Back when I was a Z28 owner, there was much discussion on the Camaro forums about the LS1 engine in both cars. It was always assumed the pallet engines were identical. Yet, the factory power ratings gave the corvette 40 more horses. With the factory dual exhaust for the C5 vs. a single exhaust pipe for the Camaro, and a cleaner intake path, it was only natural to assume this was the reason the greater horsepower rating of the C5. However, many people claimed C5s and Z28s dynoed nearly the same on any given day, or car. The Z28 crowd concluded the transaxle ate up the extra horsepower. But could the opinion from the Z28 community that the C5 and Z28 put the same power to the ground be a biased one?

Yet the Z28s would show substantial gains with bolt on mods. A typical cat back was expected to gain 15 rwhp. My 98 Z28 show a gain of 26 rwhp (unprecedented) with a K&N FIPK. However, the C5s do not seem to respond as well to bolt on mods. This doesn't seem unreasonable since the factory equipment is fairly efficient already. But if it's so efficient shouldn't it be making greater horsepower? My 2004 stock C5 with base suspension feels quicker than my 98 Z28 with K&N FIPK, Magnaflow cat back and a bunch of suspension goodies.

So here is my question. Did the C5 LS1 produce more horsepower, or did the Z28 have the exact same power plant producing the same power from the flywheel?

 

I have no clue but as a C5 owner I will say a corvette. Actually I would say they are probably the same

 

My guess is the vette generates more torque to the rear wheels!

 

That's actually incorrect.
Camaros and Trans am make more dyno power than vettes do, due to vettes independant rear suspension.
Vettes are lighter and more aerodynamic so stock for stock, they would most likely have the advantage from higher speeds.. DON"T under estimate them though.
When I had my Trans am. I would murder them at the track and they would swear I was running nitrous or something.
Believe it or not, most average vette owners don't know it's the same exact engine

edit: you are correct about how they judged the HP. They gave the C5's and WS6, SS better exhaust and better air intake as well so a regular TA or camaro was actually the better bang for the buck. Dont get me wrong, they had different suspension setups, wheels, tires as well
. then in 01 all TA's and camaros got the LS6 intake just like the vettes.

 

Just a different oil pan. Both cars will dyno comparably, usually F-Body's dyno higher as Jason said above, due to the Vettes IRS.

Corvettes are lighter and have better aerodynamics, so they tend to be faster up top.

Same engine though, minus the minor differences in the oil pan, the intake tract, and FBW throttle body.

The thinking generally accepted was that GM underrated the F-Body's to not step on the toes of LS1 Corvette owners.

 

1995 Chevrolet Camaro 3800 7.4 15.7
1996 Chevrolet Camaro Z28 5.7 14.1
1996 Chevrolet Camaro Z28 SS 5.3 13.8
1998 Chevrolet Camaro Z28 5.2 13.7
1998 Chevrolet Camaro Z28 SS 5.2 13.6
1973 Chevrolet Caprice Classic 454ci 8.7 17.0

1989 Chevrolet Corsica LTZ 9.3 17.2
1957 Chevrolet Corvette 6.6 14.2
1965 Chevrolet Corvette 6.2 14.9
1967 Chevrolet Corvette L71 5.6 13.8
1968 Chevrolet Corvette 327 7.7 15.6
1968 Chevrolet Corvette 427 6.3 14.1
1969 Chevrolet Corvette 427ci 435hp 5.3 13.8 (C&D Sep '69)
1970 Chevrolet Corvette 427 6.1 14.3
1973 Corvette 350ci L82 6.7 15.1 (C&D Dec '72)
1973 Corvette 454ci 6.4 14.6 (C&D Dec '72)
1975 Chevrolet Corvette 350 9.6 16.4
1976 Chevrolet Corvette 350 8.1 16.5
1977 Chevrolet Corvette 8.8 16.6
1979 Chevrolet Corvette L82 7.3 15.7
1980 Chevrolet Corvette L82 7.4 15.4
1982 Chevrolet Corvette 9.2 16.6
1984 Chevrolet Corvette 6.7 15.1
1985 Chevrolet Corvette 5.7 14.1
1986 Chevrolet Corvette 5.8 14.4
1986 Chevrolet Corvette Convertible 6.0 14.5
1988 Chevrolet Corvette Convertible 6.0 14.6
1988 Chevrolet Corvette Z51 6.0 14.6
1990 Chevrolet Corvette 5.7 14.3
1990 Chevrolet Corvette ZR-1 4.4 12.8
1991 Chevrolet Corvette L98 5.3 13.9
1991 Chevrolet Corvette Roadster 5.6 14.1
1992 Chevrolet Corvette LT1 5.7 14.1
1992 Chevrolet Corvette ZR-1 5.6 13.9
1993 Chevrolet Corvette LT1 5.3 13.9
1993 Chevrolet Corvette ZR-1 5.2 13.6
1994 Chevrolet Corvette LT1(auto) 5.5 14.1
1994 Chevrolet Corvette ZR-1 4.7 13.1
1995 Chevrolet Corvette LT1 5.2 13.7
1995 Chevrolet Corvette ZR-1 4.9 13.1
1996 Chevrolet Corvette Collectors' 4.9 13.3
1996 Chevrolet Corvette Grand Sport 4.7 13.3
1997 Chevrolet Corvette 4.7 13.3
1998 Chevrolet Corvette Convertible 5.1 13.5
1999 Chevrolet Corvette Hardtop 4.8 13.3
2001 Chevrolet Corvette C5-R 3.5 10.3
2001 Chevrolet Corvette Z06 4.6 13.0
2001 Chevrolet Corvette Coupe 4.8 13.1

 

Definitly agree. When most F-Body Ls1s Dyno in the 280 - 300 rwhp range, clearly the 305 factory rating was under-rated. While in many peoples opinion the Corvette was rated more honestly.

 

Bump for the day crowd.

 

Like you, I always understood the differences in HP between the LS1 fbods and the C5's to be primarily a result of intake, exhaust.

The reason your C5 probably "feels" quicker than your 98 Z is likely due to the fact the C5 is a couple hundred pounds lighter and also a physically smaller vehicle.

I had a 2000 Z28 six speed for four years and my butt-meter cannot detect much of a power difference between my old Z and my 2000 Vette.

 

Had a 99 WS6 and couldn't tell much of a difference between the two stock vs. stock in power (until around 60mph), but handling is WAY different.

 

All I know is don't underestimate the power being put down by an F-body with the LS1. They are pretty darn quick stock and respond very well to mods. (Don't ask how I know. )

 

I think it has to do with GM underating them, weight, aerodynamics, suspension, gear ratio. Lots of factors involved.

 

Gearing is the same.
Stock for stock, it's gonna be a pretty darn even race.

It'll most likely come down to the driver.

 

Stock for Stock it would take a pretty bad driver in the C5. Don't forget about the weight difference.

2001 Z28

Horsepower : 310 @ 5200 RPM
Torque (lb-ft): 340 @ 4000 RPM
Curb Weight: 3614 pounds

2004 C5 Coupe (same as the OP)

Horsepower : 350 hp @ 5600 rpm
Torque : 360 lb-ft @ 4000 rpm(auto), 375 lb-ft(manual)
Curb Weight : 3210-3246 lbs(coupe)

Although the original discussion was about the horsepower rating. Yes it is the same engine, there were subtle differences... but I think the reason they were rated was more "political".

IMO, they couldn't have the Camaro putting out the same HP numbers as GM's flagship sportscar.

 

My Coupe VS my 00 SS. The c5 is WAYYY faster...

 

 

So the Z is only a tenth quicker than a regular C5?

 

A 2001 Z maybe. There were a lot of changes between the 2001 Z and the 2002-2004 Z's

 

Being that the Z has 35 more hp and is lighter it wouldn't be a race.

Getting back to the topic, from what I've seen the Camaros do dyno pretty high for what they are rated at. My money would still be on the Vette though because of weight.

 

You guys are absolutely correct about the weight.

If you were to take a stock C5 and a Stock F-body and dyno them. Let's say they are both M6 at 3.42. The F-body will def. dyno higher. I have seen this first hand time and time again.

If you watch them run at the track "stock" they all seem to run about the same too "13.0-13.4"
My TA ran 12.9 with just Nittos

As I said. It's a drivers race.