Fuel Injection????

MaxSpeed

New member
What issues will it solve exactly? Fuel efficiency is not an issue. Cold starting is not an issue is it? It does not yield more torque than a carb as far as I know. Not putting you down just trying to understand your reasoning.
 

Kart43

Active member
If the ECU is tunable it would be a major improvement, these carbs do lack fuel efficiency accross the RPM range they are raced.
 

MaxSpeed

New member
I certainly do agree that the carbs are far from fuel efficient across the rev range, but frankly, so what? The difference is a non issue in terms of costs. I concur that fuel injection makes better use of the fuel and will also give lower emissions but again so what? If there is some performance improvement on normally aspirated motors in either torque or hp I am interested. For me the $500 is what I will be paying for the carb upgrade locally so the injection would be equally attractive in terms of cost. My understanding is that injection is valuable once you add forced induction from a performance point of view and not really any difference on normal aspiration. Am I wrong?
 

Kart43

Active member
Properly tuned(programmed) fuel injection will improve performance on normally aspirated engines, it will be more responsive, more predictable, and more reliable.
 

makoman1860

New member
Properly tuned(programmed) fuel injection will improve performance on normally aspirated engines, it will be more responsive, more predictable, and more reliable.
Beg to differ on that. A properly designed and set up carb is as reliable if not more than electronic fuel injection, offers no power loss and in fact can be more predictable. A good carb meters fuel based on mass air flow, the cheap EFI kits fudge that. The reason that EFI is the mainstay for automotive is simply cost. Its cheaper to make the EFI components than a precision carb, and simpler to tune as it takes no understanding of fluid dynamics.
 

Wes Snow

New member
A carb will make more hp N/A. Ask the NHRA pro stockers that are being forced to switch over to efi now, they are reporting losses from 55-70 hp. Good efi is very exspensive. It offers ease of fuel curve changes but everything else such as programmable ignition timing is offered for carbureted motors as well. Now if you go efi so you can run a traction control system you may be getting some where. I looked into this but the costs were really high for the amount of accuracy for the system.
 

MaxSpeed

New member
makoman I imagine that in a multi cylinder application modern fuel injection systems can offer performance benefits over a carburettor although as I stated earlier in real world applications particularly in the early generations of fuel injection systems even on automotive applications carburettors gave more power and torque. I suppose it comes down to how well designed the carb and injection system are designed. kart43 if fuel injection was superior across the board I would expect to find all high performance bike engines to be fuel injected yet they are not.
 

Kart43

Active member
Many newer sport bikes are EFI, almost all Ducati, Suzuki, etc. etc. heck even HD, Kawasaki is equipping most of their dual purpose KX line. Properly programmed fuel injection will show benefits across the entire RPM range, carburetors cannot react to environment, input, and other parameters as quickly. A dragster operates very differently to most racing engines. Yes you can tune a carburetor to be efficient at WOT.
 

Oman

Member
Skip the injection, keep the carb but run computer timing system, you might see some benefit from a decent timing map.
 

PD Power

New member
Many newer sport bikes are EFI, almost all Ducati, Suzuki, etc. etc. heck even HD, Kawasaki is equipping most of their dual purpose KX line. Properly programmed fuel injection will show benefits across the entire RPM range, carburetors cannot react to environment, input, and other parameters as quickly. A dragster operates very differently to most racing engines. Yes you can tune a carburetor to be efficient at WOT.
Karting is done at WOT as much as possible. One advantage of a well set up kart is that it permits the driver to run more at WOT.
I'll prefer a carb kart at WOT, well set up, to an injected kart, attempting to make up time with a fuel injection system.
If both the carb kart, and injected kart run close to WOT then there is no advantage to the fuel injection.
On a tight road course, there IS an advantage to fuel injection.....however small. FI is not some sort of silver bullet.
 

alvin l nunley

New member
I can't remember ever racing a kart at part throttle. WOT was always the case. Still, that doesn't mean the engine was always at the same rpm. In Sprint racing the KT runs an average 10,000 to 15,000 RPM. I can guarantee you the fuel requirements are not the same across that whole rpm range. Especially with a pipe. A carburetor, like the ones used on the KT, has no chance of keeping up with a 2 cycles fuel mixture requirements. There's always a compromise. I'm pretty sure the same would be found on 4 cycles.

Fuel injection today, with its computerized delivery system, is far superior to a carburetor. Today's modern fuel injection system can even adapt itself to your style of driving. AI, (artificial intelligence) systems are quite remarkable.
 

MaxSpeed

New member
Interesting how when fuel injection is promoted as a feature makes no mention of more power. I believe that the variable ignition timing will yield more bang for the buck. Goingbroke you are so right a lot of money to try make a silk purse from a sows ear. However since these are what we are stuck with in the class rules ......
 

Kart43

Active member
If you look at my posts, I always say properly programmed, of course you can make more power when you can tailor the A/F ratio at all RPM and situations. With the carbs on these engines we have to compensate on the low side with massive pilot jets that flood the engine at idle and low RPM then there is poor transition the WOT. Fuel injection can be tailored to RPM, engine temp, exhaust parameters, throttle position, air flow, atmospheric conditions, ignition timing, etc. etc.

"Warren Johnson: Properly tuned, carburetors make more peak power than EFI in a Pro Stock engine. A carb's pressure differential atomizes the gas a lot better than spraying fuel through an orifice. But EFI has a broader powerband and superior cylinder-to-cylinder fuel distribution. The 1,100- to 1,300-cfm dual carbs are good only over a narrow range, about 1,500 rpm at most. EFI performs well over 2,000 rpm or more. On average, if optimized, both systems perform about the same as far as how fast you get down the track. However, the EFI system is much easier to tune than a carburetor."
 

Oman

Member
F1 also have access to facilities and engineering personnel and $$$$$$$$$$$$$ to develop their systems. The injection system allows more precise metering of the fuel, but without sophisticated equipment to optimize that metering you're ****ing in the wind.
 
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