Injector Recommendations

Flex

Registered User
Hey guys. I have just ported my brother's old 93 oval port M90. The inlet opening has been enlarged as far as could be leaving enough room for a seal. I have also enlarged the outlet to the top hat as well.

At the same time, I have cut apart and redone the throttle body inlet plenum. At its smallest point, the TB opening, it is 75 mm. The rest of the tube varies from 77-82 mm and I have reshaped the inside wall to be more like an MP inlet plenum where the flow is almost straight to the blower once it goes past the corner. Obviously this will flow considerably more air than a stock oval port.

Any thoughts on what I should use for injectors with this? I have 5 or 6 sets of 36's and two sets of 42's. Any thoughts?
 
Depends if you have a chip or not. If not then stay stock injectors and MAF until you do.

Then get yourself a C&L, the right sample tube for the 42's, a chip or tuner board and get someone (Dave D) to set up a tune for you. Thats the safest way to do it.
 
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I have several MAF's including a C&L 80 mm unit with about 5 different sample tubes and a Pro_M 77 calibrated for 36's. I do have a tuner I bought for when I installed the modifed rectangular port.

I wanted to run this unit until the late model was finished and out of curiousity to see what kind of gains could be had with an oval port that heavily modified. I couldn't find anyone having posted running a 75 mm TB on an oval port.
 
I'm running one right now but haven't dyno'd it. It makes right at 15psi all the way up with 15% OD. I'm probably at about 275rwhp with a pretty stockish motor and I'm running 36's but I know I'm at 100% duty cycle.

With a highly ported early model and heads/cam the blower was not able to keep up and was losing boost at higher rpms. Power level was around 295rwhp with 10% OD. I think with more OD it could have made 310rwhp or so.
 
I wanted to run this unit until the late model was finished and out of curiosity to see what kind of gains could be had with an oval port that heavily modified. I couldn't find anyone having posted running a 75 mm TB on an oval port.

I'm unclear what you are asking. There have been many cars running a 75mm TB on an early model supercharger and inlet.

Here is an example. The car David is talking about has a 75 mm TB and a 73 mm MAF, but I don't know how much porting has been don to the inlet.

http://www.sccoa.com/forums/showthread.php?t=67342&highlight=stock+blower
 
Yes but I'm not talking about just gouging out the front of the inlet so that there isn't a miss match to the throttle body. I have heavily reworked it so that it easily maintains 75 mm or more throughout. I also cut the short side out and brought it out 1" so that the path is much straighter. I think that this should offer much greater flow capability.

Dave, do you think this has the potential to exceed your 295 rwhp setup? What are your thoughts on injectors and MAF? Should I try the 42's and the 80 mm C&L or would that pose a tunability issue?
 
Yes but I'm not talking about just gouging out the front of the inlet so that there isn't a miss match to the throttle body. I have heavily reworked it so that it easily maintains 75 mm or more throughout. I also cut the short side out and brought it out 1" so that the path is much straighter. I think that this should offer much greater flow capability.

Dave, do you think this has the potential to exceed your 295 rwhp setup? What are your thoughts on injectors and MAF? Should I try the 42's and the 80 mm C&L or would that pose a tunability issue?

It may do better but who knows? The biggest problem with the early style blower is the innefficient manner of filling the rotor case and not the plenum itself. For example, just installing a 94 blower and inlet will outperform your early model even though the inlets are basically the same.

There won't be a problem running the 80MM and 42's other than you'll have to tune it. If you can tune then its no problem. If you can't tune it, then that would be a problem. ;)
 
Flex,

If you massage the inside face of the blower inlet like the S-ports did, you may narrow the gap to the 94-95 blowers. Maybe you already did that. Basically, it looks like the profile of the MPIII inlet, but it is blended back into the inlet port. A little tricky to do, I think, but it should help fill the rotors.

Anyway, I would be interested to see what the inlet you cooked up looks like. I am working on a similar early model blower / inlet project, but I can't weld. So I am going to have to leave the main body of the inlet alone. I do have some coated rotors that should kick things up a little.
 
Dave,

I have the tuner that O bought off the board a few months back. Version 5.1 I think. Have not used it yet though.


Steve,

I thought the MPIII had a w shaped inlet. Do you have any pics you could post? I checked the board and founf nothing to refer to.

I could post some pics. If you are serious about trying to mod an oval, it is not that hard with the exception being that welding is required. I could do another quite easily.

Took me about three 6 hour days to weld and port it. I got rid of all the stupid depressions around the mounting bolts, pushed out the back wall 3/4", pulled the short turn in about 1" and enlarge the area around the TB surface so that a 75 mm throttle body could be used.
 
Take a close look at what all the updated blowers have over the old one.... The biggest thing is the bottom plate below the rotors. The old blowers is completely open there and because of the shape of the rotors, air is actually forced out of the rotors. The newer blowers keep the rotors sealed even at the bottom witch makes them alot more efficient.

The EEC Tuner can do what you want for now.
 
Ok I got it. Steve had me confused a little because he said inlet, so I thought he was referring to that.

Yes I did enlarge the outlet as well shaped like the MPX. I removed approximately 3/4" from each side taking it all the way back to the bolt bosses. I cut those back about 1/8" as well. I will post some pics of the case and inlet as soon as I down load them.
 
You heard me right, the inlet.

Right thread, wrong page. Check out the first pic on the second page of the thread that 90blkbrd found (linked here). That is the type of contouring that I mean. It is done on a late-model case there, but you could take the idea and apply it somewhat to an older case too.

http://www.sccoa.com/forums/showthread.php?t=94951&highlight=port&page=2

The bottom plate may make a pretty significant difference too. I guess there is not much you can do about that in an older case, unless Magnum Powers still has plates like that. Maybe we should ask.
 
Steve,

Ok I see where you are going, but in another post a member presented the possibility of having the rotors still trying to draw in air at the bottom at the same time that the rotors are attempting to force air out through the outlet causing a lack of seaking and messing up the blower. Any thoughts on this?

Frit mentioned the bottom plate issue as well. I am not sure what the issue is. Is it that the v at the bottom is pulled further forward? If that is the case, there is not much that could be changed in that regard.
 
If you look at the floor of the older case, you'll see the rotors are opened all the way to the front, where as the newer cases has that area filled in to keep the rotors sealed . At the inlet you'll see the floor slope up to the rotors.

See the picture of the floor at the center of the newer case style.
 

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Steve,

Ok I see where you are going, but in another post a member presented the possibility of having the rotors still trying to draw in air at the bottom at the same time that the rotors are attempting to force air out through the outlet causing a lack of seaking and messing up the blower. Any thoughts on this?

Yes, you have to be careful how far you go. The rotor lobes are spaced at 120 degrees, so the end of the inlet port and the beginning of the outlet port have to be at least 120 degrees away from each other, plus a little margin of safety. See how far MP3 blowers have reduced that angle from the stock version?
 
It would be nearly impossible to make that modification without epoxying in a extension. Welding would put in too much heat and unlikely that the piece would remain lined up with the rest of the case.

Any body know how much of a difference that makes to the efficiency of the blower? Why did they remove that at the top of the late model blower? Or does it only matter at the bottom?
 
Steve,

So the MP3 has a different angle on the rotors? Or is the positioning of the inlet altered to maintain better separation with a wider opening? I can roughly calculate how far the opening can go using the 120* dimension.

Realistically the opening will not be any larger where it meets the Inlet, it would only increase the time the rotors have to draw the air. Is that what Dave was referring to when he stated the that the early blower is innefficient at filling the case?
 
Steve,

So the MP3 has a different angle on the rotors? Or is the positioning of the inlet altered to maintain better separation with a wider opening? I can roughly calculate how far the opening can go using the 120* dimension.

Realistically the opening will not be any larger where it meets the Inlet, it would only increase the time the rotors have to draw the air. Is that what Dave was referring to when he stated the that the early blower is innefficient at filling the case?

Yes, I believe that is what Dave meant. The later model case has more area open to the rotors in the outside upper corners. The rotors can more easily draw air in at the ends than along their length, which is why that inlet design is more efficient. The MP1/2/3 uses the exact same rotors, but stretches the inlet toward the upper corners, which helps the rotors draw more air in. The 120 degrees is the spacing between rotor lobes, which is the same across all models. You just have to make sure that you don't get the inlet and outlet ports too close together. (You should not be able to get close to that limit without welding and cutting.) Also, I think the MP2 used a plate bolted in to fill the "V"-shaped depression at the bottom of the case so it worked more like a late-model case. I think the reason for it is that if you keep the outside edge of the rotors closely contained, they spin with less turbulence. That may also help to keep a low pressure area between the lobes until they sweep past the inlet port and can suck in more air.
 
Preliminary "smile" for an early oval port. I didn't want to go too far until I can recheck the rotor position again.
 

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