Supercharged but has CARBON Build up

[TOM B]

I took my blown 347 stroker apart to check it out and found some carbon build up on the pistons and heads.
Am I running to rich, it does burn the eyes a little. The engine runs very good and only a year old and has NO blow by and the oil stays very clean when I change it so the engine is in very good shape, but the carbon build up has me confused. I would like to put NOS on it also this winter and if I have a problem I need to fix it now.

 

[ForceFed70]

Definately sounds like it's too rich. Do you have a wideband O2 sensor/guage?
It should be mandatory for forced induction engines.

 

[iskwezm]

shouldnt the fuel injection be adjusting for that????

 

[TOM B]

Yes I do have a wideband 02 sensor and a 2 bar MAP sensor. I have the Holley commander TBI injection that all programable from my laptop, maybe I paniced with the blower and ran to much fuel. I would have to get the laptop out but I think I have the A/F ratio at 10.5:1 running the blower. If you guys think that its a fuel related problem then I will clean it up and put it back together then tune it down some.
ISKWEZM, What do you mean adjusting for that, Yes the 02 compensation limit does adjust for what I have the % at, but maybe I didnt do that right, the Holley fuel program is a bit confusing to me and I couldnt find anyone else that set up a blower with it on a ford. What ratio are you running.

 

[65ShelbyClone]

Keep in mind that a 2 Bar MAP sensor is only good for 14.7 psi on the boost gage. I don't think you're huffing more than that, though.

It really depends on how much time you're spending at high vacuum cruise as opposed to high boost. The idle and high vacuum cruise can be tuned up to 14.5 to 15:1 AFR since it is at such low load. Any richer than that and it's really a waste of fuel. If the carbon is dry, it is most likely fuel. 10.5:1 AFR is pretty rich for a mild F/I engine, but I'm not sure just how "mild" of an engine we're talking about.

 

[TOM B]

Please see my SIG and maybe that can help

 

[65ShelbyClone]

Ok, I was right. I stand by what I said in that case.

 

[ForceFed70]

10.5:1 is too rich. No wonder you see so much carbon buildup.

12.5:1 is good for when on the boost. 12:1 if you want to be extra safe.

 

[iskwezm]

.
ISKWEZM, What do you mean adjusting for that, Yes the 02 compensation limit does adjust for what I have the % at, but maybe I didnt do that right, the Holley fuel program is a bit confusing to me and I couldnt find anyone else that set up a blower with it on a ford. What ratio are you running.

I assumed the processor would compensate for a bad A/F, i didnt know it had to programmed top a ball park A/F.................I couldnt tell you my A/F because my cam is so wrong we couldnt even get the A/F to lean out on the dyno, so my engine is comming out this week to make a few changes and get some tuning done.

 

[TOM B]

10.5:1 is too rich. No wonder you see so much carbon buildup.

12.5:1 is good for when on the boost. 12:1 if you want to be extra safe.

Wow bottlefed, 10.5 to rich, maybe im way over kill here, I will clean it up and put back together then tune it.
I hope you guys can help me then with the tune numbers, sometimes the Wideband stuff confuses me.

 

[65ShelbyClone]

I hope you guys can help me then with the tune numbers, sometimes the Wideband stuff confuses me.

The wideband is pretty easy once you get it all sorted out.

 

[6T6coupe]

Not sure how the Holley Commander works, but the ECU is probably compensating for the AFR to some degree, based on EGO readings, but most ECU's will only do so much. A 25% change would be big. My Megaquirt is only making AFR changes in the 5-8% range.

Try moving the AFR at WOT to something in the order of 11.5:1 and see how that works out. You may actually pick up a lot of power.

 

[65ShelbyClone]

The ECU's authority to richen/lean the mix should be adjustable in the programming software. 25% is indeed a lot, but there are other safeguards that can be used if the AFR starts going too lean and the ECU doesn't have the authority to fatten it enough.