Jet size questions - WRX

[bwhinnen]

I've used the 'lovely' PHPBB search facility and have found a few entries of the jet sizes people are using...

But is there a specific formula to use, I understand that 10 - 15% of the fuel used is the guideline, but given that the fuel used across the entire rev range will be different is it a compromise?

I run 4 x 700cc injectors at about 68% IDC (@ 7000rpm), currently around the 199kW @ the wheels mark.

Currently I'm using the 0.5mm jet in a 1S system but would like to know if running a 0.7mm jet as a few others are using would be a better solution.

Jet location is in my FMIC piping, about 700mm before the TB.

Cheers and thanks
Brett

[Richard L]

I've used the 'lovely' PHPBB search facility and have found a few entries of the jet sizes people are using...

But is there a specific formula to use, I understand that 10 - 15% of the fuel used is the guideline, but given that the fuel used across the entire rev range will be different is it a compromise?

I run 4 x 700cc injectors at about 68% IDC (@ 7000rpm), currently around the 199kW @ the wheels mark.

Currently I'm using the 0.5mm jet in a 1S system but would like to know if running a 0.7mm jet as a few others are using would be a better solution.

Jet location is in my FMIC piping, about 700mm before the TB.

Cheers and thanks
Brett

In order to keeping the ratio relatively constant, you need to consider upgerading the 1s to a 2d system. The 2d tracks the fuel delivery and you can keep your w/f ratio much consistantly. If you need other ratios, just change the jet size.

Richard

[Richard L]

Could you post some pictures ?

[bwhinnen]

Hi Richard I'll grab some pictures as soon as I can.

I'll be looking at the 2d system when I get a chance, as well as upgrading from my current aftermarket engine management (a Link) to a Motec in the near future.

Cheers
Brett

[bwhinnen]

Some pictures:

Jet Mounting.
http://www.griffin.net.au/WRX/WI/DSC_11932.jpg

Relative to the Throttle Body.
http://www.griffin.net.au/WRX/WI/DSC_11936.jpg

Another angle of the above.
http://www.griffin.net.au/WRX/WI/DSC_11939.jpg

Cheers
Brett

[Richard L]

They are excellent pictures.

I just wonder if you can increase the methanol percentage since you are in the middle of summer months. 0.5mm for neat water and 0.7mm with 50W/50M mix to aid induction cooling.

Richard


Some pictures:

Jet Mounting.
http://www.griffin.net.au/WRX/WI/DSC_11932.jpg

Relative to the Throttle Body.
http://www.griffin.net.au/WRX/WI/DSC_11936.jpg

Another angle of the above.
http://www.griffin.net.au/WRX/WI/DSC_11939.jpg

Cheers
Brett