Fuel replacement % Calculation

[Jerryl]

Anyone know of a calculator to determine fuel % replacement based on PW with/without alky?

 

[Jerryl]

Come one folks, you can't tell me that no one here has any idea.
Just want to be close, that's all.

Let's say my DC goes from 15ms to 10ms (Examples only)
What is the estimated replacement %?

 

[pacecarta]

for what you should be using on fuel the trx performance calculator from joe lubrant works great

theres also fuel charts
Performance, Horsepower, Injector, Fuel, and Turbo Guide
and spreadsheet from joe
http://www.gnttype.org/techarea/misc/calcs.zip

if running alky... 10% less is a good start point

as for converting PW to a dutycycle i dont know of a chart
PW goes up with rpm so its not easy to base on that alone
if fueling is correct there should be little to no duty cycle change as rpm rises .

 

[Jerryl]

for what you should be using on fuel the trx performance calculator from joe lubrant works great

theres also fuel charts
Performance, Horsepower, Injector, Fuel, and Turbo Guide
and spreadsheet from joe
http://www.gnttype.org/techarea/misc/calcs.zip

if running alky... 10% less is a good start point

as for converting PW to a dutycycle i dont know of a chart
PW goes up with rpm so its not easy to base on that alone
if fueling is correct there should be little to no duty cycle change as rpm rises .

Thanks man!
I was aware of the spreadhseets, and realize that PW is RPM dependant.
More specifically, the AFR target changes as well, so it is a very complex model.
I was just hoping there was a calculator to plug the numbers in.

Say, I log 2 runs (PL) with the following #'s (examples only):
4500 RPM - 15 PSI - DC 18mSec - AFR 11.3 - 93 Octane
4500 RPM - 15 PSI - DC 15mSec - AFR 10.5 - 93 Octane + 100% methanol
How much fuel replacement would that be in "rough terms"?

 

[DMan]

Spreadsheets right here

The attached spreadsheets should give you what you need.

BSFCCalc - its structured around my aquamist nozzle setup but just add the equivalent amount of aquamist nozzles that equate to your current alky nozzles. In the yellow tables on the right are the flow rates by nozzle size.

Extra

PWtoMPG - a little empirical ditty to compute fuel economy based on injector pulse width.

Enjoy!

DMan

 

[Jerryl]

Thanks for sharing!!
Played with it a bit last night b4 the site went down.
Interesting results after pluggin into the numbers in both files (hard for me to belief)

Just to be clear.
All I am trying to do here is get an idea of fueling, and in some fashion predict a few things, before testing them out.

 

[ktm240z]

Say, I log 2 runs (PL) with the following #'s (examples only):
4500 RPM - 15 PSI - DC 18mSec - AFR 11.3 - 93 Octane
4500 RPM - 15 PSI - DC 15mSec - AFR 10.5 - 93 Octane + 100% methanol
How much fuel replacement would that be in "rough terms"?

It's actually quite easy if you want a "ballpark" number. If your AFR is 11.3 before meth and 10.5 after meth, you still want to be around 11.3 even with meth. The target AFR does not change.

So, 11.3/10.5 = 1.08. In other words, your injector PW would decrease by about 8%. It is the same injector scaling you use when tuning, a ratio of your AFRs. This will get you in the ballpark at least.

Remember though that when you start to pull fuel you are creating a moving target and it becomes an interative process. I just do the first calc based on my initial pump only tune to get me in the range, and then I just tune tune tune and adjust the PWs as necessary using the first one as my guide.

With my FJO progressive system on my turbo'd 240z, I am theoretically injecting around 25% of my primary fuel (based on my calcs) with methanol and I am pulling 20% more or less. I tune for 12:1, the same as just on pump gas.