Looking for an article: FI

Baketech · 11-15-2006, 8:09 AM

I'm looking for a technical article that was written a few months ago, not sure of the author, may have been Cameron...maybe not. It was a look at why the FI on bikes has evolved into two injector systems, and offered a good description of runner length vs injector position...

I cannot seem to locate it, so any help finding this article would be appreciated....

phobiaphobe · 11-15-2006, 11:05 AM

Couldn't find the article but looky what popped up in my search:

United States Patent: 6843219

Baketech · 11-15-2006, 4:45 PM

Thanks phobe, that does help...

gt702 · 11-15-2006, 5:12 PM

Quote:

Originally Posted by Baketech

Thanks phobe, that does help...

Bake, are you looking for any specific information?

Why two is as simple as the dynamic range of the motorcycle engine and the limits of current injector technology to deliver the precise metering.

Runner lengths and positioning depend on some other factors, that are a little more difficult to explain.

Baketech · 11-15-2006, 5:28 PM

Fiddling with a "project" right now, and trying to understand some flow numbers we are getting. The article gave a really good explanation of the effects of the injector positioning and how the actual related injector hardware affected flow.

Not surprisingly, the carb setup currently makes more power, even with the FI crap still in the airstream...

Hammer · 11-15-2006, 6:36 PM

Use a leafblower as a supercharger.

Problem fixed, thank me later.

gt702 · 11-15-2006, 6:36 PM

Quote:

Originally Posted by Baketech

Not surprisingly, the carb setup currently makes more power, even with the FI crap still in the airstream...

Not surprising. The real benefit of FI is that you can have it automatically adjust for temperature and altitude. Thus keeping it closer to it's optimal tune. Carbs can be very efficient, and much less complex the FI.

Are you watching the exhaust gasses to know if you are too rich?

Baketech · 11-15-2006, 6:55 PM

Full EGT...

Quote:

Originally Posted by Hammer

Use a leafblower as a supercharger.
Problem fixed, thank me later.

Leafblowers are a "power adder" and not allowed in the class....

gt702 · 11-15-2006, 7:10 PM

Quote:

Originally Posted by Baketech

Full EGT...

Just EGT?

No full Lamda sensor setup?

You're letting me down here

Baketech · 11-15-2006, 7:15 PM

Negativo...

Open loop, just like me...

gt702 · 11-15-2006, 7:24 PM

Quote:

Originally Posted by Baketech

Negativo...

Open loop, just like me...

One for tuning purposes makes a big difference. I know there are some out there for around $500 (lab instrument) that makes tuning so much easier.

Or go to a garage with an exhaust sniffer and play some. Tuning an FI system can be a real tricky thing depending on what you are starting from and what tools you have available. Lots of factors.

What kind of controller?

Baketech · 11-16-2006, 5:05 AM

Must run the OEM computer, with plug in chips only...

Carbs are currently the way to go right now, but I think they are going to get slapped with a weight penalty to encourage the use of FI...

gt702 · 11-16-2006, 9:33 AM

Quote:

Originally Posted by Baketech

Must run the OEM computer, with plug in chips only...

Carbs are currently the way to go right now, but I think they are going to get slapped with a weight penalty to encourage the use of FI...

If you have an OEM computer, then why do you ohave carbs?

I'd recommend the Better Made chips; you can get replacements in better stores everywhere

Baketech · 11-16-2006, 9:49 AM

Trying to make the decision whether to go carbs or FI...

gt702 · 11-16-2006, 10:06 AM

I'm assuming cars ... drag (no not how you dress on the weekends

), oval, or road racing? I'm assuming drag, because that's the kind of guy you are

And what brand?

If so, then it gets easier to make HP because you have limited conditions. Let me know more (PM if you want) and I might be able to help some or get you in touch with someone who can.

luvtolean · 11-16-2006, 11:26 AM

Quote:

Originally Posted by Baketech

Not surprisingly, the carb setup currently makes more power, even with the FI crap still in the airstream...

I really struggle to understand this. Making things even more complicated, the mechanical set-ups seem to be able to beat carbs. (something worth looking into)

I have a couple of books around here I can thumb through for ya....

luvtolean · 11-16-2006, 11:27 AM

BTW, AFAIK it's widely accepted you have to use a wideband O2 to tune these things all the way up...

gt702 · 11-16-2006, 12:21 PM

Quote:

Originally Posted by luvtolean

BTW, AFAIK it's widely accepted you have to use a wideband O2 to tune these things all the way up...

Yep. We used these and they worked pretty good and were reasonably priced. www.etasgroup.com/downloads/am_la4_br_en.pdf

Only reason the carbs work better now is that people understand how to tune them. At WOT (wide open throttle), a good carburetor that is metering fuel correctly should provide the same power as a correctly calibrated FI'd unit. A well tuned FI unit means that you don't have to change the carb settings if temperature or elevation changes. Tuning the FI isn't easy though. Well trained and experienced people take some time to get this right, and always seem to be tweaking it for conditions.

luvtolean · 11-16-2006, 12:29 PM

I think it's had more to do with getting porting figured out, the traditional problem with carbs has been distribution, and the fuel puddling/running down the floor of the port.

In my brain, I cannot imagine a theoretical advantage to a carb, but in application, they have always run well.

Even when it comes to the complexity of FI, and figuring in the skill of the tuner, I'd still think FI should win. Even in OL, you have so much more info with FI to figure out how to tune the thing...DJ setups are able to tune themselves!

luvtolean · 11-16-2006, 12:31 PM

Quote:

Originally Posted by gt702

Yep. We used these and they worked pretty good and were reasonably priced. www.etasgroup.com/downloads/am_la4_br_en.pdf

Those are $500? That's a good buy. Thanks, I have a project that's just about ready to kick off that is gonna need one.

Have you messed with E85?

(Sorry for the 'jack Bake)

Baketech · 11-16-2006, 12:33 PM

Quote:

Originally Posted by luvtolean

I think it's had more to do with getting porting figured out, the traditional problem with carbs has been distribution, and the fuel puddling/running down the floor of the port.

In my brain, I cannot imagine a theoretical advantage to a carb, but in application, they have always run well.

Even when it comes to the complexity of FI, and figuring in the skill of the tuner, I'd still think FI should win. Even in OL, you have so much more info with FI to figure out how to tune the thing...DJ setups are able to tune themselves!

I think there are a lot of drag tuners that make a living because they know why, but I'm having a hard time figuring it out...

That's really the root purpose of my first question...