mileage computer for a carbureted engine

[diesel_john]

Originally Posted by Cepheuz

ok so this is another, i had a 86' VW Golf GL, it had the k=jetronic fuel system, it had injectors fed by tubes to a control system that meter the ammount of fue depending on the volume of air, in this system there was a fuel pump that whe called cricket bacuse of it sound, its job was to maintain the presure the low presure injectors needed to work, once it reached this presure it shut off automaticalty

so why not natch one of this, connect it between the fuel line and the carburetor and measure the pulses of electricity when it turns on (it turns off automatiacly when it reaches a presure of 3psi i thing or something like that) and its small one just has to figure out the electrical side that sences current flow and sends a pulse, or just put a diode led and it will turn on every time there is flow and conect that led to the light thing i read about in the begining of the thread (the one with the two holes and the ball)

If its a solenoid type pumps, they turn off and on by a pressure switch. The fuel volume however is not constant for each pressure pulse of the pump. It varies depending on flow, temperature, line flex and a bunch of things I forgot. check what kind of delivery pump it is and how it is controlled. I thought the k-jetronic just bypassed but i haven't played with that system so don't know.
I have started a homemade flow meter but haven't had a time to perfect it. i'll try to get some pics.

[consaka]

The solution is a cheap flowmeter OR a positive displacement pump.
The flowmeter is the best bet and they arent even hard or sohpisticated to design. They had the little plastic ball discussed earlier, in the '70 and early 80's. Those were not very accurate but they did the job. You could also do it with a vane type design or perhaps even a impeller. ideally the design must not impede fuel flow like the ball types did. The ball types used a lightweight plastic ball that went around a little raceway and the fuel came in through a small orifice made out of rubber. This "nozzle" caused the ball to spin around that track like crazy and caused big block engines to run like crap when under any kind of significant load.

Now a positive displacement flowmeter is a bit more tricky since it attempts to seal the fuel as it goes though. Imagine is similar to a oil pump being used backwards as an hydraulic motor only with lightweight poly gears.

The best thing about using some kind of flowmeter is that it can be made to work on ANY vehicle. Carbs, diesels, Old cars, New cars.
Old cars with carbs only need 1 flowmeter. newer cars and diesels will need 2 with a little converter box to subtract return line pulses from the fuel supply pulses. The converter box would run the calculated pulses to the MPGuino. MPGuino already has some very talented programmers who I am positive would have NO trouble whatsoever converting the software to figure the pulses per gallon. The cool part would be that you should only need one number for all vehicles.
Once the design for the flowmeter is made im pretty sure they could be made very cheap over there in China or someplace. After all it only has one moving part or maybe two for a positive displacement unit.

[wagonman76]

Another problem with the ball type is it needs to be held steady and vertical. Won't happen in a car. I agree with the positive displacement type.

I am not familiar much with diesels. But with most cars, you could install a separate pressure regulator and abandon the original. Then you could install the flowmeter between the regulator and engine, hence requiring only one flowmeter and halving your margin of error.

[consaka]

Originally Posted by wagonman76

Another problem with the ball type is it needs to be held steady and vertical. Won't happen in a car. I agree with the positive displacement type.

I am not familiar much with diesels. But with most cars, you could install a separate pressure regulator and abandon the original. Then you could install the flowmeter between the regulator and engine, hence requiring only one flowmeter and halving your margin of error.

Actually my dad has a couple of those old zemco's(I think that was the brand) they could be installed in any position due to the fact that the ball was the same mass as the fuel so it really didnt matter. That ball was going pretty fast in that thing as well so even if it was a bit heavier or lighter it should still work. Wondering if a cork ball would be too light.
Those are a simple design but I dont like the design because of the fact that it adds to much restriction to fuel flow.
A lightweight paddle shape sitting in a horseshoe fuel flow shape would work alot better id think. you just have to have a flat disc with notches cut in it sitting on top of it to get your light impulse.

Diesels use the return flow to the tank to warm the rest of the fuel in the winter and they use fuel from the tank to cool the injector pump somewhat. Theroetically you could bypass the return to the tank and return it before the flowmeter but you better take some temperature readings to make sure the temp doesn't go up too much. Either that or put the return line fuel through a radiator cooler first. Of course that wont help winter time driving so if you live in the northern plain states you might want to put some kind of auxiliary heater in your fuel tank or at least before your filters.

[dcb]

It needs to be accurate at low flow rates.

[consaka]

True, that is why positive displacement is best. But still the ball ones were considered accurate enough in their day, though that was pre hypermilers I am not sure how they would stand up today. If I come up with one or make one, perhaps I shall send it to you for testing
accuracy is something I consider a must, followed by simplicity and robustness. And it should not cause a great drop in pressure. Preferably it can be made at home.
I have spent the last few days on the net looking for such an item and it does not exist. Sure there are tons of flowmeters ranging as high as $4,900 with fairly simple ones costing $1,200. Even Edlebrock carries one for some rediculous price that is over $1000.
The boating business has them as does the aviation business. Both are gold plated as far as our ends are concerned.
However as I see it if we can find this solution then we really will have a mileage computer for every car with an IC engine.
DCB, How many pulses per gallon would we really need? I mean as a minimum? So far my take on it has been the more the better but I would really like a minimum number that would allow instant mpg to work decently.
Consider here the 1 liter engines I guess.

[dcb]

Originally Posted by consaka

DCB, How many pulses per gallon would we really need? I mean as a minimum?

That's a good question. Lets set it a little optimistic and say you want to be able to measure a pulse @ at 0.1gph every 1/2 second. That works out to be 72000 pulses per gallon.

[consaka]

Originally Posted by dcb

That's a good question. Lets set it a little optimistic and say you want to be able to measure a pulse @ at 0.1gph every 1/2 second. That works out to be 72000 pulses per gallon.

thanks DCB. Thats a good starting point for us to shoot for.

[dcb]

Just for reference, there's 90840 drops in a gallon (re: IV bottle)

so if I figured this right, at 0.1 gph (small motorcycle idling) we are using 1.6 drops per second. and 10gph=160 drops per second. and 10gph is good for maybe 242hp. So not an easy range to fill accurately and inexpensively.

[diesel_john]

I started to make a recirculating ball meter out of common plastic pipe and this is the concept using a 0.12gram plastic BB. But it could made as small as needed. Those are 1/4" bolts in the pic. The groove in the inside ring was made by mounting a length of 1/2" water pipe on a 5/8" bolt and chucking the bolt in a drill press. Then used a 6mm round file to make the groove. The various size pipes were cut to 1/4" long and sanded/lapped down to almost 6 mm (the ball size). Fluid would enter through the bottom plate between the outer and second ring. Then through a small port drilled at an angle to propel the ball in the second ring. And exit through the center ring or top plate.