GMPP block/hp ratings
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GMPP block/hp ratings
A thread in "Forced Induction" started me thinking. The guy was asking about a Procharger F3R in a 4th gen, and then got miffed when people (myself included) suggested that this blower was maybe a tad to big for a stock block.
But it got me thinking. The GM Performance Parts catalog has a table listing various small blocks. The table includes a column listing hp ratings for the various Bowtie blocks. The numbers are very conservative. In the range of 650-800hp (I don't have the catalog in front of me). Many people are pushing more with a stock block, let alone a race block. So the numbers are obviously way conservative. Anyone know where these numbers come from? I assume it's more than a guess.
Rich Krause
But it got me thinking. The GM Performance Parts catalog has a table listing various small blocks. The table includes a column listing hp ratings for the various Bowtie blocks. The numbers are very conservative. In the range of 650-800hp (I don't have the catalog in front of me). Many people are pushing more with a stock block, let alone a race block. So the numbers are obviously way conservative. Anyone know where these numbers come from? I assume it's more than a guess.
Rich Krause
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Way conservative, yeah. When 850hp Winston Cup guys use them and that's the blocks max capabilty per GM.
You wonder what they would build a 2,200hp Turbo Small Block out of?
This sounds like a good question for my father.
Bret
You wonder what they would build a 2,200hp Turbo Small Block out of?
This sounds like a good question for my father.
Bret
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Originally posted by SStrokerAce
Way conservative, yeah. When 850hp Winston Cup guys use them and that's the blocks max capabilty per GM.
You wonder what they would build a 2,200hp Turbo Small Block out of?
This sounds like a good question for my father.
Bret
Way conservative, yeah. When 850hp Winston Cup guys use them and that's the blocks max capabilty per GM.
You wonder what they would build a 2,200hp Turbo Small Block out of?
This sounds like a good question for my father.
Bret
Rich Krause
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From: Grand Rapids, Mi USA
Your guy to ask about this is Mike Moran at Moran Motorsports. He is building a Twin Turbo Small Block Chevy 400+ cubic inch and the motor will be using the new Dart 11 deg. Little Chief heads. This motor if I remeber in the conversation was using the GM Performance Parts Rocket Block. This combination should make 1800 to 2000 hp plus. Twin 88mm hair dryers. Motor is being built for Rod Saboury whom will be racing the 2004 season of NSCA.
I just read what Rick said and that is really funny! This past week at the NSCA race at Stanton MI. I was looking at the blower in question (FC3R ProCharger Chain Driven) and I would have to say the guy that is getting bent probably has not ever seen one of these because they are HUGE! And chain driven! This blower was on Ross Stomps new Mustang. The problem with these monsters is they have a problem with breaking the chain and let me tell ya these blowers use a 530 motorcycle chain. Just imagine throwing one these chains at say 200 mph? Scare the **** out ya! This blower would be a touch much for a stock motor or anything along those lines. LOL!!!!! I would bet it probably takes 75 to 150hp just to run one of these.
I just read what Rick said and that is really funny! This past week at the NSCA race at Stanton MI. I was looking at the blower in question (FC3R ProCharger Chain Driven) and I would have to say the guy that is getting bent probably has not ever seen one of these because they are HUGE! And chain driven! This blower was on Ross Stomps new Mustang. The problem with these monsters is they have a problem with breaking the chain and let me tell ya these blowers use a 530 motorcycle chain. Just imagine throwing one these chains at say 200 mph? Scare the **** out ya! This blower would be a touch much for a stock motor or anything along those lines. LOL!!!!! I would bet it probably takes 75 to 150hp just to run one of these.
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My guess is that GM "rates" blocks for hp produced continuously on a durability engine. (eg Winston Cup). IMO, they don't want the block to be the weak link in the chain.
Crunching a few numbers: A Cup engine turns over a million times in a race in anger. Today's race is 300 or so laps where the engines run from about 5600 to 9300 (if you can believe the tv telemetry) 550 times or so figuring in cautions. That's probably over a million revs. Blocks last multiple races, I believe, so obviously they are not being used near their breaking point at 800+ hp.
A 9 second drag car turning 7000 average rpm turns over maybe 1000-1100 revs in anger in one run. A mil divided by 1000 is a 1000 runs. This 9 second car probably has a lot more than 800 hp.
If it's a 1100 or 1200 hp 7 second car will the block last 1000 runs? I seriously doubt anyone has tried to find out.
What's a good max hp figure for a drag engine made from a "rated" block? 1.5 or 2X the "rated" figure???? 1200 - 1600?
How does that equate to a 300 hp production engine block? Even 2 x is only 600 hp, and lots of folks are pushing more than that thru LT1 blocks. There seems to be a hp figure LT1 blocks don't like for very long. Rich is looking for that point, I believe.
My highly-opinionated conjecture, aka a "rectal extraction".
Crunching a few numbers: A Cup engine turns over a million times in a race in anger. Today's race is 300 or so laps where the engines run from about 5600 to 9300 (if you can believe the tv telemetry) 550 times or so figuring in cautions. That's probably over a million revs. Blocks last multiple races, I believe, so obviously they are not being used near their breaking point at 800+ hp.
A 9 second drag car turning 7000 average rpm turns over maybe 1000-1100 revs in anger in one run. A mil divided by 1000 is a 1000 runs. This 9 second car probably has a lot more than 800 hp.
If it's a 1100 or 1200 hp 7 second car will the block last 1000 runs? I seriously doubt anyone has tried to find out.
What's a good max hp figure for a drag engine made from a "rated" block? 1.5 or 2X the "rated" figure???? 1200 - 1600?
How does that equate to a 300 hp production engine block? Even 2 x is only 600 hp, and lots of folks are pushing more than that thru LT1 blocks. There seems to be a hp figure LT1 blocks don't like for very long. Rich is looking for that point, I believe.
My highly-opinionated conjecture, aka a "rectal extraction".
Last edited by OldSStroker; Sep 14, 2003 at 12:15 PM.
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arent they essentially rated for naturally aspirated applications?
sort of the same reasons rod manufacturers dont like to put hp ratings on their rods..... but if pressed might tell you it coult take certain rpm with certain weight pistons...
i'm thinking rpm and maybe torque/displacement are where the block ratings come from, not so much cylinder pressure which would be vastly different in a FI setup
the block is rated for 800hp at both 350ci and 427ci, but is not able to handle all the recip. mass of the 427 and cant turn the same rpms to make 1100hp
increase the cyl pressure with the same parts though.... good for more hp?
sort of the same reasons rod manufacturers dont like to put hp ratings on their rods..... but if pressed might tell you it coult take certain rpm with certain weight pistons...
i'm thinking rpm and maybe torque/displacement are where the block ratings come from, not so much cylinder pressure which would be vastly different in a FI setup
the block is rated for 800hp at both 350ci and 427ci, but is not able to handle all the recip. mass of the 427 and cant turn the same rpms to make 1100hp
increase the cyl pressure with the same parts though.... good for more hp?
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