Can a diesel supercharger be used on a gas engine?

I was offered what I am told is a GM 6:71 blower, but I understand it came from a diesel engine. I understand there is something different about the lobes on the rotors? If it takes much work, is it worth it?

Then again it is free.

 

Free? Hell yes, if nothing else, sell it/ trade it for parts you really want. 6:71 Superchargers have been stuck on top of gas v-8s for 50 years ! Now, why is it free? Cracked or scored rotors? bad bearings, bad endplates. the list goes on and on. they can be rebuilt. in fact, I'm sure Street Rodder or Rod & Custom had an article about reconditioning a 6:71 in 2005. check their tech article sections on their respective web sites.

 

Also see the "Tech request......" below

 

EVERY GMC blower came from a diesel engine!

but they turn much slower on diesels than on gas engines, and they don't make boost, they just pump air thru the two stroke diesel to scavenge the exhaust gas out and pump the fresh air in. so, the GMC diesel blowers need to be reworked a bit to run at higher speed on a gas engine, and live while making boost.

 

It depends on how much boost you want to make with these as to how much you need to do to them.
I have a 471 that came off of a diesel forklift that I am running on a slant six. The only thing that I did to it was to install high speed bearings in the back, replaced the front ones, did not pin the rotors. I have been running it for four years making 15 lbs. of boost at times, normally around 6-8 and it is still going strong.

 

Do you have a 6-71 or a V6-71? One has straight sides (6-71) and one has rounded sides that mounts with long bolts on angles. The 6-71 is an easier bolt up to be sure, the other ones tend to be given away

Flatman

 

How do I tell for sure what kind it is? I don't have a way to take pictures of it.

 

6-71 has 8 bolt holes and a flat bottom, the V series blowers have a funky shape with no big flange on the bottom.

The 53, 71, and 92 blowers are all different, the 71 series is the only one that is easily adaptable to gas engines.

here's a 6-71

 

Does it look like any other blower? Or does it have sides that are angled down and out about half way then angle back in?
The 6-71 blowers can be made to work by douple pinning the rotors and replacing both the front and rear bearing plates with beefier ones. Contact either BDS (Blower Drive Service) or Dyers for info.
I was given a GMC 6-71 awhile back that was rebuilt and douple pinned but once I added up all the things I would have had to do to bolt it up, I could just have bought a complete kit from Weiand. So i ended up just selling it to a diesel engine rebuilder.

Josh

 

uhhhh....I'd have to get out the GMC book to figure out what happens on a diesel.

but on the gas motor applications they turn the proper way if the drive is on the side show in my pic.

 

boy, what a small world. i turned on my computer to ask this exact question, i got a free blower yesterday off a detroit diesel. i removed a bunch of crap off it so it at least looks like i'm used to seeing now, but was wondering about the bearings etc. i assume the one i got is a V, since it has the slots on the sides for bolts. keep the info coming, so i'll have to ask fewer dumb questions later

 

ok stupid questions can't wait. 1. what does pinning the rotors mean, and 2. does anyone know how to get the bearings out of the plates, seems like with the bolts out just the bearings are holding the thing together, but i didn't want to crack anything by just smashing a screwdriver into the seam.

 

pinning the rotors means to drill a hole thru the rotor and it's shaft, and put a pin in there to keep the rotor from spinning on the shaft.

That's a V blower, there's no mounting flange. Not so easy to adapt those ones.

 

I'll take a look in the book....don't break it....

 

thanks squirrel. is this book you speak of a super secret old school book, or could i obtain one from somewhere???

 

my guess is that it would go a little smoother if you had the tools, and the book....here's one pic from one of the GMC manuals I have.

 

i have a hammer and a screwdriver, i'm well on my way
that almost looks like you pull the plate over the bearings and leave them attached to the shafts? thanks for the pic.

 

lots of manuals on ebay http://search.ebay.com/v-71-manual_W0QQfromZR40QQsatitleZQ22vQ2d71Q22Q20manual

 

I just finished rebuilding a 6V-92 at work last week. The superchargers are different from CW rotation, and CCW rotation engines. And to the best of my knowledge, the tolerences between the rotors is diffenert for a gas engine than they are on a diesel.

 

yep thats a v model ive got 2 6v71s and to mount a v style ya need an adapter to hook up to a normal blower intake because of the bolt pattern
if i recall http://www.fordflathead.com/blowersize.html has alot of the info ya need on hooking one up e-mail em if ya need more info their pretty quik on the replys the make the adapters too also i heard they make great air compressors pumps.

 

what has always baffeled me about V 71 type blowers is why everybody shuns them because of the angled mounting bolts. I have heard that they do tend to blow gaskets on the bottom.
It seems to me the logical answer to this would be a fabricated Manifold , made with a removable top, drill the bottom of the blower , bolt it down from the inside of the manifold, then put the top in place on the manifold. I would saftey wire the mounting bolts so they can't come out & get sucked into a port. Just my .02

Dave

 

You are living proof of what I have said for years , that alot of the High dollar mods that are a "Must Do" to use a GMC blower, are not really needed, if one uses common sense & does not try to spin the thing 200 % over on a 6000 rpm motor.

Dave

 

I am putting a V-671 on a 396 for my 69 Camaro right now. Building and adapting a V series blower is not difficult, if you have some common sense, a little know how, and access to a machine shop. I got lucky and got some excellent guidance from an nice old gentleman by the name of Creitz about 20 some years ago. He clued me in on how they used to set up blowers back in the day. I'm finally getting around to putting that info to use. I have some pics on my web page that you guys might be interested in. Here's the link. The pics and info are on the second page. Give me a shout if I can be of any assistance. RS

http://www.cardomain.com/ride/2122214


By the way, the bearings are a press fit on the shafts.

 

Is there only 4 bolts holding that blower down?

 

Yeppir..... That's all that's required on the 671. Low torque values, too. Torque 'em down and you warp the case. I now have 3 of the V671s and I picked up a small block manifold too. I have the CNC programs saved on disc so I can reproduce these parts at will. I'm running the blower 1:1 and it should make 10-11 lbs of boost on the 396. I'm hoping for about 750 hp before the nitrous. After the new bearings and seals, I'll only have about $1100 in the whole setup.

 

The mounting for the V blower is indeed very simple, and should be plenty strong, if the bolts have a lot of thread length in the intake.

btw, I looked up the reverse rotation thing...from what I can tell the blowers are the same, they just move an idler gear to a different spot to change the blower and cam rotation direction on the reverse motors. The crank is the only thing that turns the other direction.

 

I went to look at some old junk cars that this guy had. When I got there he also had quite a few older semi's. I asked him if he had any of the semi's that had those types of superchargers and he asked me how many did I need. He said that he had two 6cyl and two 8cyl. I am hoping that he will get them off for me soon. I also had some quaestions about these.

 

Hey folks,
You might try to find Street Supercharging by Pat Ganahl. S-A Design publishing. I think you can get it from Summit or Jegs.

4-71 comes off 4 cylinder engine, 6-71 off 6 cylinder, 8-71- you get the picture. 10-71 are all aftermarket.

Back to work.

 

8-71 is aftermarket also, afaik

 

i think mine is an 8V-71, (going by top gasket size from a rebuild guy on ebay) which as far as i was told by the guy i got it from, came stock on a detroit V8 in a 1972 brockway dump truck, and was fed by two turbos. must have been a workhorse, and a pain in the ass to work on.