Quote Originally Posted by MILD THUNDER View Post
Wow, was Ken sent me that last dyno sheet. Den, if those AFR ratio numbers on the right are correct, that is WAY lean for it to survive in a boat. Those numbers need to be in the low 11's, in my opinion. It may fatten up in the boat, but I dont think two full points. I'd rather have to pull a jet size or two out when installed. Wednesdays pulls were showing we were going in the right direction jetting it up, when the dyno broke. What happened!! i would be concerned with those AFR numbers on a N/A 502, let alone a 15psi blown engine. 13.7? Thats getting a little too close to stoich. A 2012 Ford Escape V6 would probably have a full throttle AFR reading similar to that.

Two things I would do. Make Joseph spend a few hundred and take his tails to the welder, and put 02 bungs in them. Then, borrow a wideband and check while running the boat. The 02 wont lie, and I wouldnt trust plug readings on a 1300HP marine engine. Second thing, drop the boost to 10-11 PEAK psi. It will still make 1100HP. Im not sure how much cylinder psi those MLS headgaskets can withstand?

I agree with you that the O2 sensor doesn't lie, but it is giving you the average of that cylinder bank. Even on boosted engines its not umcommon for the A/F to vary from cyl to cyl as much as .5. This is why plug checks should be mandatory to verify what the O2 is saying on each cylinder not to mention timing and plug heat range checks. Now if the average O2 was 11.0 there would be more of a cushion to cover the potential lean cylinder. Imagine if the average is 13.5 and one cylinder (#7) is 14.0 under that boost / power level!! Too bad the dyno sheet doesn't have fuel flow or BSFC's listed. A lot of engine shops rely on the fuel being consumed more than the O2's to get the motor dialed in.