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
Thursday, April 18, 2002, 8:26:57 PM, you wrote:
awn> Ed, mechanical fuel injection is fundamentally better than carburetion
awn> because with mfi each cylinder has its own throttle body, which can be
awn> any size necessary to assure that that cylinder gets all the air it
awn> wants. At the same time each cylinder can get the exact fuel/air ratio
awn> it wants because the system can be adjusted all at once by the bypass
awn> jet size, or cylinder by cylinder via nozzle size if necessary. Running
awn> conditions in each cylinder can be detected by an exhaust gas
awn> temperature sensor for each header. A carburetor and manifold setup
awn> always means some inequalities of airflow and fuel/air ratio between
awn> various cylinders, so they can't all give their best, some compromise
awn> is inevitable.
awn> One carb per cylinder like on many motorcycles gives very close to the
awn> same efficiency as mfi, except for whatever restrictions to airflow are
awn> created by the jets and venturis.
awn> Electronic fuel injection is extremely efficient, and makes great
awn> running engines, but if it only has one oxygen sensor with which to
awn> adjust the air/fuel ratio for the whole engine, as I understand they
awn> usually do, there must still be some minor inequalities between various
awn> cylinders. Correct me if I'm wrong, folks.
awn> Regards, Ardun Bill
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