Ram Air IV versus 455 HO

[yellowjudge]

HI, I know of the Glasgo 70 TA, It was an orig. RAIII car, converted to a RAIV. Very low mile, super nice car.

[HemiOrangeTA]

Some years ago, Muscle Car Review published an article which had Jim Wangers rate his top five fastest GTO's. Although based on period magazine tests and subjective "seat of the pants" recollections, it is nonetheless an interesting read. I believe the 1971 455 HO rated very highly.

[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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[supergonzo]

As far as the LS6 goes... Chevy has the best heads for breathing period.
Problem 1 is the 70' LS6 weighs 3850 lbs, that doesn't help
Problem 2 is the intake manifold and the exhaust manifolds are choking the engine's breathing capabilities.
In other words they s*ck.

Chevy knew people were going to take their cars racing, and throw away the intakes for better ones and throw away the exhaust for headers. Once you do that to a BBC, you got a whole different animal. A car that most brands would have a very difficult time beating.

Pontiac GTO on the other hand, was a super cool image street machine. Pontiac was selling boatloads of GTO's while others were selling 1/3 as much most of the time. Chevrolet had 3X the dealer network and 4X the advertising budget as Pontiac and still couldn't out sell them!

Pontiac built good heads, excellent intakes, good exhaust manifolds, topped with great responsive Q-jets. And very little work was required to turn a showroom car into a "street cleaner". On the street they were tough to beat, but were never meant to be all out drag strip racing engines.

Ok, thats enough of a rant.

[Chevy454]

[ QUOTE ]
"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.


[/ QUOTE ]

Sounds about right. Our Y-Camaro is anywhere from 3700-3800+ with me in the seat and a tank of fuel...and I weigh a LOT less than the NHRA's 175-pound driver allowance. I wish we could shed a little weight, but I don't think dad would see the humor in gutting the car!

Your mention of the Chevrolet heads is interesting. When I went through the Certified Stock tech for the Pure Stock Drags, there was our L-72, a Stage 1 Buick, a 440-6, and a Hemi all torn down in the same shop, so we all got to see the goods on each others combo. The comment that kept coming up was at how SERIOUS the Chevy heads looked, even though they were bone stock. Everything from the ports to the valves to the chamber...pretty impressive. Of course the hemi chamber was high-tech, but the Chevrolet was impressive in it's own right. I wish there had been a Poncho and a 427 Ford there to check out as well, but it was still neat nonetheless.

[SuperCars]

Okay, leave the 70 455HO with it's smaller D-port heads out of the question of this thread. Compare the 70 400RAIV with round port heads, and 71 455HO with round port heads. I notice the factory rating on each as: 70 400RAIV 370HP/5500RPM versus 71 455HO 335HP/4400RPM. Would it be true that the 71 HP is peaked out at 4400RPM. That's at 1100RPM under the RAIV rating, which seems to be very low RPM to rate its maximum HP. That is how the L88's were rated less than L71's in the Vettes.

[supergonzo]

These engines all used the same intakes and exhaust, the 70-71 were in heavier cars.
However:
The best breathing heads were 70 400 RAIV's
Followed by 69 400 RAIV's
Next would be 71 455 HO heads, slightly less flow on intake
Finally would be 72 455 HO heads, even slightly less flow in exhaust area. Pontiac engineers knew at this time, compression ratios were falling, and were trying to get as much torque as they could out of the heads, and not worry about upper RPM air flow, as the 400 RAIV's were built. The 455 HO's also did NOT use a RAIV cam although the heads were similar they used the earlier MUCH milder 068 (tripower) cam. Again due to emissions and better low rpm cylinder fill with low compression on those heads.

A 455HO does have a lower rpm peak than a 400.However
The 400 RAIV's were underated, as several magazine dyno test have been done (even recently) and showed in stock form they produced 400-420HP.
The 455 HO with its emission friendly cam has had dyno test in the neighbor hood of 360-370HP, if I remember correctly. The 4400 peak HP rating is definitely too low, and probably rated that way on purpose, to satisfy then very restrictive insurance rules.