Here is the deal. I had a custom one-off port injected blower manifold made. It will only fit this engine/ blower combo.The plan was to run port injection, and use carb bodies on top, for air induction only. Here is where I screwed up, by not doing enough homework before I was this far along. Today I was informed that the B&M 144(Weiand), could not be run dry, as it would gaul the rotors. Anyone have experience with this, or a solution? I know I could run EFI on the top of the blower, but port injection is so much more effecient.
I have been told this for years in regards to roots blowers, but then I saw that Kuhl was making an injection setup like what you are describing, and they said that they never had a problem with it. They said that when the roots blowers are ran on GMC diesels that they are ran dry but I am not sure about that. Of course Kuhl is not in buisiness anymore. I do know that running fuel through the blower will help to seal the blower and will make more boost. Is this going to be EFI or MFI. How are you planning to control the fuel flow during partial throttle? EFI with an O2 sensor? Brian
I have a hard time believing that they can not be run dry. There is not a diesel in the world that has the injection prior to the intake, and they ran super chargers on them for YEARS. Every 4-71, 6-71, and 8-71 you ever saw was run dry for years on a diesel motor!
That's exactly what I thought, and why I didn't look into it further.The question was posed to me by a salt flat racer, concerned it might not work. The plan was to run a Megasquirt ECU, with tps, o2 sensor, map, etc.The tri-power on top was to be used for air induction only. Last night I eaceived this email, saying my blower could be converted, but at a steep price. There has to be a different answer! I'm curious as to exactly what he proposes to do. There is a way to make your B&M work dry, but it is job that takes $1850.00 to do. I made the comment about the Eaton because the other guy had asked if one would work. The Eaton rotor is now what makes the rotor run dry and the rotor wont fit into the B&M case. Sorry if It was misunderstood. Yes, I can make your B&M race ready and run dry. It is a very special deal and I make 2-3 per year for special odd applications, including Propane. The blower gets a special pair of custom made gears as well as many other things including anodizing and special rotor timing
Is it possibly because in an auto application it would be spun a lot faster, making it more difficult to maintain proper rotor clearance?
As I see it your motor would pump 173 cubic inches every revolution at 100% volumetric E. Not unreasonable for a blown motor. Your blower pumps 144 cubic inches of air, minus tip leakage, per revolution. So we go in knowing the blower will need to be overdriven. Now do you want boost? Of course, why else have a blower? So it must spin faster. How fast will the Cad turn? 5000? 5500? how fast did your normal Detorit Desiel turn? Not very. That, I guess, Is where the rotors get into trouble when bolted to a car motor. As I told you, Bill Temple siezed his 6:71 running it dry on a Chrysler drag motor. Blowers I have seen put some fuel in the top.
Its not going to gaul the rotors, namely because they never touch each other. If they do, there are other problems. Diesel applications run at very low pressure, where the sealing of the liquid is not needed. Sealing a dry blower at higher pressures is a lot harder. You'll note that the setup that is used on funny cars and dragsters injects the majority of the fuel above the blower, and the cylinders are tuned with smaller nozzles in the ports. How bad will it leak? I have no idea.
Bills rotors grew enough to gaul with the case, not with each other. That's why they put teflon strips on the rotors now. But they can only take so much.
Rich, You made a believer of me yesterday! I'm looking for a 'fix', so that I don't have to start over with the manifold. Possibly coated rotors, some fuel into the blower as you suggested, maybe water injection? The engine will probably never be over 4000 rpm, except in a race application, then 5000. definately overdriven.
I am sure other people are doing the same thing you want to. I would guess just dump some of the fuel in top.
Its all constant flow mechanical injection. There is typically a check valve that keeps the bottom nozzles from getting fuel until the fuel pressure hits 15 or 20 psi, namely so that they don't inject fuel at idle. The majority of the fuel comes from the top, through 8 or 10 nozzles in the hat, typically all the same size. Nozzles below are tuned by changing nozzle diameters until the proper ammount of fuel is inject into each cylinder. If you wanted to copy the principles of this design with a electronic setup, I think you could do it well by just injecting the majority of the fuel in the top somehow, and tuning with the bottom injectors. Water injection on the top side would likely work well.
Rich, I think you, 4-13 and others, gave me the answer, I just didn't see it at first. I'm still going to try and find a way to run just the port injection, but here is my 'worst case' plan I was going to run a 'faux tri-power on top, for air induction only. I can use the center carb for fuel, and the outer carbs for just air. I will not need a lot of fuel from it, enough to idle, and lubricate/seal during higher rpm's. I can program the ecu to run the injectors after idle, and write the fuel delivered by the carb in as a linear equation. I will not need to make any major changes, just another fuel line, regulator, and extra programming. Thoughts pro or can?
I'm just guessing here. If i knew anyhing about EFI I would have said so. Sounds like it should work. But advice from me is worth just what it costs.
Hey, I thought all was good, until you pointed out my error. So that free advice probably just saved me a ton of money and heartaches! Thanks!
I have thought more about this. I allready said i don't know anything about this, so please keep the flames to a dull glow. It seems to me that running two systems, EFI and carburation, is unnecessarly complex. At idle the blower will be running so slow that I wouldn't think it needs any added tip lubrucation/cooling. In fact it seems to me that you would only need it at high rpm/high boost situtations. I know that Rick Yacoucci and Andy Flagg both welded bungs to there existing EFI runners and added a second set of nozzles to get enough fuel to support the kind of horsepower they were making. Both of them are very sucessful at SCTA meets. I just can't see why you can't do like the Hilborn guys and run a few EFI nozzles into the top. You seem to know something about programing the ECU and I have to believe other people are allready doing the same thing. I say again, check with Mega-Squirt or some other aftermarket EFI supplyer to see if this isn't a simple deal that we just haven't done before.
Rich, I have thought about it also. The carb solution is just my 'worst case' solution, so I do not have to make design changes. I am waiting on an answer from Megasquirt, to see if the system will handle the extra injectors, on a different parameter feed. If the system will handle it, I'll just run two injectors into the base of the carb mount. I am also looking at other ECU's, to see what they are capable of. Megasquirt though, offers a good ECU, and a price far less than the others.
It occurred to me, on the long bike-ride home, that the typical mechanical fuel injection is backwards of what would be best with EFI. At idle the blower really does nothing, with the throttle near closed it doesn't matter how well it is sealed. It would make good sense to just inject all the fuel into the ports at idle. Anywhere between off idle and full power is when you need to seal the blower, which is when you need the fuel at the top. The only hard part I think would be figuring out the transition between the top and bottom systems. I don't see anything wrong with the single carb idea though. I think you'll figure it out.
I'n the end, it seems to me this guys $1800 fix is well worth the head ache that would occur to try and avoid problems with what you really want. I'd save my pennies and do it right.
For about $200, I could add 2 injectors above the blower, and acheive the same results. Granted, it is not exactly as I had imagened it, but it is $1600 difference. Also, think about future repairs. Every time it is time to refurbish the blower, another $1800, verses about $500 for a stock 144. I'm 46, so it is doubtful that this one blower will last me forever. Could happen, though!
Here is the question I posed to Magasquirt. I will post the reply when I receive it. I'm trying to figure out everything here, so I get what I need the first time. The dizzy is an old Nash Twin dizzy, set up to run dual plug wires. What mods do I need to do to it, if any, to have the ECU control timing? The other question has to do with injection control. The blower I'm running cannot be run dry, although this is port style injection. Therefore, I need to have two injectors above the blower, to run fuel through the blower. Can this ecu be set up to run the normal port injection, and the two seperate injectors above the blower? The two injectors could be used at idle, and throughout the range, with the port injectors coming in off of idle. Will this ECU handle this, and what, if anything, extra would be needed?
Holley says the blower will lock up if run dry. Can't give me a good reason though. Megasquirt gave me the answer though. Here is the reply they sent me: You may get the best fuel distribution by putting all the injectors on top the blower, actually, particularly since the flathead's siamese intake ports actually make port injection something of a pain to get working right. But the ECU can run two separate fuel maps, one working a port injector setup under the blower and the other working a set of above the blower injectors. This just needs to be set up in the tuning software. So I'll run the normal port injection, and have it come in after idle. I'll place two injectors in the carb adapter, that will run all the time. No worries! Buddy
I think the probalem be comes one of tolerences and the fact that it is a B&M blower as opposed to a GM blower. The simple solution is to do one of two things: #1 is to run the carbs wet and lean as hell. You still take advantage of your injection you'll have to play with the fuel map a bit but that's electronic injection any way you look at it if its made to perform it doesn't run out of the box. #2 whick is probably a more old school solution is to water spray it. A lot of supercharger guys water spray 'em enyway to keep pre-detonation down (it cools the intake charge). Mix a little top end oil in it and shazaam. Problem solved.
Here is what I'm told must be done, and part of what you get for $1800: The gears have .005-.007 gear backlash between the teeth and allows the rotors to vibrate and harmonic. When this happens, the rotors touch when they get hot and Gaul without gas running through as a lubricant. A new custom gear set will need to be made, to the exact center to center distance between the rotors to give us a net backlash of .0005 Also, the rotor bearings in the front bearing plate are single row and allow the rotors to also move around under load. The bearing plate will be modified to receive a larger and precision angular contact bearing. When doing this bigger bearing, the bearing retainers no longer fit. Custom retainers will be made from Billet Steel to hold the larger bearing in place. The back side hub needs to be different on the gears also, to allow for the thicker bearing. The rotors will get a coating that produces an extremely durable rotor that has twice the hardness of stainless steel. This coating has an extremely long lifespan and can resist abrasion and corrosion. The surface will not chip or peel and it can handle extremely high heat levels without damage to the finish. The rubber seals will be taken out of the blower, and all "Viton" hi temp seals will be added. There is much much more, but I think this should give you an idea of the recipe that works so well.
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