Hello, I am putting an Eaton M112 Supercharger off a Ford lightning on a small block chevy. I am trying to use mostly re-purposed OE/Junkyard parts, One of my intake manifold ideas is to take a stock crossfire manifold and make a new top plate for it that the supercharger will mount to. The EGR provisions will have to be removed, and the runners ported/port matched. I am wondering, however if the orientation of the runners will have any negative effects on performance.


The runner openings are pretty far out, much wider spaced than the width of the outlet of the supercharger.

Would it be necessary to modify the runners (removing the red, for example) in order to provide a more direct path from the supercharger outlet into the runners?

I haven't found anything on the web about this, and given the shape, I can't help but thinking someone would have used one of these manifolds for a blower unless there is a good reason not to.

 

The ports are tiny where they meet the ports in the head. They needed to be to keep the fuel from pooling in the intake.

 

I've been looking at threads about porting these intakes on corvette forums and I haven't seen anything yet about fuel pooling in ported intakes.

I am assuming the small ports are to maintain the velocity of the air so it doesn't slow down too much in the massive plenum and screw up the mixture of the fuel/air.
I wonder if a few pounds of boost in the plenum would help to prevent this.

 

The bigger issue is that it's light years from being a good performance intake. It's the weak link in CFI.

 

I can jive with that, time to think up an adapter to a standard manifold. Thanks, Drew.

 

Offenhauser Crossram 5983. The BIG brother of the crossfire intake.
They pop up on ebay from time to time.

 

Or the Edelbrock SY-1 Smokey (Yunick) Ram. A little smaller than the Offenhauser. Only came with a single 4BBL top.
Offenhauser had single or dual quad tops.

 

The problem with the aftermarket cross rams is that they would end up costing me about as much as a regular supercharger manifold. I was trying to keep it cheap. Hence why the crossfire is so tempting.

I may have to just make an adapter to put the M112 onto a regular manifold, though.

 

I was hoping you were going for different. But I certainly do understand cheap.

 

I think what you are proposing is a cool idea. Make it work, that’s how it’s done!

 

Got the supercharger in a few days ago. Prepping it for draw through.



Stripped the rotors




Took a crappy photo of for inspiration. . .

There is a ton of measurement and fabrication ahead, but it should be fun!

 

Here is a quick run through of all the parts I have accumulated as of yet for the swap.

I think I am going to run an intake temp gauge and boost gauge. Here is my Intellitronix temp gauge.



I found this big aluminum hose nipple at the scrap yard and I may use it to make some sort of carb scoop




I will be using the factory Ford bypass valve, just need to figure out how it works.


Here is the supercharger itself

The guy I bought the supercharger from included a bunch of extra parts and some gaskets and bearings.

I got all polished stainless steel hardware that will be holding it all together.

I got this discontinued 16 rib supercharger pulley on clearance for $21, and it is exactly what I needed. Plus the extra ribs will give my 8 rib belt some adjustment.



Picked this tensioner thing up at the scrap yard, no idea what it's off, but all the bearings are mint and I am positive I can use it in some way for my supercharger setup.

And finally, the crossfire itself. This will need extensive modification, but that's where the fun lies!

 

Started making my intake manifold adapter. It bolts onto the crossfire and the supercharger bolts to it.


Here is the lower portion so far, I need to make a top plate now.


Started hogging out the ports on the crossfire, here is one almost done.

I cut the runner length down to 3", the plenum will be polished.

The water jacket is right here, not ideal as a plate will have to be welded there.


I have the subject: it is a 1991 2 bolt main TBI 350. I am going to use an L31 hydraulic roller setup, haven't picked out a cam yet. I will get it bored .030 over, new bearings and gaskets, ARP main bolts, head studs, Blueprint 64cc cylinder heads. Looking at 9.2:1 compression with .040 MLS head gaskets and flat top pistons.

 

From the pics I can't tell how thick (or thin) your top plate is. Aren't you afraid it will leak? Remember, not only does it have to seal vacuum, but boost also.

 

The top plate is only 1/8" thick. I am a little concerned about leaks, so I am probably going to put a rim on the edge to stiffen it up. The portion the supercharger actually bolts to will be 3/8" or 1/2" plate.

 

There has been some more porting. I am basing the port size off a set of Speedway intake gaskets I have and cutting the runners to ~2.25 inches. I had to cut through in two spots as you can see in the third pic, so those holes can be welded up.

 

It's coming together

 

Huh, it's too bad I didn't see this earlier, I've done quite a bit with crossfire stuff including cut apart those manifolds/milled out/changed whole sections of them, and done as much or more with Eaton blowers, including M90's, M112, M122... and I've even considered doing EXACTLY what you're doing here, using a manifold base and making a lid to fit an Eaton blower.

First, how are you locating the supercharger to make sure the blower pulley aligns with the crank pulley?

This is probably the most critical part, it needs to be aligned better than most accessories are to keep from tearing up belts, and it needs to be absolutely rigid- any flex/motion will drive you crazy when you start pushing this setup hard. You'll find some spot near the motor that is getting coated with rubber and eventually figure out that something is flexing a little bit causing the belt to slip/wear and spray rubber coating the engine bay. I wouldn't even consider 1/8" aluminum anywhere near where it mounts. I've made brackets forming a 3-dimensional structure out of 1/2" plate with braces at the front and rear of the blower and still felt that it had marginal rigidity for what it needed. 1/2" would be the thinnest I would seriously consider using spanning from edge to edge of that manifold if this is going to be stable, and then I'd be considering reinforcing ribs.

Those manifolds make massive low-end torque based on the port cross-section and length, but that hurts flow up top. Mounting a supercharger on top of it will make up for the flow up top by forcing whatever air the blower moves at the rpm you turn it down into the engine. The problem is the massive low end. Those blowers move lots of air down low also, and you're likely to just accentuate that tendency resulting in big cylinder pressures at low RPMs (say sub 2000rpm or so) making it impossible to tune, it would be prone to crazy detonation.

Hogging out the outlets of those ports typically screws up the manifold because there is no meat behind it and you can't hog out the cross-section of the rest of the port, resulting in a spot where flow just suddenly slows down (this doesn't happen with the step created with the stock port profile). Completely cutting out the runners is pretty much the best solution, you end up making it an "untuned" setup and you let blower flow decide what the powerband looks like. You'll lose some part-throttle efficiency but everything else will work better and be easier to tune.

Now the big problem- you're not thinking of mounting a carb on top of that bower, are you? They are not designed for wet flow, not only will it mess with the ablative coating on the rotors, but a few people have tried and all have wiped out the rotor bearings which are exposed to the airflow within a couple of hundred miles. Finally, assuming you get around that you won't be able to use the bypass which will cause light and part throttle to be a bear to tune and it will constantly surge.

 

FWIW, from a price/performance perspective, I decided that a Vortec truck base is probably the best cheap manifold base to start with for this kind of thing. It's a similar 2 piece deal with an aluminum manifold base, it bolts up to Vortec/fastburn heads which are superior to most SBC heads, especially with port and chamber design helping control detonation, which is huge on a blown setup, and there are TONS more of them out there available for cheap.

 

When I was doing research for this whole deal I came across quite a few older posts of yours, glad you've come across this now.

I made sure the side of the blower is square with the cylinder head, made the blower pulley level with the crank, so I know this lines up.
The manifold base is definitely going to need reinforcement. I was thinking of adding all sorts of gussets, but I may end up re-making it with much thicker material. Based on what you say that may be a good route.

I found that by the time I opened up the ports the inside was smaller, that is why I cut the runners down at the top. The idea was to create a straight path where the runner cross section is consistent.

I actually am thinking of mounting a carb. I stripped the coating off the rotors, and I'm going to clean out a set of rear bearings and pack them with fuel resistant Roots grease.

Last night I actually stumbled across the Vortec manifold by accident. I can't believe I didn't think of those earlier. The cylinder heads I am getting have the standard intake bolt pattern as well as the vortec, so it is still an option I may persue later.

I'm not experienced with forced induction, this is meant as my learning project. The more tips and advice I can get, the better!

 

I completely forgot about this picture i took of a Firebird that

was for sale local to me a few years back.

 

That's cool! Looks like an M90 on an L03, thanks for posting that up.

 

Why not just make one out of aluminum plate ?

-- Joe