Most powerful engine in a production GM car?
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Joined: Nov 2000
Posts: 16,176
From: Chicagoland IL
The '73 455 SD was rated at 310 "net" hp. There is no such thing as a Pontiac big block. 326/389/400/421/455 and others used the same block. It wasn't until the emissions era when engines like the 301 came with a shortened deck (to save weight in order to increase MPG). But internal components and heads from the older engines will bolt up to the 301.....you just can't get the intake to match up because of the shorter deck.
If we look at engines like the 454 LS-6 or 427 ZL1...even if they were under rated and actually put out 500 or so hp....they are as guion says "gross" figures. Subtract about 20% to convert them to net, and you get about 400hp.
The current LS6 is underrated a 405 "net". You do the math.
If we look at engines like the 454 LS-6 or 427 ZL1...even if they were under rated and actually put out 500 or so hp....they are as guion says "gross" figures. Subtract about 20% to convert them to net, and you get about 400hp.
The current LS6 is underrated a 405 "net". You do the math.
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Joined: Oct 2001
Posts: 237
From: St. Clair Shores Mi. USA
Back to the `71-`72 Gross vs Net figures. In `71 GM rated some engines with both Gross and Net Figures `71 455 HO in the Trans Am and the GTO was rated at 335 gross and 310 Net. also don't forget that in `71 GM dropped Compression across the board on all engines to make use of Unleaded Fuel.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
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Joined: Sep 2001
Posts: 1,308
From: Calgary
Originally posted by 9T8W66
Back to the `71-`72 Gross vs Net figures. In `71 GM rated some engines with both Gross and Net Figures `71 455 HO in the Trans Am and the GTO was rated at 335 gross and 310 Net. also don't forget that in `71 GM dropped Compression across the board on all engines to make use of Unleaded Fuel.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
Back to the `71-`72 Gross vs Net figures. In `71 GM rated some engines with both Gross and Net Figures `71 455 HO in the Trans Am and the GTO was rated at 335 gross and 310 Net. also don't forget that in `71 GM dropped Compression across the board on all engines to make use of Unleaded Fuel.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
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Joined: Feb 2002
Posts: 2,428
i found that the buick 430 cu.in. got 475ft-tq and the oldsmobile 455 got 500-510 (depending on year i am assuming that this is gross hp cause it didn't say) but a small question what does SD stand for, short deck?
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Joined: Sep 2001
Posts: 1,308
From: Calgary
Super Duty (cause you know it was super strong and super powerful) (or on CDN Beamonts (aka rebadged Chevelles, Sprt Deluxe)
Did ya ever notice that there were some Corollas with an SD designation?? Thats just sick!
Did ya ever notice that there were some Corollas with an SD designation?? Thats just sick!
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Joined: Mar 2001
Posts: 13,713
From: The Golden State
Originally posted by 9T8W66
Back to the `71-`72 Gross vs Net figures. In `71 GM rated some engines with both Gross and Net Figures `71 455 HO in the Trans Am and the GTO was rated at 335 gross and 310 Net. also don't forget that in `71 GM dropped Compression across the board on all engines to make use of Unleaded Fuel.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
Back to the `71-`72 Gross vs Net figures. In `71 GM rated some engines with both Gross and Net Figures `71 455 HO in the Trans Am and the GTO was rated at 335 gross and 310 Net. also don't forget that in `71 GM dropped Compression across the board on all engines to make use of Unleaded Fuel.
And the Highest HP factory installed Pontiac was the `69-70 400 Ram Air IV underrated at 370 HP.
The 400 Ram Air V Tunnel Port Engine was rated at 475 (closer to 525) but was only sold over the counter to racers.
The Ram Air V engine was NEVER installed in a factory Pontiac on the assembly line, and was for all practical purposes an aftermarket engine. This was hand assembled, and only 200 were installed in Pontiacs (this INCLUDES the 303 cid engines used in Trans Am racing) AFTER the car was assembled. These were used almost exclusively for racing (T/A and drag racing).
"Q: Ram Air V
I have heard Pontiac made some Ram Air V in '69 but were available in a crate only. If they were crate motors could you not have put it into a Firebird?
A: Kent sure you can but you must remove the crate first.... what I meant was that the factory didnt put these race motors in any production cars. A little over 200 were sold in the crate and some more were pieced togeather. There was 2 versions. the low deck 303 cu in version made just for Trans Am racing ( 5 litre restriction),and the 400 version . The factory tried a few experimental versions,366 and 455 but the RAV program was aimed at the drags and T/A series. They also experimented with various carb(s) and manifolds. the closest production motor to this was the 73-4 455 SD."
"Nineteen-seventy also saw the announcement of a new Ram Air V engine for optional installation on GTOs and Firebirds. The Ram V was almost a completely new engine although many of the parts interchanged with earlier engines. The heads featured round intake and exhaust ports for super top end breathing. The aluminum high rise intake manifold mounted a 780 cfm Holley 4-barrel. The camshaft was a 368/320 degree unit but worked with solid lifters for higher revs. All this plus the engine had special beefed rods, 4-bolt mains, extra webbing etc. for increased high rpm durability. None of these engines were ever installed on the assembly but it was possible—and still is—to purchase a whole Ram Air V engine"
Meanwhile, the Ram Air IV GTOs typically ran 0-60 in the 5.8-6.2 range, and the quarter typically around 14 1/2 at about 100 mph and the car weighed roughly 3500 pounds had a 3.90 axle and ran 125 mph.
370hp may be underrated, but it still doesnt seem very impressive. 3600 pound Monaros have only 302 net hp and a lower axle ratio, and they are about that quick.
The SD 455 gross rating was a rarity. GM actually rated this engine (in gross figure) close to what it actually produced installed. Compare that to the regular "cooking" 455 rated at 355 gross hp and only 255 net!
BTW, the SD455 engines were actually more powerful than the Ram Air IV
.
Last edited by guionM; Feb 20, 2003 at 08:45 PM.
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Joined: Nov 2000
Posts: 16,176
From: Chicagoland IL
Originally posted by guionM
This was hand assembled, and only 200 were installed in Pontiacs (this INCLUDES the 303 cid engines used in Trans Am racing) AFTER the car was assembled. These were used almost exclusively for racing (T/A and drag racing).
This was hand assembled, and only 200 were installed in Pontiacs (this INCLUDES the 303 cid engines used in Trans Am racing) AFTER the car was assembled. These were used almost exclusively for racing (T/A and drag racing).
The limited succes that Firebirds had in TranAm was with illegal Chevy 302's.
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Joined: Sep 2001
Posts: 1,308
From: Calgary
yeah I'll second that--the 303 was just in development stages and never ran in a Trans Am race. They were not getting the power results they wanted. (supposedly they ports oin the heads were massive--whch just kills the already meagre torque output)
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Joined: Jan 2002
Posts: 599
From: Inland Empire, CA
The GM car question has been pretty much answered, but I don't think the Viper takes the crown for most in a production car.
I do know that the Ford 427 SOHC was supposed to be the most HP in a production engine for a very long time, something like 650hp on the 2 carb version (but that's by the old gross standard).
I think these days the crown is still held by the McLaren F1 with 627hp @ 7400RPM
If they ever actually come out with it, the Bugatti 16\4 Veyron is supposed to have a Quad-Turbo W16 (two VW W8's joined together) putting out 1001hp.
I do know that the Ford 427 SOHC was supposed to be the most HP in a production engine for a very long time, something like 650hp on the 2 carb version (but that's by the old gross standard).
I think these days the crown is still held by the McLaren F1 with 627hp @ 7400RPM
If they ever actually come out with it, the Bugatti 16\4 Veyron is supposed to have a Quad-Turbo W16 (two VW W8's joined together) putting out 1001hp.