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Re: To inject or not to inject...

To: Ed Lutz <edlutz@laverdajota.com>
Subject: Re: To inject or not to inject...
From: Rick Hammond <r.hammond@sympatico.ca>
Date: Fri, 19 Apr 2002 13:29:07 -0400
Hi Ed,
Makes sense, in the case of shooting for maximum HP maybe at the expense of
day-to-day driveability.
The only exception might be if you looked at larger injectors.
I've run 900 Ducati twins; carbs and injectors, and the injection is impressive.
This was a newer bike probably with improved breathing in the head, but they 
give
a decent example.
The carbs can go to 41mm (kehin flat-slides seem to be a favorite) but the stock
injected bike has 45mm injector throats.  My point is that you can run injectors
with much larger throats and still have them well behaved, while carbs that big
would be overkill.  (My ST4 has 50mm throats; the two carbs on a rover V8 are
about 45mm ;-)  That can more than make up for the butterfly restriction.
Another example I saw in the bike mags was the GSXR; now with injectors.

Hey, I loved my old '79 F150 with a holley and 4-barrel, but the '97 with the
injection sure is easy to live with and rarely spits back/catches fire. ;-)

BTW, I have to see if he got it done, but a Ducati fellow had some 32mm 
Dellortos
laying around and was rigging twelve little manifolds for his e-typ Jag.  Can 
you
say carb synching...?
Cheers,
Rick

Ed Lutz wrote:

> OK, on the single carb to multi cylinder concern your of course
> correct. Coming from my background of motorcycles I was thinking multi
> carb setup with one carb per cylinder. Different frame of reference.
> If switching from a distribution manifold design to port injection you
> will most likely gain power. How about the single carb per cylinder
> situation though? My thought is that injection is something that will
> give better drivability due to it being more adjustable than a jet
> controlled carb, which can have problems metering properly through the
> entire rev range. Injection is probably easier to tune if you have the
> correct equipment, but for pure power delivery I don't see an
> advantage. A slide throttle carb will present a cleaner throat than a
> butterfly controlled FI throttle body, plus I believe that a properly
> setup carb does a better job of atomizing the fuel than an injector
> (what I've been told by engineers more versed than I on the subject).
> So, for a vehicle (lets say motorcycle to stay with the one carb per
> cylinder comparison) destined for Bonneville which needs enough
> tractability to properly accelerate across the salt and as much
> absolute HP as possible to gain the desired record, why would FI be
> inherently better than carburation?
>
> Of course I think you did say that on a multi carb setup as on a bike
> that you felt the difference would be minimal so perhaps the entire
> conversation is moot anyhow :)
>
> Regards,
>
> Ed

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