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Re: [turbobike] carburation vs fuel injection

Bryan Goodwin (bgoodwin@iquest.net)
Sun, 18 Apr 1999 03:37:42 -0500

N2O makes a great deal of cylinder pressure and heat. N2O often requires timing
retard and/or good fuel by itself. I do not believe you should add any boost
because of N2O.

John C Williamson wrote:

> >From a simple 'physics' standpoint a carb always has to restrict the air
> flow slightly, as this 'venturi' is the thing that actually draws fuel from
> the floatbowl. The flow through carbs is pretty efficient on modern bikes
> though so the difference will be quite small.
> It is true that fuel injection will allow more accurate fueling in all
> conditions, if money / time allows so less flat spots and possible better
> throttle responce.
> On the other hand my 1100 GSX EF used a cheap stock Mr Turbo kit with a
> single draw through carb and this was fine! Idle was a little ragged, but it
> kind of adds character! Unlike the short 'banana' drag style exhaust pipe
> that tries to turn your left leg to charcoal.
> Does anyone know how much extra boost is possible with N2O due to the
> cooling effect?
> ----- Original Message -----
> From: Lorcan Parnell <lorcan@globalnet.co.uk>
> To: <turbobike@natvideo.com>
> Sent: 18 April 1999 19:41
> Subject: Re: [turbobike] carburation vs fuel injection
> 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