V-Twin Forum banner

1 - 4 of 4 Posts

·
Premium Member
Joined
·
641 Posts
Discussion Starter #1
Just finished a build in an 07 FLHX using Bigboyz heads, 31h cam, D&D fatcat w/quiet baffle, BC overflow filter and a SERT. It tuned nice and runs good. My question is when do you know it is time to go to bigger injectors? This is the stock TB. VE numbers were good. Do you tell by the injector pulse width?
 

·
Banned
Joined
·
4,508 Posts
Injector size

On a build such as what you now have, injector size should never be an issue.
When tuning,as our EFI tuner has made mention to us, and the Dynojet training seminars we have attended,, when you are approaching the maximum duty cycle of the injector is when you would need to make a move.
 

·
Registered
Joined
·
772 Posts
bowtech40

bowtech40 said:
Just finished a build in an 07 FLHX using Bigboyz heads, 31h cam, D&D fatcat w/quiet baffle, BC overflow filter and a SERT. It tuned nice and runs good. My question is when do you know it is time to go to bigger injectors? This is the stock TB. VE numbers were good. Do you tell by the injector pulse width?
Bowtech,

Your question is a good one no doubt. From my understanding, you would have to know a couple of things here to determine the answer to your question. The first this you would have to know is the fuel delivery rating of the injector. I think (not 100% sure) its usually supplied in grams per second. Then you would have to know what percentage pulse of the rated maximum pluse your build is using to supply the selected Air to Fuel Ratio. From what I gather, the maximum pluse width used in your build should be no more the 80% of the rated maximum of the injector. You can simply divide the actual used pulse (if you know what it is) width divided by the rated pulse width then multiply by 100 to give you a percentage. To me, this would only occur under wide open throttle position. If you find out something different by all means let us know.

Agreed with Hillside where max duty cycle is equal maximum rated pulse. Hope this helps.
 
1 - 4 of 4 Posts
Top