[transam1972]

actually, I am not offended that you did not mention the 72, in fact I am well aware of its shortcomings...it is the differences between the RAIV and the H.O....and the fact that the winner is the 455 High Output...only pleases me more since I own a 1972 Trans Am...there you have it....Pontiacs ultimate engine died on the drawing board...to be continued 1971/72 455 H.O. vs. 1973/74 S.D.

['ol Pinion head]

Originally Posted by transam1972

...it is the differences between the RAIV and the H.O....and the fact that the winner is the 455 High Output...only pleases me more since I own a 1972 Trans Am...there you have it....Pontiacs ultimate engine died on the drawing board...to be continued 1971/72 455 H.O. vs. 1973/74 S.D.

Can't go that far, I've ridden in & have driven several very near stock RAIV & 455 SD cars that ran very hard.

Given the hypothetical dream build of a RAIV in a lightweight '69 or '70 Tempest or a pre-production 455 SD engine in a non a/c '72 LeMans post car, move over...

[tjtjwdad]

I don’t know the answer but it seems in stock form as they rolled off the assembly line with 3.73:1 gears, a 4-speed transmission with all of them optimized/tunes to peak potential [including fuel]; I would pick the RAIV and I would imagine there isn’t too many ticks of the stop watch difference between a 400 RAIII, 455HO or SD455 in a quarter mile run. It just seems that these three packages are pretty darn close to each other and with a manual transmission it would come down to the driver.

I believe if the test were done with an automatic transmission I would think the RAIV would not fare well at all against the others because of the cam and the gears.

My have a 1970, I first laid eyes on that particular car in November of 1971 when my uncle drove it to the funeral home of my step grandfather. I was a pre-teen, lived in the country and I had never seen one before and in those days, like today [still], you don’t see many of them. I bought it in 1978 for $2500 and that car has a sentimental value to me that no RAIV, 455HO or SD455 can ever replace. Having said that if I were looking; a 1971 or 1972 would be hard to look away from but I do prefer the seats of the 1970 over the others they’re just more comfortable.

I’ve driven both a 71 & 72 Trans Am and the behavior of those cars compared to my 1970 don’t compare at all. The 1970 is brute, tempered and ill-mannered rig whereas both the 71and 72 models were more refined and had some manners about them. Even the handling seemed different and the only thing I believe that is different is the 70 models had a different steering. The other thing I noticed was the 71 and later years sat higher up off the ground than my 1970. I also concur that the 160 speedo was “very optimistic” and a 5 or 6-speed would be a welcome addition to “any” of these cars.

What I have often wondered is how would a SD455 built in 1970 (with compression) compare to the her 455 stable mates from Buick (GNX), Oldsmobile (W-30) and Chevrolet 454 (LS6). And I say the SD455 because it has the bottom end to rev higher whereas the 455HO is limited by design in that area.

Nice discussion; to the OP, thanks for bring it up

Jim

[carnut4life]

Very interesting thread, love hearing everybody's input. Not really interested in stirring the pot but I've owned couple 71/72 4 speed TA's w/o ac(3.42) and both run very well, especially up to 4500-5000 rpm. I've also ridden in a couple 74 SD cars (one Formula/one TA)that were bone stock survivor automatics w/o ac(3.42) that ran identical. Both had the torque of the HO on the lower end but pulled HARD well past 5500 rpm and left a lasting impression on me that still brings a smile to my face. That being said I'll still take a 71/72 HO just because of the styling, but any of us that own a roundport car are fortunate in my opinion.

Never ridden in a RA IV so I don't have any input on those but like Jim, I'd love to see what a high compression SD 455 with a RA IV cam could have done in any Pontiac. Long live the roundport!

[tjtjwdad]

Regarding the 455HO of the 1971-72 era, does anyone know the history of these engines? There was a 1970 455HO but it was a different animal than the 1971-72 models. Was the 1971-72 455HO something that was really thought out or was it a piece mill for those two model years due to dropping compression ratio drops [and GM lifting the ban on putting those engines in intermediate size cars] because I’ve read the SD455 was in development during that time frame.

WRT to Pontiac not developing the 455 [SD or HO] has always been a question to me but they did have other projects going at the time; a RA-V, RA-VI and RA-VII and I believe I read once Pontiac was working with Chrysler to come up with a engine very similar to the HEMI.

[rexs73gto]

The HO engine of 71-2 is just a 455 with th 4 bolt main as the 70 version was, but the 70 modle didn't have the round port heads. The Sd was a new type of engine as they were also working on the twin turbo 301 while Mac McCeller was still alive but the amount of power that the twin 301 put out to much HP & was going to be a threat to the Corvette so Chevy had it killed but the SD was already built by then & the money was spent so it became the big Gun. As we all know it has provisions for dry sump oiling & other features that would have made it even stronger then it is. But the emission std's jumped in & there were some changes as the RAIII cam was the 1st cam to be used in the SD but it got pulled because it made to much HP & was hard on the emission side to. But it got through with the other cam & a delay switch on the dist so it would pass. The HO engine was a low comp. RAIV engine so it could keep up with the HP that chevy was putting out to stay as the power house for Pontiac , without hurting chevy in the way.

[transam1972]

what cam did the S.D. get?...its own special design?,or a previous one?...what is involved in making the dry sump functional?...does the motor need to be pulled?...anyone here ever hook theres up?!

[Formulajones]

[QUOTE='ol Pinion head;5085535]
Back to '71 HO F-body's... have ran across several stripper manual strg '71 HO Formula's that were ordered with M22's for NHRA & AHRA drag racing. Def the best F-body platform to go quick in '71. None of these so ordered '71 HO Formulas were ordered with pwr disc brakes, P/S, or RA aircleaners, the RA aircleaners were heavy & owners figured that in. Instead, two of the such HO Formulas I've ran across ran just a deep drop 14" aircleaner base snugged down with carb return springs to the intake, this allowed smooth airflow into the Q-jet at the strip.

QUOTE]

Not to take this off subject but a refresh of some NHRA history. The biggest reason these cars that were intended for dragracing (as many others) were ordered without their ram air setups is because without it the cars were automatically factored into a lower class. Those that were in the know, knew the fresh air wasn't a huge improvement in ET and it was much easier to factor the car in the lower class and run under the index.
Having collected a few different brands of "fresh air" cars myself I've run accross several R code mustangs that were missing their shakers. Owners would reinstall flat hoods to reclass the car, sometimes switching back and forth, and over the years these pieces get misplaced. Alot of people look at these cars today and can't comprehend why these expensive parts are missing. That's just what we did back in the day.

[transam1972]

Formulajones....thanks for cluing me in on these drags...I definitely look forward to the day I take my car to one...when exactly did this begin and I suppose it travels the country?...does it come to my state, N.J.

[Formulajones]

Yes they go to several venues throughout the midwest. Michigan being the favorite, but they do go East out your way. I'm trying to remember if it's ATCO or one of those tracks out there. Just to be a spectator is a blast too and you get to see more without being busy on your own car. If the weather is good then 100+ cars isn't out of the question.
Either way it's a good time and amazing to see the F.A.S.T. class with a couple of the stock appearing cars dip into the 9's on polyglass tires no less. Most of those guys will run 10's. Neat but expensive, I'm more of a pure stock racer myself, alot cheaper

[PureSD]

[QUOTE=Formulajones;5086087]

Originally Posted by 'ol Pinion head

Back to '71 HO F-body's... have ran across several stripper manual strg '71 HO Formula's that were ordered with M22's for NHRA & AHRA drag racing. Def the best F-body platform to go quick in '71. None of these so ordered '71 HO Formulas were ordered with pwr disc brakes, P/S, or RA aircleaners, the RA aircleaners were heavy & owners figured that in. Instead, two of the such HO Formulas I've ran across ran just a deep drop 14" aircleaner base snugged down with carb return springs to the intake, this allowed smooth airflow into the Q-jet at the strip.

QUOTE]

Not to take this off subject but a refresh of some NHRA history. The biggest reason these cars that were intended for dragracing (as many others) were ordered without their ram air setups is because without it the cars were automatically factored into a lower class. Those that were in the know, knew the fresh air wasn't a huge improvement in ET and it was much easier to factor the car in the lower class and run under the index.
Having collected a few different brands of "fresh air" cars myself I've run accross several R code mustangs that were missing their shakers. Owners would reinstall flat hoods to reclass the car, sometimes switching back and forth, and over the years these pieces get misplaced. Alot of people look at these cars today and can't comprehend why these expensive parts are missing. That's just what we did back in the day.

Very interesting! I was curious why my '71 455HO M22 was ordered as a stripper for racing but no Ram Air. Makes complete sense.

[tjtjwdad]

Originally Posted by rexs73gto

"...going to be a threat to the Corvette so Chevy had it killed..."

"...The HO engine was a low comp. RAIV engine so it could keep up with the HP that chevy was putting out to stay as the power house for Pontiac , without hurting chevy in the way.

Maybe it is just me but it sounds like GM had to hold the other divisions, along with their cars to "protect" the Corvette from better engineering. What an asinine approach; competition is a healthy thing and besides, these are two different platforms altogether.

Also, didn't the RAIV have a stronger bottom end whereas the 455HO did not? IMO the SD455 is a substantially improved 455HO, with all of the goodies. Besides the low compression and emission controls, I've always felt the 455HO Achilles heel was with the STD bottom end; which limits the top end of the RPM range.

Too bad Pontiac got caught by the EPA with the SD455 emissions and had to re-work the engine to pass. Makes me wonder if some Chevrolet/Corvette spy didn’t send a little note to the GM brass; or the EPA itself.

[transam1972]

I really need this answered...is the Pontiac block closer in size to a Chevrolet 350 or closer to a Chevrolet,Oldsmobile,Buick 455?...this thread has really increased my appreciation of the 455 H.O. and of course all of the roundports

[johnta1]

Also, didn't the RAIV have a stronger bottom end whereas the 455HO did not? IMO the SD455 is a substantially improved 455HO, with all of the goodies. Besides the low compression and emission controls, I've always felt the 455HO Achilles heel was with the STD bottom end; which limits the top end of the RPM range.

I always figured the 455 HO was like an interim set up until the SD got going.

Too bad Pontiac got caught by the EPA with the SD455 emissions and had to re-work the engine to pass. Makes me wonder if some Chevrolet/Corvette spy didn’t send a little note to the GM brass; or the EPA itself.

Chevrolet ruled the roost.

what cam did the S.D. get?...its own special design?,or a previous one?...what is involved in making the dry sump functional?...does the motor need to be pulled?...anyone here ever hook theres up?!

It was supposed to be like the RA IV cam, but it ended up like the 9785744 cam.
The SD cam had a smaller gear on it for the distributor.
(distributor gear was bigger and engine had bigger distributor hole)

There has been at least one set up to use the cam gear pump.
The pump housing is at the rear of the engine, so engine has to be out for it to work.
There used to be a company that made the gears to use in it?



The SD and the RA V engines were probably the best thing coming out at Pontiac at that time.

[johnta1]

I really need this answered...is the Pontiac block closer in size to a Chevrolet 350 or closer to a Chevrolet,Oldsmobile,Buick 455?...this thread has really increased my appreciation of the 455 H.O. and of course all of the roundports

In physical size?


Bigger than SBC probably smaller than BBC, close to Buick maybe?

No parts interchange between them though.

[transam1972]

yes..actual size...I am choosing my words carefully,but relatively speaking,is a Pontiac block considered a big block,medium,or small block..at this point it does not matter because the PONTIAC motor is #1 to me

[Formulajones]

I don't buy into all the talk about Chevrolet or any of the other corporates in a plot to keep Pontiac at bay, that's a bunch of hogwash and likely just pontiac lovers sitting around and bench racing and coming up with conspiracy theories, lol.

It was a direct result of EPA strict emissions compliance and the introduction of low octane unleaded gas. Chrysler, Ford, Oldsmobile, Buick, Chevrolet, Pontiac, they all had to lower compression ratios and change camshaft profiles to meet the new standards.

All this plus the rising costs of insurance premiums is what killed the whole muscle car movement.

It's happening all over again, with the government implementing stricter fuel mileage regulations every few years, with the latest coming in the next couple years, it's causing the auto manufactures to completely rethink their performance platforms,,,,again.

[johnta1]

is a Pontiac block considered a big block,medium,or small block..at this point it does not matter because the PONTIAC motor is #1 to me

Pontiac blocks are neither big block or small block.
(unless I guess you include the later years 265 and others)

The Pontiac 301 is basically the same as the other blocks, with some stuff interchanging.
(it's shorter deck smaller mains mainly)

[1971WARBIRD]

to kind of stir the pot and throw something out there.
I would have liked to see a 428 with a RA IV top end. they were working on the RA V setup with 303-400-428-455 sizes if I am right.
a 428 with the RA V rods or early nascar rods, and the RA IV top end would have really been interesting, at least to me.

[transam1972]

a number of years back I had a car mag. where a orange G.T.O. owner had a RA V in his car...are there any similiarites in the RA IV and 455 H.O. to the RA V?