6-71 blower + port fuel injection?

[exdeath]

A lot of car people here so thought I would ask here as well.

Does there exist a lower intake manifold for the 6-71 blower that is set up for port fuel injection, that is, with 8 injectors sitting at the bottom of the intake runners below the blower just above the head port?

All the 6-71 fuel injection setups I can find are carb or throttle body injection that dump air and fuel into the top of the blower so that the entire induction system contains both air and fuel.

I'm wondering if there is manifold as I described that would work like a modern forced induction setup, that is, you control the throttle on top of the blower, relying on a MAP and IAT sensor on the lower intake, with injectors in the ports. This way you only have air in the intake and blower.

Reason why is I was pondering an electromagnetic clutched crank drive pulley for a 6-71. If you had a port injection manifold that the 6-71 sat on top of you could kill the blower and open a bypass on the lower manifold and still have fuel delivery instead of dumping fuel all over the now stationary rotors.

If there exists a port injection manifold for the 6-71 it would most likely have the open area for the burst panel which would be unnecessary in a port injection system with only air in the intake, thus allowing placement of a bypass choke and secondary throttle.

Of course the on/off clutch driving the blower would have to be pulse width modulated when activated to simulate ?slipping? the clutch when engaging the blower at high engine speeds to prevent the belt from snapping, etc.

 

[compman25]

How is air going to make it through the blower if it isn't spinning? It works by compressing the air inside it and forces it out the bottom, it it isn't spinning it is like a solid wall, no air goes thru.

 

[exdeath]

Originally posted by: compman25
How is air going to make it through the blower if it isn't spinning? It works by compressing the air inside it and forces it out the bottom, it it isn't spinning it is like a solid wall, no air goes thru.

I addressed that already. Bypass throttle on the lower manifold below the blower, linked in series in much the same way a dual carb is set up. Also a bypass valve that opens and closes just behind the bypass throttle in sync with the blower clutch.

That is why port injection is needed: air can come from the blower or the bypass under the blower, independant of the fuel delivery at the point of port injection. Without a point of fuel delivery common to both air paths, multiple fuel systems would also be needed.

On classic 6-71 setups fuel is dumped into the top of the blower via carbs or throttle body injection. With the blower off, fuel wouldn't make it to the engine either. Without port injection you'd also have to run two seperate fuel injection systems, one on top of the blower and one under it with the bypass for when the blower is off. Port injection solves that problem by simply using one fuel injection system that is independant of how the air arrives. Only a bypass valve and secondary throttle when using bypass mode are needed, the fuel system stays the same for either mode of operation if port injection can be used.

There are modern Eaton blowers that are electromagnetically clutched and they incorporate the bypass system inside the blower housing itself, bypassing the rotors directly instead of bypassing the entire blower, such that air always comes from out of the blower in either mode. This negates the need for a second throttle outside the blower intake path. The 6-71 has no such bypass built in thus you would have to provide an external bypass system and secondary throttle on the lower intake under the blower in order to bypass the blower directly to the manifold. Having two seperate air paths requires two fuel delivery systems, one for each air path, unless you can add fuel at a common point between both intake paths; ie: port injection.

Thus I'm wondering if there are port injection manifolds made for the 6-71 or if something like that would have to be custom milled. Port injection wasn't common, if around at all, at the time the 6-71 was popular. However modern top fuel cars using 14-71 blowers use complex multi point fuel injection systems including injectors in the ports, so I'm guessing somewhere out there is a 6-71 blower manifold that has a hole at the base of each intake runner to accomodate port injectors.

 

[exdeath]

Ah here we go, they call them 'port nozzels'

http://cgi.ebay.com/BLOWER-SUPERCHARGER...9QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://cgi.ebay.com/ebaymotors/ws/eBayI...eCat&refwidgettype=cross_promot_widget.

I suppose you can use just about any manifold for the 6-71 and just drill out the injector openings at the base of the runners yourself.

 

[Stumps]

Let me guess....somebodies been watching way to much Mad Max?

just about any 6/71 manifold should be able to be drilled to accept injectors...I'm sure if you look hard enougth you should be able to purchase one, as for throttle bodies, well I'm sure there are plenty availible in the US...there are her in Australia.

as for get air through the blower when it's not turning, I'm not sure....I actually have a BDS 6/71 + 2x 600DP carbs sitting in my back shed with a manifold to suit a Ford Cleveland V8....I'll have a look at it later on to see how much clearance is in the rotors to let an unpressurised air flow through it....

I'm not sure it would work but you could put a clutch assembly in the blower snout, plenty of room with 6/71's...I would assume that the 6/71's being a Roots based blower like the later eaton blowers you should be able to adapt clutch mechanisms to them.

 

[exdeath]

Originally posted by: Stumps
Let me guess....somebodies been watching way to much Mad Max?

just about any 6/71 manifold should be able to be drilled to accept injectors...I'm sure if you look hard enougth you should be able to purchase one, as for throttle bodies, well I'm sure there are plenty availible in the US...there are her in Australia.

as for get air through the blower when it's not turning, I'm not sure....I actually have a BDS 6/71 + 2x 600DP carbs sitting in my back shed with a manifold to suit a Ford Cleveland V8....I'll have a look at it later on to see how much clearance is in the rotors to let an unpressurised air flow through it....

I'm not sure it would work but you could put a clutch assembly in the blower snout, plenty of room with 6/71's...I would assume that the 6/71's being a Roots based blower like the later eaton blowers you should be able to adapt clutch mechanisms to them.

Yeah Mad Max... while browsing around supercharger parts I found that Eaton makes a clutched supercharger (M62 I think) which kinda surprised me... then right away I remembered the Mad Max blower for some reason, which I always knew to be total BS with the on/off clutch, and I started thinking about how it could be done on a 6-71 like that M62 using todays technology, if not just for the hell of it, for the engineering challenge

Of course in Mad Max, with a Scott Superslot with fuel injection on top of the blower, and without the benefit of electronic engine management, it wouldn't have been possible back then. The movie didn't even use a real blower.

But yeah, for a real performance oriented engine, it seems any manifold with exposed runners near the heads would allow for drilling for injector seats as well as rail clearance. Alot of the manifolds I see without injection nozzel openings have little round raised up flat spots in the casting above the base of the runners, probably to allow for optionally drilling for injectors. I'd also opt for a lower intake that had room for a intercooler.

If not modifying the inside of the blower to allow for a straight forward internal bypass and thus unifying the air path.... I'm thinking a better system would just be a 2 speed transmission inside the snout. It would cut parasitic drag down to run the blower at say 1/5 the normal speed and gain the reduced fuel consumption for cruising that a clutched system would be needed for in the first place. But since there would be a tiny bit of boost still, you wouldn't comprimise power and fficiency at low to no boost due to the lower CR of a blown engine without a blower. Also wouldn't have to worry about a bypass, crank bending load when suddenly engaging the blower, snapping belts, etc.

That Eaton M62 is a tiny thing for, only modest OEM boost for like a I4 or V6. It probably wouldn't handle the rotational inertia of engaging a 6-71's massive rotors.

Speaking of the 6-71 in general, has anyone made a aftermarket set of twin screw rotors that would swap with the roots rotors? You'd need to plate off the intake opening to a slot near one end of the rotors and do the same on the bottom for the oposite end for the discharge plate. I'm not sure if the inside of the case has to be tapered or anything though...

Fun stuff to think about at any rate.

 

[Blazin Trav]

What sorta MPG we talkin about with this bad boy of an engine (bay)?

 

[Raduque]

Couldn't you do a throttle-body injection setup under the blower, the way you can convert dual-carb manifolds to dual-efi?

 

[Stumps]

Originally posted by: Raduque
Couldn't you do a throttle-body injection setup under the blower, the way you can convert dual-carb manifolds to dual-efi?

not with a 6/71....it would be a nightmare to setup like that...they are bloody huge.
It's better that have the throttle bodies at the top of the Supercharger.
I had the chance to have a peak in to the inlet of my old 6/71....very little clearance between the lobes of the rotors....it may work while not rotating but the airflow would be far from optimum....infact from the look of it ah heck all air would flow through it while the rotors are stationary.

the best way I could see it sort of working is to make a custom adaptor at the top of the housing which features a butterfly and a separate feedpipe that when the supercharger is switch off the butterfly opens at the back of the adaptor just below the throttle bodies or carbs and then redirects the airflow in to the lower half of a customised lower manifold...it would probably work...but not worth the effort.

one last thing to make that sort of setup with a supercharger that can be shut off and turned on work you would need a 70's Falcon coupe....not many of those left in Australia.

 

[compuwiz1]

6-71's aren't cool anymore. Time to step up. Dual 8-71's anyone?

 

[Stumps]

Originally posted by: compuwiz1
6-71's aren't cool anymore. Time to step up. Dual 8-71's anyone?

been done here....a well known car builder by the name of Gary Myers built a mad choptop 66 mustang with a hemi and twin 8/71's in it for the Canberra Summernats....it's an AWESOME car.

 

[exdeath]

Originally posted by: compuwiz1
6-71's aren't cool anymore. Time to step up. Dual 8-71's anyone?

This was purely a engineering feat. It would be solved by using a air bypass on the lower intake and port injection to ensure fuel delivery at a common point to both air sources. Any 6-71 lower could be used provided the base of the intake runners were exposed for injector drilling and rail placement. Because port injection eliminates fuel in the blower and upper intake, the blow off plate on the lower would not be needed, thus leaving a large opening for the bypass throttle system.

But now days 8-71's aren't cool anymore either. In modern times, Kenne Bell and Whipple is where it is now.

30 lbs of boost out of a twin screw the size of a large shoe box Quicker boost and higher boost and less parasitic drag due to low inertia of smaller rotors thanks to modern alloys and tolerances, etc.