If you look at the power teams chart you will see that two 350's were available, one is the Chevrolet small block and the other is the Pontiac. This continued for a while but by 1976 no Pontiac 350 was available in a Canadian built car, just the sbc.

The other thing is 1971 was a transition year for horsepower ratings so that both Net and Gross Horsepower are shown. A 400 V8 was 300 HP gross = 200 Hp Net. That is about a .70 factor. Good to keep in mind when comparing HP of say a 1969 vs. a 1972 and later car.

So that 396 Beaumont with 325 HP was gross HP, really more like 230 HP net.

And stated the other way around a 73 400 GTO with 230 Net HP was more like 325 HP gross.

If you look at the power teams chart you will see that two 350's were available, one is the Chevrolet small block and the other is the Pontiac. This continued for a while but by 1976 no Pontiac 350 was available in a Canadian built car, just the sbc.

The other thing is 1971 was a transition year for horsepower ratings so that both Net and Gross Horsepower are shown. A 400 V8 was 300 HP gross = 200 Hp Net. That is about a .70 factor. Good to keep in mind when comparing HP of say a 1969 vs. a 1972 and later car.

So that 396 Beaumont with 325 HP was gross HP, really more like 230 HP net.

And stated the other way around a 73 400 GTO with 230 Net HP was more like 325 HP gross.

-- Edited by 73SC at 01:10, 2009-01-24

But you also need to take into account compression ratios. The change from gross to net ratings corresponded with a general lowering of compression ratios. 1970 and before, all the 4 bbl V8's were running at least 10 to 1 with high performance versions in the vicinity of 11 to 1, by 73 because of emissions, 8 to 1 was the norm. By the mid 70's American Pontiac engines were getting by with 7.6 to 1!

A lot of the 1970 and earlier high performance engines were actually underated with respect to hp because of the insurance reasons. A Ram Air IV was factory rated at 370 hp gross but there is no way it was only putting out only 250 net hp at the flywheel nor do I think that if you strapped a 73 GTO 400 on the dyno would it be putting out just 20 hp less than a 70 RAIV.

-- Edited by Astro Jet at 11:07, 2009-01-26

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Hillar

1970 LS4 (eventually an LS5) Laurentian 2dr hdtp -and a bunch of other muscle cars...

Hillar, I believe my analysis is valid. The 1971 engines are "low" compression in the 8:1 range. We also know that as much as the engines were under-rated many were also over-rated as the horsepower war heated up.

We can only go by what the manufacturers chose to publish not what we assumed. In this regard we need to be mindful that a 325 HP rated engine in 1969 is NOT comparable to the Net rating in 1971 and beyond. I think that comparatively it should be understood that there is a reduction factor needed to be applied so that the playing field is leveled. In published 1971 data this is about .70.

I have mentioned this many times before and it explains why the legendary 1964 GTO which had 330 HP or so from a 389 and 4.11 gears did 0-60 in 7.5 seconds and a 1/4 time of 15.4 and say a 1986 Monte Carlo SS with 180 HP from a 305 with 3.73 gears went 0-60 with in 7.5 seconds and has a 1/4 time of 15.8.

I would also note that by far the vast majority of "muscle cars" were high 14 to mid 15 second runners regardless of horsepower published. There is an interesting article on this in the June 1984 Hot Rod magazine, they list times for pretty much every year and model from 61 to 70 and only about 4 "Super Muscle Cars" (Hemi Cuda, LS6 Chevelle...) that dipped into the 13's and also only a handful of "Factory Drag" cars that hit the 12's"

The Ram Air GTO's are on the list, mid to high 14's. So with your theory of under-rating with well over 200 more Gross horsepower they only beat an 86 SS by a second.

Ray, I think the 64 GTO you are referring to had something like 3.23 gears, but in any event there were always variables with respect to the transmission used, tires, the driver's abilities, the rear end ratio, the weight of the vehicle, etc. I have seen many tests of RAIV cars where they dipped into the 13's or were running very low 14's. That's why my comment referred to dynos. I have no hesitation whatsoever is saying if we strapped a 70 RAIV and a 73 400 on the same dyno back to back, the RAIV would be putting out at least 100 net hp more. This comes from my experience with numerous engine builders and high performance shops with dynos over the last 25 years. Oh and beating someone by a second in the quarter mile is a pretty fair accomplishment. A tenth of second generally equates to a car length so a win by a second would put you about 10 car lengths ahead, a pretty good spanking.

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Hillar

1970 LS4 (eventually an LS5) Laurentian 2dr hdtp -and a bunch of other muscle cars...

My original point was simply that 1971 was the first year of the new SAE standard to measure Net HP and it appeared side by side with the previous Gross measure.

The two are not comparable without taking into account some factor to discount or mark up one or the other.

While your Ram Air car is a classic "Red Herring" to my argument lets assume you are right and it really had 425 Gross HP. That would be 136% more power than the 180 HP SS I used as an example BUT yet it only covers the 1/4 mile faster by 8.23%. That pretty much proves my point.

I'm not saying the Ram Air car was not fast because it was, just saying some reasoned thinking needs to be applied when comparing pre and post 71 cars. We are also talking about factory production cars and last time I checked a car travels 100 feet per second at 60 MPH, about the length of an average East York lot. We're talking about cars that might hit the traps at 85 to 90 MPH. Considering it has "245 more HP", not so great accomplishment imo.