Crate engine HP ratings??
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,993
Likes: 9
From: Gig Harbor WA
Crate engine HP ratings??
How do the figures for crate engine HP ratings compare with stock engines...in other words, my 72 350 is rated at 200 HP...my new ZZ4 is rated at 355HP...So is the ZZ4 almost twice (1.78X) the HP as the stock 350, all else being equal??
Somebody set me straight!
Somebody set me straight!
Drifting
Joined: Feb 2005
Posts: 1,738
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From: San diego ca
In any case the net numbers as have been mentioned include all accessories and full exhaust as installed in car.
GMPP crate motors (with a few exceptions) are all gross rated - meaning full length headers - no accessories - open exhaust and whatever carb the test cell has on hand.
So in short while it is still more than your 72's 200 hp its closer than it appears to be.
Last edited by fauxrs2; Aug 18, 2007 at 10:07 AM.
Race Director
Joined: May 2005
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From: Millington Illinois
St. Jude Donor '08-'09
35% loss of hp with all accessories and driveline taken into account.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
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From: Connecticut
IIRC 1972 was the 1st year of SAE Net HP ratings, in fact I thought most 72 engines were advertised with both the SAE net and gross numbers. For example the 72 LT1 motor was rated at 255 hp, but it was in fact largely unchanged form the previous years 330hp (i think) rating - the difference? Gross vs. net.
In any case the net numbers as have been mentioned include all accessories and full exhaust as installed in car.
GMPP crate motors (with a few exceptions) are all gross rated - meaning full length headers - no accessories - open exhaust and whatever carb the test cell has on hand.
So in short while it is still more than your 72's 200 hp its closer than it appears to be.
In any case the net numbers as have been mentioned include all accessories and full exhaust as installed in car.
GMPP crate motors (with a few exceptions) are all gross rated - meaning full length headers - no accessories - open exhaust and whatever carb the test cell has on hand.
So in short while it is still more than your 72's 200 hp its closer than it appears to be.
"Starting in 1971 automakers began to quote power in terms of SAE net horsepower (as defined by standard J1349). This reflected the rated power of the engine in as-installed trim, with all accessories and standard intake and exhaust systems. By 1972, US carmakers quoted power exclusively in SAE net hp. The change was meant to 'deflate' power ratings to assuage the auto insurance industry and environmental and safety lobbies, as well as to obfuscate the power losses caused by emissions-control equipment."
A '72 220 HP should be 280+ gross HP.
As fauxrs mentioned, the crates are generally rated at gross HP as there is no sure to calculate which components will be used with the application.
Last edited by Bob Onit; Aug 18, 2007 at 10:17 AM.
Drifting
Joined: Apr 2007
Posts: 1,892
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From: Springfield Illinois
Here we go again!!!
Net or Gross its all the same because its not important! Not to mention, Chevrolet always kept the HP "RATINGS" down to keep insurance prices and taxes down!
Here's a perfect example IMO:
1967-69 corvette L88 427 - 430 HP Gross
2006 - Z06 LS7 427 - 505 HP net
In a drag race, the L88 would beat it in a heavier car w/ bias tires!
The only HP you should be worried about RWHP.
Net or Gross its all the same because its not important! Not to mention, Chevrolet always kept the HP "RATINGS" down to keep insurance prices and taxes down!
Here's a perfect example IMO:
1967-69 corvette L88 427 - 430 HP Gross
2006 - Z06 LS7 427 - 505 HP net
In a drag race, the L88 would beat it in a heavier car w/ bias tires!
The only HP you should be worried about RWHP.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
I also see a few people comparing the "same" engine. What you also have to understand, is that every year they added on more emissions crap and dropped the compression. So for ex. a 70' LT1 is not going to produce the same HP as a 71 LT1 and so on.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,993
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From: Gig Harbor WA
But..all I was originally asking...really... is how much "seat of the pants" difference I'll notice from the tired stock 350/200 (OK..270) to the fresh ZZ4 350/355 (net or gross I could care less!!)Thanks all!!
Melting Slicks
Joined: Mar 2006
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From: Connecticut
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Drifting
Joined: Apr 2007
Posts: 1,892
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From: Springfield Illinois
Your right about it all starts with FWHP. But when your driving your car, it takes HP to turn the alt and w/ all of the accessory pullies, the tranny, and the differential. What I was telling him is to worry about the HP that actually reaches the pavement.
However, it sounds as if he already has the engine. He was just curious and wanted to compare his original engine with the ZZ4. I've heard lots of good things about the engine from people who own them. So I am sure he wont be disappointed.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
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From: Connecticut
I understand your point somewhat John.
I would be willing to bet the ranch that GM does not under rate their crate engines.
Theres would be no benefit to do so and theres plenty of competition as well.
I would be willing to bet the ranch that GM does not under rate their crate engines.
Theres would be no benefit to do so and theres plenty of competition as well.
Drifting
Joined: Dec 2002
Posts: 1,861
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From: New Zealand
....so don't forget about those numbers....have fun with your motor swap
Race Director
Joined: Apr 1999
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From: NM
IIRC 1972 was the 1st year of SAE Net HP ratings, in fact I thought most 72 engines were advertised with both the SAE net and gross numbers. For example the 72 LT1 motor was rated at 255 hp, but it was in fact largely unchanged form the previous years 330hp (i think) rating - the difference? Gross vs. net.
In any case the net numbers as have been mentioned include all accessories and full exhaust as installed in car.
GMPP crate motors (with a few exceptions) are all gross rated - meaning full length headers - no accessories - open exhaust and whatever carb the test cell has on hand.
So in short while it is still more than your 72's 200 hp its closer than it appears to be.
In any case the net numbers as have been mentioned include all accessories and full exhaust as installed in car.
GMPP crate motors (with a few exceptions) are all gross rated - meaning full length headers - no accessories - open exhaust and whatever carb the test cell has on hand.
So in short while it is still more than your 72's 200 hp its closer than it appears to be.
I had this same question so I contacted GMPP direct for an answer. Basicly the "replacement" crate engines are the same as the production engines and carry the same HP. But the engines like the ZZ4 that do not have a production counterpart are rated at GROSS HP. GMPP said that they did not know the type of car the engine would be going into, the intake or exhaust system being used, or the accessories being attached. So all the crate, non-production, engines were rated at GROSS HP.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
Ohh, I agree... I was talking about the engines that actually came in our cars..
Melting Slicks
Joined: Mar 2007
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From: Frederick Maryland
The L88 wasn't under-rated at 430 hp for insurance purposes...it was to dissuade buyers from buying it for street use...it was a pure racing engine. For less money a buyer could get an L71 rated at 435 hp. The racing crowd knew the engine and car for what it was and is.
The rating wasn't really inaccurate...it was 430 hp at the rpm's specified. The published specs just didn't say how much higher the red line was or how the peak horsepower and torque would continue to rise until it hit the redline.
The rating wasn't really inaccurate...it was 430 hp at the rpm's specified. The published specs just didn't say how much higher the red line was or how the peak horsepower and torque would continue to rise until it hit the redline.
