AFBCamaro

Hey guys i just got my hands on a used(in good condition) 6-71 roots blower. It is a GMC diesel.

Before anyone says anything. I am building a 385 in the garage and was bored so now i feel like putting a blower on the 305 until it goes.

My 305 Camaro Currently does 14.4 in the quarter mile.

My question is does anyone know what you have to do to convert a GMC diesel blower to work on a Street engine?

I imagine that you must surface the bottom of blower flat to allow for fitment to the intake but asside from that can i just buy a drive, cover plates and stick it on like that???

I have found no information on this thing at all.

Thanks for your time!

Dan91Z

i bought an 871 that was on a diesel for my 95 k1500 with a 305,.. let me just give you one huge warning. Parts for these are EXTREMELY expensive. Hopefuly you can find them at a good price. Clean the rotors off and put new teflon strips on them (if the rotors are in good shape, if not, I've seen new rotors on ebay for around 100 bux before), clean the inside of the case, heck, clean the whole thing real good. If the bottom needs surfacing to fit properly, you should do it. Use pulleys that will keep the boost down, unless you have the engine set up to handle it :-)
So if it's in good shape just basicaly clean it up and get the parts it didn't come with.

B4Ctom1

This place (there are probably many others) offers overhaul and conversion of your unit for performance use on an exchange basis I believe. http://www.speedwaymotors.com/

AFBCamaro

thanks Dan91Z Thats what I wanted to hear. I have the 6-71 version so it is flat underneath. I thought that u had to do something special to it, but it is flat :-)

I only have the blower itself. Im fabricating a single carburator plate out of aluminum. It will be feed by a 930cfm variable venturi predator carb. Maintains the fuel at a constant 12.5 mixture throughout the range. I will put 76cc heads ported by me. So compression will be at 7.6s. Then I am shooting for around 8psi with water injection to ward off detonation. Should be pretty safe.

How did the blower work on your car Dan91Z? Im really interested. How did it drive. How did it sound. I dont physically have the unit yet, im going to pick it up now.

I need the end covers and the drive mechanisim which i heard is patetically expensive. But you cant beat that 3 inch thick belt sicking out of your hood. :-)

Also Dan91Z did you convert it yourself. I thought that the Diesel units did not have teflon strips......Will they....BOLT IN?? HEHE

Thanks again guys

Dan91Z

Mine isn't on at the moment, still trying to get REALY REALY REALY expensive parts at a descent price on ebay. I refuse to pay what autozone/summit/jegs/etc want for the peices. When it is on it's only going to be set to put out about 4 or 5 lbs, but that's on a bone stock motor. I know it's a waste of a 871, but it looks cool :-)

I'm working on a way to use tpi with it, so it's going to take me a while. Alot of hand made stuff in the works, and a lot of dead plenums....

My friend has an s10 with a 350 & 871 running about 12 lbs, it sounds great. His was also an ebay special from a diesel, it was still yellow when he got it. He just cleaned his and used it the way it came, slightly scratched rotors and all. He lucked out and got about everything needed with it except for the belt and pullies. The main reason I got mine was for the sound, looks was part of it but now i'm sorta leaning towards making it fit under the stock hood (that's why i'm working on using tpi with it). It'll still look good when the hood is up :-)

The teflon strips probably didn't come on diesel ones, and heck, you realy don't need them unless you want to make alot of boost. I just like having them for some reason. Although with them you can spin it a little slower to acheive the same boost, which prolongs the life. The strips would probably have to be replaced after about 4 years at 8 psi, which isn't to bad. I bought a set of rotors with the strips on them from ebay, didn't realy pay attention to the ones that came in it, probably didn't have them though.

AFBCamaro

Dan91Z YOU ARE THE MAN!!!!!

You said I dont need them(teflon strips). Then hell Im not going to use it unless it will hurt something.

A waste of an 8-71 HELL No. I admire tinkerers. Im not much for the oh look I got it in the mail and I am just like everyone.

Im more like....Hey I found this big monstrosity on an old diesel engine lets stick it on and see what it does. Much more manly!

I too wanted the blower to be under the hood. But the other days I went to a classic car cruise and I saw an 6-71 sticking out of the hood......DAMN.

I too want it mostly for the whine. Its sad a huge blower for the nice whine and the novelty of having it.

The teflon strips are not an issue for now. Its going on a 305 and the more bost I bleed for now the better

Hey keep me updated on the parts you need left. Odds are I will need them to. So if you find a good deal on something let me know. Ill do the same.

Thanks again

AFBCamaro

Hey by the way I just had a vision. The 8-71 should work with the tpi. First you will need the....... I have the vision I just cant explain it yet. Its probably what you are doing right now.
Sort of a tinny little ramjet ontop of the 8-71 with the Throttle body up in front.???!!! Man im tired!

If its what im thinking you are going to do you will need bigger injectors and alot of computer tunning. But might save about 5-6 inches of height. It might still be an incredibly tight fit.

B4Ctom1

if you had the hood space I think something configured like this would do.

B4Ctom1

like this

AFBCamaro

HOLY SHIIIIAAT...

YES YES SOMETHING LIKE THAT.

Thats seems like a modern eaton roots blower. It doesnt seem that hard to do.

Dan91Z

That picture makes me realy want to keep working on it :-) The way i been trying to go is with a tpi manifold that will be changed slightly , runners about 3 " long curved like elbo macaroni to a plenum with the side holes filled and holes made on the bottom for the runners. I was thinking some type of divider in that plenum which will be about 2 inches high, so the runners will be about 2 1/4 Inches high after the curve. (kinda like a realy short tunnel ram) Then the blower, then another cut up plenum on top of the blower to the throttle body. Should have enough room on the outside of the runners for the injectors/fuel rail still. I was only planning on using 24 lb injectors, only shooting for about 265 hp here at the moment. That might change though ;-) And I'll probably use a 749 ecm to control it.

NTChrist

That is freakin' cool!

I don't know my blowers very well, but is that a Whipple?

Any more details on the engine you can shed, Tom?

Apeiron

It's sort of similar to a roots but has screw type rotors.

<img src="http://www.whipplesuperchargers.com/images/howitworks/compressor_cutaway.jpg">

http://www.whipplesuperchargers.com

NTChrist

Heh, thanks, but what I was asking if that IS a Whipple blower.

JoBy

I agree that it looks cool, but it does not make much sense to keep the TPI runners. You don't need the long runner length to make midrange tourqe because the blower will make sure that you get enough air in there. They will only add extra height and restriction.

Using a low profile manifold like this makes more sense.


I think that they are available modified for injectors and fuel rail.

If you are going to modify a stock manifold I think that the LT-1 or miniram would be much better than a TPI to start with. You could cut off the top of the plenum and weld a flange to mount the blower on it. Then you bolt a plenum to the top of the blower with a TB pointing forward.

B4Ctom1

I agree, I think the only reasons that guy did it was for show and because he was using a little M90 on tha car.

Apeiron

Haha.. yeah I see that now.

SATURN5

BW

Kingtal0n

<b>I think that they are available modified for injectors and fuel rail</b>

if you find one let me know. I couldnt.

I even considered using the Do-it-yourself kit from holley to add injectors / fuel rail to the blower manifold.

wouldnt work. the injectors hit the blower, where it curves out. if you angle the injectors to fit, then the fuel will spray against the intake port as opposed to the intake valve. very very bad. I cannot see how you would fit an injector there, anywhere, the blower is just too big.

and this is on a the smallest weiand 142 you can get.

Kingtal0n

And one more thing...

According with weiand (holley) the blower NEEDS fuel to hit the rotors at some point because it acts as a cooling method. without fuel to cool the rotors they get REAL hot REAL quick, expanding, and eventually warping and hitting the sides of the case.

So the multi point injector theory is out the window. TBI would be more suited to a roots blower application.

83 Crossfire TA

iTrader: (2)

Use the roots+it's manifold, and make a little plenum that mounts where the carb would go with a TB flange on the front and 8 injector bungs along the sides...

Much less work then trying to get the blower to sit on the plenum over the runners. What the hell do you need the runners for with a positive displacement blower anyway?

Kingtal0n

<b>and make a little plenum that mounts where the carb would go with a TB flange on the front and 8 injector bungs along the sides...
</b>


basically TBI but with 8 injectors right? why not just use TBI then? Going through the top of the blower, either way, 8 or 4 injectors shouldnt make a bit of difference. even spray pattern means nothing since the rotors mix it up anyways.

stevedave454

and make a little plenum that mounts where the carb would go with a TB flange on the front and 8 injector bungs along the sides...



basically TBI but with 8 injectors right? why not just use TBI then? Going through the top of the blower, either way, 8 or 4 injectors shouldnt make a bit of difference. even spray pattern means nothing since the rotors mix it up anyways.

http://www.project33.com/article.cfm?ID=118

look at BDS fuel injection kit, 83 crossfire is talking bout doing the injectors like that... but instead of bolting the injector hat/scoop to the plate he's talkin bout bolting a plenum with a TB to it.... i am picturing something that looks like the the upper plennum of a TPI unit, with a tpi TB... of course with the TPI upper plennum would have to have a big hole on the bottom for the air to pass through and have the runner holes covered up (kinda like the upper plenum of the stealth ram).... i dont know if im describing this good, but its an idea i've been playing with for awhile, but i wanna build a turbo motor so maybe later on in life

3.8TransAM

Saturn5/bob lol I love the look of your engine bay lol.............im styaing with single on the drvr side so i can keep my air conditioning :-) lol

boot roots blowers for us all around and cheap to acquire

LAter
JEremy

83 Crossfire TA

iTrader: (2)

What TBI would you use? I've managed to bore the factory TBI's to just over 2" (about 54mm), and I don't know of any of the aftermarket that bores them over 1.8". You can build a small block that would use all that airflow NA easily, why waste your time building one that needs a blower to do it? Blowthrough, like with a turbo or an eaton mounted off to the side is another story… then the issue becomes enough fuel flow.

yea, that's about right… A plenum with TB's would basically serve the same function as the scoop/throttle plates in that setup, and both would pretty much be interchangeable… you'd just have a little more flexibility with packaging if you built a plenum/TB assembly specific to the application.

mw66nova

iTrader: (13)

you could run the holley commander950 with a 900 cfm throttle body on it. 900cfm is alot...don't see why it wouldn't be enough on a roots blower.

614Streets

My blower motors.
The 355 might eventually be dual tbi. I fyou go to holleys website they offer a dual tbi computer that can run two of their 4 barrel tbi units and provide fuel support 1200 plus! You wont be dam near 1200!

Gumby

614Streets

I notice in some early pics you had a NOS plate under the "carb" Where did it go???

614Streets

On the 2.8 and the 355 there is Nitrous plates underneath the carbs and the tbi.

Kingtal0n

Why does it look like there is only 1 Injector over that blower?

614Streets

There are two 85 lb injectors, its a 670 cfm holley tbi with a 400 cfm tbi throttle shaft. cUstOm. Normally a tbi sits horizontal. Mine I fabricated to sit linear. Basically it a 454 tbi on a 2.8 v6:hail: