Taking on a pretty big project here, and I have plenty of questions. The overall build is documented here: http://www.jalopyjournal.com/forum/showthread.php?t=601019&showall=1 Here is the short info on the powertrain: - Seagrave 462ci V12 flathead - 6v92 blower, mounted potvin style (originally meant for a 6*92ci=552cubic inch diesel) speed will be similar to the diesel - NV3500 transmission - 2.79 rear end gears - Megasquirt EFI - 6 injectors directly onto the 12 valves (siamesed intake ports) - Planning to run between 4 and 5 psi - In tank pump (need to build a new tank anyway) - One of the original distributors with Megasquirt handling the timing What I'm planing to do: - Run the blower directly off the crank with only some air cleaners on the intake. - Overpressure plate on the exhaust side of the blower - Piping to the throttle body, with a BOV (blow off valve) referenced to the intake - Throttle body (100mm or so, don't have this part yet) - Single log type intake with 6 runners to the block with 6 hidden injectors, 60lbs injectors is what I'm thinking Question, will any of these cause me trouble? - The blower will be dry - Air metering (throttle body) will be behind the blower (similar to most "modern" setups) - Double BOV" one for general over pressure, one referenced to the intake for handling surges when closing the throttle (shifting and slowing down) - injectors right sized? Thanks for any help you can give me.
Interesting project to say the least. Couple of comments. The 6v92 blower originally ran dry anyways (no fuel, diesels are direct injection). What it ran for oiling, I am not sure. Remember, those old Detroits were 2 strokes, so they used twice as much air at a given rpm as a similar sized 4 stroke. Do you need to rely on the throttle body for air metering? Can you accomplish the same thing with your fuel / timing maps running off a MAP (manifold air pressure) sensor and throttle position sensor? In other words, eliminate the mass air flow sensor all together. I have done it successfully on a turbo charged 500 cc 4 banger, with an open loop system. Although, I am sure you will be running a closed loop system with O2 sensors. I am concerned with only using 6 injectors. Injectors for 4 valve heads normally have a dual spray cone so each valve gets a uniform charge of fuel. If I understand your system correctly, you are going to spray one cylinder when it is on the intake stroke, but the adjacent cylinder will be closed. I would be concerned about fuel pooling on the valve, and then creating a weird (for lack of a better term) intake charge that includes the fuel pool and the spray volume, possibly causing some strange burn characteristics, plug fouling, etc. To me it seems like it would almost act like an enriching jet, but I am not sure that would be a good thing. Good Luck and keep us posted.
I am with FrozenMerc about the injector issue- Factory siamesed ports draw from a plenum of fuel/air mixture that is already emulsified. Contrary to popular belief, injectors give off pretty big droplets that dont emulsify as well as a carb- this is why a crisply tuned carb can create more power than a typical injector- (when really tuned right). I'm not saying it cant be done- but you'd have to confer with the modern efi builders to determine if your idea will act like a typical "batch-fire" setup.- if so then you're good to go, if not then another tactic will be needed. maybe you'll need to move the injectors father away from the dividing wall to that their spray/air will be drawn in- or maybe double up the injectors and lengthen the divider wall to un-siamese them... -rick.
First, thanks for the great feedback. Yes, the car will not have a mass air flow sensor. TPS, Manifold pressure, O2, engine temp and intake air temp are all the inputs needed to run the EFI. It will be batch fire, that's for sure. I could do both: - Put the injectors further away, maybe even in the plenum? or just way up high in the risers. - Double up the injectors and fire each of them in a batch.. 6 in one batch, 6 in another. Two in each intake port pointed at one of the valves. I'll check tomorrow if I can make separate intake runners, should be possible by splitting a tube down the middle.
I put my nozzles way high away from the valves. Salt cat (Buick straight eight) runs two nozzles in each port, I think. His system works very well. maybe better than anything else I have seen. I would inquire there for good, hands on info. Beats guessing after reading about EFI in HRM. Usually car blowers run a lot faster than Detroits. And Detroits don't make any boost. A Segrave isn't going to spin any faster than a 6:92 I guess. And I don't think at crank speed you will build boost either. If you don't have any thrust on the rotors,maybe you don't need fuel for cooling. Still what's the harm in putting some in the top? What might happen if you don't? Risk verses Reward. Make your choice.
RichFox, I think it will create some boost.. While it is true that the Seagrave only spins slightly faster than the 6v92 diesel there are some differences. The Seagrave is a 4 stroke, only needed half the air load of a 2 stroke, the Seagrave is 462ci, compared to the 552ci of the 6v92. The Seagrave volume per rotation is only 42% that of the 6v92, that is a considerable amount excess air to build some boost. Been doing some pretty extensive research on fuel injection intakes, the important design aspect seems to be to inject the fuel into a moving airstream, one way to achieve this with my planned setup is to use 6 injectors in a radial configuration behind the throttle body in the plenum running in a sequential setup firing once every 2 cylinder fires, this should keep the fuel/air mixture in constant movement limiting droplets from forming. Also figured out I should be able to run lost spark ignition using 2 EDIS6 setups on one signal wheel and 4 six cyllinder coil packs, firing all 24 spark plugs with the timing controlled by the computer. Will have to hide the coilpacks (ugly) but that should give me a pretty strong and even burn.
I went thru this with my Siamesed intake 250 six. Answer is to use 1 injector per port, as far away as possible from the valves. Otherwise you get charge-robbing. I batch fire mine, so it acts like a throttle-body unit, with the response of ported.
Do you have any pictures of your setup? interested to see how you solved the distance question. Thanks,
Here is how I made a manifold for a Buick. Nozzles are just below the throttle bodies. I don't understand why you are blowing through the throttle body and constantly working the pop off. Very rare for you to be at WOT so it follows it would be rare to produce boost, with the intake throttled.
RichFox, my blower will be out front of the radiator right below the grille, not much space for throttle bodies and air cleaners, plus at least 5 ft of 4" tube away from the intake, not the right setup for throttle response. It would get even worse if I do my injection before the blower, the gas will have to move up into the intake, can pool in the sideways mounted blower and has plenty of time to condensate. Compressed air with fuel mounted on the front of the car sounds like a recipe for a pipe bomb, bad performance and safety.
I see. I thought you were going to do a Chuck Potvin type of set up. But you are doing your own deal on a front mounted blower. What ever works, works. Here is a picture of one I made for a Plymouth flathead four. Didn't look like it would work but it sure did. Kind of ugly though. At any rate, moving the nozzles away from the valve seems to be a good idea.
That is very similar to what I have in mind. Setup will be similar to the Chuck Potvin idea, but he didn't make many bolt on items for the V12 seagrave, he seemed to be stuck on hemi and sbc. One of the big issues with the earlier potvin installs was the long runner and thus huge load of unburned fuel/air under pressure, caused a few nice explosions on backfires. That's the reason many ended up putting the injectors in the intake, but they did run the throttle bodies on the blower in the front.
I like the blower setup. I am somewhat familiar with the Segrave engine a friend has a few of these and 2 1936 V12 Pierce Arrows. I am building a 29 Ford pickup with a Ford flathead V8 and a 6V53 front drive blower.
The big update is that I'm moving to another continent and will be selling this (and some other) projects and cars.
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