Fuel Injection, mech vs electronic

[rouse]

What I have found is that the leaded gas doesn't make any difference in the O2 sensors, you don't make enough runs or put enough time on them to hurt.

I change mine out after going racing three or four times, Not because they're not working, but just to make sure. Never had one go out because of leaded fuel.

Additionally, I have heard that running a lead fouled O2 sensor in a B&S on methanol for a couple hrs. will renew the sensor.

Rouse

[Rex Schimmer]

One of these days (the starting phrase for subsequent BS to follow) I am going to try a Hilborn/Kinsler direct injection system and use an electronically proportional pressure relief valve along with a high performance electric fuel pump and see if I could come up with a  somewhat crude electronically controlled constant flow injection. As jacksoni said, once the engine is at high rpm (which is where the hp is anyhow) an EFI system is almost the same as a constant flow system. When you change the main jet or the high speed jet on a constant flow system all you are doing is changing the system pressure that is being supplied to the nozzles. More pressure= more fuel to the engine. With an electronically controlled proportional pressure control valve a O2 sensor and some dyno time I would think it would be fairly straight forward to graph a fuel pressure vs rpm vs air fuel ratio (lambda) that would be pretty good in the higher rpm and hp ranges. Not something I would use for a street car as I would think that at low rpm it would be difficult to make the the system work well at the low pressures that may be required, but I am only thinking about racing applications. . Obviously all kinds of electronics can be added to automatically compensate for air temp, altitude, engine temp etc but then you just as well have started with an electronic system anyway! I am only thinking of something for guys, like me, whose favorite tools and a 14 inch crescent wrench and a 3-1/2 lb ball peen hammer!, that can understand and it would give you adjustability without having to be changing return jets, bypass springs etc.

Now it only requires some time (being retires helps in that area) and some cash (being retired doesn't help in that area!).

Rex

[oj]

Well, if you can't fix it with a 3 1/2lb ball peen hammer then its electrical.

[WOODY@DDLLC]

Those Crescent micrometers are easy to use, too! A little hard to calibrate though!  

[Ron Gibson]

Not if you have the very rare "left handed" ones.

Ron

[Seldom Seen Slim]

And then there's the not-so-rare style, of which I've got more than a few examples.  Those are the ones that were used at Bonneville for measuring a certain item - perhaps well-seasoned suspension bolts on the push truck - and then got tossed into the bed of such truck and left for a few months.

From then on the device is permanently set to the correct size no matter how much WD40 you throw at it.

And thus ends a tidbit of wisdom that each and every one that races at the salt has learned.

[Stainless1]

My hammer preference has always been the 1 pound hammer.... don't mistake the 1 lb hammer for the 1 pound hammer...
the 1 pound hammer is large enough that it only takes 1 pound   

Back to our injection discussion....
I failed to mention that our motor choices have all been south of 100 ci... my thought is they are harder to adapt to mechanical injection.... although I think  Rex now has a mechanical injection 1 liter.... can't wait to see how they did that.

[Ron Gibson]

Slim
There is little thing on top of the WD40 can where you can spray some on whatever you want. I can't se how it would do any good to throw it unless throwing it punctures the can and it sprays. Or you hit it with Stainless's 1 pound hammer. (Literal interpretation of words  }

Ron

[Seldom Seen Slim]

Good try, Ron, but I was using the archaic Old Norse/Swahili interpretation of the word "throw" to mean "apply liberally and without regards to life, limb, or liberty."  Now you get it?

[kiwi belly tank]

My hammer preference has always been the 1 pound hammer.... don't mistake the 1 lb hammer for the 1 pound hammer...
the 1 pound hammer is large enough that it only takes 1 pound   

Back to our injection discussion....
I failed to mention that our motor choices have all been south of 100 ci... my thought is they are harder to adapt to mechanical injection.... although I think  Rex now has a mechanical injection 1 liter.... can't wait to see how they did that.

Mini Sprints have been using mechanical alky injection on the bullet bike engines for years now.
  Sid.

[manta22]

One of these days (the starting phrase for subsequent BS to follow) I am going to try a Hilborn/Kinsler direct injection system and use an electronically proportional pressure relief valve along with a high performance electric fuel pump and see if I could come up with a  somewhat crude electronically controlled constant flow injection. As jacksoni said, once the engine is at high rpm (which is where the hp is anyhow) an EFI system is almost the same as a constant flow system. When you change the main jet or the high speed jet on a constant flow system all you are doing is changing the system pressure that is being supplied to the nozzles. More pressure= more fuel to the engine. With an electronically controlled proportional pressure control valve a O2 sensor and some dyno time I would think it would be fairly straight forward to graph a fuel pressure vs rpm vs air fuel ratio (lambda) that would be pretty good in the higher rpm and hp ranges. Not something I would use for a street car as I would think that at low rpm it would be difficult to make the the system work well at the low pressures that may be required, but I am only thinking about racing applications. . Obviously all kinds of electronics can be added to automatically compensate for air temp, altitude, engine temp etc but then you just as well have started with an electronic system anyway! I am only thinking of something for guys, like me, whose favorite tools and a 14 inch crescent wrench and a 3-1/2 lb ball peen hammer!, that can understand and it would give you adjustability without having to be changing return jets, bypass springs etc.

Now it only requires some time (being retires helps in that area) and some cash (being retired doesn't help in that area!).

Rex

Rex, some time ago I had an idea for controlling a MFI system that is similar to yours. My idea was to control the air/fuel mixture by adjusting the fuel bypass flow. Normally the fuel flow is controlled through the spool by the throttle position and through the bypass valve (pill). By controlling the bypass valve, the fuel flow can be made leaner or richer as needed. An EFI oxygen sensor in the exhaust could control the coil of a servo valve that acts as a bypass valve. A feedback system would allow the air/fuel ratio to be controlled over the whole RPM & throttle position. Adjusting the throttle mixture would be as simple as turning a knob on the dash panel. It would be an MFI system with an infinitely variable pill. I think it would work.

Regards, Neil  Tucson, AZ

[kiwi belly tank]

Also been around dirt track racing for years, it's called a dial a jet or a jet selector.
  Sid.

[manta22]

Yes, Sid, but this is continuously variable and fully automatic. No jet steps selected manually.

Regards, Neil  Tucson, AZ

[RichFox]

I think the bypass on Hilborn injection for turbocharged cars is a diaphragm boost controlled valve. I guess also continuously variable and fully automatic. Don't know how that applies to your idea.

[manta22]

I think the bypass on Hilborn injection for turbocharged cars is a diaphragm boost controlled valve. I guess also continuously variable and fully automatic. Don't know how that applies to your idea.

Rich;

The boost-controlled diaphragm valve that you mentioned is a variable bypass pill that is controlled by boost pressure (the opening vs pressure curve is determined by its internal spring). It is in parallel with other fixed bypass pills and/or ones that are controlled by pressure such as a "high-speed" bypass.

Controlling the bypass flow by the output from an oxygen sensor would let the MFI self-optimize its A/F ratio to whatever the driver wants it to be.

I've been advised that there is a system out there already that uses this idea but he uses a stepper motor to control a rotary valve in the bypass. The drawback to this approach is that the motor/valve has much slower response time than a servo or proportional valve. I should have worked on this idea long ago. 

Regards, Neil  Tucson, AZ