First of all there are two distinctly different types of EFI, Programmed fuel injection, and mass air fuel injection.

The first one, PGMFI, has a preset program that will only compensate very little for variations in altitude or air density. The other type, mass air, is much more effective and responsive to atmospheric changes and therefore modifications such as pipes and free breathing intakes.

The difference is that instead of preprogrammed values and 6 different sensors that make up PGMFI the mass air system uses only two sensors . It's principle works on a "hot wire". The more air that flows past the wire the more it cools off hence the more fuel that is injected by the computer. This is exactly what makes it more able to adapt to changes in air flow.

I used to own a 86 mustang that came with PGMFI and after adding tens of thousands of dollars engine mods was very disappointed in my gains, until I swapped out for a mass air system. That took me from mid 13 second 1/4 mile runs down to mid 11 second runs.

Problem is that most manufacturers seem to prefer PGMFI so that is more than likely what you will see on most EFI quads. I would prefer to stick with a carb.

 

[quote]
Originally posted by: Coyotechaser
curmudgeon- An ill-tempered person full of resentment and stubborn notions.

Thank you for clearing that up for us.[img]i/expressions/face-icon-small-happy.gif[/img]

 

I saw on a PDF from Suzuki that states that the King Quad is a speed density system. That is the type of system that uses a manifold air presure sensor to calculate the air that the engine ingests and squirts in gas accordingly. This system is not capable of accommodating engine changes without either being modified or reprogrammed. The reason we care about what suzuki did, is probably because that is probably what Polaris did and it is probably what Kawi will do (reasons in next paragraph).

Most cars made since the mid 90s are MASS FLOW, which uses an air flow sensor primarily to measure air flow. This system can accomodate changes to a certain extent. I don't think we are ever going to see Mass flow EFI in a quad since the sensors are too delicate.

So, if you mod the and engine with a speed density system, you will either need a new ECU, or some other electronic gadget to help accomodate the engine mod. Engine mods are going to be a lot less common and probably more expensive on those efi models.

BTW, there are only 2 common types of EFI (mass flow and speed density). PGMFI is a proprietary name used by honda, it stands for "programmed fuel injection". I couldn't tell if it is Mass Flow or Speed Density by searching the web, but it doesn't matter since it is just a honda term.

 

NYROC... I agree... the EFI ( non mass air flow sensored ), will be great for average users, & people who very frequently change altitudes, while riding... & likely the sensitive sensors, & cost, will keep us from an easily modified EFI system ... several years down the road, it will be easy to hop up these EFI systems, but for the 1st few years, it may be very difficult, & there will likely be people who will make the mistake of trying to do typical mods to their new EFI quads, only to find out that they have actually hurt performance...

is anyone familiar with Cannondales system??? it was my understanding, that alot of these were build for competition, so they must have had a system that was more easily modified, for competition, & would still have to be reliable with the abuse that comes with competition...

 

That is one thing I really like about the B-force, it still has carbs. I have had ZERO problems modding my carbs (and also zero carb problems).

I don't know about the C-dale. But, from all the performance bikes out there, I honestly believe that there is something we can stick on our machines other than the electromotive or haltech units. We aren't the only 90* V out there. Alltoys found some ignition stuff, but I bet there is more EFI stuff out there.

That speed density system is 100% cool if you can program it whenever your machine changes.
Now that I am employed, I wouldn't mind paying a few bux for a programmable system. I bought an electromotive system a few years back, and was able to dial it in much more easily than any carb. Plus I could tweak everything exactly like I wanted it. It had more goodies than we need, and was about as big as a shoe inclusing the direct fire modules it had on top (a bit large for an atv).

 

Nyroc, has the ritht idea. There are little goodies out there for EFI machines where the injectors can be adjusted and oxygen sensors to be changed to allow for performance gains. Sleders have had them since EFI came out on sleds. It is cheaper to improve performance on an EFI machine than a naturaly asperated motor. I had a programable EFI on my latter machine the performance and reliability was 10 times better than the old OEM system. Couple this with a better igntion and look out. EFI is here to stay I can't believe Kawi didn't do it on their 750, truly disappointing!!

 

"It is cheaper to improve performance on an EFI machine than a naturaly asperated motor. "
???
Wow, I didn't know EFI included a pressure adding device like a blower, turbo or nitrous. Now I understand why people want it. [img]i/expressions/face-icon-small-wink.gif[/img]

 

Supermotard,

I like that although EFI will help with a better fuel mix at all rpms where as carburetors are always working on the last stroke of the motor.

 

Regardless of any theoretical benefits of EFI, the real reason you'll see it on ATVs is because it will be mandated by the government as a way to reduce emissions. This will eventually evolve into "tamper resistant" systems that will attempt to keep you from making changes to fuel delivery. Then, anyone who wants to change the mixutre will have to use expensive and/ or semi-illegal devices to attempt to do something that used to easy to do with a screwdriver, a jet and a shim or two. What amuses me is that all of this nonsense is being marketed to us as a performance enhancement despite the likelyhood that it will evolve into systems that discourage peformance enahcements. Don't believe that the EPA has any goal other than to create as lean of a mixutre as possible, and to eventually make it difficult and expensive for you to change that. EFI will be designed to acomplish the goals of the EPA, not yours.

 

All we need to mod EFI is more smarts. Some people on this forum are just about smart enough to design their own EFI.
Also, there are other machines out there that we could take parts from to do the trick.