[uneasyrider]

Just some guesses from some people that have done some dyno runs please on what an engine running 414hp and 458ftlbs at the rear wheels with a four speed would be running at the fly wheel. I'm guessing 500hp? I know there are plenty of people on here with some real world experience that have run their engines both on chassis and engine dyno's that have a good feel for what the losses are. Just a guess I know but I would like the "best guesses" only please.

Thanks,

[360Rocket]

automatic average powertrain loss is about 12% - 15%

so probably 450 to 475HP & 513 to 527 Tq.

automatics can rob you of 20% average.

so probably 500 hp & 550 Tq.

[uneasyrider]

Originally Posted by 360Rocket

automatic average powertrain loss is about 12% - 15%

so probably 450 to 475HP & 513 to 527 Tq.

automatics can rob you of 20% average.

so probably 500 hp & 550 Tq.

So with the 4-spd around 450-475. COOL!

That sure is a damn nice looking GTO! BTW, how did you get the big picture to post at the bottom like that?

[360Rocket]

Thanks for the compliment. Uhhhhh....signature....uhhh.....had it made? I'm too computer illiterate to make a nice sig like that. I bet Old Blue 66 (Paul) would know where to get that stuff.

[quick67bird]

Hey I will race you with my little old Firebird... I might even spot you a few lengths. I dont want to race for any distance though as I know what that car can do once it gets going.

Robert

[ponjohn]

Whats the combo?

[uneasyrider]

Originally Posted by quick67bird

Hey I will race you with my little old Firebird... I might even spot you a few lengths. I dont want to race for any distance though as I know what that car can do once it gets going.

Robert

You still have to see it Robert. That's Chad's Roadrunner BTW not my rig, just to make sure we are on the same page. I don't think Scott's even looked at my car yet. I've ridden in your car remember and it wasn't even as fast as it's going to be and I'm fairly sure it will beat that Roadrunner the way it was much less how it will be! Yes, if you and I raced for a mile or more I might stand a chance.

[DScruggs]

414hp/458ftlbs = 0.90393HP/Ftlb

Oh? Wait? You mean this wasn't a Math question? My bad!

[uneasyrider]

Originally Posted by DScruggs

414hp/458ftlbs = 0.90393HP/Ftlb

Oh? Wait? You mean this wasn't a Math question? My bad!

LOL! Ooops, it was supposed to be 414hp^458ftlbs

[harry k]

stick shift trans is 17%

automatic trans th400 up to 23-25%
th700&th350 up to 20-22%
th2004R up to 18-20%
all auto trans are non lock up torque converter figures

official http://pontiacdragdays.com/Sponsors.htm dyno sponsor

[uneasyrider]

So 414/.83 = 498.8 @ 17%? That's what I had guessed but just wondered if any of the "dyno people" had actually seen it "in the field" you might say. It sure does haul butt I know that.

[Z Code 400]

My 11.25:1 compression 429 Ford made 410 HP at the wheels and the dyno operator estimated that to be about 512 at the crankshaft. I have no idea how they calculate this. I hang around the dyno a lot, but I don't operate it...Robert 10851man@gmail.com

[74t/a]

You cannot just say 15% or 17% for an exact figure with a 4 speed.

You have to first know brand and kind of dyno it is. For example, if it is a dynojet enertia type, the figure is 18% for a 4 speed, around 20% for autos with low stalls, and around 22% for high stall combos. The reason why I say "around" is because different trannies have different frictional losses.


Different dynos have different correction factors based on the size of the rollers, load sensing software, etc.

[uneasyrider]

Originally Posted by 74t/a

You cannot just say 15% or 17% for an exact figure with a 4 speed.

You have to first know brand and kind of dyno it is. For example, if it is a dynojet enertia type, the figure is 18% for a 4 speed, around 20% for autos with low stalls, and around 22% for high stall combos. The reason why I say "around" is because different trannies have different frictional losses.


Different dynos have different correction factors based on the size of the rollers, load sensing software, etc.

It's a dyno jet I think, big drum that you spin. But it sounds like either way it's a 500hp+ engine which was what we were guessing.

[dbiggs]

Impressive numbers...over 400HP for a street car. Whats the combo?

[uneasyrider]

Originally Posted by dbiggs

Impressive numbers...over 400HP for a street car. Whats the combo?

The honest truth is we know vary little about the engine. It was pulled out of a guys braket car that was looking for some extra cash. He sold it to my friend and then got pissed because he sold it cheap so he started asking for parts back off of it. He got a couple things back when my buddy said "WTF, you NEVER said a word about the engine not comeing complete and that's that!" So the guy got ticked and wouldn't give him the cam card or anything. all we are sure of is that it was a 440, it's supposed to be 472 now, it has a solid cam and roller rockers, single plane manifold, old Holley dbl pumper (890cfm I think) and what we were told were old Stage II heads. That's just about it. It runs fine on pump gas and pulls fine to 6,500rpm.

[dbiggs]

Wow...a '70 Roadrunner...with air grabber hood. I had a '70 but sold it last Summer. Here is a few pics. It was a 4 sp 383 car. I have a '74 Challenger now with 440 and built for 500 HP...haven't dynod it yet though.

[uneasyrider]

Originally Posted by dbiggs

Wow...a '70 Roadrunner...with air grabber hood. I had a '70 but sold it last Summer. Here is a few pics. It was a 4 sp 383 car. I have a '74 Challenger now with 440 and built for 500 HP...haven't dynod it yet though.

Nice ride!

Yep, the poor old thing was twisting itself apart so we put subframe connectors on it last fall. It's been ridden hard and put away wet it's whole life but it is a real Roadrunner but of course not numbers matching anymore. It's ratty around the edges but it will surprise the hell out of people when you push on the gas!