I’m currently working on a fuel table based on RMP Vs. boost pressure for a “near future” 8 injector setup. This is a different EIC than the ones we’ve been typically seeing around here (034 or port fueler) so I’m starting from scratch with the fuel map. The controller I’m looking at uses the injectors duty cycle percentage as the user input variable for the amount of fuel being added to the system. For example: an input of 1 on the controller would fire the injectors at a 1% duty cycle at X psi of boost at Y RMP. I’ve got the theoretical calculations for what duty cycle/psi of boost is needed. But what I need to know is, how does RPM affect fuel consumption? I know fuel demand must go up as the RMPs increase…but it’s probably not a linear as I first thought. Because as RPMs go engine load goes down…right? So, is there a basic rule of thumb, or formula to figure out rate of fuel consumption Vs. RPM? If so…do the same rules apply while under boost? Right now my table looks pretty silly and/or scary with the same duty cycle percentage throughout the RPM range per boost pressure increment.

And if someone posts a link to a similar topic I’m gonna feel pretty stupid ‘cause I searched for about 2 hours :P TIA!

Since noones replied, here's at least a bump in the right direction hopefully.... I think you're looking at BSFC (brake specific fuel consumption) concerns. Corbin's fuel pages have the best explanation of this I've seen. Also if you get lucky with a search, Metaljim and Corbin posted some Excel spreadsheets with fuel calculation formulas that might include what you're looking for. Also, the book Maximum Boost, by Corky Bell is a must-read if you don't have it already.

What fuel computer is this?

Originally posted by thedawg
Since noones replied, here's at least a bump in the right direction hopefully.... I think you're looking at BSFC (brake specific fuel consumption) concerns. Corbin's fuel pages have the best explanation of this I've seen. Also if you get lucky with a search, Metaljim and Corbin posted some Excel spreadsheets with fuel calculation formulas that might include what you're looking for. Also, the book Maximum Boost, by Corky Bell is a must-read if you don't have it already. What fuel computer is this?

LOL...thank fo the bumb :thumbsup

The BSFC is that .525 number right? That changes with RPM? I guess I'm gonna have to read ALL of Corbins site again....not just the formulas...heh. I'll look for those excel spreadsheets also.

this is the controller I'm seriously thinking about useing.


http://www.cnk.co.za/Products/DIY_Products/programmable_eic.htm

also here...more info but not as a professional looking page.

www.extremeevolution.co.za

thanx for the help dawg

>> I’m starting from scratch with the fuel map.

The only way to do this is on a dyno or with an extensive datalogging system. You CAN NOT guess or calculate a fuel map from scratch. You won't even get close.

>> I've got the theoretical calculations for what duty cycle/psi
>> of boost is needed.

Throw any theoretical calculations out the window.

I hate duty cycle maps.

I can post one of my DFI maps if you'd like, so you can see the relationship to RPM.