#38 or #42 injectors!?! 190 or 255 fuel pump?

Sampo

Registered User
What do you think!? Which is better to my car? I´ll install 76mm MAFS and 75mm TB, fresh air system and raised blower top etc.

And what other mods I should do if I´ll change injectors/fuel pump? ( The MAFS should be calibrated to match injectors size...Something else?)

How "big deal" is to change those?

I would appreciate very much your opinions! Thanks! :)
 
If you are changing the pump there is never any reason to go smaller.225lph.
I feel the same with the injectors If you are buying them anyways then might as well go big unless fuel economy is what you are looking for...
 
With injectors fuel economy will not change, but idle and starting characteristics will. The further you go away from the stock size, the more chances you will have with starting and idle. Also, the further the MAF function is skewed by using a calibrated MAF, the further off the EEC's internal calculations will be. You want to go big enough to cover your intended eventual HP numbers but no bigger and then plan on a dyno tune if you want any assurance that your AF ratio is correct in the end.

stock - 250rwhp
36's - 300rwhp
38's - 325rwhp
42's - 400rwhp
50's - 500rwhp
60's - 600rwhp

This is a general guideline and not a fast rule.
 
XR7 Dave said:
With injectors fuel economy will not change, but idle and starting characteristics will. The further you go away from the stock size, the more chances you will have with starting and idle. Also, the further the MAF function is skewed by using a calibrated MAF, the further off the EEC's internal calculations will be. You want to go big enough to cover your intended eventual HP numbers but no bigger and then plan on a dyno tune if you want any assurance that your AF ratio is correct in the end.

stock - 250rwhp
36's - 300rwhp
38's - 325rwhp
42's - 400rwhp
50's - 500rwhp
60's - 600rwhp

This is a general guideline and not a fast rule.



Thanks for that! :)

I think 38´s will be enough for me.

If I´ll take those 38´s, 255lph and 76mm MAFS, do I have to "reprogramm" something or are those just bolt-ons together..?

I just want to be sure before I´ll decide anything, and then go totally wrong!
 
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