Ram Air IV versus 455 HO

[StealthBird]

The 71/72 455HO Trans Am's and Formulas were always legit mid 14 second cars straight off the showroom floor, without any tinkering, and with the factory wheels and tires in place. All the 71/72 Formulas and Trans Am's had large 15" wheels and some pretty fat F60-15 rubber underneath, and the limited choices of rear gear selection made these cars pretty consistent from one example to another. Very impressive for a 3800+ lb. car running on regular gas.

The 69/70 RAIV cars were a bit more finnicky. The 3.90 gears were standard with the RAIV, and a/c was not available. With F70-14 tires, it was all up to the driver and their launch technique to determine whether a RAIV car was a mid 14 second car or a high 13 second car. In reality, most 69/70 RAIV cars WERE low 14 second cars straight off the showroom floor (as were most every other Musclecar in TOTAL showroom trim), and just like the others, a little traction put a RAIV car in the mid 13's. The 69 Firebird RAIV weighed in around 3500 lbs, while the 69/70 GTO was around 3650 lbs.

The 73/74 SD455 Formulas and Trans Am's were also legit low 14 second cars straight off the showroom floor, but in my opinion, they were the most impressive of all the factory Pontiac performance cars. The SD455's had a horrible, highly restrictive exhaust system, an EGR manifold, 3.42 or 3.08 gears (with or without a/c), they ran on regular gas, and didn't even have the benefit of a cold air induction system, or even an aluminum intake manifold. With the scoop opened up, these cars were touching the 13's, and raising the compression ratio a couple points from a pathetic 8 to 1 to a more reasonable 10 to 1, and removing the restrictive exhaust system (PMD claimed 50 hp reduction through the pipes and the factory crossflow muffler) to put the car in a "1970 era" mode, these cars were solid mid 13's on factory rubber.

[supergonzo]

"Pontiac dropped the ball in 1970 by not having a 455 RAIV ready" This is correct/ Pontiac 455 HO motors were made after compression ratios had already dropped to 8.2 to one.
Even at this rating 455HO's are strong motors. The 1970 455's were not high performance motors. Pontiac of course got in one more shot in 1973 with the 455 Super Duty, which is the ultimate Pontiac 455 motor. And could run with any muscle car ever built. The exhaust manifolds on SD cars are quite good, among the best Pontiac ever produced, however the pipes went back to a crossflow muffler in front of the gas tank, that REALLY added alot of backpressure to the excellent 455SD heads trying to breathe. Similar to big block chevy muscle cars....un cork the exhaust and you made ALOT more power. 50HP is very accurate.

As for RAIV's 400's, They were mid 13 second cars straight off the showroom floor, if you knew how to re-curve the distributor, and reset the timing correctly. If you removed the cleverly designed factory removeable pre-heater crossover and used block off plates you got another 10th out of em'......How do I know?? I have 2 of them now, and run them frequently in pure stock condition on radial tires and they run low 13's to 13.00's depending upon track temperture. I regularly beat my LS6 70' Chevelle. Weight has alot to do with that though. Go look up any pure stock/factory stock drag results and you will see these cars all running close to 13.00's on bias ply tires!!

I am also the organizer of this years Northeast Factory Stock and FAST Drag race. www.musclecarrace.com
Come out an see RAIV's as well as LS6's and HEMI's and alll the heavyweights do battle.

Anyone who has even looked at a set of Pontiac heads/intake and exhaust and compared RAIV parts and standard Pontiac performance parts would see an OBVIOUS difference.

As a side note. Both my 69 RAIV GTO's weigh 3700lbs
My 69 400 Firebird weighs 3450 lbs.

A 69' RAIV 400 Firebird or T/A properly tuned is a top performer. There is one that runs in pure stock classes running 12.70's again on bias ply tires.

[StealthBird]

Supergonzo, I think your quote "I regularly beat my LS6 70 Chevelle" would stir up a few people here.



Not sure about the weights. I've seen the weights on several early Birds and GTO's on NHRA digital scales (this was at Route 66 Raceway, the state of the art NHRA track). I have yet to see a 69 Firebird 400 under 3500 lbs. I weighed mine on the scales several times, and it weighed 3520 lbs without me. It's a 69 Firebird 400, TH400, P/S, PDB, no a/c, and on lightweight side, I had aluminum heads (66 lbs. lighter than #62 steel heads), aluminum water pump (4 lbs lighter than stock), aluminum intake (24 lbs. lighter than a cast iron), headers (6 lbs. lighter than standard manifolds), and a Reactor battery (21 lbs. lighter thand a Delco 1000 amp). In original form, it was 3641 lbs. Only thing that may get this under 3500 lbs. would be a 4-speed, manual brakes, and manual steering but even that would be close I think.

My friend weighed his 69 Firebird 400 ragtop, TH400, P/S, PDB, no a/c. It weighed a staggering 3950 lbs (without driver) on the NHRA scales. I simply could not believe it.


My brother's 68 GTO, TH400, P/S, PDB, hideaway headlights, 455 HO heads, 455HO exhaust manifolds, aluminum intake, weighed 3710 lbs. without driver.

The 67/68 Firebird were about 3450 lbs for the hardtops. My friend had his to 3350 lbs. with an aluminum intake and headers, manual steering and brakes, and a transplanted TH350.

Those dern Camaros always seemed to be lighter.

[supergonzo]

"Those dern Camaros always seemed to be lighter" Actually my own 69' Yenko clone weighs 3600 lbs, weighed it 4X times.
But I think its a little heavy for some reason.

I have to admit my 69' firebird has a fiberglass hood, 4spd, aluminum radiator,manual brakes. I would say 3520lbs would be more accurate for a typical model. Your right the earlier years are lighter.

I am certain the 68-69 goats all weigh close to 3700 lbs, I have 4 of them now, and have owned about 20 others. The 64-67 goats all weigh close to 3600lbs, depending upon options.
I was actually surprised the Firebird / Camaro's weighed that much.
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If Pontiac would have made a high compression 455HO in 1970 instead of a low compression motor in 1971.They would rank right up there with LS6's and Buick 455 Stage 1's as one of the baddest of all times. As it is in todays world , where most people build for near 10 to 1 compression for pump gas, they are very tough street machines to beat,as now the field has been equalized.
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[yellowjudge]

I think the 68/9 birds would of been quicker than GTOs. I have a 69 raiv TA, it seems like it is faster than my 70 raiv judge.

[supergonzo]

Should be its about 200-250lbs lighter. probably 2 tenths quicker

[StealthBird]

[ QUOTE ]
I think the 68/9 birds would of been quicker than GTOs. I have a 69 raiv TA, it seems like it is faster than my 70 raiv judge.

[/ QUOTE ]

This was the reason that Pontiac placed a throttle stop on all 1967-1969 Firebird 400's. They didn't want the Firebird outrunning the GTO.

[tog1937]

The 71 455 HO is basically a slightly lower compression and milder cammed 455 cubic inch RAIV (to meet emissions) and includes the 4-bolt mains. Just drop in some 10.5:1 forged pistons and a modern cam and have the best of both worlds. For even more fun top it off with a nice Holley HP mechanical secondary carb and an Edelbrock Performer RPM intake. Massive torque and unstoppable top end, a positively killer combination especially when mated to a Richmond Gear 5-Speed !

[tjs44]

The 455SD was designed as a race engine but GM got their hand slapped when caught messing with emission.The block is a 4 bolt main with all joined lifter bores like the RA Vs and also provisions for a dry sump oiling system.Diff cam altogether as it has a smaller dizzy gear on the cam and a larger gear on the dizzy to handle the 80 LB supplied in the engine.Too bad they could not get it ready for 1970 with high compression and a IV cam. They had to go back,run a smaller cam and a iron intake from the the engine that was given for emissions.Pre dated the VW cheating scandal.FWIW,Tom

[442w30]

Originally Posted by tjs44

The 455SD was designed as a race engine

Race engine?