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Re: [turbobike] carburation vs fuel injection

Lorcan Parnell (lorcan@globalnet.co.uk)
Mon, 19 Apr 1999 00:06:28 +0100

Christer,

I don't mean to say that carbs don't work well - they work perfectly well in
most circumstances. But I don't believe they can equal an EFI system on
anything but cost.

>Yes a state of the art EFI will be ahead when it comes to
>managment and to be in control, but do You need it ?

If it gives me an advantage, then yes.

>When it comes to emissions and saving fuel ,EFI is definatly ahead,
>but then again is that something that interests this crowd?

Probably not, but it's a bonus.

>An EFI is able to operate much closer to being to lean then carbs are.
>How come that bikes that are much more power oriented than cars
>doesent use carbs to the same extent as the everyday cars?

I don't understand your point, even my van has EFI.

>The guys who orginally built My turbo system have built many turbo
>bikes but has stopped making efi versions simply because the carb
>versions runs just as well and the efi just adds to the costs.

Yes, it is more expensive, but speed costs - how fast do you want to go?

>What was wrong about My point regarding flow through the plenum?
EFI systems can run on MAP (manifold absolute pressure) sensors alone.
Combine with an array of other sensors (air temp, engine temp, lambda,
throttle position etc) they are extremely sensitive. Some systems can
compensate for individual cylinders (for different flow, temperature etc)
and can respond in one cycle - faster than a slide can lift.

>When comparing proīs and conīs between efi and carbs at least I have
>the costs in the back of the head, maybe You donīt?
Oh I do. My ECU was Ģ650 including a datalogger and software, my injectors
were $15 each, used. The costs will come down as more people use it.

>Why should I spend thousands of $ on something that gives no additional
>hp or increases drivability, and adds complexity?
You don't *have* to....yet.

>What kind of bike do You have that needs 16 injectors?
A bike that was built to run 60lb boost on alcohol. It's a long story!

Cheers

Lorcan




Lorcan Parnell skrev:

> Christer,
>
> I have to disagree. It is not possible to match the performance of EFI
with
> carbs. If it was, the F1 teams would use carbs. Indycars would use carbs.
> They don't.  EFI will always be ahead and as technology improves more so.
> Your point about the variations in flow is simply wrong. Yes, you need 8
> injectors, possibly more (my bike has 16). Bikes of the future will all
use
> EFI. The only reasons to use carburettors is because they are cheap, or
> because the rules (like in Pro Stock) don't allow EFI.
>
> Regards
>
> Lorcan
>
> -----Original Message-----
> From: Christer Johansson <christer.johansson@mbox383.swipnet.se>
> To: turbobike@natvideo.com <turbobike@natvideo.com>
> Date: 18 April 1999 16:52
> Subject: Re: [turbobike] carburation vs fuel injection
>
> I thought of going to EFI ,but I saw no reason to do it.
> Efi does have some advantages in that you can map the fuel
> and ignition curves more precisly. But itīs possible with carbs
> and a adjustable ignition module to.
> As long as the engine gets the right A/F ratio there is no advantage
> in EFI powerwise. To know what A/F ratio you have,you will
> need a lambda cell, also a EGT sensor would be nice.
> This goes for both Efi and carb setups.
> During the dial in period I will use a lambda cell and EGT sensors in
> all 4 exhaust pipes and the collector, on the new system.
> Also, blow through carbs could prove more "forgiving" to the design
> of the plenum etc than a EFI would be. If you get sligtly more flow
> through some carbs the injectors on a EFI system will still spray
> the same amount of fuel, on a carb system it will drag the fuel needed.
> Also if you run a high hp EFI system you will need 8 injectors on a
> 4 cylinder engine ,otherwise you could get trouble with idle as the
> injectors would be qite big.
> Carbs gives better fuel atomizing at low engine speeds.
> But a EFI setup looks cooler though....
>
> Christer