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1970 Ram Air IV vs. 1971,72 455 H.O.
does anyone on the forum own a 1970 T/A Ram Air IV?...and it being high compression were they "harrier" than the 1971 and 1972 455 H.O.s?
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This will spark a "lively" debate......
Pontiac actually had a TV commercial in 1971 that pitted a 70 Ram Air IV GTO againt a 71 455 HO GTO to show the performance was similar/equal..... The Ram Air IV was "harrier" in a 1969 Firebird because of the cars lighter weight... |
commercial
I have seen that commercial..of course Pontiac wanted the new cars to win...but I would like to know real life...70 T/A RA IV against the 455H.O. T/A...does the last year for high compression in a Pontiac engine in the T/A body make a different animal?
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The extra 55 cubic inches on the low compression H.O. has to more than even the playing field with the high compression RA IV. There is no replacement for displacement!
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You'll not likely get a fair answer as most on here advocate modifying original engines when they are rebuilt.. your dealing with the "Stock appearing" crowd now... this goes for almost everywhere...
Aside from making it, you cant get the gas the 1970 car really requires. |
I'm not trying to highjack this site but please go to the post Loss of a friend & read them if you are a friend or know Bruce Zalai, he was a big SD fan & owner who we lost on wed. He had just turned 60 on dec. 2nd. Thank You for reading & rest in peace good friend.
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stick vs. auto
I am into keeping everything stock..pain about the gas though for 1970 and earlier owners...I knew along time ago my low compression engine was a good thing....what about the M22 vs. the Turbo Hydramatic 400...if stock...who wins?
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Gears will make the bigger difference in what you feel.
Given the choice I'd take the IV any day of the week. |
The 69 and 70 RA IVs were beasts with HPs in reality terms closer to 500...Add the bigger gears and lighter cars you got a better comparison for the RA IIs which shared cams and comp ratings. 455 HOs are just good fun cars to drive to race, race, and go home with a smile...
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You really don't have to look any further than the pure stock drags and come to your own conclusions.
Once you attend a few of these things, understand the rules, and build and race a car for it, you'll see which cars are the more advantageous packages and which are "lacking" performance. Given the fact that the cars all follow the same rules, and run on the same tires, it's really the only true comparison nowadays. For those that don't want to research, the ram air IV cars (including the A-bodies) consistently put up quicker ET's and higher MPH's than the few HO cars that participate. That's from what I've seen in person and participating myself. Alot of that has to do with the more radical camshaft the IV's get right off the bat, coupled with more compression, they make power, usually in the ballpark of 400 rwhp on a chassis dyno when tuned and tweaked. The HO cars lack a camshaft and compression, but they do make a nice torque curve. But with the tires being an equalizer so to speak, low end torque isn't necessarily a good thing. They do however put up very respectable times. |
Ram Air 4
o.k. so its possible to say a RA4 is less mannerly than an H.O.?..and an H.O. is perhaps more refined?....would anyone care to tell me how or what parts evolved from the RAIV to the H.O....thanks!!
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I wouldn't say the HO is more refined, it's just a victim of strict emissions and lower octane unleaded fuel that was making the scene at the time.
The heads and intake were the major pieces from ram air IV development that were carried over to the 455 with minor changes (to keep the description brief). If the engine would have had the camshaft and compression ratio to go with it you would have had a very potent package. As is, it's still a nice performing engine that will run on the cat pee gas we have nowadays. So under those circumstances, in some peoples eyes it does make it appear to be a more attractive package. |
Sounds like a time for a shoot out to put this to bed.
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No better place than the pure stock drags, if you have something, bring it on out and have at it :D
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Way to many variables. In a 1/4 mile from a stop chances are the HO will get out of the hole faster. But, I think because the RA IV has the ability to keep pulling where as the HO will fall off, the IV would beat it up. 18 degrees of duration @ .050 on the intake and 2 points of compression will surely out perform a 55 cubic inch size advantage. Now, recam the HO and things change completely. But were talking stock.
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Stock is the only real comparison apples to apples, and I believe that's what most people mean. If you start modifying things to each owners tastes, well then anything goes and comparisons get lopsided ;)
That's what is sweet about the pure stock drags, the rules apply accross the board so any gain or advantage you find in the rules is the same for the next guy. |
455 H.O. mods
my engine is 100% stock...I hope to never have it rebuilt or modified...however, can a RAIV cam go in a H.O.?..what happens?..obviously I am sure there are other things to fine tune...interesting idea to upgrade a H.O. to RAIV standards,if only this was 1972...time span and gas what it is doesn't make it feasible I suppose...I am on the lookout on this forum for modified H.O.s...any ones thoughts on limited mods to the TH400?...such as a shift kit?, does it need it?...I wouldn't(I don't think?!)but a nice looking Dual Gate would be cool!...I have never been able to enjoy my H.O.perhaps 500 miles in my life??,
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Plenty of people over the years have installed the ram air IV camshaft in the HO cars with "decent" results. However the engine really doesn't have the compression ratio to take full advantage of it.
One advantage you have is that the ram air IV cam is much more tame in an HO with 55 more cubes to soak it up. It's a swap that might be worthwhile to you. |
The 041 cam runs very well in the low compression 455's. Probably not the best choice and if you are using an auto trans then it will feel like a slug unless you have some convertor behind it. But, they do run well.
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I agree with Ferris.
I'd definately want some converter behind it if you run an auto. |
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"supposed to be stock suspension..." I watched a stock 71 Cuda AAR with disc brakes , get brakes gone, all impact bars, GONE, and lots of lightening, when done, you couldnt tell... same treatment went into a "ZL-1" Camaro So its back to "stock appearing" in my book Also a Trans Am was never meant to drag race....makes me sick seeing them on the drag strip, and looks dumb too |
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I believe Pontiac HAD a high compression round port 455 in the master plan for 1971,but the EPA put a stop to that. |
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As far as the engines go,,,they are as stock as one could expect after 50 years. The rules allow 1 mojor change and that's compression ratio. That's for obvious reasons. After 40-50 years of use these engines have been rebuilt 2 and sometimes 3 times or more. They need bored, decked, milled, etc... All of which will increase the compression ratio, you just can't help that. So the rules implement a .070 overbore maximum and a 1.5 compression bump over the "advertised" compression. Since rules dictate all casting numbers must match the HP and model claimed, you can't use aftermarket blocks. Heads are as cast, no port work allowed of "ANY" kind, same goes for intake and exhaust manifolds. All have to be factory correct for the HP and model claimed. They aren't worried about date codes. Carb is also the same way, and chokes must be present and functional. Cam and valvetrain also have to be stock per HP and model claimed. They only allow 130 lbs. seat pressure on the springs which is stockish, this keeps people from spinning these engines higher than a stock engine would normally go and making more power. So for all intensive purposes these engines are as stock as one can be, and believe me this stuff is checked, they will perform complete tear downs for certification, they check bores and strokes, camshafts etc.. to make sure everything is on the up and up for your model and HP claimed..So everyone is on an even playing field. As far as suspensions, no trick springs or fancy shocks allowed, sway bars must be attached and functional. No traction bars allowed etc.... A couple things they will allow are "no hop" bars on coil spring cars, and they allow clamping the leaf springs on a leaf spring car,,,,,that's it. Now you can tweak things like pinion angle. Another trick that I employed was to shim the front sway bar frame bushings so they didn't "crush" the bar. This allows the front end to move more freely. Most guys now just hone out the bushings so there is no "crush". Technically legal because the bar is still hooked up and functional. Some will go as far as to employ a similar tactic to the control arm bushings. Another simple trick I did on the front suspension (and it's not really a trick) is that I ran, and still run, oil filled shocks on front because they move more freely than a gas filled shock. These simple mods are all in an attempt to hook those little bias ply tires. These simple and basic tricks got me 1.8 60 foot times on stock rubber. Others have gone even quicker nowadays. There are no trick transmissions allowed, no lightweight parts allowed in the engine or transmission. They do allow rearend gear changes of your choice since most cars came optional with just about anything anyway. No fuel system upgrades of any kind, it must all be stock. As far as lightening goes, it's not allowed at all in pure stock. One of the reasons why people will choose an advantageous platform for racing this class to begin with. You may see things like heater and radio delete, just like cars were back in the day, but you won't see door bars cut or lightweight suspension pieces. Low option, small package cars that are already lightweight are the best ones to start with. Formulabruce seeing brakes gone (or more likely lightweight brake package), door bars gone, was most likely a F.A.S.T. series car. Completely different. They appear stock and parked right next to a pure stock class racer you wouldn't be able to tell them apart, but the rules are different in F.A.S.T. Engine rules just as above but they allow stroker cranks (has to be stock block though) They allow all the porting you want, but again has to be stock cast parts. They also lighten as much as they want, making most pieces and brackets out of aluminum (once painted you can't tell) and swiss cheesing anything out of sight. Radios and gauges may appear intact and functional but on the back side all guts are removed, it's out of sight. Overall the F.A.S.T. cars must appear as the day they rolled off the assembly line, but anything out of sight is fair game. There are literally dozens of tricks in the F.A.S.T. class that would take a book to list here, but I've typed enough. |
This answers my questions. But, how do the rule makers police the trick transmissions? Im assuming winner gets the routine teardown on the motor? But do they do the trans as well? Do they get technical like NHRA does by measuring port volumes ect? Do they allow protest and all that if somebody feels another racer is "cheating"?
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You can even volunteer your car before hand and have all this done before a race, which then your car becomes certified. There are a handfull of very quick pure stockers that have exploited what was already an advantageous package. A couple of L88 Corvettes which are an excellent package for many reasons and I believe they still reign top. The 68 ram air II Firebirds are very quick, great engine, well designed exhaust manifolds and lightweight car, good package and probably the best there is as far as pontiacs go in the pure stock class. There are also a few pure stock Hemis and 6 pack cars that are very tough. |
So you can only race a car that the factory installed the engine in yes? So a Yenko Camaro with a 427 for example would not work because it was a dealer installed motor. Is that correct?
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The only cars that aren't invited are the cars built specifically for racing that generally didn't come with any type of warranty, cars like the Hemi Darts, Swiss Cheese Pontiacs, any of the lightweight cars like the early Dodges and 409/427 Impala's. Simply because these were cars not available to the general public, you had to be an established racer at that time to get your hands on one. So they aren't really mass produced production cars, so to speak. I think the rules specify any V8 rear wheel drive car with dual exhaust up through 1974 or there abouts, that came with a 4 barrel carb, is generally accepted as a performance oriented car and can compete. That includes any car that you want to build as a clone, it doesn't have to be a real car, however the clone built must represent the HP and model claimed to be right down to the correct casting numbers, trans, rear, etc... There are quite a few real cars that compete, I'd say probably 70% of what you see if I had to guess. There are clones mixed in, and most of those you'll see in the F.A.S.T. class. |
RAIV vs 455HO
In stock GM form, as if you just drove a 70 RAIV T/A off the dealers lot and pulled up next to a 71/72 455HO T/A that just left the dealer also, I think the RAIV would win a 1/4 mile street race by just 1 or 2 car lengths. It would be a close race. I have driven both cars in close to stock form. 2 different animals. They both have their advantages and disadvantages. I have also driven a 455HO T/A with stock 70 RAIV 614 castings and Crane blueprint RAIV cam. Now that was Fun! It would have kicked both cars asses. (It didn't take long before it blew the head gasket from the high compression) Like Jack said, there are soooo many variables. 2 absolutely IDENTICAL cars will run different quarter mile times. Just my opinion from real world past experiences.....
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Poncho Motor
since the RA IV and H.O. were the last true incarnations of the Pontiac block,how do they compare to previous versions?...in other words what are the best of the best Pontiac motors?...if only it could have evolved from the H.O. and the SD ....I can only imagine a version of those engines in all of the 1979 Trans Ams
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you do realize you have a slap shifter in your TA if it is still stock. pull back into low, push up and to the right you have 2nd gear, let it center it's self, push up and to the left and you have drive. you would not believe how many guys I have met over the years that didn't know they had a ratchet shifter in their car. when I built my first 71 HO, I did: +.030 TRW pistons, new valves, Hooker headers(back then couldn't find good manifolds), and a crane blazer cam, 218-230 duration, .450-.465 lift on a 114 centerline. this was just a little bigger than the factory 068 cam approx. 215-225/.410-.410. 3.31 posi, 4 speed, LR60x15 radial TA's, it was a fun ride. |
Top Ponntiac Motor
I would like to think are a few #1 Pontiac motors, and I may be wrong...what of the 1968 Ram Air II?...or perhaps it is because it was the first round port?...I would think RA IV is up there,
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I would say the 71 HO was a better running motor, as delivered from a dealership, than the RAIV. 71 HO was the fastest running engine between 71-74 series of Firebirds 455 ci engines-including the SD's(sorry SD guys). The RAIV's cam was too much for a 400 ci engine. when tuned correctly it can run well, but it was a service nightmare back in the day(from what I have heard)- had difficulty with idling/running rich therefore. All of us who have/or have had Pontiac 400 ci engines must admit they are sort of a disappointment. They just do not have the torque numbers that the 455's do. And the IV had less low end torque that a regular 400, it's power was in the upper RPM's, but as we all know street racing red light to red light (which is a beauty of Pontiac engines) was all in low end torque.. The 71 HO was the best of the 2nd gen 455's, even better than the SD in my opinion. The HO did not have the mystique of the Super Duty, but it was the best of its breed of engines. The last Pontiac engine that was pretty much bare engine without any pollution controls/restrictions. Yes the SD had great internals, but the HO's were sufficient. The 71 HO's engine originally came with Pontiacs 068 camshaft. The RAIV's 400ci engine cam was a bit much for the car, but as a rule.. moving up 10-20% in ci's allows moving up a step or two in camshaft. The HO will benefit and run well with a RAIV's camshaft or similar( a couple steps above the 068 which was used in the RAlll's(400 ci engines) as well as the stock HO).
If I were building a new 455 HO, I would use a roller valve train ,including a roller camshaft, would not mess with porting the heads, just gasket match and clean up any burrs, run as much compression as available(9.75-10.00) considering current gasoline. And for straight-line racing/red light to red light driving, the TH400 cannot be beat with a Muncie. Personally I prefer the Muncie, but an automatic is idiot(me) proof and always allows for lower et's. This RAIV vs the 1971 HO engine rivalry has been going on for years. Even knew and saw a survivor RAIV where the original owner was embarrassed his car only had a 400 under the hood after the 1971 engines were released. He put 455 callouts on the scoop and rattle can painted the engine 71 HO color to hide the fact he only had a 400 ci engine. Truth be told, as delivered the RAIV was not the best running engine. With custom tweeking, could run ok, but the 71 HO was a fine engine as delivered and if anything was a bit under cammed. I have often suspected lowering the compression(which is commonly accepted as Pontiacs concession for the EPA) was not the only concession GM gave the EPA, but the cam choice were in fact what Pontiac did to appease the Fed's. The HO engine could have easily been delivered quite street able with a RAIV or similar camshaft. As someone has already stated, no substitute for cubic inches , and the '71 455 HO was the least messed with per pollution/gas buring regulations of the 71-74 455's. So long answer to your question, in my opinion the '71 HO is the best running and easiest to improve upon without drastically changing( up compression and up cam) of these two engines . The RAIV is hindered by being a 400 ci based block. The HO is too similar to the RAIV(intake design,head design etc) which makes me thing Pontiacs engineers understood better than I do that the larger ci's was the answer for their performance round port program. Yes the RAIV has the mystique for their low production numbers, but short of 5000+ RPM racing, the IV was not as streetable as the HO-not by a long shot.. disclaimer this is just one guys opinion, I do not portent to be the tree of knowledge when it comes to Pontiacs, so I could be wrong. This is just y opinion. Oh, and I have no malicious intentions here and apologize if my post offends any members of this board- that is not my intention. |
455 H.O.
well said 70RAIII,...that was not the answer I expected....since I own a 72 455 H.O. I have gained new respect for it....I do not think there will be a debate here
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71 455 HO
I have a 71, luckily it was orig down to starter. Had nos RAIV cam, lifters, valves put in,, It's a runner,, unfort now in resto prison, awaiting it's pardon from it's 8 yr long sentence..
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Notice RAIII never mentioned the 72 455ho in that analysis. If I read it correctly and have to agree torque is fun in a car when it's all about driving.
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sorry
sorry to hear about your friend, wow 60, not very old. I'm only 15 yrs younger, makes you realize, life is short..
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Good reading all the way around. I have ridden in all these cars, but I was only 6-7 at the time. My father used to drive them every day as company cars when he worked for Pontiac. I do recall in past conversations how customers complained about the RAIV and drive ability. Especially the automatic cars. Let's face it, they were not targeted at ma and pa to take on a Sunday drive. Neither were the LS6 Chevelle's and the hemi Cuda's. But many ended up doing just that. I would agree the mild mannered HO cars likely did run better and surely were more user friendly.
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67-68 birds are the lightest of the bunch so that's a huge advantage. Again look no further than the pure stock drags and you'll see a handfull of 68 round port birds running. Jim Mino was the first to bring this to light in the 80's when he was cleaning house at the muscle car drags against all comers. When Pure Stock was born a short time later these little birds quickly became the car to beat. It's HP to weight ratio is very good. They are consistently the quickest pontiacs at the Pure Stock drags hands down and easily run with any of the big dogs that have a 50+ cubic inch advantage. |
Most any real gear head or old timer like myself compares a cars performance on the dragstrip, the oldest measuring stick. Lets face it, that's what started this whole muscle car craze.
When you guys start talking about all around street cars and driveability that really changes the ball game, especially when there are no rules and guys are sticking any camshaft or cylinder head on a car, stroking, etc....the whole mess becomes impossible to compare, we aren't talking about "stock" packages anymore. You can throw money and parts at any car and make it perform exactly how you want. There are no rules on the street. When thinking in that sense, of course any car can be made to be a pleasure to drive. Anything with an 068 cam is going to be very docile and easy to drive back and forth to the grocery store or take a vacation with the family. The HO cars were a great example of that yet still had respectable performance thanks to cubic inches. They are a pretty nice overall package for a street car. |
My recently purchased '71 Formula 455HO M22 will be delivered to me in just a few days. I'm excited to compare against my SD but will have to wait till spring time. The SD is a TH400 so it will be a different experience and feel. I'm extremely excited about the '71 455HO especially after reading 70RAIII's post.
The '71455HO was rated at 335hp and the '72 455HO at 300hp. What was the difference between the two? Just Pollution adds? |
Are these cars stock for comparisons sake?
Driveability is going to be nearly identical between the HO and SD, those cars are a toss up. Again, look at the pure stock drags, there are a couple of very good running SD's and HO's currently running,,,both examples run nearly identical times and there are more than 1 of each to compare. I believe they have all dipped into the high 12's at about 110 mph now. Very respectable running cars that are restricted to their stock camshaft, with the only major change being a 1.5 allowable bump in compression over "advertised", which these engines desperately needed. Even with that bump it can still be a pump gas car because you only wind up at about 9.9 - 10:1 final. With that being the only major change from OEM I'd say they run pretty damn good. |
71 and 72 HO's are near identical. The only difference was in how the horsepower and torque were rated. Gross (71) and net (72). No pollution controls on either except TCS.
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71 & 72 455H.O. differances
perhaps someone knows the important differences between the years...aren't the heads slightly different?....I believe 71 has a 800cfm carb. and 72 is 750cfm...any slight intake changes?....seems to me 71 had extra black hose plumbing...I do not know what that is,just emissions?
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the 71 head has a better high lift flow potenial because of some small changes in the port shape. i have had it explained to me, just can't explain it myself. 1972 had a small change to the intake floor that has been documented to decrease flow slightly, all FACTORY over the counter replacements have this change if produced after 1971, no matter what part number. |
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71 intake has better flow I believe. 72 heads have funny port notch cut outs. I can attest RAIV cams work very well in a 455, but harder cold starts, lumpy idle charecteristics, and as said with auto, shift kit and higher stall converter. I think a built HO or SD trumps a 400CI usually, but stock I would bet on RAIV with both in tune. How car is set up is big as power curves, RPM ranges, gear ratio, tranny are the deal breakers. As great as HO and SD's are, both are handicapped by less than ideal factory cams in relationship to the rest of the engine potential.
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