[superdutybob]

Originally Posted by Super Duty D

That's because he is all MOPOOR now, oops, did I misspell ?? Sorry Bob.......had to do it !

SDD

Just let me know when you're ready to line them up! I'll even leave the A/C on! You'll love the tailights. All 169 LEDs.

[1qikta]

Originally Posted by superdutybob

Just let me know when you're ready to line them up! I'll even leave the A/C on! You'll love the tailights. All 169 LEDs.

Ill take some of that! Where do I sign? Just to be fair I will leave my ac on too!

[sdbob]

Remember when the SD first came out. There was a track test,I think there were 4 cars total. A Laguna,a Charger, and forget the rest. Lets just say the SD was tops by a wide margin. Move Over Pontiacs Are Racing(MOPAR). :-D

[superdutybob]

Originally Posted by 1qikta

Ill take some of that! Where do I sign? Just to be fair I will leave my ac on too!

Just so you're clear Jay, we're running top end, not just 1/4 mile! LOL

[superdutybob]

Originally Posted by sdbob

Remember when the SD first came out. There was a track test,I think there were 4 cars total. A Laguna,a Charger, and forget the rest. Lets just say the SD was tops by a wide margin. Move Over Pontiacs Are Racing(MOPAR). :-D

They tried to do a comparison test on the new Charger with a G8 but there were none to be had. GM killed them! Times they are a changin!

[Pepi]

Originally Posted by sdbob

Move Over Pontiacs Are Racing(MOPAR). :-D

Or, Move Over Pontiacs Approaching Rapidly

[ripper1991]

i have been getting conflicting info on what piston i can use for the 73-74 sd rod.does anyone who actually built or has a sd engine know what piston brand i can buy with part # if possible to use with a factory sd rod? any help would be appreicated.thanks brian
bmwjmw@verizon.net

[Brewster]

Received my new Hemmings Muscle Machines magazine yesterday and it has a nice write up on the 73-74 SD-455's.
Enjoy,
Brew

[bluebird455]

Good article. I just don't understand how it says that with a good driver a sd455 is good for high 13's on the 1/4, which I truly believe. But then it goes on to say that some sd expert thinks the 290hp net rating to be correct? Am pretty sure the net total is alot higher than 290hp.

[Formulabruce]

Originally Posted by bluebird455

Good article. I just don't understand how it says that with a good driver a sd455 is good for high 13's on the 1/4, which I truly believe. But then it goes on to say that some sd expert thinks the 290hp net rating to be correct? Am pretty sure the net total is alot higher than 290hp.

Keep in mind that those are NET ratings, at the wheels, Im not sure the article even goes into that, and havent read it yet

[Lloyd-TX]

Originally Posted by Formulabruce

Keep in mind that those are NET ratings, at the wheels, Im not sure the article even goes into that, and havent read it yet

Actually, Bruce, those are net ratings at the crankshaft, NOT at the wheels. But those engines were GROSSLY under-rated . . .

Subtract approximately 22-25% (auto) or 12-15% (stick) from factory net HP ratings to get an approximation of RWHP numbers.

[Formulabruce]

Originally Posted by Lloyd-TX

Actually, Bruce, those are net ratings at the crankshaft, NOT at the wheels. But those engines were GROSSLY under-rated . . .

Subtract approximately 22-25% (auto) or 12-15% (stick) from factory net HP ratings to get an approximation of RWHP numbers.

Im confused. I thought that GM began rating the horsepower at the wheel ( net) to show a lower HP to the EPA?
So you are saying the "real net on a 73 is 22% less than the 290? Thats interesting, I stand baffled , Thanks for setting me straight !

[bluebird455]

The article does not go into whether the rating is based on crank or rear wheel measurements, I know it's always being stated as crank measurements in all publications I've looked at. Therefore if the "expert" is to be believed, 290hp minus 20-25% loss at the wheels, would not equal 1/4 times in the high 13's. not even high 14's for that manner.

[Lloyd-TX]

Originally Posted by Formulabruce

Im confused. I thought that GM began rating the horsepower at the wheel ( net) to show a lower HP to the EPA?
So you are saying the "real net on a 73 is 22% less than the 290? Thats interesting, I stand baffled , Thanks for setting me straight !

Sorry, Bruce, I should have explained it a bit better . . .

NO vehicle that I'm aware of is rated at the wheels.

The "SAE Net" HP and Torque ratings began in 1971, and most manufacturers advertized their vehicles with BOTH the old "SAE Gross" and "SAE Net" ratings Then for the 1972 model year the SAE Net ratings became the law, and if I'm not mistaken ALL manufacturers were required to advertise the Net ratings ONLY.

A couple of Pontiac examples: 1971 L78 400 4V was rated 300 Gross HP, and the 1972 L78 (with dual exhaust) was rated 250 Net.

The 1971 LS5 455HO was rated 335 Gross HP, and the 1972 was rated 300 Net HP.

That is also why you'll notice that for a few model years after 1971 engines were rated differently when equipped with single or dual exhaust. Until duals went away . . .

The major differences between gross and net ratings are that engine is required to pump it's own coolant and fuel, turn it's own alternator and other accessories, and breathe through it's as-installed air cleaner and exhaust system.

[Lloyd-TX]

For horsepower comparison purposes, leave the 1/4 mile ET out of the conversation. Too many variables like traction, gearing, torque converter stall speed (on an auto), etc.

1/4 mile TRAP SPEED is a MUCH better all-around indication of REAL, to-the-wheels horsepower (vs. the total vehicle "race" weight, of course).

Another real world example (that's not TOO far removed from a stock SD455) would be my Formula. I Don't wish to bore everyone with all the details, but is a 467" 455, ported 7F6 heads, VERY mild solid lifter cam, STOCK HO intake, SD Q-Jet, stock Ram Air system, R.A.R.E. 2.5" outlet exhaust manifolds into an OLDER 2.5" PYPES exhaust system (not the better new system with the free-flowing muffler), TH400 with a GM converter, 3.08 gear, etc. 3925# "race" weight.

On a conservative engine dyno (and running stock 2.25" SD455 exhaust manifolds) we got a best of 430 corrected HP.

Later, on a conservative (Mustang, eddy-current) chassis dyno we got a best of 299 corrected RWHP. A 30% loss on my car, due in part to the restrictive single muffler.

My car runs a consistent 105 - 106 MPH 1/4 trap speed, in the heat.

[superdutybob]

The difference between net and gross is pretty simple. Both are measured at the crankshaft. Gross is the engine only with no accessories hooked up and running free air intake and exhaust. Net ratings are done with the correct vehicle exhaust system, all accessories, and the correct vehicle airbox or filter system in place. It takes power to turn the accessories, therefore a lower number.

If you'll notice, the 73-74 SD-455 HP was rated at 4000rpm. The engine continues to make power well past that rpm. Probably made 350ish at 5200 would be more correct.

There is a new SAE rating system that the manufacturers started using 5-6 years ago where you actually do a net rating with a witness from SAE that certifies all of the parts of the engine. It levels the playing field between all of the manufacturers. You MUST rate your engine HP +/- 1% of what it makes on rating day.

[Lloyd-TX]

Originally Posted by superdutybob

The difference between net and gross is pretty simple. Both are measured at the crankshaft. Gross is the engine only with no accessories hooked up and running free air intake and exhaust. Net ratings are done with the correct vehicle exhaust system, all accessories, and the correct vehicle airbox or filter system in place. It takes power to turn the accessories, therefore a lower number.

If you'll notice, the 73-74 SD-455 HP was rated at 4000rpm. The engine continues to make power well past that rpm. Probably made 350ish at 5200 would be more correct.

There is a new SAE rating system that the manufacturers started using 5-6 years ago where you actually do a net rating with a witness from SAE that certifies all of the parts of the engine. It levels the playing field between all of the manufacturers. You MUST rate your engine HP +/- 1% of what it makes on rating day.

VERY well stated, Mr. Woodard.

Your point about the "rated" HP RPM for the SD engine is a point I most certainly meant to make, and completely forgot. Thanks for chiming in!

[rwinkles]

Originally Posted by 1qikta

Ill take some of that! Where do I sign? Just to be fair I will leave my ac on too!

Hey Jay, I'll take some of that action and I will do it in the 1/4 mile! And I'll leave my A/C on too with the top down!

[Formulabruce]

Interesting read, thanks for all the clarification! Lloyd, Bob...
I do seem to remember the lower numbers being better suited for insurance companys??
Oddly enough a mild 455 can pull 500 lb ft of torque , hehe thats higher than most trucks of that era :P

[Brewster]

Holly Bat Caves its Dick Winkles