Gross Horsepower LT-5

[Hog]

Originally Posted by Hib Halverson

The only gen II LT1 which made 300 SAE net was the version in Corvettes and it was available from 1992-1996 with automatics and from 1992-1995 with manuals. That engine never made "377-78" gross at the flywheel. More like 340-350 on a good day.

The Camaro used a less powerful version (275-hp SAE net) of the Gen II LT1 from 1993-1997. There also was an even milder version (260-hp SAE net) used in the Caprice and Impala of the mid-90s.

The Gen II LT1 was, also, not the most powerful "traditional" (Gen 1/Gen II) SBC. That honor goes to the LT4, used in 1996 manuals. It made 330 SAE net about about 370-380-gross hp.

.

Obviously I was referring to the 92-96 Y-body Vette LT1, although there isnt much different power productionwise between the F-Body and Y-body LT1(cam, exhaust, air intakes). There were 315hp F-body LT1 engines with optional intakes and exhausts.

You are correct about the LT4 being the highest output GEN I/II engine. The material I was referencing was written in 1994 hence my oversite of the LT4 which was used in the 96 Vettes and the 135 1997 Camaro/Firebirds(which actually use a stock LT1 F-body calibration, for emissions, without the Vette LT4's 6412 rpm rev limit, along with extrude-honed stainless steel exhaust manifolds and balanced and blueprinted longblocks UNLIKE the stock 1996 Y-body LT4's). The LT4 was a great engine, LS1 power in the standard 4" x 3.48" GEN I/II package. 1997 LT4 SS Camaro runs high 12's same as a a stock LS1 equipped 98-02 Camaro, both equipped with the T-56 trans of course.

I respectfully disagree about your LT1 hp assertions.
The 1970 LT-1 was rated at 370 gross hp.
The 1971 LT-1 was rated at 330 gross hp(less cr)
The 1972 LT-1 was rated at 255 SAE net hp. (little difference to the 71 LT-1).
The 92-97 LT1 Y-body engine outputs more gross hp than any GEN I engine, even the 70's 370 hp LT-1 and the 60's 375 gross hp L84. This fact is in print by sources including GM.

To complete the GEN II story, yes, the LT1 was used in the 94-96 B-body(Caprice/Wagon/9C1 Police PAckage,Impala SS, Buick Roadmaster/Wagon), 94-96 Cadillac Fleetwood. Although these LT1's used iron heads which flow slightly more than the aluminum Y/Fbody cousins. All 94-96 iron headed LT1's used the same 191/196 0.412"/.428" 111ºLSA which is also shared by the 1996-2002 L30 Vortec 305 230hp at 4600rpm/280 lb/ft torque at 2800rpm, and 96-2003 L31 Vortec 350 with 255 sae net hp at 4600rpm/330 lb/ft torque at 4600rpm.
This same roller cam is also used in the other "baby" GEN II engine, the 94-96 4.3l 265 cid V8 RPO L99 that made 200 sae net hp and 245 lb/ft torque used in the B bodies. This engine got better fuel economy than the 5.7 LT1. The 4.3 V8 uses a 3" stroke crank and special length 5.94" PM rods coupled with 3.736" Vortec L30 305 pistons to get to the 265 cid. If this 3" 2 piece RMS crank is dropped in any 1 piece RMS 4" bore block and you now have a more modern 5.0 302 SBC engine. GMPP built a GEN II 302 that made over 420hp with 7000rpm capability.



peace
Hog

[mrx86]

OK

The 90 ZR-1 LT5 / 5.7L have Stock SAE Gross 425HP and 375HP net.

The 1968 Camaro ZL-1 7L Stock have SAE Gross 425HP and 376HP net.

The 1971 Dodge Challenger 7L HEMI have SAE Gross 425HP and 350HP net.

The 1968 Ford Mustang 7L GT500KR have SAE Gross 400HP and ??? HP net.



properly ?

Mrx86

[mrx86]

Originally Posted by mrx86

OK

The 90 ZR-1 LT5 / 5.7L have Stock SAE Gross 425HP and 375HP net.

The 1968 Camaro ZL-1 7L Stock have SAE Gross 425HP and 376HP net.

The 1971 Dodge Challenger 7L HEMI have SAE Gross 425HP and 350HP net.

The 1968 Ford Mustang 7L GT500KR have SAE Gross 400HP and ??? HP net.



properly ?

Mrx86

[Hib Halverson]

Originally Posted by Hog

(snip) There were 315hp F-body LT1 engines with optional intakes and exhausts.

And what company put such an engine in a production vehicle?

I respectfully disagree about your LT1 hp assertions.

Disagreement respectfully noted

(snip)The 92-97 LT1 Y-body engine outputs more gross hp than any GEN I engine, even the 70's 370 hp LT-1 and the 60's 375 gross hp L84. This fact is in print by sources including GM.

Ok. If it's in print and GM released the info is should be a simple task for you to post some facts to support your disagreement or at least direct me to some location on the web where I can read those facts.

[Hog]

Originally Posted by Hib Halverson

And what company put such an engine in a production vehicle?

Disagreement respectfully noted

Ok. If it's in print and GM released the info is should be a simple task for you to post some facts to support your disagreement or at least direct me to some location on the web where I can read those facts.

1995 Firehawk, LT1 rated at 315 sae net hp.

1994 Chevrolet Power-The Official Factory Performance Guide" 1994 General Motors Corporation Page 10

There is an actual reference to an actual gross number for the GEN II LT1, but I cant locate it at this time.

peace
Hog

[Paul Workman]

Originally Posted by Hog

1995 Firehawk, LT1 rated at 315 sae net hp.

peace
Hog

Yeah, I ran across one of those driven by a couple gals. It was right after I had finished my top end porting on the Z (somewhere in the 400 at the wheels area) The Firehawk was impressive, and I guess the gals thought they were picking on some ordinary C4, but they were entirely overwhelmed by the Z.

But, back on topic, there's gross and SAE net and RWHP and RWHP "under the curve". JMO, but HP at the wheels, where the rubber meets the road is the only meaningful measurement. Everything else is just so much hot water generated that means nothing, far as performance goes, methinks.

P.

[tpepmeie]

Ok I found the article. March/April 1998 Legend magazine. Page 14 is an article by Graham describing the 93MY changes.

"405 bhp was realized in GM Test 1 spec, which means with full vehicle inlet and exhaust system,

in GM Test 20 form, ie., dyno headers and no inlet restriction the 1993MY engine produced 445 bhp with optimized spark and fuel (LBT/MBT)."

So we have two different GM test specifications, with a 40bhp difference with headers and optimized tuning. What I don't know is what atmospheric correction factor GM uses for each of these tests. I believe it is probably 77F / 990mbar (SAE J1349) conditions, but I can't certain.

Doesn't really answer the original poster's question, but offers some insight into the difference with open headers/intake.

[Hib Halverson]

Originally Posted by tpepmeie

Ok I found the article. March/April 1998 Legend magazine. Page 14 is an article by Graham describing the 93MY changes.

"405 bhp was realized in GM Test 1 spec, which means with full vehicle inlet and exhaust system,

in GM Test 20 form, ie., dyno headers and no inlet restriction the 1993MY engine produced 445 bhp with optimized spark and fuel (LBT/MBT)."

So we have two different GM test specifications, with a 40bhp difference with headers and optimized tuning. What I don't know is what atmospheric correction factor GM uses for each of these tests. I believe it is probably 77F / 990mbar (SAE J1349) conditions, but I can't certain.

Doesn't really answer the original poster's question, but offers some insight into the difference with open headers/intake.

Glad you found the article, "tpepmeie".

Seems I was wrong about the early engines...375 SAE net and 415-hp (rather than 425) gross seems to be the case.

The SAE net is SAE J1349. I've heard of the other test, but never knew what the GM designation was nor do I know the correction, but I'd say you're right on 77°F. It wouldn't make sense that GM would use two different atmospheric corrections.

[Hib Halverson]

Originally Posted by Paul Workman

(snip)
But, back on topic, there's gross and SAE net and RWHP and RWHP "under the curve". JMO, but HP at the wheels, where the rubber meets the road is the only meaningful measurement. Everything else is just so much hot water generated that means nothing, far as performance goes, methinks.

Originally Posted by efnfast

I must agree with Paul, all this manipulation of numbers is meaningless. As Paul said, "where the rubber meets the road". SAE corrected or not, me and the guy next to me are breathing the same air when the right foot hits the floor.

I'm not so sure we should rush to accept the idea that chassis dyno numbers are a true "benchmark" of engine performance.

There are many factors which skew chassis dyno numbers but have nothing to do with engine performance. In no particular order, some of them are:

1) tires...casing design, tread configuration and tread compounding. (I once did a back-to-back test of two tires just comparing tread confiuration and compounding-the tires were both on the same casing design-and the differece was 5-hp at the wheels. Same dyno, same pressure, same vehicle, some IAT and ECT, and tests 10-min. apart.)
2) tire pressure
3) dyno type, inertia or brake
4) single roller, two rollers or no rollers (direct connection to axles)
5) roller surface
6) wheel spin or lack thereof
7) trans type
8) trans lubricant and lubricant temperature.
9) rear axle ratio, lubricant and lubricant temperature
10) powertrain mountings
11) coolant temperature and temperature rise during test
12) different in IAT of more than 7°F regardless of correction
13) technique of dyno operator
14) condition of dyno

So, you see...chassis dyno numbers should be taken with a "grain of salt". They are embraced by the aftermarket performance industry and the enthusiast community because chassis dynos have been well-marketed by their manufacturers, they're loved by the automotive press and widely used by tuners. Chassis dynos are cheap and easy and perfect for bragging rights but fraught with potential inaccuracies.

I'm first to admit to using chassis dyno data all the time. Sometimes I strive to eliminate as many of the potential inaccuracies as possible. Sometimes I don't, but I know in the back of my mind that engine dynamometers are far more accurate devices for comparisons.

As for corrections...the belief that atmospheric corrections don't make a difference is just ridiculous. In fact, when I look at chassis dyno data, I'm more concerned with whether or not a correction has been applied and if so, what correction than I am with the inaccuracies of chassis dynos.

Recently, I was discussing a particular engine modification package with an aftermarket vendor. I asked for some of his confidential test data and he provided it. Same engine, same dyno, same test run...the engine made 646.0-hp "standard" corrected and 613.9-hp SAE-corrected.

See why the aftermarket and braggers like "standard" corrected data rather than SAE-corrected?

But, SAE-corrected is much more characteristic of the real world because of its use of 77°F for intake air temperature.

Lastly...

Originally Posted by scottfab

(snip)
HP #s are great talking points but ETs are better

ETs are either the most inaccurate way to bench mark engines or the most accurate way to benchmark the whole "package"...driver and car.

Do drivers are bragging about their engines. The first driver who majorly sucks on the starting line and has crappy tires but has a really good 350 in a ZR1 might go 13.2 The other driver who gets really good 60-foots, has his/her tire configuration just perfect but has a so-so 350, can run a 12.8.

So...who's got the best motor?
But...who's got the best ET?

[scottfab]

Originally Posted by Hib Halverson

ETs are either the most inaccurate way to bench mark engines or the most accurate way to benchmark the whole "package"...driver and car.

Do drivers are bragging about their engines. The first driver who majorly sucks on the starting line and has crappy tires but has a really good 350 in a ZR1 might go 13.2 The other driver who gets really good 60-foots, has his/her tire configuration just perfect but has a so-so 350, can run a 12.8.

Sounds like a line of hair splitting to me.
ETs can be the best way to measure overall performance there is.
Sure some exceptions can be brought to bear but there's many more exceptions that can be added.
Why even the effect of the moons gravity has an effect and the
imperfections on the asphalt under the right rear wheel. There
could even be a mosquito hit the windshield and slow it down.
Same driver running two different cars on the same night could even have
different wind conditions, a huge fly hit the windshield plus the major effect of 0.01oz of more fuel in one car vs the other. gezzzzzz
Seems like an exercise in futility to me.
A huge amount of meaningless exceptions can be added to dyno derived HP numbers too but I won't go there right now.

HP numbers are a fine metric but so is how many dimes you have in
the change holder. Being able to wave bye bye puts the "P" in performance. It's all together a better metric whether it's SAE or standard or pure air guitar corrected numbers.

Originally Posted by Hib Halverson

So...who's got the best motor?
But...who's got the best ET?

Whose got the shiniest dimes in the change holder?
Depends on the quality of the eye looking at it and the ambient air quality that the light goes through. But it should be SAE corrected air quality else
it's all for naught. And one should use proper wide spectrum light to test with and of course the angle of reflection should be at 90deg +/- 0.0000001 deg or the error will be so great that all bets are off.
Which is the better car?
1. 10,000 rpm V8
2. 502ci V8
3. 1800lb with driver
4. first over the 1/4 line

Answer: depends on which one I'm sitting in and Voltage measured at the spark plug of course.
Any hair that is split can always be split again until it looses meaning.