NautiSouth

This 496 is flowing a lot less fuel, and making a lot more power than your first two engines!!

SB

iTrader: (1)

Compare your old motor's Fuel Use (located under Fuel A+B) vs your new motor's Fuel Use (again, located under Fuel A+B)

Either the fuel flow meter is f*k'd or your poor engine is absolutely drowning in fuel.

This needs to be found out.

NautiSouth

Based on the aforementioned carb jetting, my bets are on the flow turbines being miscalibrated.

SB

iTrader: (1)

Remember 1st post. His carb was flooding out.

No one caught lack of PV's when tuning.

I do agree with you Naughty. Would be a good bet. However, we know where assumptions leave us #1, and #2 he paid for a dyno test. He did not get a fair one.

This should have been caught during dynoing. Very obvious ! Definately not a next day or later catch.

Sucks.

NautiSouth

Agreed. He paid for a service he did not receive, it appears. I would push for another day on the dyno, gratis.

ramos45

iTrader: (1)

Yea, I can see the comparisons between my older build and the newer ones. The new ones are brutal. I'm heading to the shop this weekend to grab the other graphs and talk to the builder. he says he has other charts with lower BSFC numbers so I'll have more info after Saturday.

For now in my current set up I would like to ask what is the "proper" procedure for testing plugs? Is it WOT then shut down while at WOT and in gear or do you pull the sticks back and then shut down?

Budman II

iTrader: (1)

Pull the sticks back and then shut down as quickly and safely as possible - i.e., without getting swamped by your wake or run over by that cruiser that is trying to keep up with you. Crack a beer, let it cool for a few minutes, and then pull a couple plugs. Definitely do not shut it down while the sticks are at WFO. That would probably not end well.

ramos45

iTrader: (1)

Thanks, will do this weekend. That's exactly how I did it on Sunday after a run at 3800rpms. I posted a pic of the plugs a few pages ago. I will test again this weekend from WOT along with the other tests I need to do.

MILD THUNDER

iTrader: (3)

Installing an O2 sensor in the riser, and getting a wideband, would be the best money you can spend at this point IMO. I know pulling the engines to go back to the dyno is probably not a feasible option at this point.

I'm just not a big fan of reading plugs. If you can get someone to weld bungs in, and pick up a NGK wideband for about 250 bucks, dialing it in properly will probably much offset the cost, based on fuel savings, or worse, hurting the engines. I also think those GM dual planes are hurting you a bit. I'd like to think there is also a port mismatch between the Brodix heads and that intake port design, unless the heads were port matched.

tpabayflyer

yup.... I got an AEM wideband for about $175 from summit complete kit with gauge.... works like a charm and is the best way to accurately tune your boat as installed with your exhaust.....I have a warmed over 502 with ported aluminum heads and an airgap intake and 82/88 jets work perfectly for my 850 mighty demon...... forget pulling the plugs until you get it close using the wideband... I bounce around 13.5-14.5 at idle and 13.5 @ 3.500RPM cruise..... going to full throttle with everything wide open and power valve kicking in I am right at 12.5 and then 12.2 at 4,900rpm max..... I bet I am not too far EFI efficiency at cruise but the only way you will ever know is to get the wideband hooked up. I did get a tapped spacer plate to install in between the riser and manifold for $95 and so far so good! TBF