Ram Air IV versus 455 HO

[Belair62]

455HO is probably comparable to an LS5...

[Chevy454]

From what little Poncho exposure I've had, I tend to lean towards the 455HO. In Pure Stock competition the quickest Ponchos aren't the RAIV, but the RAII's and the 4550HO's. Granted, the IV's run well, but I put more faith in the II or HO combos as a whole...

[SuperCars]

This is all good feedback. I think Rob has good input from pure stock competition. Aside from lower compression, what I glean out of this is the 71 455 HO with more displacement and large round port heads had a lot going for it. Kind've like the 71 LS6 Vette, had to say that for Belair.

The RA IV's are great, and I'm not knocking them as I own a 69 and 70. But just quite surprised that Pontiac Engineers only felt a 10 bolt was needed, and that translates to performance in a round about way. The 71 455 HO W/ round port heads, and Pontiac engineers putting a 12 Bolt behind it would give me the impression that was their top performance drive train combo. Just my opinion.

[Belair62]

Didn't the 455 have a silly amount of torque ?? 500 or so...what is the diff between BOP 10 bolt and Chevrolet ?

[StealthBird]

The RAIV cam was the first computer designed camshaft in the industry. It was so effective, the camshaft is still widely used even today in Pontiac rebuilds, even with 35+ years of aftermarket cam grind technology available. Besides, we don't know any better.

The predecessor to the 1969 RAIV was the 1968-1/2 RAII. The RAII was basically a RAIV, but without the RAIV 1.65 high lift rocker arms, and without the nifty RAIV two-piece aluminum intake. On paper, the RAIV was a stronger combo.

But Jim Mino's 1968 RAII Firebirds seem to tell a different story. There has been a lot of speculation as to why the RAIV doesn't seem to do as well as the RAII and 455HO in the shootouts. In all honesty, I firmly believe that no one has really taken a RAIV to the same level that Mino took his RAII Firebird (or Jensen with his 455HO car). Those guys had a firm understanding of the Pontiac drivetrain, head flow, etc., and spent a great deal of time and effort assembling their combos. It appeared as if they were cheating, but they weren't. It was hard to believe a little 400, rated at a measly 340 hp, or a low compression 455 rated at 335 hp, could beat up on on so many high compression, big cube, solid lifter cars, 400 + hp cars, but they did. Mino's 68 Firebird was a lightweight, and so was Jensen's GT-37, but not "cheater" lightweight. They just found cars that were originally ordered in a street racer way. Jim Mino did a thorough teardown of his RAII a few years ago for a magazine, and showed every conceivable part of his 400 to the cameras. It was absoltely bone stock, unported, unmolested. He just assembled the engine with great care.

Pontiac 400's and 455's are low revving combos. They were so effective on the street because most street races lasted about 5-10 seconds, and during that time a person cannot take advantage of a 6000 + redline. Pontiacs focused on a broad torque curve rather than peak hp, and that made for a great street racer.

[Chevy454]

Hey Mike! Talk about your good running Ponchos! I'd still love to see that 'Bird of yours in action! But only if I get a "spot"!

Pete can jump in here if this is wrong, but I *believe* the Glasgo's have a '70 IV TA that they run at the PS events. If I'm not mistaken, it's in the high 12-range, and looks KILLER. One of Minos old RAII 'Birds is running PS with us, as well as another RAII 'Bird. I was sandwiched between these 2 cars in Stanton last year with my 12.47. And Jensen's HO car is sleeper if there ever was one...but you'd better choke up if you're gonna tangle with that T-37! Hard to go wrong with any of those packages.

[StealthBird]

There was also a BOP 12-bolt, which was essentially a 10-bolt with a 12-bolt cover. This was the rear end that made it into the BOP heavy duty applications in 70-72. It uses bolt in axles, not c-clips, and the cover has a different shape. This is what's under my 69 Firebird.

Rob, thanks for the I really have to make the trip to see these Pure Stocks in person. BTW, they just released those coveted RAII/RAIV exhaust manifolds for the 67-69 Firebirds, and believe it or not, they have a version with a 3" collector! I was seriously thinking of going back to RAIV heads and using these manifolds to see what would happen, but I realize some of the really serious "stock" guys have a lot more serious internal engine mods than I care to perform right now. I still have a hydraulic cam, cast rods, and big ol' TRW slugs.

[yellowjudge]

Hi, the 71 455 HO TA only received a 10 bolt, 3:08,42,73 ratios. I think the 455 H.O. great street mtr, just does not have the mystique of the RAIV. I have both, the H.O> a better cruising car.

[Charley Lillard]

The Pontiac 10 bolt is stronger than a Chevy 10 bolt. Might have 10 bolts but it is better.

[Jeff H]

Is the BOP 10 bolt like the later Chevrolet 10 bolt?