Air fuel ratio???What is ideal??

[Real-slo98]

When i got my terd dynoed a couple weeks ago they also had a A/F jobby on it. It seemed pretty lean to me (15-1) until about 3900rpm and then it richened up(11-1) is this normal??

Adam

[RacerGT]

Originally posted by Real-slo98
When i got my terd dynoed a couple weeks ago they also had a A/F jobby on it. It seemed pretty lean to me (15-1) until about 3900rpm and then it richened up(11-1) is this normal??

Adam

That's about right... maybe a little lean until 3900, but up top it's supposed to be rich. Get a tune. :thumb:

[Brandon Alsept]

Try to get it around 13:1 across the board for a N/A car, some go to 13.5:1 but that is starting to boarder on needing higher octane gas.

[Bill Putnam]

Exactly what Brandon said 13:1 across the board is optimal. Most cars are a little lean early on in the RPMs but usually before 3500-4000 the car is below 13:1.

Bill

[Real-slo98]

Mine is about 14.80-1 from 3000(1st reading I can see) to 4000rpm. Then is gets richer from 4000-4600 where it goes to about 11.75-1 and continually gets richer until the last reading at 5400rpm. My peak power is about 4000-4600 but drops off after that. Can I adjust my pressure/ratios with an aftermarket regulator? Or is there more involved than that....thanks

Adam

[Bill Putnam]

When you adjust the FP at the rail you are only increasing the base pressure and from there the same curve will happen. So you might richen it up in the lower RPM range but it will just get richer towards the top end.

Bill