old deisel supercharger questions.

ive got two 6-71 blowers from old diesels, worth it or not? i hear theres a ton of money that needs to go into it. i scored them for free. i see a lot of them for sale for good money.

 

Depends on what you want to do, and how good they are to begin with. New endplates, teflon strips, forged gears, snout, belt, tensioner, pulleys, makes for lots of money involved. Conventional thinking was that the wipers were required, but that has been violated quite a bit. For a street car, it doesn't take a ton, for a race car certainly get new bearing plates and gears. David

 

i was thinkin more like machine work or what id have to change to make it work on a gasoline engine.

 

Originally,they didn't use Teflon seals on the rotors.


Take a look at the price of a blower drive before getting to excited.
Free is good,you can always sell them.

 

The price was right! Now get ahold of Mikey and see what he can do for you.

 

I was talking to a diesel mechanic for the fire dept about the diesel ones and he said they were more for scavenging air. It didn't make much sense to me. This was 12 yrs ago, so I may not remember everything correctly. Can you tell much of a difference in the ones you have and a gas blower? I may have access to one if this may work is why I ask.
Any pictures? I would like to see what they look like.....

 

oldmule-the major difference i see is the ribs on the casing, there are only a couple compared to new blowers, i hear that they are plain old 6-71's modified to work on deisels. oh and plus they're not polished.

 

unkl ian- yes i was noticing that they are not cheap!!!! but if i can make this thing work for 2000, i figure im ahead of the game. or i could sell it.

 

the GMC blowers were used to scavenge exhaust air (by pushing fresh air in from the bottom) on the 2 stroke diesels.

The core value of a raw diesel blower is probably about 5-10% of the total price of a (converted) street blower and drive setup.

 

you can use the case.....thast about it really.

 

my 6-71 has the original case, rotors, and gears. The bearing plates and cover should be upgraded for performance use...although some guys get away with stock parts, and only change the bearings/seals and clearances.

 

Until fairly recently, GM rotors were about the only game in town....and they are still used on the vast majority of blowers sold for automotive use today. Nearly all use GM gears, the older style.

As Squirrel points out, the back plate should either be changed, or reinforced (PITA, it's easier to buy an aftermarket one) & the original bearings can be iffy, at best.

Jeffie, you might want to buy the book Street Supercharging by Pat Ganahl, or peruse it in the local bookstore...he describes exactly what's necessary to do to convert one. Not impossible for a novice, but not exactly easy, either.

As a rule it is generally cheaper, at least for a SBC or BBC, to just buy a complete kit. Other engine brands...it depends....

 

it also depends on if the blower is off an in-line or V series diesel, V series are undesirable (s**** value).

 

go turbo

 

A local blower guy rebuilt mine for gas for $250, including reinforcing and pruning the rear plate. What can get expensive is the rest of the stuff like the intake and drive.

 

Well, I think you're getting "backwards" info. Plain old 6-71's were standard fare on those 2-cycle diesels. Modifications are required for use on gasoline engines.

 

Right, and the teflon is a race kind of deal. On the street you want a more clearance than a race blower.

 

There was a lip on the stock GM blower case that let it hang on the side of the engine in Squirrel's drawing. It needed machining off! Then there's the pop-off valves that are part of the intake system? I ***ume these are helpful on street motors too?

 

The popoff valve is usually built into the intake manifold.

 

The roots design was originally used to move fresh air into mines - later adapted to the GMC Detroit Diesel and then adapted to the race cars.

Your cores need a lot of work to be race ready & only slightly less to be street ready.

The V series are being adapted to engines as well - as the price of inline blowers goes up due to supply & demand, the innovators adapt.

 

I have personally done the complete conversion for a small block Chevy. It can be done and it is reliable,but it is definitly the hard way to go about it. buy a kit from Summit you will spend the same money and save all the labor,hunting,h***les. then send me the old cores, I like em!

 

thanks for all the info guys.