[obzidian]

Care to explain how the 5.8l gt500 with 556hp puts down 600rwhp+ stock?

Oh.. let me help. Its really making 700hp.

What about the 6.2l hellcat engine? 707hp = 640-650rwhp??

Nope.. guess again. Shall i go on?

[xgnxs]

Originally Posted by obzidian

Care to explain how the 5.8l gt500 with 556hp puts down 600rwhp+ stock?

Oh.. let me help. Its really making 700hp.

What about the 6.2l hellcat engine? 707hp = 640-650rwhp??

Nope.. guess again. Shall i go on?

Isn't the GT500 rated to make 662 hp? That would be a 10% drive train loss. Same thing for the hellcat. I know a lot depends on the dyno but maybe we're in the age of only 10% loss instead of the expected 15%? That sure would be great!

[ULTRAZLS1]

Originally Posted by xgnxs

Isn't the GT500 rated to make 662 hp? That would be a 10% drive train loss. Same thing for the hellcat. I know a lot depends on the dyno but maybe we're in the age of only 10% loss instead of the expected 15%? That sure would be great!

Drivetrain efficiencies have improved no doubt.

What I don't understand is how one can guess and extrapolate a hp figure they consider accurate that is based upon a guess on top of a guess. For one you are guessing how accurate the given dyno is and also guessing drivetrain loss. Not to mention readings can vary depending on operating temp, proper air to the engine during testing and tire pressure just to name a few.

Also figuring drivetrain loss will only become more inaccurate as horsepower increases. 12% drivetrain loss of a 300 hp motor would equate to about 265rwhp. So in this crude example it takes 35 hp in this make believe car to spin all the accessories, transmission and wheels etc. So now take that same car and put in 600 hp and change nothing else..... Is it now going to take 70hp away going to the wheels instead of 35 like when it had 300 hp? No

Drivetrain loss is a guess and so is the accuracy of the dyno. I put more stake in the new sae standards for hp compared to results that vary as much as 30hp from reading to reading across the country lol.

[xgnxs]

Originally Posted by ULTRAZLS1

Drivetrain efficiencies have improved no doubt.

What I don't understand is how one can guess and extrapolate a hp figure they consider accurate that is based upon a guess on top of a guess. For one you are guessing how accurate the given dyno is and also guessing drivetrain loss. Not to mention readings can vary depending on operating temp, proper air to the engine during testing and tire pressure just to name a few.

Also figuring drivetrain loss will only become more inaccurate as horsepower increases. 12% drivetrain loss of a 300 hp motor would equate to about 265rwhp. So looks like it takes 35 hp to spin all the accessories, transmission and wheels etc. So now take that same car and put in 600 hp and change nothing else..... Is it now going to take 70hp for it to turn instead of 35 like when it had 300 hp? No

Drivetrain loss is a guess and so is the accuracy of the dyno.

Right. I guess we should've asked obzidian for links to his dyno numbers. If the engines aren't underrated (which I don't believe they are) and the C7 really is putting down 420rwhp, that would literally be a drive train loss of ~9% for that specific dyno / conditions / what have you. Which is why I said it seems way too good to be true, but awesome if it is.

[SuperSound]

Originally Posted by ULTRAZLS1

What I don't understand is how one can guess and extrapolate a hp figure they consider accurate that is based upon a guess on top of a guess. For one you are guessing how accurate the given dyno is and also guessing drivetrain loss. Not to mention readings can vary depending on operating temp, proper air to the engine during testing and tire pressure just to name a few.
.

Very good point. FI engines are more succeptable to atmospheric conditions compared to NA. I wonder what the standards are for SAE testing in terms controlled atmosphere.

[ULTRAZLS1]

If there is a 420 rwhp dyno it proves nothing to me. I've seen dynos of them only reading 400rwhp as well.( done by a mag)

If you use that number it's pretty close to 12%. But of coarse owners will focus on the higher reading dynos. See the pattern ? This trickles down to under rating rumors. And don't think for a second some dynos don't read high for happier customers etc.

[Bhobbs]

Originally Posted by obzidian

Care to explain how the 5.8l gt500 with 556hp puts down 600rwhp+ stock?

Oh.. let me help. Its really making 700hp.

What about the 6.2l hellcat engine? 707hp = 640-650rwhp??

Nope.. guess again. Shall i go on?

Oh so you know they exact drive train loss for the GT500?

[ULTRAZLS1]

Originally Posted by SuperSound

Very good point. FI engines are more succeptable to atmospheric conditions compared to NA. I wonder what the standards are for SAE testing in terms controlled atmosphere.

http://www.sae.org/certifiedpower/details.htm

Doesn't talk about testing conditions but that will point u in the right direction. I would say just look up the new standard code and some details should be available.

[xgnxs]

Originally Posted by ULTRAZLS1

If there is a 420 rwhp dyno it proves nothing to me. I've seen dynos of them only reading 400rwhp as well.( done by a mag)

If you use that number it's pretty close to 12%. But of coarse owners will focus on the higher reading dynos. See the pattern ? This trickles down to under rating rumors. And don't think for a second some dynos don't read high for happier customers etc.

Ahhh yes now I can see how you get underrating rumors spreading about, especially if people are expecting the "standard" 15% loss. 400rwhp is still great out of a 450hp engine! No doubt that some will read higher than others.

Originally Posted by SuperSound

Very good point. FI engines are more succeptable to atmospheric conditions compared to NA. I wonder what the standards are for SAE testing in terms controlled atmosphere.

Really? I would think that FI engines would be less influenced by atmospheric conditions vs NA, since you're forcing the air into the engine as opposed to just whatever the engine can grab. Interesting, learn something new every day!

[SuperSound]

Originally Posted by xgnxs

Really? I would think that FI engines would be less influenced by atmospheric conditions vs NA, since you're forcing the air into the engine as opposed to just whatever the engine can grab. Interesting, learn something new every day!

NA motors struggle at high altitude due thin air reducing the amount of air they can push in the cylinders. This is why superchargers/turbochargers came about in WW2 to help piston engine planes produce power at high altitudes. So yes NA can feel the effects strongly too. From my understanding, ambient air temp and humidty hurt FI worse than NA because of even hotter intake air temperatures (due to boost) and humidity reduces the amount of boost produced (air is thicker and harder to compress). IHRA Pro Mod class allows FI and N20 cars to compete and is the best example to see how much atmosphere can affect performance. The FI cars love high altitude and cold air temps but suffer due to traction. N20 cars deal with the heat much better because N20 also cools as it is injected and is more predictable in power output compared to FI.

I'm sure someone on here can give a better explanation on the effects. This is just my limited understanding of the situation.

[VADER SS L99]

If the car has a weight of 3700lbs with a 8L90E and 450HP/460TQ LT1 like predicted then we will see mag times in the 12.4-12.6 range with hero runs in the high 11's. You can quote me on this and we can revisit in a year. Add 400lbs to the Vette and that is what you get or replace the 6L80E with the 8L90E (already proven to be worth .1 tenth) remove 200lbs and add 50HP/50TQ to the 5th gen L99. I don't even bother with 0-60 times anymore.

[toehead93]

Originally Posted by ULTRAZLS1

http://www.sae.org/certifiedpower/details.htm

Doesn't talk about testing conditions but that will point u in the right direction. I would say just look up the new standard code and some details should be available.

Ultra is dead on with this. Go pay to have your car dyno'd at ten different chasis dyno shops and you get 10 wildly different results. Have you engine removed and dynod on 10 engine dynos and you get almost identical readings as long as the air is controlled (temp, pressure, humidity).

Extrapolating real engine numbers from chasis dynos used to be the only way to see truly if manufactures were under rating but even then those estimates were just as inaccurate as they are now. The only accurate ratign system in the US are SAE certified numbers. This why high end shop that develop cams use engine dynos for testing and developing.

Back to the topic...
LT1 C7 (3300lbs) - 0-60 = 3.8. 1/4 =12.0
LT1 Camaro (3700lbs) - 0-60 = 4.1 1/4 =12.4
All of the magazines I've seen show the 1LE faster than the SS in 0-60 times because of gearing and sticky tires. So the SS could range 3.9-4.2 depending on gearing and tire options.

[tswilie]

Ok Guys the thumbnail analysis was pretty good.
SS 6 speed manual, 0-60 4.3, 1/4 in 12.3

From what I can tell the stang 5.0 6M is 4.5 and 12.9 or 13.0
Challenger Scat Pack is 4.5 and 12.5

I understand the auto is quicker but as Jay Leno would say you need a proper gear box

[SuperSound]

Originally Posted by tswilie

Ok Guys the thumbnail analysis was pretty good.
SS 6 speed manual, 0-60 4.3, 1/4 in 12.3

From what I can tell the stang 5.0 6M is 4.5 and 12.9 or 13.0
Challenger Scat Pack is 4.5 and 12.5

I understand the auto is quicker but as Jay Leno would say you need a proper gear box

6th gen manual is 12.5. Auto is 12.3

Sent from my SAMSUNG-SM-N900A using Tapatalk