HP rating for factory block

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supernova
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HP rating for factory block

#1 Post by supernova » Thu Mar 04, 2010 7:00 am

Does anyone know how much power a GM factory tall deck block will handle and live?
I've been told they will handle 1200 hp but that sounds like a lot.
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1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#2 Post by sc racing » Thu Mar 04, 2010 8:24 am

Not the same but we did a stock std deck 454 filled to the waterpump holes it made 1400hp. I think filling the block plays a big part.

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Re: HP rating for factory block

#3 Post by CDR Performance » Thu Mar 04, 2010 8:52 am

Most factory BBC stuff may be good to 1000-1200. We have seen block failure @ 1200 hp +.
Over 600 hp we always recommend front and mid plates. This will reduce cylinder wall distortion.
When using plate always incorporate fore and aft engine limiters as, the plate can flex in this plane.
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Re: HP rating for factory block

#4 Post by supernova » Thu Mar 04, 2010 9:17 am

My engine is in the car with solid motor mounts (class rule to prove the motor is in the stock location), front and back motor plates and limiters. The block is filled to the water pump holes.
I would like to put more nitrous on it and run a new class that is a 5.30 1/8 mi. cap class but am not sure what the block will handle.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#5 Post by K-Star Automotive » Thu Mar 04, 2010 11:19 am

The single biggest thing that will kill it at those levels is detonation. If you ring it one time good and hard you will probably have pieces. Keep a close eye on the tune and if you don't know how, spend some time researching how to correctly read spark plugs.

Another little tid-bit for you is, keep and eye on the valve cover bolts. If they are always coming loose, it's in detonation at some point in the run.


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supernova
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Re: HP rating for factory block

#6 Post by supernova » Thu Mar 04, 2010 11:54 am

Thanks for the info everyone. Good stuff.

The class I normally run is a carb limited class. A 4150 carb only. I have a Pro Systems 1000 hp Holley so I don't even know if it will run the # with carb restiction and there is too many things to change at this point to put a dominator on it. I'll just have to pill it up and see how fast it will go when the time come.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#7 Post by CDR Performance » Fri Mar 05, 2010 5:18 am

Do you have link to the class rules?
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Re: HP rating for factory block

#8 Post by John_Heard » Fri Mar 05, 2010 7:02 am

The old tall deck 505 I had in my car was making I'd guess 800 hp or so N/A, would run 9.90's @ 3400 with tall gears and tight converter, 8.70's on a 300 shot but could have went faster with more tuning I think. It was a filled block that originally came from an old promod with a big ol huffer on it. No problems with the block, it was a Marine model with 4 bolt mains on each cap. Those are some pretty good old blocks, only issue is small bore which might hurt air flow some, along with the whole bore vs stroke design thing.

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Re: HP rating for factory block

#9 Post by supernova » Fri Mar 05, 2010 8:35 am

CDR Performance wrote:Do you have link to the class rules?
here's the rules page for the true street class. With the nitrous cap the class is about a 5.50-5.70 1/8 et class. I would also like to run the new 5.30 et class the only has 2 rules, 275-60 D/R's only and no wheelie bars.
I want to pill up the nitrous and see if it can run closer to the 5.30 mark but no sure what the block will take.

http://www.texastrueten5.com/Rules/True ... fault.aspx
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#10 Post by supernova » Fri Mar 05, 2010 8:46 am

John_Heard wrote:The old tall deck 505 I had in my car was making I'd guess 800 hp or so N/A, would run 9.90's @ 3400 with tall gears and tight converter, 8.70's on a 300 shot but could have went faster with more tuning I think. It was a filled block that originally came from an old promod with a big ol huffer on it. No problems with the block, it was a Marine model with 4 bolt mains on each cap. Those are some pretty good old blocks, only issue is small bore which might hurt air flow some, along with the whole bore vs stroke design thing.
Hey John,
The block is a 74 model truck tall deck that had never been apart when I got it so ib was not a hot rod motor. No damage no issues. It is a 4 bolt main on all mains and I had the core check for shift and it had perfect core shift.
My motor is a 4.310 bore and 4.500 stroke, 525ci. It should make 830+ n/a.
It will take a 350+ hp nitrous hit to make enough power to get close to a 5.30 but that could be death to my block. They did change the rule in the true street class to allow after market blocks but I don't have time or the money to change that right now. I can latter this yr.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#11 Post by John_Heard » Fri Mar 05, 2010 9:07 am

Spray the snot out of it, I don't think you're going to hurt that block.

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Re: HP rating for factory block

#12 Post by supernova » Fri Mar 05, 2010 10:01 am

I'm shooting for April 16 for the first 5.30 et race. I guess we'll find out then. :scratch:
Last edited by supernova on Sun Mar 07, 2010 9:50 am, edited 1 time in total.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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Re: HP rating for factory block

#13 Post by wikd69 » Sun Mar 07, 2010 4:10 am

supernova wrote:I'm shooting for April 19 for the first 5.30 et race. I guess we'll find out then. :scratch:
Are you really ? Cool beans !!!!!! :D :D :thumb:

I didn't think you were that close. Man, I may have to figure out how to do a Customer visit in the DFW area sometime around there. :mrgreen:
1969 ProStreet Camaro RS Best 9.75@139 1.46 60'
Blown 427 BBC, TH400 w/Brake, Back-Half Ladderbar
Narrowed 12-Bolt, 4.10 Gears, Spool, Moser 33 Spline

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Re: HP rating for factory block

#14 Post by hsutton » Sun Mar 07, 2010 6:20 am

supernova wrote:
John_Heard wrote:The old tall deck 505 I had in my car was making I'd guess 800 hp or so N/A, would run 9.90's @ 3400 with tall gears and tight converter, 8.70's on a 300 shot but could have went faster with more tuning I think. It was a filled block that originally came from an old promod with a big ol huffer on it. No problems with the block, it was a Marine model with 4 bolt mains on each cap. Those are some pretty good old blocks, only issue is small bore which might hurt air flow some, along with the whole bore vs stroke design thing.
Hey John,
The block is a 74 model truck tall deck that had never been apart when I got it so ib was not a hot rod motor. No damage no issues. It is a 4 bolt main on all mains and I had the core check for shift and it had perfect core shift.
My motor is a 4.310 bore and 4.500 stroke, 525ci. It should make 830+ n/a.
It will take a 350+ hp nitrous hit to make enough power to get close to a 5.30 but that could be death to my block. They did change the rule in the true street class to allow after market blocks but I don't have time or the money to change that right now. I can latter this yr.
How heavy is the car and what body style? Not likely its going to make over 800 h.p. and still respond to a lot of nitrous. It will probably take more nitrous than that if the car is a G.M. "A" body, like a Chevelle. It is also not likely that a stock block is going to clear a 4.5" stroke. The biggest that a stock block can handle is about a 4.25". The rails can't be ground on much before you hit water or the main bearing oil feeds which go down the side of the block. The Bowtie CNCs and the aftermarket blocks, Dart and Merlin, have relocated the main bearing oil feeds with a priority main system to eliminate this problem. The thicker cylinder walls will also be much more rigid but the block will weigh another 60 lbs., or thereabouts, (220 vs. 280).

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Re: HP rating for factory block

#15 Post by supernova » Sun Mar 07, 2010 9:28 am

First off I'm not going to argue with you over my factory tall deck truck that has a 4.5 stroke in it and has run with no oil or water problems. The motor made on the dyno 756 hp with out of the box Darts heads and an old team-g intake. Now the heads have been fully ported and polished, back cut valves, flowed 411 cfm's, new intake edy 454 td worked over to watch and flow with the heads, new cam....... I am sure with out go to the dyno that it will make at least 70-80 more hp than it did prior the all the new work. And NO, I'm not putting back on the dyno.

Now then, Here's your lesson for the day!!!! My motor is big relative to a stock 427-454ci motor (mine, 525ci). Where do you think mountain motors came from 30 yr's ago? Putting a 4.5 stroke in a tall deck block is not new.... A big motor is a big motor no matter how you slice. Now my motor isn't that big compaired to the Pro Mod nitrous motor of today which now can be over 800 ci's, but 30 yr's ago factory blocks is all they had to work with. Ok here's the lesson on nitrius. bigger motors like more NITROUS!!!!!! The bigger the motor the more nitrous it can handle.......... Thats all I have to say about that!!!!!!

I'm not trying to start bs with you but please do your homework before pop'in off...................

Stock block with a 4.5 in. stroke running!
http://www.youtube.com/watch?v=JOfNk2SykqU

My car weights 3400 lbs with me in it. Here's a pic.
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Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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