SGOS's - L99 A6 Dyno results (after dyno tune)

[GMRULZ]

Originally Posted by silverfox

OK guys i'm having a procharger sc and arh full system but keeping the stock mufflers installed at dtp racing next week. I will post dyno charts and numbers after.

Hey man, I live in western branch of chesapeake. I would like to check out the dyno runs when Brent gets everything installed. Would you mind if I came and watched? You can pm me if ya want when you know when its going on the dyno. I`m debating on blowers and want to see what options will be avail.

Thanks!

[Tillman Speed]

To the comment about 20% drivetrain loss on the automatic. That was an older general rule of thumb. 15 or 16% for manual, 20% for automatic. Anymore, though that's not neccessarily the case. I know we compare everything to the mustang, but this is very valid.

Stock Manual GT - 3.55 Gears - 18" Tires - 300 engine horsepower - 260-270RWHP SAE Corrected on a Dynojet - That's rougly between 10-14%.... through a Tremec 3650 5 speed in 1:1 ratio (4th gear).

Stock Auto GT - 3.31 Gears - 18" Tires - 300 engine horsepower - 250-260RWHP SAE Corrected on a Dynojet - That's between 13-17% drivetrain loss maximum... through a 5r55 5 speed auto in 1:1 ration (4th gear).

To be safe, I would apply the base horsepower number times .85 and that would be a valid automatic output. I would figure the stock output (after atleast 2500 miles of break-in) to be somewhere along the lines of 330-340RWHP.

We have to remember the 1:1, though... which the CLOSEST would be 4th, we'll leave that alone for arguments sake.

Again, larger tires and steeper gears are going to affect the output, but on a stock vehicle this is what to expect.

[SGOS252382]

Originally Posted by Tillman Speed

To the comment about 20% drivetrain loss on the automatic. That was an older general rule of thumb. 15 or 16% for manual, 20% for automatic. Anymore, though that's not neccessarily the case. I know we compare everything to the mustang, but this is very valid.

Stock Manual GT - 3.55 Gears - 18" Tires - 300 engine horsepower - 260-270RWHP SAE Corrected on a Dynojet - That's rougly between 10-14%.... through a Tremec 3650 5 speed in 1:1 ratio (4th gear).

Stock Auto GT - 3.31 Gears - 18" Tires - 300 engine horsepower - 250-260RWHP SAE Corrected on a Dynojet - That's between 13-17% drivetrain loss maximum... through a 5r55 5 speed auto in 1:1 ration (4th gear).

To be safe, I would apply the base horsepower number times .85 and that would be a valid automatic output. I would figure the stock output (after atleast 2500 miles of break-in) to be somewhere along the lines of 330-340RWHP.

We have to remember the 1:1, though... which the CLOSEST would be 4th, we'll leave that alone for arguments sake.

It all depends on which car you choose to base your forumla on. Some engines are very underrated while others are very overrated.

If you used that formula on the LS1 M6 Z28s, they have
0% drive train loss? They dyno in the 310 - 320 rwhp range. Thefact is the engine makes more power than GM claimed.

My LS1 A4 Z28 dynoed in the 280s rwhp and was only rated at 305 hp. That would be around a 5% drive train loss (which we know isn't true). And we now know the LS1 engine actually makes around 350hp.
That would really equate to around a 19-20% drive train loss for my LS1 A4 z28.

The 05/06 GTO's (automatics) dyno anywhere from 305 - 330 rwhp on average (depending on dyno and stock tune). That's very similar numbers that we're seeing form the L99 Camaro.


The only way we would know 100% for sure is to take an L99 straight off an engine dyno and drop it into a new Camaro. Then run it on a chassis dyno and calcuate the drive train loss.

20% could be a little high, but it might not be in the case of the new Camaro.

[rpepka]

Based on that infomation, almost all of the L99's on this forum are NOT producing 400hp at the crank.

[SGOS252382]

Originally Posted by rpepka

Based on that infomation, almost all of the L99's on this forum are NOT producing 400hp at the crank.

Most would agree that 18-20% drive train loss is a pretty much the standard for most automatics.

400 x .18 = 72
400 - 72 = 328

400 x .20 = 80
400 - 80 = 320

So based on this "standard" a stock L99's should dyno somewhere in that range (320 - 328 rwhp).

So the L99's that are dynoing around 305 rwhp are definately not making the claimed 400hp (more like 375hp).
But over in the other Camaro forum there seems to be quite a few guys that are dynoing in the 320+rwhp range - stock. (I guess they got lucky or their dynos are a little more generous)

[Tillman Speed]

Right, this is all solely based upon the advertised numbers at the flywheel actually being correct.

All things aside, I think the reality is that GM's numbers are probably pretty precise. We don't have an exact 1:1, we have results from inertia/eddy current dynos, results from broken in engines, results from engines that aren't broken in.

I guarantee the L99's will receive some updates in calibration, unless they find a mechanical problem in the exhaust (like being discussed bm GM for some of the people here) that is leading to the rich condition. From my experience, GM has always had rich calibrations, so that's causing more confusion on the basis of "is this normal?".

Give GM a few more weeks of *****-footing around and we'll all probably see the story unfold.

Chris

[ElAntonius]

Honestly, there's also a difference between less than ideal tuning and tuning that is preventing advertised performance.

If the camaro achieves advertised numbers on the stock tune, then that's fine, even if a dyno tune can improve it.

Now, hopefully GM will continue looking at the issue and issue calibrations to the stock tune to improve consistency.