Because 454 Cubic Inches Just Isn't Enough: AMC Marlin Racer Gets Twin Superchargers

Murilee Martin
by Murilee Martin

The Speed Holes Racing AMC Marlin took home the Organizer’s Choice award at last year’s Colorado 24 Hours of LeMons race, because A) it has a 454 yanked from a wrecked GMC truck set back about three feet from the Marlin’s normal engine location, B) it has a Jaguar XJ6 rear suspension and differential, C) it has hundreds of speed holes punched into the body and, most of all, D) it’s an AMC Marlin. The Marlin wasn’t exactly fast (the tall Jaguar gears and very tired 300,000-mile EFI small-valve engine didn’t make for great acceleration out of the turns), but the handling was surprisingly good for such a big car. For the 2011 B.F.E. GP, Speed Holes Racing decided that more power would be needed.

The LeMons Supreme Court gave Speed Holes a generous residual value after last year’s race, allowing them to dump another few hundred bucks into the car. Changing the differential gearing from 2.75:1 to 3.73:1 will help de-dog-ify the acceleration at hilly, oxygen-poor High Plains Raceway. Adding forced induction should cause the engine to spray connecting rods in all directions alleviate the oxygen-shortage problem.

In charge of this upgrade is Speed Holes Racing team captain Cadillac Bob. Cheap junkyard superchargers are easily obtained, as long as you go for a Toyota Previa centrifugal blower or a GM 3800 V6 Roots blower. Bob went for the latter option, figuring a pair of superchargers meant for an engine of 231 cubic inches displacement apiece should be just about right for a single engine displacing 454 cubes.

The plan is to push about 5 PSI of boost down the factory throttle body, using this industrial pressure gauge to keep the driver in the know.

Bob fabricated a plenum and mounted the blowers backwards on its sides. The compressed air will come out the top, once he cuts a hole and mounts a flange for ducting.

Because the supercharger input shafts will now rotate backwards, Bob had to do some surgery to flip the internal drive gears around and keep the vanes rotating in the correct direction.

The nice part about this setup is that removal of the entire supercharger assembly should be pretty quick, when if something goes wrong with one or both of the blowers at the track.

Meanwhile, Bob’s shop has filled up with projects. In the foreground is a LeMons-bound Jetta that needed its janky cage fixed. In the background is my ’66 A100 van, which is getting new axle kingpins.

In the rafters of the shop, an early-60s-vintage rail dragster.

Beneath the dragster, a seriously chopped Coupe DeVille.

Nearby sits an old-timey hot-rodded Model A four-cylinder engine, awaiting installation into Bob’s super-slammed Ford coupe.

What sort of car should receive this WW2 military-issue Cadillac flathead V8?

The B.F.E. GP takes place weekend after next, so there’s plenty to do between now and the green flag. Still, compared to last years’ panic-stricken thrash, this time around should be a walk in the park. I look forward to hearing those blowers screaming on the race track!














Murilee Martin
Murilee Martin

Murilee Martin is the pen name of Phil Greden, a writer who has lived in Minnesota, California, Georgia and (now) Colorado. He has toiled at copywriting, technical writing, junkmail writing, fiction writing and now automotive writing. He has owned many terrible vehicles and some good ones. He spends a great deal of time in self-service junkyards. These days, he writes for publications including Autoweek, Autoblog, Hagerty, The Truth About Cars and Capital One.

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  • Mazder3 Mazder3 on Jun 28, 2011

    How much weight did they shave by cutting in these "speed holes"? It's an old car with nice thick sheetmetal so each one has to be at least worth a pound, right? Will the Jag dif be able the handle the torque of a blown 454? I'm gonna be generous and give them five laps until everything goes KA-BLOOEY!

    • See 1 previous
    • Bryce Bryce on Jun 29, 2011

      @PrincipalDan SBC into XJ6 usually means diff overhaul next

  • Geozinger Geozinger on Jun 28, 2011

    OK more quetions: Why two blowers for a total five pounds of boost? I bet you could get a couple of crack-addicted hamsters to add more boost... Will those blowers work in an (nearly) inverted position? I don't know what the lubrication requirements are, but that would s*ck if they seized because they don't work lying on their sides... Why bother mentioning the Toyota blower? There must have been about 12 'eggs' equipped with them. The Eaton blowers are way more prevalent. That must be one tired 454. If it were up to me, I'd add about six bottles of nitrous and use a push to pass strategy. If you're going to expel rods all over the place, do it with style! Note to builders: Find a LS3 out of a late model pickup or Trailblazer. Much better...

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    • Shane-O Shane-O on Jul 01, 2011

      Well too much psi makes things go BOOM faster. With 2 blowers you get more air in total,at a lower temp. When compressing air the lower the psi the less your heating the air, so actually 2 blowers work better than one. AND this a LeMons racer, 1 is never enough when you can use 2! P.S. LS3 motors are way too expensive for LeMons racing, at the moment at least........

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