[Sven59]

SAE certification has a 1% tolerance, the max the fat kitty could be is 714.

[Jeffro19]

Dyno numbers are just for tuning and bragging rights. You cannot use a dyno to estimate a power for a certain vehicle. The numbers vary greatly.

[Denis]

Originally Posted by SuperSound

And you need to stop using chassis dyno numbers as the holy grail. What happens if you use 10 or 12%? Much closer to what is advertised right?

im not arguing about this at all, but how do we know the current numbers are more towards 10% as opposed to the 20% we all used to use? are we just assuming greater efficiency or have their been studies to prove it?

[Sven59]

Originally Posted by Denis

im not arguing about this at all, but how do we know the current numbers are more towards 10% as opposed to the 20% we all used to use? are we just assuming greater efficiency or have their been studies to prove it?

http://www.caranddriver.com/columns/...olution-column. This!

[Denis]

Originally Posted by Sven59

http://www.caranddriver.com/columns/...olution-column. This!

that article didn't say anything about drivetrain efficiency. It was about SAE and the difference between HP and PS.

[Sven59]

Originally Posted by Denis

that article didn't say anything about drivetrain efficiency. It was about SAE and the difference between HP and PS.

It is 1 standard vs. Ole's dyno.

[SuperSound]

Originally Posted by Denis

im not arguing about this at all, but how do we know the current numbers are more towards 10% as opposed to the 20% we all used to use? are we just assuming greater efficiency or have their been studies to prove it?

Well for one look at the fact that all of the cars lately (Dodge, Ford, GM, etc...) are using SAE ratings and all show more power at the wheels than the 20% assumption which dates from decades ago. This means either all are underrated the same (which is BS) or the drivetrains (not just transmissions) have become more efficient. So it's reasonable to assume you can't assume a figure for old 3 or 4 speed lockup converter transmissions still holds true for these modern 8+ speeds fast shifting autos.

When you think about CAFE it's obvious the auto industry needs their engines and transmissions to be more efficient to meet those MPG targets. They have been making steady gains but it really wasn't obvious until these new 8, 9, and 10 speeds autos started showing up. The technologies they are using to get those fast shift times is related to the drop in parasitic loss between manuals and autos. Granted the additional gears are contributing too.

I'll have to look around but there was an in depth tech piece on the ZF 8 trans speaking to it's improvements in power loss. Maybe someone else can post some evidence.

[GretchenGotGrowl]

Originally Posted by cal45

Yes, FCA advertises it at 707hp but the stock auto Hellcats have been dyno'ed anywhere from 600-630 RWHP. So, if one uses a 20% parasitic power loss crank to wheels - crank comes in around 750hp......yeah, I know fuzzy math but there is credence to the fact that these are pushing more than their advertised 707hp.

.

Or there is less drivetrain loss that 20%. Remember, all the manufacturers are trying to get as much fuel economy as they can out of cars. They aren't getting gains by just making the engine more efficient. The whole point of the 707 HP thing was so they could have bragging rights. If it made 750 HP then they would have advertised that.

[DenverTaco07]

oh...and why would Dodge advertise LESS HP if they are actually MORE???

We all know that 90% of the hellcat's marketing is the 707HP because everyone's jaws drop when they hear that...AND Dodge's own marketing says "707HP end of discussion"...

so if they were 740HP I would bet my life's savings they would instead say "740HP end of discussion".

Edit...yeah, what Gretchen said.

[Raven87]

I can see where the logic would be that if the HC made anything MORE than 707, why wouldn't Dodge say what it is? But...

Let's say the motor actually does make 740-ish - GM or Ford comes in all cocked and locked with a ~720 HP pony car only to find out that the HC still can wax the offering with 'only' 707 HP? Makes for some good press and a little embarrassment to the GM/Blue Oval bunch IF this were the case.

Granted, this is a HUGE stretch to consider (and most likely not true) but the numbers say there is one of two things - either the HC makes a lot more than 707 HP (and to move that much mass at those ETs I'm guessing this is the case) OR, there is far less parasitic loss in the drivetrain.

Maybe CAFE restrictions, EPA restrictions, etc get tighter the higher the HP? Could be any number of reasons Dodge would underrate the HC...

Good discussion either way!

[Mr. Wyndham]

Does the Hellcat advertise "SAE certified" 707hp? Because if that's the case...then it's 707, end of story...too many controls embedded in that test procedure to believe that the manufacturer can underrate the engines, anymore.

[DenverTaco07]

Originally Posted by Mr. Wyndham

Does the Hellcat advertise "SAE certified" 707hp? Because if that's the case...then it's 707, end of story...too many controls embedded in that test procedure to believe that the manufacturer can underrate the engines, anymore.

i believe this is the answer:

http://articles.sae.org/13227/

[Jeffro19]

Originally Posted by DenverTaco07

i believe this is the answer:

http://articles.sae.org/13227/

And there we have it...

[Battlezone580]

About a year ago I made a thread my Dad got a Hellcat after I got my ZL1, both manual.

His car is bone stock, I have a CAI intake, pulley, and tune and keep up with him. Depending on who has the better launch really factors in to who wins. Assuming I'm making 650 at the crank with 200 extra pounds than the new ZL1, it should be able to easily pull on the hellcat.


The Hellcat is a vicious car, a true muscle car heavy and fast as hell (literally). No need to bash it because you can't beat it.