R5 Bonneville Engine

[mfg]

Does anyone know if the fellow who owns the original Granatelli R5 engine has ran it yet..or intends to? It's really an amazing story how He managed to purchase all those rare, 'one of a kind' pieces that made up that engine. Those parts could have so easily been throw away when the Granatelli's were getting out of Studebakers. Just shows what determination can accomplish! Hats off to Him!

[Gunslinger]

I've seen the engine. It is a really interesting story as the pieces to the engine were removed and more or less scattered around. At the time the Paxton people never considered it a part of Studebaker history as much as a collection of parts that were commodities that could be used elsewhere and repurposed. Greg (the owner)' bought the basic engine about 1969 and it took until a few years ago to locate, obtain and rebuild it all.

To the best of my knowledge the engine has not been run...at least not in a car...maybe a test stand.

As far as his intentions with the engine, the last information I have is that the gentleman who owns the very first prototype Avanti, which became the Due Cento would like to reunite the engine and car. The sticking point is whether it becomes a joint venture or he buys the engine for the car, or the other buys the car for the engine. At least that's how I understand it...and that's at least second hand so take it with skepticism.

[Avanti83]

From the Studebaker Intl 2012

Bob

[mfg]

Awesome photo of that one of a kind engine....Thanks for posting it!

[mfg]

Taking a second look at this one and only Studebaker R5 engine, I see that both air AND fuel passes through the Paxton superchargers. Would a system like this be at all practical on the street? I mean if the fuel injection setup seen here was replaced with a carburetor, all worries of sealing that carb would be eliminated as it would be on the intake, not the outlet, side of the supercharger. I suppose there might be tremendous throttle lag though.

[PackardV8]

Think about it. How many draw-through centrifugal supercharger setups do we see on the street? Pretty much none. It's not just throttle lag, it's also raw fuel puddling in the supercharger and ductwork during cranking.

jack vines

[Charlie Kile]

Back fires can be Awesome!!

Charlie RQB3921

[Devildog]

Most of the larger Pratt & Whitney and Wright radial aircraft engines run the air/fuel mixture through the supercharger. These engines have an intregal supercharger turbine disc in a 'blower case' that is on the crankshaft immediately behind the cylinders.

I have thought a SBC engine design using a combo flywheel/compressor turbine would make an efficient supercharged engine. No additional moving parts, no oiling concerns of turbo-super, no belts, no coking, nice steady 2-6 lb boost, use bleed air run the A/C.

Joe

Edited April 3, 2014 by Devildog

[Charlie Kile]

A major part of the reason the Air/Fuel mixture is run through the superchargers on the big Radial engines is to ensure a more even distribution of the mixture.

CharlieRQB3921

[PackardV8]

"I have thought a SBC engine design using a combo flywheel/compressor turbine would make an efficient supercharged engine. No additional moving parts, no oiling concerns of turbo-super, no belts, no coking, nice steady 2-6 lb boost, use bleed air run the A/C."

Exactly like Smokey Yunick saw when he was in the AAF in WWII and tried on his NASCAR engines about fifty-eight years ago. The problem using existing parts is the clutch and pressure plate were impossible to seal sufficiently to generate much real boost. Then, if it did make boost, there'd have to be a blowoff valve and pressure modulators. That and NASCAR rules against any form of supercharging.

Bottom line, aircraft engines run at steady state and load at cruise. At other times, the pilot is manually adjusting all the engine parameters. The output shaft compressor technology has been common knowledge for seventy-five years now. If it were practical, easy and cheap to do in an automotive application, it would be in common use. It's none of the above.

[mfg]

So this R5 is basically an R3 with two Paxton superchargers and the fuel injection? Did the Granatellis ever dyno this engine and publish horsepower figures?

[Gunslinger]

I believe it's more than simply an R3 with two blowers and fuel injection. There's a number of differences beyond that. As far as horsepower ratings, I've seen two different numbers published...575hp and 638hp. Which, if either, is correct I doubt if anyone really knows or who is the original source for those numbers. I would think any numbers are probably gross horsepower as that's how they were rated back then. Net horsepower ratings didn't become mandated until about 1971.

[mfg]

I researched this a little, and found out that there were cam and piston changes made by the Granatelli's on the R5. (compared to the R3) It was still a 304.5 CI engine. They may have tried more than one cam, and the front crank damper was comletely different. A rod let go at Bonneville and broke a hole through the block. So this is either the original repaired block, or a substitute block.

[brad]

I supplied Greg with basically NOS R3 Forged True pistons. The R5 pistons were angle milled on the top to reduce compression.

This is the repaired original block. Only the oil pan rail was damaged, not the main webs, or water jacket. You can follow the build in the AACA forums, and some in the SDC forum.

[mfg]

Great info! What really needs to happen here, in my opinion, is to somehow reunite this marvelous engine with the Avanti it was originally installed in. Hopefully, someday in the not to distant future this happy marriage will happen!