Moparts
Blower Size On Smallblock??
Posted By: Blucuda413
Blower Size On Smallblock?? - 06/06/14 03:03 AM
What size blower is the largest which can reasonably be made to work on a smallblock?? Is it a 6-71, 8-71, or 10-71?? The Indy site shows a 6-71 on a sbm but they also use an offset distributor. Is the offset dizzy required? BTW would go on a 454" smallblock.
Posted By: MR_P_BODY
Re: Blower Size On Smallblock?? - 06/06/14 03:32 AM
Quote:
What size blower is the largest which can reasonably be made to work on a smallblock?? Is it a 6-71, 8-71, or 10-71?? The Indy site shows a 6-71 on a sbm but they also use an offset distributor. Is the offset dizzy required? BTW would go on a 454" smallblock.
If you plan on a 454ci down the road you better think
BB and base your blower on that.. if it turns less
speed it makes less heat
Posted By: SpareParts
Re: Blower Size On Smallblock?? - 06/06/14 05:06 AM
Have you thought about a procharger?
Posted By: bigtimeauto
Re: Blower Size On Smallblock?? - 06/06/14 05:19 AM
Quote:
Have you thought about a procharger?
must be for show....
Posted By: Cab_Burge
Re: Blower Size On Smallblock?? - 06/06/14 07:58 AM
The bigger the blower rotors the less RPM on the blower needed to make the amount(volume) boost you want, the less rotor RPM the less heat the blower makes, hot air is less dense than cooler air
I'm thinking your going to need at least a 8:71 , if you could run a crank trigger ignition then a 10:71 would be even better yet
Posted By: 1Fast340
Re: Blower Size On Smallblock?? - 06/06/14 10:43 AM
consider a twinscrew moves plenty of air without a huge case.
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/06/14 01:34 PM
Quote:
The bigger the blower rotors the less RPM on the blower needed to make the amount(volume) boost you want, the less rotor RPM the less heat the blower makes, hot air is less dense than cooler air I'm thinking your going to need at least a 8:71 , if you could run a crank trigger ignition then a 10:71 would be even better yet
I believe it is SSI that makes a front offset blower,if you went with a 10-71 it may not be too long.I think you need an 8-71 and it would be fine.
Posted By: Dragula
Re: Blower Size On Smallblock?? - 06/06/14 01:58 PM
Posted By: 1Fast340
Re: Blower Size On Smallblock?? - 06/06/14 02:11 PM
fits with most any distributor good for about 750Hp.
Posted By: Blucuda413
Re: Blower Size On Smallblock?? - 06/06/14 04:49 PM
This may sound stupid but I plan to develop both a roots blower system and a Procharger system. I have the Procharger and the installation brackets and am gradually buying all the other parts. I also have a 12-71 that I must trade for a smaller blower. For that system I have a birdcatcher for fuel. I plan to build my own manifold when I get the right size blower. My question on the roots was to figure out what size I could use without too much hassle. These are both long term projects but you have to start somewhere. BTW I need about 900hp to attain my bucket list ET of 8.99.
Posted By: FastmOp
Re: Blower Size On Smallblock?? - 06/06/14 05:09 PM
I'd just use what you have. 12-71 is not unheard of on a blown alcy 454.
You better have a big Procharger if your trying to compair the two.
Posted By: 1967dartgt
Re: Blower Size On Smallblock?? - 06/06/14 05:24 PM
Quote:
I'd just use what you have. 12-71 is not unheard of on a blown alcy 454.
You better have a big Procharger if your trying to compair the two.
A f2 would compair easily with that. There is a f2 on this board that goes 4.70s at over 3300 lbs on a bbm.
Posted By: MR_P_BODY
Re: Blower Size On Smallblock?? - 06/06/14 05:27 PM
Quote:
This may sound stupid but I plan to develop both a roots blower system and a Procharger system. I have the Procharger and the installation brackets and am gradually buying all the other parts. I also have a 12-71 that I must trade for a smaller blower. For that system I have a birdcatcher for fuel. I plan to build my own manifold when I get the right size blower. My question on the roots was to figure out what size I could use without too much hassle. These are both long term projects but you have to start somewhere. BTW I need about 900hp to attain my bucket list ET of 8.99.
JMO.. but I would run either a 6-71 or a 8-71.. if
you go larger on a SB it might be way too long to
fit
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/06/14 05:36 PM
here is some info that may help you decide.My 8-71 take about 70/90 hp to drive at 10%OD with 240*F air temps and I have read that a 10-71 at lets say 6%OD to make the same hp was 20*F cooler IAT and that 20*F cooler temp make 20 more hp +/- 5 I would say.
Posted By: Slingshot383
Re: Blower Size On Smallblock?? - 06/06/14 06:01 PM
Clanton, fuel injection with nozzles at the hat is different than running with carbs on top, then if you add the down nozzles, you can really tune for each cylinder and make the blower work a lot better. I'd be more concerned on keeping the bottom of the motor together running either style blower at the 900 - 1000 hp level on a small block.
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/06/14 06:13 PM
I did not see where he said it was injected!I was also waiting to find out what block he has.
Posted By: TRENDZ
Re: Blower Size On Smallblock?? - 06/06/14 07:14 PM
Use the 12 71 but mount it out front. you can intercool it and use standard intake manifolds. Plus, it would be way cooler than doing it the "standard way"
Posted By: Blucuda413
Re: Blower Size On Smallblock?? - 06/07/14 05:41 PM
TRENDZ, the old Potvin kit trick. It's been a long time since I've seen one of those. Good idea but no space. Is anyone currently using a 8-71 on a small block and if so what manifold and how much clearance between blower and distributor??? Thanks, Max
Posted By: Slingshot383
Re: Blower Size On Smallblock?? - 06/09/14 06:20 PM
Clanton, in his second post, he said he had a bird for the roots blower, that's where I got it from.
Posted By: Sherminator
Re: Blower Size On Smallblock?? - 06/10/14 12:22 AM
wow
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/10/14 06:45 PM
Quote:
Clanton, in his second post, he said he had a bird for the roots blower, that's where I got it from.
OK then. 
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/11/14 01:44 PM
So tell us about the discharge opening[Delta,square,other?]Will you change the design of the intake depending on the opening?
Posted By: Blucuda413
Re: Blower Size On Smallblock?? - 06/11/14 08:43 PM
Clanton, since I don't have all those parts it's really hard to say. I think I would go with the standard opening and hopefully find a W2 tunnel ram I can make the intake out of. Might not work its been a long time since I had a tunnel ram in my hands. If I can find a good aluminum welder it shouldn't be too difficult. Since I don't really have a negative response as yet I'll plan on a 8-71 until I can verify it will not work. I'm also interested in what length snout people have used for the smallblock It seems like there's not a lot of info out there on the smallblock. If anyone has a setup that will pm me info I sure would appreciate it. Thanks, Max
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/11/14 09:26 PM
Thanks for the reply,I just wanted to see what your ideas were.
Posted By: fed
Re: Blower Size On Smallblock?? - 06/11/14 10:20 PM
How do you modifie the tunnelram for the blower?
I have a 6-71 and a Holley Pro dominator intake that i would like to use on my 340.It made 640HP on the dyno with a singleplane and a dominator.
Any pics on an tunnelram/blower intake?
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/12/14 12:39 AM
To start to measure for the blower nose you go off the front most intake bolt to the front of the crank damper[straight edge]and start subtracting the blower case length.
Posted By: polyspheric
Re: Blower Size On Smallblock?? - 06/12/14 01:48 AM
Posted By: Blucuda413
Re: Blower Size On Smallblock?? - 06/12/14 02:26 AM
Polysperic, thanks for the info that is exactly what I had in mind I just haven't selected the manifold. I just dug up a picture of the W2 tunnel ram and the plenum is much smaller than I remembered. It could still be made to work but you would have to build a plenum. I have saved a sheet of 5/8 aluminum which I will use for the blower mount. Clanton I will be using an X block I've been using for a number of years. In current NA form it is about 600hp, maybe it will hold 900 to 950 for some period of time.
Posted By: Clanton
Re: Blower Size On Smallblock?? - 06/12/14 03:04 AM
you may want to do a half fill on the block,main cap studs[caps?],The proper steel rod/bolts.
Posted By: polyspheric
Re: Blower Size On Smallblock?? - 06/12/14 05:04 PM
There's another intangible factor involved that I didn't address.
GMC etc. blowers do not actually compress the charge internally, all boost occurs when the engine's capacity is fully satisfied (manifold vacuum is zero) - boost is pressure against the previous intake cycle. If the blower is too small or spun too slowly not only is boost = zero, you will have big pumping loss and vacuum @ WOT: negative horsepower.
This means that the time to develop pressure is somewhat affected by plenum volume - more storage = slower to pressurize.
Regarding discharge port location, it's not clear in my remarks. Any straight rotor should just have the window (more or less) centered over the plenum like dual carbs. Any helix rotor will tend to charge nearest the front, even if the port window is rectangular. I have a gut feeling that some running older helix blowers with square windows have plated the windows into triangles to reduce charge temp and improve mix distribution, but they're not talking about it!
Posted By: Blucuda413
Re: Blower Size On Smallblock?? - 08/17/14 06:51 PM
fed, here is a link concerning SBM tunnel ram to blower manifold. Looks like these boys are from your part of the world. His work on the Pro Dominator is exactly what I would contemplate. My son found this link for me and I just saw it last night. Anyway looks like a lot of work but could be done. Might be better to get one of the Indy Modman manifolds and modify it for a W2. If anyone has additional info sure would appreciate it. Thanks, Max
Posted By: jim sciortino
Re: Blower Size On Smallblock?? - 08/17/14 07:24 PM
Get a Whipple screw up there and thank me later. No comparison to an old roots style charger.
Way more power, with way less heat and looks killer. 1000+hp with 93 pump gas on a good small block and drive anywhere.