(Hemi) and other motors horsepower at flywheel very interesting

[bigj3341]

I was watching the speed channel the other day. Some show was rebuilding different high performance motors as close to bone stock as possible. This was to see how the rated HP was against the actual HP. A 302 ford put out 600hp, a 396 chevy put out 700 some hp, and so on and so forth. Different Frds and Chevy's all actually surprising me. Then came the 426 hemi. That motor put out over 800 Horsepower at the flywheel. I was speechless. These were all stock as possible(ex: pistons, cams, intake, carbs, etc) the only thing was if the block needed bored out due to the cylinder walls being bad. 800HP+++ you gotta say a hemi is damn powerful. That all said i had a question. How does 800+hp at the flywheel become 425 at the wheels? Is there a way to figure that out?

[Dick]

The power rating of 425 HP wasn't at the rear wheels. That was the flywheel rating installed in the car. Dyno ratings are done with no power robbing accessories, unrestricted exhaust and ideal conditions of tweaking.

As far as the Hemi goes, it has been said that factory ratings were fudged a bit down to make the cars insurable by the buyer. I don't know if that was true or not, but it makes sense.

Horsepower ratings today are much closer to reality.

[bigj3341]

Originally Posted by Dick

The power rating of 425 HP wasn't at the rear wheels. That was the flywheel rating installed in the car. Dyno ratings are done with no power robbing accessories, unrestricted exhaust and ideal conditions of tweaking.

As far as the Hemi goes, it has been said that factory ratings were fudged a bit down to make the cars insurable by the buyer. I don't know if that was true or not, but it makes sense.

Horsepower ratings today are much closer to reality.

yea makes sense, i know theydid underate it but even 425 rating and 800+hp (in ideal conditions and non restricted) is just outrageous. Not bad very cool to me

[jelsr]

Supposedly the old method was a blueprinted unit in an atmosphere (temp, humidity, etc.) controlled dyno facility with no accessories. The later method is supposed to be a unit plucked out of the assy. line and tested as installed in a vehicle. Kinda makes the later ratings stand out a little, huh! Don't know if the newer ratings are corrected though.

[bigj3341]

Originally Posted by jelsr

Supposedly the old method was a blueprinted unit in an atmosphere (temp, humidity, etc.) controlled dyno facility with no accessories. The later method is supposed to be a unit plucked out of the assy. line and tested as installed in a vehicle. Kinda makes the later ratings stand out a little, huh! Don't know if the newer ratings are corrected though.

i see, i know bmw is still very understated as for other companies, i have no idea.

[MOPEkid]

I don't find that possible that a stock Hemi made 800 HP. One of the featured cars in Mopar Muscle had a stock-spec Hemi built by some engine shop (Ray Barton I think) and it made 590 HP at the crank. But 800 HP? You can't tell me that even a racing-based engine made more power-per-liter (100+) with 40-year-old technology (even though it was advanced for its time) than engines today designed with computers and years of testing. They had to have done something differently with those old muscle car engines they tested. I think even 600 would be pushing it a bit. IMO the street Hemi made around 550 HP max on a good day, because even a blueprinted version of that engine made an honest 590 HP.

[cudabob496]

Originally Posted by MOPEkid

I don't find that possible that a stock Hemi made 800 HP. One of the featured cars in Mopar Muscle had a stock-spec Hemi built by some engine shop (Ray Barton I think) and it made 590 HP at the crank. But 800 HP? You can't tell me that even a racing-based engine made more power-per-liter (100+) with 40-year-old technology (even though it was advanced for its time) than engines today designed with computers and years of testing. They had to have done something differently with those old muscle car engines they tested. I think even 600 would be pushing it a bit. IMO the street Hemi made around 550 HP max on a good day, because even a blueprinted version of that engine made an honest 590 HP.

I'm sure the Mopar guys pulled a fast one, and that "stock" Hemi had a displacement near 600 cu in, some nice highly ported heads, and a serious cam! Probably also slipped the dyno guys a few hundred bucks to "calibrate" some output guages!

[bigj3341]

Originally Posted by MOPEkid

I don't find that possible that a stock Hemi made 800 HP. One of the featured cars in Mopar Muscle had a stock-spec Hemi built by some engine shop (Ray Barton I think) and it made 590 HP at the crank. But 800 HP? You can't tell me that even a racing-based engine made more power-per-liter (100+) with 40-year-old technology (even though it was advanced for its time) than engines today designed with computers and years of testing. They had to have done something differently with those old muscle car engines they tested. I think even 600 would be pushing it a bit. IMO the street Hemi made around 550 HP max on a good day, because even a blueprinted version of that engine made an honest 590 HP.

NAW, this was stock for all motors built buy a shop. the 327 chevy put 750 at the flywheel that was the other big surprise. This was not done by manufacturers(ie:dodge crates, Frd Crates, Chevy Crates) These were regualr regular motors built to factory specs with factory equipment 'as close' to 100% stock as possible. Granted i dont know what was the exact parts going ino the hemi and or the 327 but thats why i said i was speechless about the hemi having 800 at the flywheel. I woulda said something about the chevy and frd's in more deatail but i dont want to offend anyone. lol Speed channel man i didn't produce it or build the motors just saying whats on the show was what is saw.

[djswwg]

All "stock" except pistons, cam, carbs, intakes, etc., well what the hell ya got left but the block! No wonder the power ratings are so high! Replace all those back to original units and then see where your dyno readings are!!! Still lotsa crack in use out there or what?..djs

[dodger1]

600 HP out of a "stock" Chev 302?? Come on, guys! If anyone truly believes that, I have a very nice bridge to sell you, located in Brooklyn. I happen to have had the pleasure of driving a 1968 Z-28 Camaro brand new and I can assure you that, while the car was very quick, it was no 600 hp beast. It was rated at 290 hp gross at the flywheel, and was generally considered to be somewhat "underrated", as was the 290 hp 340, which I think NHRA adjusted to 325 hp or so for the same reason. I also got to drive a 68 427 390 hp hydraulic-cam Vette, and that was fast as hell, too. But stop with the horseshit already. Jelsr is correct in stating the power rating measurements at the time were "gross", no accessories or exhaust restrictions, very carefully tuned, and measured at the flywheel. Sometime in the early 70's, the factories went to a "net" flywheel horsepower rating, running all the normal accessories and stock exhaust system. Still do to this day. But hey, the TV guys will do anything to make a buck, and there are only a few of us O.F.'s out there who know they're lying.

[bigj3341]

Well i didn't make the show or build the block. THEY said everything was stock. Ie : STOCK cams pistons and such IE means in example for those that dont get it. Anyway thats what they said they got like stated above im sure all parts were brand new probably better octane and perfect conditions. So take it and run, im just stating what they did

[MOPEkid]

I was never saying it was your fault or anything. It's just doesn't make sense that the people who made the show are lying to people telling them that all these "stock" muscle car engines are making 100+ HP per liter.

[JVMopar]

I would have liked to see that show. Something is way off. I have run a superflow engine dyno and dynoed a chev 350 with a .040 overbore, flat top zero decked pistons, 327 cam, and it made no where near that 750 hp mark. But it would be neat to see my 5hp briggs and straton make 20 hp on their dyno.

[sanborn]

There is an old saying---"Don't believe anything you hear and only one half of what you see". Apparently this show streeeetched the truth to a greeeeeat degree.

I have been watching the comments on another site about the first show. The general agreement among most was the 421 Pontiac and the 409 Chevrolet dyno runs were close to accurate; but the Ford and Hemi dyno runs were not even close---way overstated.

What can I say? The speed channel has always played "fast and loose" with the facts---this goes way beyond that!

[WCLARK]

That show showed me what they think the intelligence level of their viewers is. A little fudging might have been OK, but this went way beyond fudging. It was outright deception.

[OHD]

Well it is written on the internet, it has to be true......

Offer the builders 100K for EACH of those stock engines, IF it has that level of power, on the dyno of your choice. Then watch them fold up and crawl back to their crack dealer.

[bigj3341]

hence my term speechless and me asking how from the flywheel to rear tires is a 50% reduction in power.

[crisser]

I think the producers of that show were on something.

[dodger1]

And/or the engines. Laughing gas, anyone?

[Ray Bell]

Definitely won't be stockers with that power...

600hp from a 302? That's better than F5000 engines did with fuel injection at full race tune!

[pcrmike]

Those were FAST entries. Factory Appearing Stock Tires. I saw teh build on it in MA. It was over 800 horses thru manifolds, and stock induction. Over 600 cubes now though. :-)PCRmike

[pishta]

Ford Sells a 380HP 302 crate motor, why not a 600? 600 out of a stock appearing 302? Maybe a 347 stroker with 14:1 pistons and a cam that has a torque curve that dynos like a knife edge. Get real.

[RacerHog]

better yet...Don't watch tv.... It's full of B.S.

[dodger1]

OK, assuming all these engines are OHV, 2 valve, pushrod (single cam) single 4 bbl carb stock displacement iron block and heads. How many of us here in this forum who have had their engines on a dyno can show 100 hp. per liter. Got a 520 hp 318?, How about a 560 hp 340? Anyone have a dyno chart for a 820 hp 440? If it's a F.A.S.T. class car, then all bets are off - pretty much run what you brung which might get you a 100 hp/liter motor.

[JVMopar]

What was the name of the show and when did it air. I've been searching the speedtv web site for a little while now and can't find anything about it. But the F.A.S.T. thing would make alot more sense.

[bigj3341]

honestly no idea i work 16 hr shifts and it was on i dozed in and out sorry. Maybe it was fast i dunno i tried finding it again but i dont know what im looking for

[DartGT66]

Old Direct Connection chassis book had "true" horsepower ratings for different engines. If I remeber correctly, according to the book, 426 streethemis true output was 390-410 hp. According to some cahssis dyno results I have seen of completely stock hemi cars, in the low 300 hp range, that seems to be about right. 800 hp claim is total nonsence, even the first years of pro stock race hemis made nowhere near that amount running low 10's- high 9's in the 1/4 mile at around 3000 lbs.

[Jack_440 Savoy]

How many people have Actually seen this Show ??? I Watch Too Much TV and I have Never Seen it ???

[adodgemann]

American Muscle Car series BIG BLOCK shoot out on speed. Rules were pretty open, production blocks, stock bore/stroke plus up to .060 over bore. Period correct carbs and intakes. Tube headers. Blueprinted stock cam, what ever that means. Thats it. 409 chevy made 406 hp, 427 ford made 637 hp, 421 pontiac made 488 hp, 426 hemi made 820 hp and 427 chevy made 527 hp. So take it for what its worth. Hyped up TV, I think so. Anyway, we all,already knew the HEMI kicks A$$ !!!

[RacerHog]

Amen dodgeman....Im with you.....Goooooo HEMIS

It was on speed channel......it was units modifided for that year eara..specs where limited....take it for what is was......i belive it was a guy back east who did nostaliga engine make overs....Buttner or butler or bucky or something like that...
Is was talking about how thing where under rated for insurance reasons.

Just my 2 cents