Does anyone know of any tests showing realistic top speeds of the various engine combos? All the tests I've seen are with cars using short gears (eg. 3.90s) which results in pretty low top speeds due to being rev limited.

Kinda silly to say that a RA II car is only capable of 115 mph when it gets to 108 in a 1/4 mile. I know I've taken my '69 well into the 140 mph range with 2.56 gears and an essentially stock RA III engine.

There is only one I can vouch for personally.

1988 Mustang GT 5 liter, 5 speed manual, 3.08 rear

143 mph indicated on Autobahn A81 near Heilbronn, Germany

Okay, that helps a bit. I had no trouble outrunning one of those locally.

Back in 75 had my 68 FB 350 HO with 3.08's 140 mph. Still go'n but had to much lift. Manual steering felt like power steering.
Not exactly stock, but;
Next yr w/a 70 RAIII/th350/3.73's with taller tires.
Two yrs later w/a 70-455(same #12 hds and sft cam) with same 3.73's and tires.
Never got brave enough to try'n bury it.
FWIW, no spoilers.
Buddy had his 72 GP 400 with 2.93's spun back aroud to 10-15 mph few times.
Dont remember what top # it had had speedo. Think 120?

Took my wagon up to 120 once...

Had my 350 2bbl w/3.23s coupe with the speedo passing 137(last I saw) years ago. Course the speedo could've been off by 10mph or so. You really start to wonder how old and how much tread those tires have on them about then. Young and about as much sense as god gave a turnip.

I know our cars can clock some good numbers but I was hoping to find some published tests instead of personal bests.

had mine up to about 110 once n shut it down, felt like I was going to nose up for takeoff....likely different dynamics with the top down....more drag

no `Maro Snowplow , eh? those help.....at higher speeds...

Did 320 today... oops that was in a boeing 737... Had cammer up to 95 2 days ago.. will go more think red line is 6,500 was over 3800 rpm ..

There really is no true high speed test based on engine. The top speed of any vehicle can be calculated based on vehicle specs.

RPM x rear tire diameter x .0029749 / rear gear ratio (assuming the trans is a 1 to 1 high gear)

In your case if you max out at 5500 rpm with a 2.56 ratio and say a 27” tire = 172mph top speed theoretically.

Same with a 3.90 gear = 113MPH

The top speed can also be limited by having the available HP to overcome the aerodynamic drag of the vehicle and frontal area. You may top out on power before ever reaching that top speed - thus this is the only time the engine might come into the equation (based solely on the higher available HP if needed).

That is VERY true. Using the formula you could attain a theoretical speed, but as the speed increases, you need far more horsepower, far more than you would think, to overcome aerodynamic forces.

I recall reading once where a Bonneville team made it to 190 mph in an older A-Body car, with around 500 hp. They needed something like another 150-200 hp to get another 10 mph.

Look at the new Dodge Challenger, a car with a good amount of hp, overdrive trans, and is very aerodynamic compared to our older cars. They can barely attain 140 mph. Back in the 90's, the then-new 1998 Ram Air Trans Am's were capable of 150 mph, and that was a slippery body, with 300 net hp, 6-speed overdrive trans, and 2.73 gear.

Most of the older cars (68-72 GTO, 67-69 Firebird) were capable of around 125 mph. Some could go higher, especially those cars that had engines capable of higher revs than that of a Pontiac V8.

http://www.youtube.com/watch?v=ZnGdiOv-A18

Cd of 0.353; some sources say the '69 Firebird was around 0.42, not very different considering. I'd like some other sources to back that up though.

1/4 mile in 13.3 for the SRT8, aided by sticky tires, and again not much different than can be expected from a RAIII Firebird. No reason not to expect at least 150 mph when the SRT8 can reach 170 mph with close to the same rear wheel hp even with higher drag.

The engine is what makes the hp that determines the top speed of the vehicle when not limited by too short a gear. That's why I was asking about a published test.

I can provide anecdotal evidence myself but not many doubters are convinced by that. I was hoping someone had seen something in print.

To me that's the only case that is of interest, not the rpm limited (to me artificial) top speeds.

Motor Trend tested a 303-RAV powered 1969 Trans Am, with a 3.90 gear, they (and Tom Goad, engineer) estimated 135 mph with the engine screaming at 6300 rpm. They believed the 303 would wind to 7000 rpm, and speculated a 150 mph top speed. But they didn't do it.

So a RAII or RAIII car, with a 3.08 gear, may be able to hit 140 mph. The limiting factor is their 5500 rpm redline. As we know, holding a Pontiac V8 at 5000 rpm for 10-15 seconds on a top speed run is asking for it. Pontiacs just weren't built to run high rpms for extended periods of time the way Chevy and Mopar engines were.

I stand corrected on the new Dodge Challenger. I was thinking of the "Top Gear" episode where they ran a mile (on the salt flats), and could only get the Challenger to 150 mph after some nifty duct taping of the front end to make it more aerodynamic.

Everyone should keep in mind that a LOT of modern muscle car owners have dialed in an aftermarket computer tune that will eliminate the factory RPM cut off by the time they put the 1st tank of gas in.

I did!

Yet I did at least a dozen 140+ mph runs with no damage - after upgrading the fuel delivery. I ended up putting that engine (about 380 hp) in a Street Stock oval track car that hammered the Chev and Mopar engines that were running the same class; two seasons with no failures despite the stock rods.

No, the Pontiacs didn't rev as freely as some other engines of the time but they certainly made good power and more than held their own on the street. I once had a long run against a '68 GTX with a 440 4 speed and rather enjoyed toying with him when he ran out of revs at about 125 mph. I made a point of backing off and running up on him several times as he could only maintain his speed for fear of blowing his engine. All he could do is glare at me.

I find myself imagining how much fun I'd have in my '69 with 200 lbs less weight on the front tires and another 140 hp - just dynoed an all aluminum L92 engine (long block weighs 380 lbs) from a 2008 Escalade with a very pretty aftermarket IR EFI intake system, mild cam and headers that made 450+ ft.lbs of torque from 3000 rpm up and 520hp at 6000 rpm. Stopped at 6000 because of the stock rod bolts; adding ARPs would add another safe 500 rpm, high enough to find the real hp peak. Idles with a nice burble at 750rpm.

That was a customer's but I have my own all aluminum 6.0 with 243 heads waiting for a new abode. This is the same basic engine that we run in the NASCAR Canadian Tire Series with the addition of forged crank, rods and pistons that run to 8000 rpm regularly with hydraulic lifters! Crazy how stock these engines are and make 500+ hp with a 390 cfm carb. They make 550-560 streetable hp with a bigger carb.

I'm impressed with the LS engines.

Pontiacs were the best street engines. No argument about that. But they weren't built for racing (at least not the post SD421 era engines). They can take a lot of abuse, but they were designed for street duty, not track use.

I know many folks that are fans of other makes, and they are shocked and stunned when they discover how the bottom ends on a Pontiac V8 were built. Cheap cranks, cast rods, 2-bolt mains (on most), small runners, lousy head flow, yet....they fly on the street. And with that, these guys are embarrassed to be beaten by a Trans Am or GTO. That's not supposed to happen.

That's one of the beautiful things of owning a Pontiac.

Engines like the LS6, L-88, ZL-1, 426 Hemi, etc. were designed for the track, not the street. With that reputation, many owners (and collectors) naturally assume they were the fastest cars on the street. But that's not always the case.

Brilliant Pontiac engineers. They did more with less.

I had a '70 440 6 pack 'Cuda for 13 years. It was a driving resto-in-progress as it was both my daily driver and foolish youth car. The entire drivetrain was out of a Dodge while the original 440-6, 4 speed, track pack Dana drivetrain was very very very slowly being rebuilt, one paycheck at a time. It had a 2.76 rear, a 440-4 and 727 auto out of another car. The 160mph speedo was not calibrated, but the 8K tach was accurate. I ran M50-14 Pro-Trac belted tires on the rear (26.5" diameter).

I ran a guy on I-75 with a '69 Camaro SS. There is no doubt his car was quicker. After a few miles, my speedo was hovering near the peg and he could not gain on me. I could see the fuel gauge creeping down, and the lane dividers looked like strobes, and the steering wheel did not feel well connected to the front tires.

Using any online calc with 5500 RPM redline, diameter of rear tires, 1:1 3rd gear and 2.76 rear (it would handle more than 5500 rpm for a while, and did...stock fuel delivery was better) it will calc out to about 157 mph top end. I do believe the car actually made it there once. I needed three lanes of pavement to keep it on the road and never tried that again.

Another 'Cuda, my '74 318, was caught in a severe storm. I had gone up to Ubly to drag race, but it was called off due to a severe thunderstorm warning. My drive was about 50 miles down a two lane highway with deep (8') ditches on both sides between cornfields. I was driving about 75 straight south, and the wind came up from the south and lifted the front of my car to the point that I had zero steering due to lift. I braked hard (always be sure that your rear brakes are properly adjusted) to drop the speed, and had to stay under 50 the rest of the way home due to gusts. Weather reports later claimed 65 mph gusts. With lift like that at an effective 140 during gusts, I do believe that the '70 was going quite a bit faster.

I am absolutely sure that the factory 3.90 in the 440-6 would have limited me to 115-120 tops. Although anyone could beat me off the line, in the long run I could cruise right on by and even hit kickdown at 80+ mph.

No doubt there were some fast cars out there, Vikki!

I missed the chance to try a '71 Sebring with a breathed-on 440-6 when my Firebird refused to shift down into first at 30 mph, and second was slow enough that he didn't think my car was worth a top end run. Could have been fun!

I had set up my suspension for much better than stock handling, and the top speed runs were arrow straight and one finger if I was foolish enough. Slowing down required braking in stages to avoid cooking the brakes though, even with discs and semi-metallic pads.

Ah, the stupid old days!

I'd have to disagree the head flow, on my flow bench a #48 flowed more than a Bowtie racing head; 240+ cfm stock vs 230 on the Bowtie, and flow is what makes power. No surprise to me why Pontiacs are stout performers on the street.

The biggest issue was always the cast rods as the nodular crank and 2 bolt mains can handle a fair bit of power. I've taken the stock rods past 6000 rpm with the engine ready for more (clean and strong) but not very often for fear of ventilating the block.

The small block Chev was never the best engine but almost always the cheapest; that's what it was designed to be.

Well, by lousy head flow, I'm talking about in a racing format. 230-240 cfm is fine, but 300+ was needed to feed sustained 7000 rpms in a 426, 427, 428, or 429 on a NASCAR track. Even though Chevrolet, and GM, were officially out of sponsored racing, Chevrolet still developed full tilt racing engines for use in the Can-Am Series.

Pontiac's Ram Air Series (I, II, III, and IV) were street engines. They were fine at the dragstrip where 5500-6000 rpm could be seen for a couple of seconds, but Pontiac V8's were not contenders in any other racing series. In fact, when Titus/Godsall went SCCA Trans Am racing in a pair of 1968 Firebirds (and later 1969 Firebirds), they used 302 small block Chevys, not 303 Pontiacs.

Obviously Pontiacs are strong enough to run well on the street, and with some work, can run on a road course or superspeedway.

4-bolt mains were not a necessity, but it's hard to explain that to the Chevy guys sometimes, who love to brag about their precious 4-bolt blocks! Nearly all Pontiac V8's used 2-bolt caps, with blocks drilled for 4-bolt. Even Oldsmobiles, which used forged rods and forged cranks in their wicked W-30 and high revving W-31 350 engines, all used 2-bolt mains.

The 426 Hemi, LS6, L-88, ZL-1, Boss 429, and a few other engines, were just in a different league from Pontiac V8's, as far as strength goes. Those engines were designed for racing, detuned for the street, while Pontiacs were designed for street use. That's one of the reasons that in stock, off-the-showroom floor performance, a Pontiac ran as well (if not better) than some of the other more "notorious" cars.