Fuel injection upgrade?

[OwnyTony]

I was reading Travman's http://ducatimonsterforum.org/index.php?topic=31347.0 and there was a part about switching from efi to carb.  The reasoning (it seems) is that the carbs are able to dump more fuel into the engine. 

It was mentioned

I have always been lost at were the power comes from on the 100 hp carbed 1000ds.  The 45mm throttle bodies should have more airflow than the 41mm FCR's, are the factory injectors being maxed out.  I know they are often installed with short intakes, how much do the shorter intake runners contribute to 100 hp?  Or is it just the ease of tune and a 1000ds with a nemesis should make similar power?  On these conversionsis the ecu still used for ignition control, or is that swaped over for carb parts also?

What is the reasoning to switch to carbs?  Can our stock fuel injectors be upgraded at a higher flow rate and what would be the downside to this (besides possibility of running rich and lower fuel economy).
I know when my bro was upgrading his WRX, he needed

[battlecry]

See if you can fit an adjustable fuel pressure regulator (to raise the fuel pressure=more flow) and a PCIII with an accelerator pump upgrade.  It is a tight fit for a new regulator.   

[Speeddog]

There are *very* few Ducs that need larger/higher flow injectors.

Unless you've done a shit-ton of motor work, the OEM injectors can handle the job.

[battlecry]

Speeddog, Brad Black's dyno charts for the M800 show the A/F out of whack below 3200RPM with slipons and filter mods.  The A/R ratio hover around 18 or so.  For slow city driving right around that RPM range, something this beast is not well suited for, would it be better to increase fuel flow with a longer duration squirt using a PCIII or have a shorter duration higher pressure spray?  Would the higher pressure atomize better?  Seems like most injectors operate at 3 bar pressure, so maybe the flow dispersion was optimized for that. 

[Speeddog]

IMO, adjust the fuel with a PCIII.

Changing fuel pressure means you'll have to change the whole map, to preserve the areas that are correct already.

[battlecry]

Thanks.  Would be cool to have a dyno to play with.  R

[brad black]

Speeddog, Brad Black's dyno charts for the M800 show the A/F out of whack below 3200RPM with slipons and filter mods.  The A/R ratio hover around 18 or so.  For slow city driving right around that RPM range, something this beast is not well suited for, would it be better to increase fuel flow with a longer duration squirt using a PCIII or have a shorter duration higher pressure spray?  Would the higher pressure atomize better?  Seems like most injectors operate at 3 bar pressure, so maybe the flow dispersion was optimized for that. 

you've misread the graph and misunderstand the concept.

the graph is a wide open throttle run from a closed throttle, and the air fuel trace has started from leaner than 18:1 at a closed throttle.  as the throttte is wacked open tha air/fuel ratio drops to that shown.

the wide open throttle run bears no relation to the mixture at "slow city driving right around that RPM range".  the fuel map has lots of totally independant points.  even with carburettors it bears no relation.

if the air/fuel ratio is wrong then it needs to be fixed.  if the air/fuel ratio is right then these engines will run happily under 3,000 rpm all the way down to 1,200 even.

the only way you'll get more power with the carbs is if the potential flow thru the carb is higher than thru the std throttle body (including any manifolding upstream and downstream) and if the engine can make use of the potential.  airflow makes more power, fuel flow only needs to be appropriate for the airflow.

there's a guy with a 1123cc 1000ds motor that has out demanded the original injectors of the 50mm 916 throttle bodies he is using, altho it does hold the power to the top end with the short 916 inlet trumpets.

[battlecry]

Thank you, Brad.