2005ArcticWhite

400 HP is outstanding

C-INRED

I'm sure the marketing people told the engineers that "it must be at least 400" to get it out of the 300+ realm.

I believe the Z06 was originally announced at 500hp, but then tested out under the new SAE rules at 505.

I don't know if the C6 has been re-tested under the new SAE rules...I suppose it may actually have 400+ under those rules. Maybe there's someone out there who knows if it's been retested.

Low12s

conecrusher

I think 400 HP was a good choice from a marketing perspective- people like nice, round numbers.

Some of the real dufery takes place over at Ford. My daily driver is an '02 Cougar, which has an all-aluminum DOHC v6, with a Cosworth cast block. Beautiful piece of work, even if it is only 170 hp. What does Mercury do? They cover it with a cheap hunk of plastic and call it a "Duratec"...... That name sounds like it belongs on a lawnmower!!!!

Marina Blue

I asked a Corvette powertrain engineer at the assembly plant what the actual dyno output of the LS2 was. He told me LS2s dyno at 406, 407 and sometimes 408 horsepower. Those are logical numbers. They do not want to sell a car that has less power than what they are rated. The LS6 in the C5 Corvettes most likely dyno somewhere between 410 and 415 horsepower. The LS7 in the C6 Z06 is closer to 530 horsepower according to what I have read.

Crush1

Unlike a lot of the rice burners who were caught cheating when the new updated SAE specs came out, GM has a history of being meticulously honest on their HP ratings. The 2006 Z06 was originally billed as having 500 HP if you will recall. It no doubt put out a little more than that to assure that their rating was a little on the conservative side. That was just befoe the revised SAE specs went into effect for the 2006 model year. A little later, the Z06 was upgraded to 505 HP as a result of further certified dyno runs to the new spec. It may actually put out a few more HP.

I have been told by someone in Chevy that I cannot quote that the base C6 measures, with the new SAE specs, in the range of 410-415 HP. Prior to the revised specs it measured in the 405-408 range (as reported in other posts in this thread) so for the 2005 models they rated it conservatively at 400 HP. If the base C6 had not been released until 2006, it would have been rated higher. I suspect for marketing reasons they chose to leave the rated HP alone for 2006.

You cannot directly compare todays HP ratings with the cars of the 60s. Up through 1971 the old SAE "Gross" rating system was used. With this method extreme measures were taken to eliminate or reduce parasitic losses such as removing assessories, minimizing exhaust back pressure, no air cleaners etc. In 1972 everyone switched to the SAE "Net" system which supposedly standardized things a bit by requiring the engine driven assesories to be in place etc. A rough rule of thumb is that an engine would rate at about 80% on the Net system of what it would rate on the "Gross" system. So a car rated at 425 HP then would be roughly 340 HP today.

But the reason for this latest revision in the SAE net system is that there were still some loopholes in the 1972 Net standards that companies could, if they so chose, exploit and claim exaggerated HP ratings. The changes made in the latest updates to this spec included requiring an independent witness to be present during the runs who has to certify they were done honestly. One Japanese company had to revise a V6 downward from 220 HP to 197. Others were not so dishonest. For example, the Honda S2000 was rated at 240 and then 237 under the latest system. You will note that GM did not have to reduce their advertised numbers for any engine that was carried over from 2005 to 2006. The impacts of these new SAE standards on various manufacturer's ratings have been reported in sidebars in various auto magazines but there never has been a big eveing news type coverage so most people are unaware of it.

It is to GM's credit that they have been honest. I am long time friends with a man who spent an entire career working on engine development for GM and he has always maintained that over the years they were very careful to be correct and honest. That is not to say that there were not some games played back in the 1965-70 timeframe when insurance companies and Congress was raising hell over too much horsepower. The early '66 Corvette high HP 427 was rated at 450 HP; a few months into production it was revised downward to 425. They simply went down the RPM curve a little ways to where it was putting out 425 instead of 450. It was exactly the same engine.

pitrider

Good post

TheJimer

Crush1, nice post, thanks for the info!

Jim

LTC Z06

And GM did exactly what with them???

da-googoo-man

lawnmower sorry, hard day...that one hit me in the right place..

legalgus

Whose "consistent" is it, "your" or maybe, should be "you're". Typos R US is catching!

smdio

right right, my bad !

TxChristopher

I thought the new standard was tougher, not easier. No motor should make more under the new standard than it did under the old standard.

Above you are saying it will rate HIGHER under the new standard ?????

.

AC54ME

What

Must be the Army food - should have joined the Marine's

Oh, I forgot, Marines parents must have the same last name

JK JK JK

AC54ME

No, 600+ is outstanding, such as I get from my 427

LTC Z06

See post #29

LTC Z06

It's 16 cubic inch increase.
Go here to read all the specs for the LS2, unfortunately this article compares the LS2 to the LS1, they should have used the LS6.
http://corvetteactioncenter.com/spec...05/intro4.html

Then go here for for the differences from LS1 to LS6.
http://forums.corvetteforum.com/show...75&forum_id=49

I would love to find one resource that catalogs all the changes from LS1 to 7 with full explanations of why and what the change accomplished.

The increase of bore from 99mm to 101.6 accounts for the .3 liter increase; and compression went up by .4. Heads are basically the same, most of the other significant changes don't make HP. My original point was that they kept the advertised number below the LS6 to help the dealers sell the remaining inventory.

BLU2FUL

I am suspicious the stock C6 engine is more than 400hp at the crank. My C6 A6 tested out at 335 rwhp on the dyno and other engines in this forum have tested at this level also. Typically there is about a 20% drivetrain loss, particularly with an auto tranny, which suggests about 419hp at the crank. Think GM is low balling to play safe?

Blue Raptor

Didn't I read 407 HP dyno from the factory??

"She's like heaven, my 407...."

Goodnight, now.

Crush1

It depends on how the earlier readings were made. A lot of manufacturers were cheating and the new system forced them to admit significantly lower HP ratings. Apparantly GM was not cheating. I do not know why the GM ratings seem to consistently be a few HP higher with the revised system, but it is. It could be GM, in its apparant efforts to be conservative, may have been overly conservative on the way the dyno runs were made.