Gross Horsepower LT-5 - ZR-1 Net Registry Forums

mrx86 · 10-22-2012

Hello Guys.

a question:

OK the Stock 90 ZR-1 have 375 HP.
And the "Gross Horsepower" Rating is for this Engine ???
440 HP or less ?

What do you think?

Bye
Mrx86.

Kevin · 10-22-2012

there's a section in the drivers book and the coffee table book, I think, that talks about this. I don't have either with me right now or i'd be able to answer you. if you have the two books i'm talking about, they're in the owners kit, you can find them yourself. i'm sure someone else can get it to you before I do which will be tomorrow at the earliest

XfireZ51 · 10-22-2012

Quote:

Originally Posted by mrx86

Hello Guys.

a question:

OK the Stock 90 ZR-1 have 375 HP.
And the "Gross Horsepower" Rating is for this Engine ???
440 HP or less ?

What do you think?

Bye
Mrx86.

Are you asking about not SAE CORRECTED? Or gross without accessories?

1990 quasar blue · 10-22-2012

I believe the answer he's looking for is without accessories. If memory serves it's 425 but I'll have to double check.

ghlkal · 10-22-2012

I have the coffee table book here, but I can't find gross numbers (although I may have missed it). It does state 375 SAE net on a number of pages though

mike100 · 10-23-2012

The SAE numbers seem like a much more practical measure. There was so much going on gaming the system to cheat the insurance companies..or maybe the other way around faking the funk to lure customers with overrated claims.

the 1970 hemi was rated at 425 hp at 5000 rpm (officially), but I heard it made 470hp if you revved it out to 6000 rpm...and probably more than 500 if you put headers on it.

tomtom72 · 10-23-2012

Our 375 and then 405 ratings are what used to be called "gross" hp back in the old days of the 60's & early 70's.

The OE's used to rate each type engine without any accessories in a test cell. That was the number they gave to the world at large as how much hp the motor produced. I guess the insurance industry used that number for the risk level of a car???? Anyway there was much skullduggery going on. In 1971 the SAE folks wanted some accessories to be included; by '72 it was agreed that a motor should be tested with all it's accessories in place and with the exhaust manifolds and later CATs in place ( I'm 100% sure about the CATs ) and that hp figure would be called SAE corrected net hp. They were trying to get as close to "as installed" as they could to give a hp figure. I figure that would include W/P, Alt, A.I.R. pump, P/S, exh manifolds, all emissions' controls and programing. Anyway, since 72 all engines are tested in this formula (?) to give apples to apples numbers and no funny stuff.

As an example, since I had one of these, the 70 C3 LT-1 yielded 370 hp @ 4800 rpm; a 71 C3 LT-1 yielded 330 hp @ 4800 rpm; a 72 C3 LT-1 = 255 hp @ same rpm. The only running mechanical changes were larger combustion chamber heads for 71 & 72 vs 70; cams were made a bit milder as time went on proly due to CC size, 64 cc chambers in 70 to 76 cc chambers in 71 & 72. The blocks, pistons & rings & rods and piston top ring to deck measurement at TDC remained the same. Im my 72's owners manual the graphs for hp and T/Q stopped at 4800 rpm unlike our graphs that run out to the real peak rpm points. So I'm guessing that the SAE also eventually required the OE's not play games with the rpm that they used to get a max reading.

Tom

Kevin · 10-23-2012

tom,
I don't believe that's true. http://ateupwithmotor.com/automotive...orsepower.html

i used to know what the gross rating was since I hung around with classic muscle car guys but I've long since forgot it

mrx86 · 10-23-2012

OK

how much have the "90 ZR-1" SAE Gross Horsepower
without accessories now ???

90 LT-5 ZR-1 5.7L Stock:
SAE NET Horsepoer = 375HP
SAE GROSS Horsepower (without accessories) = "unknown spirit"

some specialists say 440 HP.

has not measured?
(measurement method as in 60 years...)

Bye

Hog · 10-23-2012

Gross hp
SAE net 70's
SAE "Certified" Power started with the LS7 in 2006 which is rated at 505hp/470 lb/ft SAE Certified using the J2723 which is a voluntary 3rd party rating in addition to the J1349 rating of Aug 2004.

http://www.sae.org/certifiedpower/details.htm

The 375hp and 405 hp LT5's are rated using SAE net hp, certainly not gross rating methods.

The 92-97 LT1 5.7 had a net raing of 300hp, which was about 377-78 gross hp which made it the highest output SBC in history eclipsing the 375hp fuelie 327 and 370hp LT-1 350.

peace
Hog

10-22-2012	#1
mrx86 Join Date: Dec 2008 Location: Switzerland Posts: 28	Gross Horsepower LT-5 Hello Guys. a question: OK the Stock 90 ZR-1 have 375 HP. And the "Gross Horsepower" Rating is for this Engine ??? 440 HP or less ? What do you think? Bye Mrx86.

10-22-2012	#2
Kevin Join Date: Jun 2005 Location: pittsburgh Posts: 4,632	Re: Gross Horsepower LT-5 there's a section in the drivers book and the coffee table book, I think, that talks about this. I don't have either with me right now or i'd be able to answer you. if you have the two books i'm talking about, they're in the owners kit, you can find them yourself. i'm sure someone else can get it to you before I do which will be tomorrow at the earliest __________________ It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B"

10-22-2012	#4
1990 quasar blue Join Date: Feb 2004 Location: Ma Posts: 404	Re: Gross Horsepower LT-5 I believe the answer he's looking for is without accessories. If memory serves it's 425 but I'll have to double check. __________________ 1990 ZR1 #2574 Medium Quasar Blue Metallic 1 of 19

10-22-2012	#5
ghlkal Join Date: Jan 2012 Location: Wisconsin Posts: 887	Re: Gross Horsepower LT-5 I have the coffee table book here, but I can't find gross numbers (although I may have missed it). It does state 375 SAE net on a number of pages though

10-23-2012	#6
mike100 Join Date: Feb 2011 Location: San Marcos CA Posts: 1,802	Re: Gross Horsepower LT-5 The SAE numbers seem like a much more practical measure. There was so much going on gaming the system to cheat the insurance companies..or maybe the other way around faking the funk to lure customers with overrated claims. the 1970 hemi was rated at 425 hp at 5000 rpm (officially), but I heard it made 470hp if you revved it out to 6000 rpm...and probably more than 500 if you put headers on it.

10-23-2012	#7
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,645	Re: Gross Horsepower LT-5 Our 375 and then 405 ratings are what used to be called "gross" hp back in the old days of the 60's & early 70's. The OE's used to rate each type engine without any accessories in a test cell. That was the number they gave to the world at large as how much hp the motor produced. I guess the insurance industry used that number for the risk level of a car???? Anyway there was much skullduggery going on. In 1971 the SAE folks wanted some accessories to be included; by '72 it was agreed that a motor should be tested with all it's accessories in place and with the exhaust manifolds and later CATs in place ( I'm 100% sure about the CATs ) and that hp figure would be called SAE corrected net hp. They were trying to get as close to "as installed" as they could to give a hp figure. I figure that would include W/P, Alt, A.I.R. pump, P/S, exh manifolds, all emissions' controls and programing. Anyway, since 72 all engines are tested in this formula (?) to give apples to apples numbers and no funny stuff. As an example, since I had one of these, the 70 C3 LT-1 yielded 370 hp @ 4800 rpm; a 71 C3 LT-1 yielded 330 hp @ 4800 rpm; a 72 C3 LT-1 = 255 hp @ same rpm. The only running mechanical changes were larger combustion chamber heads for 71 & 72 vs 70; cams were made a bit milder as time went on proly due to CC size, 64 cc chambers in 70 to 76 cc chambers in 71 & 72. The blocks, pistons & rings & rods and piston top ring to deck measurement at TDC remained the same. Im my 72's owners manual the graphs for hp and T/Q stopped at 4800 rpm unlike our graphs that run out to the real peak rpm points. So I'm guessing that the SAE also eventually required the OE's not play games with the rpm that they used to get a max reading. Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

10-23-2012	#8
Kevin Join Date: Jun 2005 Location: pittsburgh Posts: 4,632	Re: Gross Horsepower LT-5 tom, I don't believe that's true. http://ateupwithmotor.com/automotive...orsepower.html i used to know what the gross rating was since I hung around with classic muscle car guys but I've long since forgot it __________________ It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B"

10-23-2012	#9
mrx86 Join Date: Dec 2008 Location: Switzerland Posts: 28	Re: Gross Horsepower LT-5 OK how much have the "90 ZR-1" SAE Gross Horsepower without accessories now ??? 90 LT-5 ZR-1 5.7L Stock: SAE NET Horsepoer = 375HP SAE GROSS Horsepower (without accessories) = "unknown spirit" some specialists say 440 HP. has not measured? (measurement method as in 60 years...) Bye

10-23-2012	#10
Hog Join Date: Jul 2010 Location: Woodstock, Ontario, Canada Posts: 1,275	Re: Gross Horsepower LT-5 Gross hp SAE net 70's SAE "Certified" Power started with the LS7 in 2006 which is rated at 505hp/470 lb/ft SAE Certified using the J2723 which is a voluntary 3rd party rating in addition to the J1349 rating of Aug 2004. http://www.sae.org/certifiedpower/details.htm The 375hp and 405 hp LT5's are rated using SAE net hp, certainly not gross rating methods. The 92-97 LT1 5.7 had a net raing of 300hp, which was about 377-78 gross hp which made it the highest output SBC in history eclipsing the 375hp fuelie 327 and 370hp LT-1 350. peace Hog