-2012 08:18 PM

I'm also building a 455
 
3 Attachment(s)
I was wondering what my Horse Power would be on my 1971 HO 455 Pontiac. I've heard it would be less than the factory, (330). I can't belive that. I have a 278 duration cam and lifters from Edelbrock, Edelbrock Perfomer manifold (spread Bore), it's bored 30 over with a Edelbrock 1411 750 Electric Carb. Roller rocker arms, Edelbrock 110 fuel pump, with a HEI dizzy. TH 400 Trans rebuilt with a B&M 2500 stall and B&M shift kit. The engine had 70000 original miles on it. My guy that did the machine work says at least 425 HP, 495 torque. Another guy that build engins says I went backward in horsepower, SMH.....everything I've read says 425 is a realistic number. I even got the billet pullies and an electric fan.... :confused:

cobalt327 06-12-2012 10:04 PM

Quote:

Originally Posted by billonwheels
I was wondering what my Horse Power would be on my 1971 HO 455 Pontiac. I've heard it would be less than the factory, (330). I can't belive that. I have a 278 duration cam and lifters from Edelbrock, Edelbrock Perfomer manifold (spread Bore), it's bored 30 over with a Edelbrock 1411 750 Electric Carb. Roller rocker arms, Edelbrock 110 fuel pump, with a HEI dizzy. TH 400 Trans rebuilt with a B&M 2500 stall and B&M shift kit. The engine had 70000 original miles on it. My guy that did the machine work says at least 425 HP, 495 torque. Another guy that build engins says I went backward in horsepower, SMH.....everything I've read says 425 is a realistic number. I even got the billet pullies and an electric fan.... :confused:

It depends on how much work (if any) was done to the D-ports on the engine now. If it had the original heads it might be making more power than the estimated 425 hp and 495 ft/lb.

It should be a strong running combo, though. Easy 12's. If you take it to the track or if you've already been, the mph and weight will give you a good estimate of the hp.

I would be a little concerned the TC stall might be higher than 2500 if that estimate was based on a 350 SBC like many converters are. Hopefully the actual stall speed is at or below the torque peak.

68NovaSS 06-12-2012 10:32 PM

I've split this into it's own thread, please do not hijack other threads, make your own.

Mr. P-Body 06-13-2012 12:10 PM

A '71 455HO has "round port" heads. Large chamber, though.

We recently built one ('71 455HO) for a man in Mass. He dynoed it just Monday (chassis, '69 GTO). Heads were ported to 250 CFM @ .600 (int). Comp solid roller 236/242 @ .050, .620 lift. Torker II, AED 850HO, Super Comps.

With 93 octane, it made 407 RWHP and 435 RWTQ. That "converts" to about 480-500 GBHP and 540 or so lb. ft.

I doubt you're making more than 400 -420 HP with that Edelbrock cam ("generi-grind"). But you ARE probably making 500 lb. ft.

Dave took his car to the track a couple weeks back (same car). It went 12.32 @ 111 (best ET) and 12.45 @ 114 (best MPH). 60' times were in the toilet, as he had "street" tires (1.9-2.0). 3,810 lbs. with him in it (weighed on the track scales). With good traction, easily an 11 second car.

FWIW

Jim

billonwheels 10-14-2012 09:10 PM

I'm happy with how my Grand Prix's running. What type of cam do you suggest to get more out of my Pontiac? Just curious, My buddy has a 72 Lemans with a 400 bored 30 over and he's dying to run me smh. I dont think he willbe able to keep up.....

AutoGear 10-15-2012 09:16 AM

262XE would be my guess (from Comp) or similar in say the VooDoo line from Lunati.

Edelbrock cams, for the most part are all catalog grinds from probably the late 70s; made by one or 2 companies and boxed for several vendors.


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