From the fertile mind of Mickey Thompson in the early ’60s came this fascinating creation, a Pontiac V8 with twin GMC blowers and a pair of seriously crazy cylinder heads. Time for a closer look.
Mickey Thompson (1928-1988) was one of the great innovators in motorsport—at Indy, Bonneville, desert racing, most everywhere. (Read about his wild Ford 427 Hemi here.) The rest of the automotive world is still catching up with some of his lesser known but fascinating experiments. Like this one, for example. For some years now, a few curious photos of unknown origin (to us, anyway) have been circulating on blogs and forums around the internet. They show an M/T project from circa 1962 featuring a twin-supercharged Pontiac V8 with an unusual breathing arrangement, to say the least: The intake and exhaust ports are on the same side of the cylinder heads. But there was actually some method to the madness, as we will see.
Mounted in a dragster chassis (above) is a 389/421 Pontiac V8—Mickey had a major sponsorship deal with Pontiac in those days—with a pair of GMC blowers mounted outboard and driven by Gilmer belts. This seems to be somewhere in the mockup phase, and the cylinder heads definitely appear to be new aluminum castings rather than modified Pontiac production pieces. Note: There’s an extra cylinder head on the floor at lower left in the photo that can give us a clue as to what this engine is all about.
This detail enlargement provides a better look at the M/T cylinder head arrangement. We can see that yes, the intake passages have been rotated 180 degrees so now they are on the same side of the head as the exhaust ports.
While it seems counterintuitive to jam the intake and exhaust ports together on the same side of the head in this manner, evidently there was some sensible logic behind it. By flipping the intake ports around to the “back side” of the head, now they no longer had to snake around the pushrods and the top, inside row of long head bolts. The intake ports could now be shorter and straighter with minimum resistance to airflow. In theory, anyway.
As we see it, the drawback was reduced cross-sectional area available in that portion of the head. And since the layout has never caught on in all these years, It’s safe to assume that for whatever reason, the approach was ultimately a dead end.
There was also a naturally aspirated version of M/T’s contrary V8 using a pair of Carter AFB four-barrel carburetors. Since the conventional V8’s cylinder firing sequence would create some carburetion problems with this arrangement, it’s possible that a 180-degree crankshaft, aka flat crank, was used. This would transform the Pontiac V8 into two separate-but-equal inline four-cylinder engines on a common crankshaft.
Just to show that M/T wasn’t the lone ranger on this unusual approach to engine development, camshaft maker Bruce Crower also experimented with the setup on his Chevy small-block V8 Indy car engines in the late ’60s, first in normally aspirated form, then in a 203 CID turbocharged version. (Crower called the configuration “sidedraft,” evidently.) While the engine never managed to qualify for the Indy 500, it generated plenty of attention, eventually appearing on the December 1970 cover of Hot Rod magazine, below.
Oh, to have the mind to think, and question, and the wherewithal to create, and test one’s theories…what may this man have been capable of, had his genius not been stifled in such a tragic way.
Thanks for this insight into a little known experimental idea which I had previously been unaware of.
What a pleasant 81st Birthday present from Motor City Garage to this old motor head. What a genius was Mickey Thompson , innovative and always ready to “give it a try”. And then there are the tried and true Carter AFB units , used on my late father’s 1957 Pontiac Star Chief 2 dr HT. Great stuff as usual from MCG. Keep it coming.
Mickey certainly had a sponsorship with Pontiac. In fact from 1957-Jan of 1963 , Thompson, Smokey Yunick, and Ran Nichels engineering were all at one time on Pontiac engineering’s payroll. Nichel’s stay was the longest, the entire57-63 span. That was until the GM 14th floor pulled the plug on any racing activities. That’s why 1/2 way through the 63 racing season Pontiac and Chevrolet stopped winning races or for the most part not competing at all. In Pontiac’s case it was good and bad. Good because Pontiac left racing on top and bad for the loyal Pontiac racers and fans. Another precarious position for Pontiac was How do you remain #3 in car sale if you can’t race and attract new blood. Taking performance off the track meant to Pontiac creative minds putting it or some of it on the street…….Anyone heard of Pontiac GTO
Wow, Sir Mickey was a multi-make innovator!
Any percieved benefit would have been negated by drag and extra weight. It would probably be smarter to rearrange the head bolts. Use cap screws through the port floor to get the casting out of the way. Then plug the roof of the port with a screw in plug.
As a lot of performance 6s have done for decades. And more than a few drag engines as well of all size.
How times have changed too, a big effort but still using pressed tin rockers. Which surprises me as rollers were available [expensive] in that time.
And as many will know you get more power generally using them as you in effect get more duration by the action of the roller tip. And they smooth up the valve train harmonics as well.
With all the LS parts becoming available, 20 years after they arrived I am surprised by the number of people not using them
It might have been. But that isn’t the point of the exercise. The two most important words in human history, “What if . . . ” without that, your idea may have been the “easy way” out. These guys looked to making the impossible, possible. Not easy. Not likely to work but less than they wanted. Getting right the first time only means somebody should have already done it.
back in the mid 60’s at Lions Drag Strip, Mickey showed up with a pontiac compact that ran with 4 different engines, a v8, a v8 cut down to a v6, a v8 cut down to a v4, and a v8 cut down to a v2. went and looked at the car afterwards, said hi to Mickey, he said hi back, said it is all very interesting to me, he said it is indeed. al
In the mid 1960’s, I had a boat rigged by a shop in El Monte, CA. On the shelf in the shop was a set of huge cylinder heads. I asked the rigger about them, “They are Mickey Thompson’s”. From a 534 c i Super Duty Ford truck engine. Mickey was thinking about using a SuperDuty Ford truck engine in a raceboat.
Unfortunately, according to the rigger, when the heads were flow-tested, they were worse than an old flathead! Project dropped!
Mickey was always ahead of the curve in his thinking!
My older brother had a set of M/T on his 66 Chevelle (My brother was a poet and a very special kind of man). R. W. , He was my first look at building hot rods 327 chevelle ’66 he did all kinds a planin an shaving polisshin and portin its all Greek to me. But I’ve always loved looking at cars and I base my opinion of each one on how it stacks up against how much I love a well done chevelle like my brothers Black ,66 Malibu built by Trevor
Mickey was my all-time drag racing and Bonneville hero when I was in my teens and twenties. I could not wait for my latest Hot Rod to arrive so I could see what he was up to at that time. He was truly a genius with internal combustion engines.
It’s not true that this didn’t catch on; Reverse flow cylinder heads have always been common on 2-valve inline engines. Shortest distance to the valve, of course. If there were performance problems with this on ultra-high-performance applications, it would be sort of interesting to know what they were. I wonder if short intake runners were a problem, but I am just making that up. You could build 100 million Buicks and Chevrolets with reverse flow heads and not run into issues Mickey Thompson might be thinking about.