When changing injector size what needs to be changed?

Mad Professor · Post by **Mad Professor** » Wed Dec 28, 2005 6:49 am

Hi All.

At this point in time I am running my car on it's stock injectors 214cc/min.
I have a set of 390cc/min injectors that I want to change over to.

When I do this what settings do I need to change, or is it a case of start from scratch again?

Thanks for your time.

Big Creek · Post by **Big Creek** » Wed Dec 28, 2005 10:30 am

Assuming they are both of the same resistance (low versus high impedence) you should only need to change your required fuel. You will probably still need to do some fine tuning on your VE's and priming pulse. I am no expert so hopefully others will chime in here.

Todd

Bernard Fife · Post by **Bernard Fife** » Wed Dec 28, 2005 10:42 am

Todd,

Yes, that sounds just about right. You might also need to adjust your cranking pulse widths and accel times. Bascially, anything in millseconds will need to be scaled, anything in % (VE table, warm-up, afterstart, etc.) will not.

Lance.

Mad Professor · Post by **Mad Professor** » Wed Dec 28, 2005 11:03 am

Well thats good news.

Means I don't have to start all over again.

Lordprimate · Post by **Lordprimate** » Wed Dec 28, 2005 5:38 pm

I just went from the stock 19# injectors to 50# injectors...

I had to adjust Req_fuel , prime pulse, AE, and Scale down my VE table(scaled it down .3-.5 %, dont remember EXACTLY

)

Mad Professor · Post by **Mad Professor** » Thu Dec 29, 2005 2:13 am

So the main thing to change over is
From This:
1905cc - 214cc/min Upper Req_Fuel: 14.9, Lower Req_Fuel: 14.9
(-40Â°F) 88% (Upper Req_Fuel / 100 * 88) = 13.112
(170Â°F) 23% (Lower Req_Fuel / 100 * 23) = 3.427

To This:
1905cc - 390cc/min Upper Req_Fuel: 8.2, Lower Req_Fuel: 8.2
(-40Â°F) 88% (Upper Req_Fuel / 100 * 88) = 7.216
(170Â°F) 23% (Lower Req_Fuel / 100 * 23) = 1.886