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Actually, the fuel pulse width needed at 1,000rpm is "close enough" to what's needed at 6,000rpm, as you have stated; but only if throttle opening stays the same (at WOT for example).
So this could work if throttle movement is limited to "cruising use" only. Sort of like replacing the 4 stock carbs with a single lawn mower carb, but hey I've done stuff like that!
BobD

yes love the explanation...im an aircraft mechanic but i do have backgrounds in cars and such Macka i do believe i would be creating a lean condition not rich when opening throttle because the engine rpm would not increase because of lack of fuel but the air would increase yeah it was a though im just trying to figure out a cheap way to do this i have a gl1000 engine and a frame coming to put it in but i dont have any carbs that dont need rebuilding lol....i can fabricate anything i need its just well money is an issue here and rebuilding carbs isnt cheap.....i need to search this out more i have a little geo that would have a donor tbi i would just need to figure out how to get it to work lol..... going to try (and big word try if i dont run out of parts and money lol ) to build a custom chopper GW with girder front end, forward controls and such just need a fuel system for the motor lol.......

oh yeah and yes when you gave the explanation it doned on me about the acceleration.. that system would work similiar to a cessna mechanical fuel injection.... all the carb does is meter the amount of fuel going to the injectors based on the amount of air passing through venturi, they do have an accelerator pump put nothing that would work for constant engine speed changes. and since in an airplane you really dont have a whole lot of load changes on the engine it works rather well.

Megasquirt I can do an ok job controlling tbi or batch injection and can trigger off the stock Honda ignition signal. About $400 to get outfitted with a new one though.

fmutters wrote:yes love the explanation...im an aircraft mechanic but i do have backgrounds in cars and such Macka i do believe i would be creating a lean condition not rich when opening throttle because the engine rpm would not increase because of lack of fuel but the air would increase yeah it was a though im just trying to figure out a cheap way to do this i have a gl1000 engine and a frame coming to put it in but i dont have any carbs that dont need rebuilding lol....i can fabricate anything i need its just well money is an issue here and rebuilding carbs isnt cheap.....i need to search this out more i have a little geo that would have a donor tbi i would just need to figure out how to get it to work lol..... going to try (and big word try if i dont run out of parts and money lol ) to build a custom chopper GW with girder front end, forward controls and such just need a fuel system for the motor lol.......

I found this on uwharrie

Its just TBI. Basicly its a glorified carb that continues to pump fuel no matter what direction the vehicle is in.

The computer doesnt have to control the Timing, to fuel inject the vehicle.

You should be able to piece this system together out of most anything, and just run a hall effect distributor to an ignition module.

Ford escort computer(no crank position sensors on most old fords), TBI off of anything, wire in the o2, TP Sensor, and run the leads to the injector. Use a buick adjustable vacuum operated Fuel pressure regulator. Its not exactly brain surgery.

macka wrote:

fmutters wrote:yes love the explanation...im an aircraft mechanic but i do have backgrounds in cars and such Macka i do believe i would be creating a lean condition not rich when opening throttle because the engine rpm would not increase because of lack of fuel but the air would increase yeah it was a though im just trying to figure out a cheap way to do this i have a gl1000 engine and a frame coming to put it in but i dont have any carbs that dont need rebuilding lol....i can fabricate anything i need its just well money is an issue here and rebuilding carbs isnt cheap.....i need to search this out more i have a little geo that would have a donor tbi i would just need to figure out how to get it to work lol..... going to try (and big word try if i dont run out of parts and money lol ) to build a custom chopper GW with girder front end, forward controls and such just need a fuel system for the motor lol.......

I found this on uwharrie

Its just TBI. Basicly its a glorified carb that continues to pump fuel no matter what direction the vehicle is in.

The computer doesnt have to control the Timing, to fuel inject the vehicle.

You should be able to piece this system together out of most anything, and just run a hall effect distributor to an ignition module.

Ford escort computer(no crank position sensors on most old fords), TBI off of anything, wire in the o2, TP Sensor, and run the leads to the injector. Use a buick adjustable vacuum operated Fuel pressure regulator. Its not exactly brain surgery.

Most TBI systems I've worked with use a MAP sensor as well to measure the manifold pressure and gauge load and adjust fuel. But that should be easy enough to add. The injector size is gonna matter a bit as well. A 1bbl TBI off a 1.9L 4cyl is gonna flow a lot less air and fuel than say a 2bbl TBI off a 454 V8 with bigger bore and injectors. With any computer controlled system there are fuel maps to consider too, even on the TBI. 1100cc Vs. a 1900cc fuel map is gonna flood the smaller engine at WOT without a custom fuel map. Me personally I'd use a 2bbl TBI unit off a gm 2.8L, 4.3L V6 or 5.0 & 5.7 (truck) V8 (all the same just higher flowing injectors in the V8s). The unit is 99% self contained, and a dime a dozen. Just mount the map sensor somewhere and run a vaccume line from the manifold to it, add a inline fuel pump and get a chip to be able to tune your own fuel map.

It's worth noting that fuel injection doesn't (and usually isn't) timed to any ignition event. As macka suggests, the fuel per rev is more important than fuel per cylinder fire.

Only direct injection motors truly time the fuel to the intake stroke of the motor. Even sequential, multi-port fuel injection systems operate as batch systems at everything except idle and cruise. There simply isn't enough time in 1/4 of a rotation to get all the fuel in the pot.

-Deek

socrace wrote:Actually, the fuel pulse width needed at 1,000rpm is "close enough" to what's needed at 6,000rpm, as you have stated; but only if throttle opening stays the same (at WOT for example).
So this could work if throttle movement is limited to "cruising use" only. Sort of like replacing the 4 stock carbs with a single lawn mower carb, but hey I've done stuff like that!
BobD

Right. For a car with a lot of drag or when driving up hill, for instance, you would need more fuel to maintain speed. In that case you would normally open the throttle and add air and fuel. In the case of a fixed pulse width setup like we were discussing, that would cause a lean condition.

-Deek

Old75_Ratafe wrote:...With any computer controlled system there are fuel maps to consider too, even on the TBI. 1100cc Vs. a 1900cc fuel map is gonna flood the smaller engine at WOT without a custom fuel map. Me personally I'd use a 2bbl TBI unit off a gm 2.8L, 4.3L V6 or 5.0 & 5.7 (truck) V8 (all the same just higher flowing injectors in the V8s). The unit is 99% self contained, and a dime a dozen. Just mount the map sensor somewhere and run a vaccume line from the manifold to it, add a inline fuel pump and get a chip to be able to tune your own fuel map.

Yes, a customizable fuel map is absolutely necessary. Even if you found a fuel injected motor with 1000cc displacement capable of supplying fuel/air up to 10,000 RPM you're going to be hard pressed to make it run well at idle, accel, decel and cruise.

The 2bbl TBI units are rock solid and the injectors are damn near indestructible. They also operate at a lower fuel pressure than typical port injectors and a relatively "weak" pump would do the trick.

-Deek

One could pair them up, a tbi on each side kind of like the dual carb set ups, then run a microsquirt to map stuff. Unless of course you know someone who can flash Eproms and run a piggy back single controller. The nice thing about the metro is the built IAC.

macka wrote:One could pair them up, a tbi on each side kind of like the dual carb set ups, then run a microsquirt to map stuff. Unless of course you know someone who can flash Eproms and run a piggy back single controller. The nice thing about the metro is the built IAC.

That's just what I was thinking!

I've dinked around with methods for modifying OEM ECU's to make them work on modified engines. It's almost always an exercise in futility for a lot of reasons. The greatest is that OEM ECU's are purpose-built for a very narrow range of functions. They are also typically the bare minimum required to make the engine run.

The older the ECU the worse it is. The early GM ECU's have 4 by 4 fueling maps. That means there are 4 "bins" into which RPM will fall and 4 "bins" into which manifold vacuum levels fall. There is linear interpolation between these points, but you get the point; the engine's condition is constantly changing, accelerating, decelerating, cruising, there are temperature changes, air density changes, etc... and the ECU can only react in one of 16 ways. It's one reason electronic fuel injection was a less efficient design early on; if you error on the side of a slightly rich mixture, the engine can cope better.

Another big problem is that many older ECU's are designed to work with sensors that can't be substituted and you end up cobbling things together to make them fit.

It can be done, of course, and there are many motors out there with bolt-ons and a chip that do very well. What we're suggesting here is not a bolt on, rather a heart transplant and brain re-wire.

I don't want to discourage anyone, but in my experience, when someone goes down this path with a car, they end up at a fully customizable engine management system. Megasquirt, FAST or the Edlebrock thing are all great choices.

-Deek

I talked to a Ford Engineer, and yes the chip is essentially a large "if-then" circuit. The biggest issue isn't what happens in the input, but what the voltage being sent to the inputs for the chip from said sensors. You need compatible sending units, or adapters to send the corrected voltages. If you know your electronics/electrical engineering, its more a matter of sweat equity then spending cash. The advantage of the mega/micro squirt systems are they are easily programable by the average gear head.

macka wrote:One could pair them up, a tbi on each side kind of like the dual carb set ups, then run a microsquirt to map stuff. Unless of course you know someone who can flash Eproms and run a piggy back single controller. The nice thing about the metro is the built IAC.

little overkill don't you think? I mean if one unit can support close to 300hp that should really be more than enough on a wing.

Old75_Ratafe wrote:

macka wrote:One could pair them up, a tbi on each side kind of like the dual carb set ups, then run a microsquirt to map stuff. Unless of course you know someone who can flash Eproms and run a piggy back single controller. The nice thing about the metro is the built IAC.

little overkill don't you think? I mean if one unit can support close to 300hp that should really be more than enough on a wing.

a metro with a stock injector supports max 120 hp. That is up to around 5800 rpm. It falls on its face pretty quick. The dual tbi set up allows for fuelling up to 7800 rpm easily. I also want to get rid of the nasty stock restrictrive airbox, and install an alternator.