In the December 1968 issue of Hi-Performance Cars (aka CARS) magazine, automotive writer Roger Huntington examined four GM cars with ram induction systems — a Camaro Z/28 with the cowl plenum intake, an Oldsmobile 4-4-2 W-30 and an Olds Cutlass Ram Rod 350 W-31 with Force-Air Induction, and a Ram Air II Pontiac GTO — to see if these systems really improved power at higher speeds. Here’s what he found.
Cold Air and Ram Air
Hood scoops have been a popular form of automotive costume jewelry for decades. In many cases, they’ve been strictly decorative — at most, they might provide a bit of extra clearance for some under-hood component. However, in the late 1960s and early 1970s, there was a brief vogue for functional scoops, designed to admit outside air to the engine.
Huntington began by recapped why one might want functional hood scoops, which fell into two categories: cold air and ram air. He explained:
You all understand the effect of cool intake air on engine horsepower and torque. The simple fact is that cool air is just heavier or denser than hot air. Since an engine cylinder can suck in only so many cubic inches of air/fuel mixture on the intake stroke, you will get more power and torque if the air is cooler—because you will be sucking in more weight of air/fuel mixture. The difference between drawing in cool outside air at maybe 80 degrees F. temperature and pulling hot underhood air at 130 or 140 degrees can add 3 to 5 percent to your horsepower. That would be 10 to 15 extra hp on the average Detroit engine. And it doesn’t cost you a thing.
The photos on the above page are of an aftermarket ram induction system offered by Joel Rosen’s Motion Performance on Long Island, New York, although that system wasn’t tested in this article.
Ram induction systems also claimed an additional benefit beyond cooler intake air:
There’s another vital factor in this air scoop picture and that is ram effect from the car’s forward speed. In other words as the car goes faster the air is literally forced or rammed into the carburetor through the air scoop, under a slight pressure. The faster the speed the higher this “ram pressure.” And of course the engine hp at a given rpm should theoretically go up and up as this ram pressure goes up. That is, you should get more hp (at a given rpm) in high gear than you get in the next lower gear at the same rpm, because the car speed is higher. Furthermore this hp increase due to ram pressure will be added to the hp increase due to the cool air—so you could end up with as much as 30 or 40 hp more at the car’s top speed than you would get at peak rpm in low or Second gear, where car speed is only 50 or 60 mph.
Of course, simply having an open section doesn’t make a scoop functional. There has to be a sealed channel to the air cleaner inlet so that the engine will draw air through the scoop rather than from under the hood, and the shape and placement of the scoop have be designed to actually admit air when the car is in motion, rather than just collecting rainwater and dead bugs.
Force-Air Induction scoop under the bumper of a 1969 Oldsmobile Cutlass S W-31 /RK Motors
The photos on the top of the page above are of a Motion Performance Camaro with a highly modified 466 cubic inch Chevrolet big block and a functional hood scoop. (CARS editor Marty Schorr was a good friend of Motion founder Joel Rosen, and the magazine use Motion’s shop and dynometer, so Motion Performance/Baldwin-Motion cars and products got a lot of ink in the magazine.)
Huntington continued:
All this is theory. But it got me kind of interested. Especially as the different companies have such widely different air scoop layouts. Some are on the hood, some have high hood openings, others low and streamline. Chevrolet’s inlet is under the cowl vents, where the heater air comes in. Olds puts their scoops ’way down below the front bumper, piping the air to the carb through long flexible tubes.
It occurred to me that some of these air scoop systems must be more efficient than others. They’re all so different in design that they couldn’t all work with the same effect. For instance it is known that there is a “boundary layer” in the air flow along the hood that causes the air to slow down close to the hood surface. Wouldn’t this hurt the efficiency of the GTO air scoops, which arc very low on the hood? By the same token, Olds puts their scoops down below the front bumper in an area of high ram pressure. Wouldn’t this setup be more efficient than hood scoops? Or would air flow friction losses through the long tube ducts cancel this improvement? Chevrolet’s system that uses the cowl vents is in a region of “over-pressure” at high car speeds. But the air has to make a complete turn to get back to the carburetor. Would this kill the efficiency of the cowl vents?
I decided to do a little testing and find out for sure.
In this era, you would ordinarily expect the testing strategy to focus on standing-start quarter-mile ETs and trap speeds, which were still the principal performance focus of American supercars. However, while trap speed is a strong indicator of an engine’s developed horsepower, an increase in trap speed or a decrease in elapsed time with functional hood scoops might be due to a cooler intake charge, a ram air effect at higher speeds, or both.
1969 Dodge Hemi Coronet R/T / Mecum Auctions
However, Huntington had already developed a methodology for calculating a car’s actual engine power at the flywheel based on speed and accelerometer readings. (These estimates pop up from time to time in the various road tests he wrote for auto magazines, and he compiled many of them in his 1983 book American Supercar.) Using this methodology, he decided to measure the test cars’ power at the same engine speed at increasing road speeds, “to show the effect of increasing ram pressure.”
426 cu. in. (6,974 cc) Hemi with “Ramcharger” cold air hood / Mecum Auctions
He obtained four test cars for this purpose: a 1968 Camaro Z/28 with the rare cowl intake plenum kit; a 1968 Pontiac GTO with the Ram Air II engine package; and two 1969 A-body Oldsmobiles with Force-Air Induction: a Cutlass S with the W-31 350 and a 4-4-2 with the W-30 engine.
1967 Chevrolet Camaro Z/28 with cowl plenum intake / Mecum Auctions
The hood scoops were open on a 1968 Pontiac GTO Ram Air II, channeling air into the air cleaner / Mecum Auctions
The text doesn’t explain why Huntington limited this exercise to GM cars. It sounds like the new Chrysler system wasn’t yet available when his tests were performed, but it’s not clear why he didn’t include the system offered on the Ford 428 Cobra Jet engine.
Force-Air Induction scoops were under the front bumper on the 1969 Olds 4-4-2 W-30 / Mecum Auctions
The 1969 Oldsmobile Cutlass S W-31 also had the Force-Air system, although the scoops are harder to see in this lighting / RK Motors
Since this test required holding specific engine speeds at different road speeds, the test cars all had four-speed manual transmissions. Ideally, they would have also had the same axle ratios, giving the same speeds in gears, but all of these cars were rare, and Huntington presumably had to settle for what was available. The GTO and 4-4-2 had 4.33 axles, the Z/28 the standard 4.10, and the Cutlass a 3.42 axle with a wide-ratio rather than close-ratio gearset.
1969 Oldsmobile Cutlass S four-speed with Hurst floor shifter / RK Motors
He ultimately decided to measure the horsepower of the GTO and 4-4-2 at 5,000 rpm in second, third, and fourth gears, and to measure the output of the Olds W-31 at 5,000 rpm in first, second, and third. For the high-strung Z/28, power was measured at 6,000 rpm in first, second, and third.
While he was at it, Huntington also used accelerometer readings to calculate “the actual peak hp put out by these various engines in the bread-and-butter highway speed range around 60 to 80 mph.” These figures are loosely comparable to modern net output ratings, although I don’t know if Huntington’s calculations included correction for air temperature and atmospheric pressure as a DIN or SAE net rating would.
Ram Air Test Results
Here are the results Huntington calculated for each car:
Chevrolet Camaro Z/28 with Cowl Plenum
- 276 hp @ 6,000 rpm @ 51 mph (first gear)
- 273 hp @ 6,000 rpm @ 69 mph (second gear)
- 274 hp @ 6,000 rpm @ 88 mph (third gear)
Huntington observed:
Note that the cowl intake on the Z-28 gives no ram effect at all. In other words there was no increase in HP with increasing car speed. However, on a separate test we did determine that this sytem [sic] was effective in getting cool air to the carb. We checked hp with the plenum duct disconnected, so the engine was getting hot underhood air. The difference was anywhere from 8 to 12 hp at different rpm’s between the hot air and cool air. So the Z-28 cowl system is effective in getting cool air—but gives no appreciable ram effect at increasing car speeds. (At least not up to 90 mph.)
Unlike the later ZL2 ducted hood, the early cowl plenum intake drew air from the ventilation ducts in the cowl / Mecum Auctions
He calculated that the 302 cu. in. (4,942 cc) Z/28 engine had a peak output of 290 hp at 6,500 rpm. Chevrolet rated this engine at 290 hp at 5,800 rpm, although it would certainly have justified a considerably higher gross rating.
Pontiac GTO Ram Air II
- 301 hp @ 5,000 rpm @ 55 mph (second gear)
- 300 hp* @ 5,000 rpm @ 71 mph (third gear)
- 322 hp @ 5,000 rpm @ @ 91 mph (fourth gear)
* The summary on p. 25 actually said “200 hp @ 71 mph,” but this was clearly a typographical error inconsistent with the main text.
Huntington said:
The GTO hood scoops did better than I expected. There was no ram increase between 55 and 71 mph; but we got an extra 23 hp between 71 and 91 mph. Apparently the air flow over the hood is not too good at medium car speeds, so the system is effective only in pulling cool air. But above 75 mph or so the air flow apparently smooths out and hugs down tighter against the hood, so the low scoops get a solid bite of ram air.
Pontiac Ram Air II engine was rated at 366 gross horsepower / Mecum Auctions
He calculated the peak power of the 400 cu. in. (6,554 cc) Ram Air II engine as 315 hp at 5,500 rpm, and called the Ram Air GTO “a strong, solid car” that “pulled strong in every rpm range.”
1968 Pontiac GTO Ram Air II / Mecum Auctions
Oldsmobile 4-4-2 W-30
- 286 hp @ 5,000 rpm @ 54 mph (second gear)
- 292 hp @ 5,000 rpm @ 70 mph (third gear)
- 316 hp @ 5,000 rpm @ 89 mph (fourth gear)
Huntington found that the Oldsmobile Force-Air Induction system was very effective, remarking:
Obviously the Olds system, with the low bumper scoops and ram ducts to the carb, is the most efficient of all. Don’t judge the system on the basis of absolute hp increase—but on a percentage increase basis. That is, between about 70 and 90 mph the 4-4-2 system gave about one full percentage point greater hp increase than the GTO hood scoop system. … The increase given by the Ramrod 350 is even more remarkable.
Oldsmobile W-30 Ram Rod 400 engine was rated at 360 gross horsepower / Mecum Auctions
However, he still found the W-30 engine’s output disappointing, calculating that its peak power was only 295 hp at 5,200 rpm. He felt that the 400 cu. in. (6,554 cc) Oldsmobile engine was hampered by its longish 4.25-inch stroke, which meant “more friction inside the engine—plus higher inertia forces and bearing loads.” He wished for the return of the 1966–1967 E-code Rocket 400, which was very slightly smaller in displacement (6,548 cc), but had a wider bore and shorter stroke.
1969 Oldsmobile 4-4-2 W-30 / Mecum Auctions
Oldsmobile Ram Rod 350 W-31
- 252 hp @ 5,000 rpm @ 45 mph (first gear)
- 258 hp @ 5,000 rpm @ 60 mph (second gear)
- 290 hp @ 5,000 rpm @ 76 mph (third gear)
Oldsmobile’s smaller W-31 engine benefited even more than the W-30 from the cold air system. Huntington said:
The [power] increase between 60 and 76 mph was over 30 hp—or some 12 percent. This is really more than it should be, by theory; but it’s possible there was some air flow blockage condition at the lower speeds that choked off the engine. I know the car felt tremendously strong in Third gear around 70 and 80 mph. And then when you shifted to high the acceleration felt almost as strong at 90 and 100 mph as at the lower speeds. … It was obvious that the ram pressure from the car’s forward speed was really getting to the engine above 70 mph.
The readings Huntington calculated were particularly impressive if you consider that the road speeds in each gear were significantly lower than for the other cars, which didn’t demonstrate much ram effect below about 70 mph.
Huntington calculated that the peak power of the 350 cu. in. (5,737 cc) W-31 engine in the 60 to 80 mph range was 310 hp at 6,000 rpm, 15 hp more than the bigger W-30 engine.
Oldsmobile W-31 Ram Rod 350 engine was rated at 325 gross horsepower / RK Motors
He observed:
The [Ram Rod 350] engine would wind to 6200 rpm without a whimper, and the pull between 4500 and 6000 was wild. It’s obvious that the 308-degree cam is a lot more effective in this small-inch engine than in the bigger 4-4-2 engine. And I think the relationship between valve size, port size, port contour and cylinder size is just about right. This looks like one of those “natural” engines for performance like the small-block Chev. We pulled a solid 310 horses at 6000 rpm—and that might even go up another 10 or 20 horses at car speeds above 100 mph, due to more ram pressure. This is a fantastic combination.
Given the power he measured at the clutch, he felt the W-31 engine’s 325 hp gross rating was highly conservative — a big advantage in the NHRA stock stock classes, which generally classified cars based on their ratio of shipping weight to advertised horsepower. “Ramrod 350’s have been winning more than their share, and now I can see why,” he said.
1969 Oldsmobile Cutlass S W-31 / RK Motors
He concluded, “I think you’ll have to agree that Detroit has really given us some effective ‘free horsepower’ in these new cool-ram air systems.”
I must admit I’m somewhat dubious about the methodology of this exercise, although I imagine that a more elaborative procedure, such as setting up a chassis dynamometer in a wind tunnel, would have been prohibitive for cost and logistical reasons. Also, while Huntington found that these systems did produce more horsepower, this article didn’t attempt to quantify what that was worth in actual performance. (He had previously evaluated a 1968 W-31 Cutlass set up for the strip, but hadn’t made any attempt to evaluate how much the Force-Air system contributed to its performance.) Judging by other contemporary tests, the answer was “a little bit”: a few tenths of a second through the standing quarter mile, with the benefits not really felt until speeds that were illegal on most public roads in the U.S.
1969 Oldsmobile 4-4-2 W-30 / Mecum Auctions
For hardcore drag racers — the kind who would consider ordering a GTO or 4-4-2 with a 4.33 axle ratio a reasonable choice — that was probably worthwhile, but they were the minority even among contemporary muscle car buyers. For most people, ram air systems were expensive relative to their benefits (the W-30 package listed for $263.30, the W-31 for $310.69), and often involved obnoxious practical limitations (for example, the W-31 package wasn’t available with power brakes and couldn’t be ordered with front discs).
1969 Oldsmobile Cutlass S W-31 / RK Motors
The most common of these systems at the time was none of the three versions tested, but rather the slightly later Camaro RPO ZL2 ducted hood pictured below, which was also the cheapest of the bunch, listing for only $79 when new. According to the Camaro Research Group, the ZL2 option was ordered on 10,026 1969 Camaros, and since modern reproductions are available, it seems to be a popular collector add-on. The earlier cowl plenum kit was much rarer, as were the Pontiac Ram Air and Olds Force-Air Induction systems.
ZL2 ducted hood on a 1969 Chevrolet Camaro Z/28 / Mecum Auctions
Today, they’re now far more common in clones and “tributes” than original survivors, inevitably accompanied by vehement arguments about authenticity and performance bragging rights — ironically generating far more hot air than cool.
Related Reading
Curbside Classic: 1968 Pontiac GTO – Redpop! (by Joseph Dennis)
Curbside Classic: 1969 Pontiac GTO Convertible – Hi-ho Silver! (by J P Cavanaugh)
Curbside Classic: 1969 Pontiac GTO The Judge: Here Come Da Judge! (by J P Cavanaugh)
Vintage R&T Road Test: 1968 Chevrolet Camaro Z-28 – “7500 RPM Is A Good Shift Point” (by Paul N)
Curbside Classic: 1968 Oldsmobile 442 – It’s All In The Numbers (by Paul N)
What I find interesting is that these systems seem to be a blend of actual science/engineering with a side of marketing/profit.
That is, under a very narrow set of circumstances, these systems do provide a notable bump in power, which the Marketing Department ran with to the extreme.
This was really interesting. I always figured that the functional scoops did a little something, but always wondered how much. Now I have a better idea. It seems that a properly designed system provided at least a little of the effects of a super/turbo charger but without the cost or complexity.
There is no doubt the ads and badging applied to these cars was a marketing success giving an aura of that something extra special in the car. What didn’t make sense when I first saw them on friend’s cars were the fact they would be allowing something foreign into engine compartment. Some made more sense than others in the way they were set up. I guess I looked at them from my standard “what happens when it need fixing”?
I’ll only comment on the Olds set up. They seemed like nothing more than two giant vacuum cleaner inlets that would pick up dust, small rocks, insects, water, small animals, snow, etc. and send it straight towards the carb. Better keep a stock of air filters in the trunk.
Maybe I missed something in this article addressing my thoughts. Either way, they were bitchin’.
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The Olds Force-Air system is more or less how most modern cars get their intake air: They draw from under the front bumper, passing the air through a hose (or, on many more modern cars, a molded plastic tube) into the air cleaner. The intake air still has to pass through the air filter (unless you remove the filter element, which people did sometimes for drag racing), and since the air cleaner is “uphill” from the intake end, rain and debris isn’t typically a huge problem, EXCEPT perhaps going too fast through a deep puddle, which can send a large gulp of water up the intake tube with bad results. (Modern cars are also susceptible to that, and while it’s not super-common, it is enough of a risk to make it prudent to slow down when going through standing water in a dip or something.)
Intake systems mounted in the hood or cowl typically have some kind of drainage outlets to keep rainwater out of the intake, although I fear that would be iffy in a torrential downpour, or in weather that would allow the scoops to get packed with snow or ice — the Chrysler system that let you close off the scoops from the dashboard was more sensible in that respect.
The likelihood of scooping up a small animal on the move is low, but as people living in more rural areas can attest, rodents can find various spots to nest under the hood, and from a rodent’s perspective, the air intake and air cleaner is very convenient: a dark, concealed tunnel leaning to a warm nook that even provides a paper element to shred for nesting material — five stars on MouseBNB!
I loved these cars when they came out and still do so I don’t want you to think I’m dissing them because I’m not! The badging alone brings back a lot of memories, way more good than not..
I’ve worked on more carbureted cars than I care to think of. Yes, I have worked on several of these models. I agree with Aaron’s explanation provided these (or anything) is properly maintained. The key word he used was “except”. We all know life is full of exceptions!
The little animal; I was joking. On the Olds I have seen caked mud, build up grass, twigs, bugs, and other stuff. Why? The owner didn’t maintain the vehicle. Nasty air filters were the main culprit on any of them.
This article made me wish I could get in one of them right now and drive the hell out it. They were a lot fun.
“a dark, concealed tunnel leaning to a warm nook that even provides a paper element to shred for nesting material — five stars on MouseBNB!”
I LOL’d – on a day that really needed one, too.
I absolutely loved my 69 GTO. Triple black, ram air, just a beast. What was I thinking when I sold it, stupid.
This is interesting and surprising, as it goes against what I distinctly remember reading and what I know about aerodynamics. Yes, the Olds system makes perfect sense. But air flowing over a relatively flat plane like a hood or roof creates a low pressure zone in the middle area, almost exactly where the GTO hood scoops are. And there is a very strong high pressure zone at the base of the windshield, where the Chevy intake is. I’ve attached an image below which roughly shows that, but not the exact airflow, which tends to curve upwards over the flat hood and roof.
I distinctly remember reading about NASCAR drivers using the full cowl fresh air intake and plumbing it in a ram air feed to their engines back in the day. And that Chevy had spent quite a bit of aerodynamic testing on their system, to work for maximum benefit on the Trans Am racing Z/28s. And I remember reading about the uselessness of hood scoops in the middle area of the hood, other than the benefit of letting in cool air.
Not wanting to contradict Huntington, but maybe there were other variables, or?
The cowl area is a high-pressure region, and Huntington found that the ZL2 was effective in admitting cold air — he said it was worth 12 hp, which is not too shabby. However, his data suggests that the amount of pressure didn’t increase with speed, at least not enough to provide a useful ram effect. Since the highest speeds in the test were about 90 mph, he allowed that there might be some at higher speeds.
Local air pressure is not the only factor: Ram recovery for a scoop or intake duct depends on mass-flow ratio, on the shape and angle of the intake itself, on the design of the lip, and how the shape of the body affects the boundary layer in the vicinity of the inlet. (Boundary layer flow is incredibly complicated; here’s more than anyone other than an aerodynamicist could want to know: https://eaglepubs.erau.edu/introductiontoaerospaceflightvehicles/chapter/introduction-to-boundary-layers/.) Judging by Huntington’s results, the Ram Air scoops had poor ram recovery at lower speeds, so their efficiency was not ideal, but it wasn’t negligible either.
I’ve got to mention one of the first ram air setups – from Dearborn – on the ’64 Thunderbolt. Ford removed the two inner headlights and ducted the air to a sealed air cleaner assembly. I’m not sure how effective it was, but it was definitely worth something.
Practically speaking, the best ram air setup possible wouldn’t amount to much on the street. It would make a car faster on the top end, but you need speeds far beyond most speed limits to see significant gains. That said, some of these “ram air” setups did make significant gains, even at lower speeds. The importance of getting cool outside air to the carburetor was pretty well understood, but for some reason, most of the attempts you saw to address that – attempts that made it to production anyway – were pretty feeble initially, even when the horsepower wars were in full swing. At least most of these “ram air” systems fixed the issues of hot intake air and restrictive ducting.
I’m a little doubtful of the results suggested in this article, although it’s possible. Even taking them at face value, most of the benefit a typical driver would see would be from having a good cold air intake more so than a ram air effect. Moving forward, I wonder what manufacturer’s own data showed. You certainly saw ducting improve in the 70s and 80s, and the 80s seem to have been they heyday for fake hood scoops. I guess the one that sticks out to my mind, however, is the SN95 Mustang Cobra with the dual simulated scoops. I’ve gotta believe they made functional prototypes, and that leaves the question of whether they had real gains and the bean-counters killed it, or if the gains were so marginal that there wasn’t a practical argument for making them functional. Ultimately, I think the “ram air” concept – while valid – is one that’s more for show and marketing on the street, at least for its stated purpose.
Finally, I’ve got to mention an example of a functional hood scoop that wasn’t what it appeared to be. I’ve got a Porsche 924 turbo (aka 931) which came with a NACA scoop on the hood. It gives it a bit more of a racy look, obviously, but it just dumps right into the engine bay on the passenger’s side – where the exhaust and turbo are. I’m not sure if it’s a matter of necessity or not, but the only function is to get more cooling air to the turbo, and I think it’s as much for cool-down when the car is sitting as anything (it makes a pretty good chimney – you can feel hot air coming out when you stop). It’s another example where the scoop is a benefit, but not the one you’d think.
Well, one of the basic issues is that scoops and ducts are primarily dictated by styling, and what stylists think looks cool doesn’t necessarily coincide with engineering realities in any meaningful ways. The same is true of grille design and aerodynamic addenda.
I wouldn’t assume that those were the only possibilities. Functional hood scoops can involve a variety of practical drawbacks beyond whatever effect they have on performance, e.g., “The engine might not start if the scoops are completely blocked off by snow and ice,” or “Cutting holes in the hood puts us over the limit on drive-by noise.” Those are tradeoffs that a serious drag racer might accept, but that might inconvenience Joe Schmoe from Kokomo too much for the comfort of the sales organization.
Look at this high-pressure region of this Chevy Monza locate in the trunk…a slight smell of autumn. You thought the Oldsmobile system was complicated? https://www.youtube.com/watch?v=wv9F9P8gjpo
What is pictured for the Camaro (rubber duct from air cleaner to the firewall cowl area) does not match the “Cowl Induction” hood, which should have used the raised center section of the hood itself as an air duct, the hood itself being sealed to the air cleaner directly below.
On page 25? Yikes, you’re right: I hadn’t looked closely at those photos since the article has no other photos of the actual car (and is cluttered with photos of the unrelated Motion Performance Camaro). I replaced the color photos and amended the text.
Good looking out, I appreciate it.
Shocked that he could measure such significant improvements… I totally expected the difference to be minimal if anything, the best benefit being the cold air intake vs ram air effect.
We’ve long debated the merits of ram air in motorcycle intakes; most testing showed no real benefits at “street” speeds, with the true increases only available at extremely high speeds. Look up Kevin Cameron’s article on Motorcycle Ram Air on the Cycle World site – he notes 3% increase at 160mph.
I think that one of the various limitations of Huntington’s methodology is that it doesn’t really differentiate between actual ram air effect and the system’s ability to admit cold air varying with speed. For instance, my suspicion is boundary layer issues meant the Pontiac Ram Air scoops weren’t doing much of anything between idle and 85–90 mph.
It’s a shame that the efforts by Ford and (especially) Chrysler weren’t tested. Chrysler began their open-air game in 1969 with both the Ramcharger (Dodge) and Air Grabber/Coyote Duster (Plymouth) systems of which seemed to be relatively useless, other than making more noise from the unsilenced air cleaner.
OTOH, Chrysler aerodynamic team discovered that there was a ‘boundary layer’ of air flowing over the hood that prevented air getting into the engine compartment through any hood surface openings.
So, they came up with what is arguably the most effective OEM air scoop on top of the fiberglass hood of the A12 440-6v. The opening was high enough from the hood surface that it was actually able to get cool, effective air to the engine intake.
It was followed the next year with a similar set-up on the 1970 Challenger T/A.
I had also heard the placement of the scoops on the 68 Shelby GT350/500 at the leading edge of the hood was theoretically superior to the mid hood placement, GTOs actually moved their scoops in an almost identical fashion to that spot for the 71-72s
Pontiac probably picked that little trick up from Oldsmobile, who moved the effective under bumper scoops to the leading edge on the 1970-72 442.
To that end, I would imagine the flush ‘scoops’ on the 1970-72 didn’t do much. Likewise, the NACA-style scoops that went on the 1970 Shelby cars, followed by the 1971-73 Mustang Mach 1 wouldn’t seem to do much, either.
I’ve wondered about the similar 1970 ‘Cuda AAR, too, mainly because, although it was flush, it had quite a bit larger opening than the other flush scoops.
With the new direct injection systems a high pressure area scoop could actually help.
I think many more modern cars are benefiting from this technology. My 2017 Honda Pilot has the air intake ducted to the grill. Likewise many turbocharged cars and trucks are using air to air or air to water intercoolers to cool the charge air going to the engine.
I always thought the best
Olds big block engine was the ’65 to ’67 425cu in V8. It could rev. The 455 was a torque monster but ran out of breath at higher revs. The 1st 400 Olds engine was a 425 with a smaller bore to meet GM’s internal requirement for maximum size in a mid size car. I’m not familiar with the 2nd Olds 400. The Ramrod 350 is a very interesting engine that kind of reminds me of the Chevrolet 302. I recall from other sights it was rated at 325 hp at 4000 rpm. But it produced as much as 385 hp at 5000 rpm and was considered underrated. It’s very rare.
“The 1st 400 Olds engine was a 425 with a smaller bore to meet GM’s internal requirement for maximum size in a mid size car. I’m not familiar with the 2nd Olds 400”.
I believe it was the other way around. The 1965-1967 400s were over square engines, and the 1968-1969 400s were the under square ones with the smaller bore and longer stroke of the 425. From what I’ve read this move was in deference to lowering costs by having commonality with the 425 and thus saving them from having to have a block just for the 400, itself not a high volume engine used only in the 442.
The 1965–1967 Olds E-code 400 was a de-bored 425, sharing the same stroke; it was oversquare, but only very slightly. The 1968–1969 G-code 400 was a de-bored 455, and very undersquare.
Very good, thanks for the info.