AEM Infinity Wall Wetting

I have my steady state tuning complete on my supercharged big block in the boat running infinity. Now on to accel enrichment, which it is not happy with the default settings, on a quick rev I can watch in the logs engine goes very lean 19-20 af then coughs being that this is a larger displacement engine with a roots blower, I have to imagine these default settings are not close and may need to be doubled or tripled, maybe shifted to the the left in the table a bit so it comes on a bit sooner. Anyone willing to share their wall wetting table in a supercharged application? Just curious and looking for a better starting point so I can at least free rev.

Thanks,

Nick

Some information, like where the injectors are mounted, the sensor setup, even the fuel, would be useful - the more info' you can provide, the greater the help the pro's can offer.

That said, it wil probably come down to trial and error.

Good call. Its using a 3bar MAP sensor, fuel delivery is using a injection plate using 8 injectors that sits under the throttle bodies and above the blower attached pic for reference and I am running 93 pump.

Nicholas,

With that injector location, you're working against the delay time between an injection event occurring, and that fuel reaching the combustion chamber. Asynchronous injection during accel enrich will help get fuel injecting sooner, rather than waiting for each cylinder's normal start of injection time, so that's one area of potential improvement, but it doesn't shorten the physical distance the fuel has to travel.

Injecting extra fuel during rapid throttle opening will help wet walls that may be stripped dry as a rapid airflow increase occurs, and it seems you have a lot of surface area to wet, but keep in mind that doesn't help the fuel get to the combustion chamber any sooner, so you may still get a lean spike, potentially follow by an over rich condition, so adjust accordingly.

Also keep in mind if injection is entering a blower's open plenum, it can end up in any cylinder, so things can get extra messy/uneven in transients when you are injecting pre blower.

"In theory" the air passing through the 'blower already has the right amount of fuel added at the injectors, but in practice...

As you're already running 8 injectors, have you considered adding bosses to the manifold and using them there instead?

Mike,

Thanks for the response ill get some fuel added in the wall wetting table. Goal is just to get free rev not to cough going way lean. As its in the boat acceleration is rather slow compared to a car so under load I should be able to get it decent.

Gord,

With this blower the fuel needs to be introduced above the blower to help cool and lube the seals and rotors.

Thanks,

Nick

Nick,

If you choose to work around this by applying throttle slowly, I would back it off slowly too, since there's likely a lot of fuel wetting between injectors and combustion chamber. If you lift abruptly, that can all get sucked down into the engine and cause an abrupt over rich condition, perhaps a hiccup as well.

If you ever wanted to improve transients and accuracy of fuel distribution in general, you could add a set of injectors in the manifold, then just spray enough through the blower to meet your other needs.

Ill get as close as I can with wall wetting and then ill mitigate the rest of the issue the best I can with throttle. Its a ‘family’ boat so sudden throttle drops will be controlled unless its an emergency. Every family boat needs a blown big block :).

Sounds good, that looks like a LOT of fun. Enjoy!

I just connected the dots that you are the same Mike I have been listening to on a few podcasts :). I appreciate all the help.

Awesome, you're welcome!