Landracing Forum
Tech Information => Technical Discussion => Topic started by: oj on January 25, 2017, 09:44:56 AM
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Which system is better? Naturally asperated and running at WOT for a brief time.
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In my limited opinion it is going to be determined by the air delivery system more than how the fuel is delivered.
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OJ;
Running at WOT the two should be equivalent if set up properly. The electronic system gives far better fuel /air accuracy at part-throttle.
Regards, Neil Tucson, AZ
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Generally, I agree with Neil, but here's a thought -
Air density changes constantly on the salt, and it's not unreasonable to expect it to be different 4 miles down track.
Additionally, air speed around your air inlet can have an impact on the air density your intake sees.
What may be "spot on" at the starting line might be a lean condition at speed at WOT at the 4 - or maybe too fat.
An electronic system will monitor and accommodate such changes during the run.
IMO, I'd rather let the computer do the fine tuning real-time.
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How long will the O2 sensors last and what about oxigenated fuel? Can I run alcohol or is that considered 'fuel' and changes the class?
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How long will the O2 sensors last and what about oxigenated fuel? Can I run alcohol or is that considered 'fuel' and changes the class?
My O2 sensors lasted an event on leaded 119 octane. Event gas - 3 grades available, which are the only gasolines allowed at Bonneville - includes an unleaded option. Alcohol is considered "fuel" in LSR at Bonneville.
It varies from year to year as to which gas is available and as to how ERC formulates their products - they're always working on their formulations. Often, it's little more than a change in the suffix letter with minimal changes to the effectiveness.
Can't remember what was available last year - maybe somebody else can answer?
http://www.ercracingfuels.com/sxs1.htm
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How long will the O2 sensors last and what about oxigenated fuel? Can I run alcohol or is that considered 'fuel' and changes the class?
My O2 sensors lasted an event on leaded 119 octane. Event gas - 3 grades available, which are the only gasolines allowed at Bonneville - includes an unleaded option. Alcohol is considered "fuel" in LSR at Bonneville.
It varies from year to year as to which gas is available and as to how ERC formulates their products - they're always working on their formulations. Often, it's little more than a change in the suffix letter with minimal changes to the effectiveness.
Can't remember what was available last year - maybe somebody else can answer?
http://www.ercracingfuels.com/sxs1.htm
Thanks for that, I was wondering.
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How would you like to heat your home, with a coal burning stove or a temperature control on the wall? :-D
Sid.
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It is common practice on bikes to use the O2 sensors only for mapping and to disconnect them and let the mixture trim be adjusted as needed by the environmental sensors.
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Electronically controlled direct injection is opening the door to a whole new world for gas engines. If I had the means that's where I'd be applying them.
Yes Sid, going from my wood stove to a thermostatically controlled wood pellet stove a couple of years ago brightened the light I'm seeing :-D
Ed
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My 2013 street Triumph has a Keihin EFI system. Sometimes I tweak the mapping a little bit in the shop. Then, the engine is turned on and idled for 10 to 20 minutes to get up to operating temperature at closed throttle opening. The EFI takes a reading from the O2 sensor when the engine is fully warm to adjust the fuel trim for closed throttle. Usually this is between 15 and 20 minutes after the engine is started. Then it is time to go riding in order to set the trim at partial throttle opening. Off I go up the freeway to a neighboring town. About ten minutes after I leave the ECU takes an O2 reading and it adapts the part throttle trim. It takes another reading on the way home.
What this says is that if the bike was raced at Bonneville the O2 sensors would not be used by the ECU during the race. We bike guys realize this, and often set the mapping on a dyno using the shop O2 meter stuck up the tailpipe instead of the bike's O2 sensors. Some guys toss the sensors and do not use them at all. In my case, with leaded gas, the jetting is set on the dyno based on torque and horsepower readings. Sometimes we do not use an O2 sensor for the dyno work. This elaborates on a previous post. It is possible to dance around the o2 sensor and its issues. This makes electronic fuel injection more attractive.
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We tune with EGT, each cylinder. If we used an O2 (and don't because of leaded race gas) the O2 is in the collector and would read a combination of 4 cylinders of an 8cyl. But then, we can't change the tuneup as it goes down the track either - well, just a little.
But my experience is drag race and just a few seconds at WOT.
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All of my experience is limited to modifying the keihin street system to something that could be used for LSR. Like said, there are other sensors that the control unit uses to keep track of things. The O2 sensor is used every 10 minutes when at partial throttle so it is a minor player on the triumph. The other sensors do most of the input that is used more of the time and they are not sensitive to lead in the gas.
These comments about how us bike guys deal with the O2 sensor is all I can contribute. I do not know much more about EFI and zip about mechanical injection. In the desert racing world it is not unusual to start out on a freezing cold morning at one elevation and to go through lots of temperature and altitude changes throughout the race. EFI gives a competitive edge 'cause of its ability to adapt to conditions.
Conditions do not change as much at B'ville, although they do. It sorta gets down to personal preference, ability, and how much an extra little bit of power is needed. I am real bad at electronics so the mech system would be a better fit if I had to set it up. The EFI would work better if someone smart set it up and my involvement was minimal. The human factor is important. The most accurate and precise system is no better than a simple one if the folks working with it cannot figure it out.
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Density altitude only changes about 5000 ft through the day.... and depending on how long you are in line it could screw your tune unless you guess well. Oh, unless you are blown alcohol and then you can run a little rich and be ok... We ran an AEM by cylinder data system on Max's Liner (blown alcohol mechanical injection) one year... the data kept telling us it was lean... the drag racer influencing Max's tuning decisions said it was rich... the hole in the piston told us never listen to drag racers at Bonneville....
So an aftermarket EFI, MOTEC, FAST, AEM and a variety of others can tune by cylinder, update on the go to compensate for manifold ram air pressure and make your tune whatever you pick. Leaded fuel will not kill your O2 sensor in several years of racing.... ours has survived 5 years, start with a really good lab grade Bosch sensor... you can limit it's adjustment range should it decide to die suddenly from lead poisoning. You can use EGT and O2 in each cylinder to influence your tuning decisions to ensure you are getting all you can from your motor...
We used to be carb guys, used weather station to pic jets 5 back in line... thrashed to get them in the 4 carbs and driver in on time... Now we use the MOTEC, get our coaching from Dave Dahlgren at Engine Management Systems, he can set you up from start to finish. Appropriately for the Voodoo of EFI, he is located in Mystic CN... :-D
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Tune-ability has been well covered here with EFI getting the vigorous nod. If you are talking HP mech and EFI in the same manifold are going to be pretty close though either have the possibility of changing injector location and there may be some atomization/spray pattern differences that might make a small difference for which dyno testing is the only solution. People also talk about when to inject the fuel- on an open valve, a closed valve, a hot valve half way or any way you can think of with EFI. Part throttle might make some difference. WFO high rpm not so likely as the duty cycle is going to likely be more than the valve open time duration so you become not too much different than MFI.
Many folks will argue whether a carb and EFI can be equivalent or which is better HP wise. Fuel economy and part throttle and driveability and especially emissions aside (who cares about that at Bonneville) with a right tuneup it is going to be a toss up. There are lots of folks who will say a carb will win a HP battle. The problem with those tests (my opinion) is that air flow and manifolding become more important and they cannot be apples to apples comparison. And Stainless mentioned the tune issue with a carb when the DA shifted a bunch while in line trying to get a carb right. And yes holes in pistons and burned valves are a problem if you don't get it right and blame the gasoline off the ERC truck. (have seen that happen). An then there is my crewmember/friend who built a car in Maryland and was tuned here, last minute deal and loaded and left for Bonneville with nary a spare part or jet or plugs and barely a screwdriver in the tool box and set a new record off the trailer with no tuning adjustments. YMMV
With a MFI you need about 3 wires (ok run a mag)- Ign switch and starter button. With EFI fuel and ignition, you will have about 50. You pays your money and takes your choice..... :-) :cheers:
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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
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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
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Well, if you can't fix it with a 3 1/2lb ball peen hammer then its electrical.
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Those Crescent micrometers are easy to use, too! A little hard to calibrate though! :-D :cheers:
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Not if you have the very rare "left handed" ones. :cheers:
Ron
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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. :cry:
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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 :-o :cheers:
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.
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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 :-D :-D :-D}
Ron
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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?
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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 :-o :cheers:
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.
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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
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Also been around dirt track racing for years, it's called a dial a jet or a jet selector.
Sid.
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Yes, Sid, but this is continuously variable and fully automatic. No jet steps selected manually.
Regards, Neil Tucson, AZ
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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.
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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. :-P
Regards, Neil Tucson, AZ
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Seems to me the simpler system is the better. If we are running at WOT mechanical has an advantage, it throws fuel into the cylinder at a predetermined rate. The tuner is the one to figure the rate. Seems simple enough for me, if you burn a piston you know who and what to blame. It'll take an engineering conferance to figure why theres a hole'd piston in a computer controlled engine.
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OJ, been to Bonneville?
One thing you hear is a lot is stumbling... burbling... those usually occur while the motor is trying to get cleared out enough to get to WOT. Is that a tuning problem? I don't really know...
It is not that hard to tell what happened if you burn a piston with EFI... it is the same as MFI.... you failed to provide enough fuel compared to air.....
it is all about selection :cheers:
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No, I haven't been to Bonneville and regret running my mouth, it was a morning post while on my 3rd cup of coffee. I dunno what I'll use, I'm not even ruling out carburetors. It is as much an intake design consideration as the means of getting gas to the intake valve. I think those long nozzles that sprint cars use on mechanical injection have the advantage, but I'm not familiar with all the forms of electronic injectors either.
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Seems to me the simpler system is the better. If we are running at WOT mechanical has an advantage, it throws fuel into the cylinder at a predetermined rate. The tuner is the one to figure the rate. Seems simple enough for me, if you burn a piston you know who and what to blame. It'll take an engineering conferance to figure why theres a hole'd piston in a computer controlled engine.
Our FAST EFI shows the air fuel ratio on laptop from start to finish at all rpms and even corrects 20% rich or lean
Biggest problem is learning the system or knowing someone who does.
We made 2080 hp at rear wheels with mechanical but was unreliable starting. EFI 2350 hp starts right up.
This with centrifugal blower harder to set up than roots type.
Unblown mechanical would be simpler. And their is data recorders and sensors that record air fuel and lots of
other things. But it cost $
JL222
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Airflow Performance mechanical injection is an alternative to EFI and conventional mechanical fuel injection :
http://airflowperformance.com/index.php/store-2-2/
It's a Bendix mechanical fuel injection normally used on aircraft that they modify to allow external mixture adjustment . Similar to a Rochester MFI . Being intended for aircraft it works fine at all throttle positions . I learned about it from Ken Walkey and chose it because ram air pressure doesn't throw it off and it fit in my limited space . You mount on your own manifold .
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John,
I think you have discussed this injection before. Since you have one how about a pic or two?
Rex
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I din't have a digital camera . This is the best shot I have .
http://www.motorsportsinnovations.com/Bvile-pics/bs%20blisters%201-2006%20(4)%20med.jpg
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Airflow Performance mechanical injection is an alternative to EFI and conventional mechanical fuel injection :
http://airflowperformance.com/index.php/store-2-2/
It's a Bendix mechanical fuel injection normally used on aircraft that they modify to allow external mixture adjustment . Similar to a Rochester MFI . Being intended for aircraft it works fine at all throttle positions . I learned about it from Ken Walkey and chose it because ram air pressure doesn't throw it off and it fit in my limited space . You mount on your own manifold .
Interesting but Norton flags the web-page as malicious! :-( Farce-book page is OK! :cheers: