[angryBits]

Originally Posted by GrabTheWheel

So am I wrong if I thought stock hellcats put down 620-630 WHP stock if not a little more?

I don't pay much attention to Hellcats. But if they put 630 whp, that sounds underrated to me. Or maybe their drivetrain is more efficient.

I know my Shelby GT500 put down ~600whp stock and it was rated at 662hp.

I'm the furthest thing from an authority but I believe it's all a game.

I recall in the past there were some cases where a manufacturer announced a number and then there were tune issues and when the car settled it ended up low and consumers were pissed.

If I were a manufacturer I'd underrate the car just to allow for that wiggle room + some people only get 91 octane + some people live at high elevation or high temps etc. Regardless of what is true (SAE correction mistakes -- who knows), if consumers' expectations are over hyped then you're going to get a bad wrap.

Just my 2 cents.

EDIT: BTW -- I would guesstimate that about 1/3 of the time I take my car to a dyno I get asked if I want to fudge the numbers on paper. What? Seriously? No.

[JamesNoBrakes]

Originally Posted by angryBits

Purely based on numbers.

85% x 650 = 552.5 at the wheels.

85% drive train loss is a general guess but it seems to be about right.
it might be interesting to look at numbers for M6 vs A10 to see if theres much of a difference. Guessing not much if any, the A10 is very modern.

Yep, dependent on many things, hard to just pick a number, but it can get you started in the right direction. The WRX I used to own was supposed to be "under-rated", that was BS when you hooked them up to a dyno. What they did have was short gearing and a good kick in the pants from the turbo and AWD, which made them feel quite fast at lower speeds. They did pick up a bit of HP when they changed to the 2.5 block, but the HP ratings for all manufacturers were revised at the same time, so it wasn't apples to apples anyway.

You only start to get a good idea when you see a bunch of dynos posting similar numbers for similar circumstances.

I'd say that manufacturers for the most part do not under-rate because they realize it's a paper-game and that's how most people buy their car. Few people, if any, are going to unleash all the HP on a test drive and it'll come down to what each is "capable of". Those that are buying the higher end cars are more in the "know" and they are likely buying a BMW or Audi for reasons other than just the HP, so less of an effect there.

[angryBits]

Originally Posted by JamesNoBrakes

Those that are buying the higher end cars are more in the "know" and they are likely buying a BMW or Audi for reasons other than just the HP, so less of an effect there.

I would say the opposite. I'd say those buying a BMW or Audi are less in the know and just buying a brand.

Audi has a nice interior and a refined ride but unless you go for the R8 there's not much to talk about.

BMW's haven't been the ultimate driving machine in a very long time. Anything other than the M3 (M4) or Z cars isn't sporty and not even that nice. I respect the M3 but it's fallen down a few notches in the last 7 or 8 years IMO.

Honestly if I went Euro, I'd get a Mercedes AMG GT-R.

[Aliveguy5]

I think where some people feel this car is underrated gets lost into the torque curve of the engine. Doesn't the LT4 have diesel like torque curve where almost (tq mgmt aside) or all of the torque is available at 2k? If that's the case, that is my guess why everyone feels this engine has more than advertised.

[Markoz28]

In today’s date there is no reason to under rate as every car is getting dynoed and the numbers are shown. Plus Hp/Tq numbers mean nothing anymore unless you can put the power down. I’ve raced a 2014 gt500. It’s supposed to have 662hp and I put a beating on that thing. At 120mph I was about 4 cars ahead.

[angryBits]

Originally Posted by Markoz28

In today’s date there is no reason to under rate as every car is getting dynoed and the numbers are shown. Plus Hp/Tq numbers mean nothing anymore unless you can put the power down. I’ve raced a 2014 gt500. It’s supposed to have 662hp and I put a beating on that thing. At 120mph I was about 4 cars ahead.

I'm a Camaro guy now so I have to let go of my former GT500 allegiance...
BUT -- I must call out, you're comparing an A10 to M6.

They definitely do have 662hp. Mine dyno'd at 600whp stock.

[angryBits]

Originally Posted by Aliveguy5

Doesn't the LT4 have diesel like torque curve where almost (tq mgmt aside) or all of the torque is available at 2k?

Yes definitely more low end than LS series motors.

In fact, I recall reading somewhere about a review of the LT1 in the Grand Sport and Camaro SS vs the LS7 in the previous z06 and Z28. Reviews said that even though the LS7 made 505hp/470tq, the LT1 felt as powerful and even torquier until 4k or 5k. Something like that. If I were not so lazy I'd find the review...

Maybe find some stock dynos of the LT4 and compare to the LS9 stock dynos and see how the curves compare. My guess is the LT-series is gruntier.

3 minutes later...

I got unlazy...
This thread compares the engines
It's not the review I was referring to but it has a comparison dyno.

[Aliveguy5]

The LT1 is Beefy!

[Markoz28]

Originally Posted by angryBits

I'm a Camaro guy now so I have to let go of my former GT500 allegiance...
BUT -- I must call out, you're comparing an A10 to M6.

They definitely do have 662hp. Mine dyno'd at 600whp stock.

And I agree with you and have no doubt the gt500 really does make that much power but for some reason, transmission, gears, suspension, weight, or whatever the power just doesn’t translate at the track.

It’s a combination thing. It’s like a gt350 to a GT. The GT has less power but is much faster in the 1/4.

[BMWM.D.]

The LT4 is SAE certified (as others have mentioned), and the chassis dyno numbers are right where they should be in my opinion. I’m not sure what other manufacturers do the SAE certification thing, but what was stated about BMW and the other German cars is very accurate. It makes comparing different brands a little tough if you’re not aware. Since we’re talking about engines being underrated, I think it’s a valid subject.

I remember Ford getting into trouble back in the day with the Mustang Cobra. The cars didn’t make the advertised power, and Ford had to suck it up, admit it, and update customers’ cars to fix it. I’m betting they learned from that and are on the conservative side.

[Can'tHave2MuchHP]

Agree with the above. The LT4 is very consistent and makes right what it should.

Now, the Hellcat definitely has something going on. Either they made the holy grail drivetrain and gotten below 10% or there is huge inconsistency in which case I'm not sure how they got the engine certified. Hellcats around me almost always put down 620-650 RWHP. I've seen a few putting down high 600s like 670-680 RWHP. We've had this discussion on this forum before and I've been a proponent of the Hellcat being underrated. I recall a Mopar engineer or something saying the Hellcat engine is a 740 HP class engine, which would line up a lot more. Again, I'm not sure about all of this but just go look at the stock dyno threads on the Hellcat forums. They're definitely a happy engine.

[GrabTheWheel]

Originally Posted by Can'tHave2MuchHP

Agree with the above. The LT4 is very consistent and makes right what it should.

Now, the Hellcat definitely has something going on. Either they made the holy grail drivetrain and gotten below 10% or there is huge inconsistency in which case I'm not sure how they got the engine certified. Hellcats around me almost always put down 620-650 RWHP. I've seen a few putting down high 600s like 670-680 RWHP. We've had this discussion on this forum before and I've been a proponent of the Hellcat being underrated. I recall a Mopar engineer or something saying the Hellcat engine is a 740 HP class engine, which would line up a lot more. Again, I'm not sure about all of this but just go look at the stock dyno threads on the Hellcat forums. They're definitely a happy engine.

All of this makes the ZL1 all the more impressive when compared to the redcateyedemon or whatever marketing mopar is pushing now. I must say they are damn good at promoting their product but if they don't bring back the VIPER they'll never have my attention...

[angryBits]

Originally Posted by Markoz28

And I agree with you and have no doubt the gt500 really does make that much power but for some reason, transmission, gears, suspension, weight, or whatever the power just doesn’t translate at the track.

It’s a combination thing. It’s like a gt350 to a GT. The GT has less power but is much faster in the 1/4.

Stock, the GT500 would do 11.5 and that was severely crippled by the rear tires (285s). I recall someone got into the 10s with just a set of drag radials.

The Shelby was and still is an amazing car IMO. Great on the street and drag strip -- terrible at the track. I modified my suspension to the point of hating the car anywhere but the track and so I sold it.

Pretty sure that car was underrated.

[JamesNoBrakes]

And we see the effects on straight-aways of the LT1 or LT4 being over-powered by cars with better power-to-weight, gearing or less drag, but when they get into the turns, these cars own. Just go watch half a dozen track videos. I would conclude based on how they run and the cars they are compared to (some of which ARE under-rated) that these are not under-rated.