Mechanical / Electronic Fuel Injection

[power58]

I was showing the pictures I had taken at speed week to a friend, and he asked why you had to run mechanical fuel injection.  My only thought was to keep cost down and to revive the old days.  What are the reasons and guidelines as far as injection goes ?   

[Jonny Hotnuts]

If I can remember you can only run mechanical FI in the vintage classes. Electrical FI means you will have to have some sort of electrical control circuitry and was not available to the motors that the cars had been originally equipped. Electrical control systems are prohibited as well unless used for engine monitoring....so even the controls to run electric FI in those classes would not be legal.

Electric FI is legal in everything else I think.

I have it on my busa motor.

[JackD]

Mechanical fuel injection is not limited to the vintage or classic classes.

[landracing]

If I can remember you can only run mechanical FI in the vintage classes. 

Electric FI is legal in everything else I think.

I have it on my busa motor.

You mean to tell me that Burkland's 450 mph streamliner, and Nish's 400+ potential streamliner who both run mechanical FI have to run in vintage classes?

think again..

Jon

[landracing]

Here is a picture of Nish's Mechanical FI.

http://www.landracing.com/gallery/displayimage.php?album=107&pos=21

How about the true answer to the first question in the first post is simplicity.

Jon

[1212FBGS]

well jon, wasn't it simple for you to get on the phone and find a replacement haltec efi box when yours melted?  oh, oh and wasn't it simple for you to find a replacement for your replacement that disappeared? oh the good old days of mechanical thingy's... i'm still trying to get my bullshit efi boxes sorted out... oh, oh i also remember being in the big crowd of people watching you and Randy chasing an EFI problem on the Ack liner down to a simple pin connector... yep the thoughts of just getting into a laptop and tuning your racer just ain't that simple...
kent

[landracing]

Kent,

You need to re-read the posts.

The posts asked why were they running Mechanical FI - NOT Electronic FI.

And I said that they run Mechanical FI for simplicity...

Electronic sounds easy in theory, however it's far from it.

[JackD]

You guys both need to spend some time at Hilborn's knee.
I can arrange an introduction for you.

[power58]

Seems to be a little of both simplicity and vintage class. Never played with mechanical injection but I can see it takes a great deal of skill selecting the right pill and setting the barrel valve. Have worked with electronic injection and it is a hand full for sure. Thanks for the Nish
injection photos. What are the ports about half way up above the injectors on the  Nish set up ?  From what Ive seen its about the same money for either system, but I think it would be  lot easier to sort out a mechanical system.       

[836dstr]

There is nothing like the seat of the pants thrill when after push-off and the Mechanical FI cleans out and off you go (actually the engine cleaning out).

Nothing about fuel or ignition systems is "SIMPLE".

[panic]

40 years ago the Ramchargers added another bypass to permit a car with limited stall to idle and stage without killing the plugs. I would guess that it covered the throttle position needed to clean up to fast idle in gear, then drop out as the throttle opened to shock the converter for launch?
IMHO most purely mechanical systems could be made more "drive-able" with more bypass valves, keyed to throttle disc angle, manifold vacuum, even gear selection (like the extra one closes on the shift into high gear?).
Could be solenoid valve (viz. digital on/off with signal), ball valve with short throw (on/off) or long throw (analog and variable with position).
What's nice about this is that unless activated they don't affect flow or pressure through the main pill and nozzles (although obviously any more bypass area will drop system pressure).

[panic]

Afterthought: easy, 1-step bodge to make throttle response slow and careful off idle, but speed up to go to WOT with multi-piece linkage.

The link to the throttle arm is a "bracelet" or bicycle chain section, but doesn't need sprockets. It anchors on the OD of a snail cam (axle adjuster, etc.), which is rotated by the throttle pedal.
At idle, the chain sits on the base circle of the cam. As the cam rotates away, the "lobe" moves up pulling the chain towards the cam, and increases chain movement by 50%, 100%, 500%, whatever you want; it's the proportion between the lobe and the base circle. Needs a light return spring on the throttle arm to keep the chain under light tension.

[JackD]

You can vary the operating rate with just the linkage between the slide/butterfly and the barrel valve easy.

[panic]

Not to the same degree. You can make the throttle disc angle motion per .001" of linkage travel 1% or 1,000%.

[SteveD]

Sorry guys I'm a newbiw to the forum not motorsports.  I would go with EFI any day!  You can data log and change what injectors doing what, cause they aren't always they same even when you buy a matched set of injectors.  We reset our old record in WF this year with a factory computer C/PS9382.  If I had 10 laptop battery with me I could have paid for my trip up there,  bunch of cars needed help w/o tuners.  You would not believe how many guys wanted me to try tuning they're cars and others that went back to carb cause they could never make it work.  I know the tune from Houston Texas is way different up at the flats.  The new car we are working on for next year will be ran with a Fast XFI set up for sequential and also an EGT for each side of the motor.  We will continue checking plugs the old fashion way between runs.  If your class requires mechanical fuel injection your stuck but the if EFI is allowed you can't get any better.  Just my 2 cents.

Steve Drier
From Houston TX