blue thunder

If you were running x boost and had a/f ratios of 11.6, then changed pulleys to add 2psi, what would you expect the a/f ratio to do? Go richer, go leaner or stay the same?

I would expect leaner, but that appears incorrect. They actually went richer to about 11.25-11.3. Is this normal?

BT

Smitty

All depends on how the original mapping was set up.

jspeeddemon

It's sounds as though itis running in a different fuel table cell with the additonal boost, I would not question the accuracy, sounds reasonable.

zt260

Yes it depends on the mapping, provided it's EFI. My mapping outside of the normal ranges, is on the rich side. Its safer for the stort term.

blue thunder

Sorry, 1050 dominators. No Efi.

zt260

Who setup the carbs? There not box stock are they? Setup is the key.

blue thunder

The carbs are merc 525sc takeoffs. I am tuning them with an o2 sensor. I'm just curious if getting richer a/f readings is the norm when upping boost. I was expecting it to go leaner.

Turbojack

Is based on the vacum signal past the ventures. I would have guessed since you up boost the amount of air thru the carb goes up thus richer a/f or the same.

B BOATER

If your motor doesnt require more fuel.be its out of cam, cant flow enough air, load on motor is less(Less load
less fuel needed) ect.... can make this happen. On our 1000hp motor we had to take fuel away up top because the cam was to small and couldnt make enough power past a certain rpm. Also is your system boost regulated?
are you running the same rpm or are you pulling more due to power gain?

blue thunder

Interesting. I didn't seem to get hardly any rpm increase. I attributed this to it going richer, but you bring up some valid thoughts. No boost regulation.

Did you notice the need to pull jetting out after a boost change upward?