has anybody used the wego II sensor and weaterproof digital read out on there boat ? my bike builder say's it's sweeeet www.daytona-sensors.com they sell for about $395.00

would like to hear from others, what ratio should you strive for. Car guys
seam to think that 14.7 is the magic number, boat guys say ritcher.

Actually, 12.8 - 13.2 AFR are good safe numbers for a Naturally Aspirated combination and 13.4-13.6 will generally make the most power upon an optimized combination.

Forced Induction AFR ratios are dependant upon the BSFC of the combination, most positive displacement blowers will fall into a general range of 11.2-11.8 AFR, while "low boost" centrifugal superchargers can safely run in the 11.4-12.2 range, and a turbocharged application can usually run a leaner 11.6-12.4 range.

14.7 AFR is the Stoichiometric air fuel ratio, this is the mixture an engine management system will attempt to achieve in light load or cruise situations.

I see higher BSFC in turbo motors then blown motors. The optimal afr for every setup will be different. Start at 11:1 in blown/turbocharged motors then lean em up a bit at a time. As far as na motorsgo start at 12:1 and go from there. Every setup will like more fuel at peak cylinder pressure i.e peak torque area, then you will lean it out a bit to redline. same goes for cars. 14.7:1 is a good afr for light load for fuel econimy new cars go evenleaner, but to achive this they use wideband afr targeting. When putting around inthe no wake zones you too should be in the 14.7:1 range.

I thought n/a engines are supposed to be tuned for 14:1 at part throttle, 12:1 WOT.

14.7 just happens to be the afr that catalytic convertors operate best at.
Nothing really to do with optimised engine performance.

I used the Innovate Motor Sports O2 system. I had the sensor bungs installed at CMI. I set my NA engines (Holley #7320 1150 CFM) at an AFR of 13.5 -13.7 from 3000-5400. The 3.5 PV's cut in at 5400 RPM and the AFR changes to 12.5-12.6. We ended up with the jets at 87 X 87. It is possible I could go to 2.5 PV's. That will be a next season test.
This AFR gives a nice safe slight tan color plug reading at cruise... and plenty of safety from 5400-6800 RPM.
This was my first time tuning with a wide band O2 sensor system...i will never go back to guessing by just using the dyno. I started with 93 X 93 jets (based on the dyno) and the AFR was about 10/1.

14.7: 1 ( by weight) is the Chemical stoichiometric of Gasoline. meaning the optimal burn ratio. there are a ton of factor that pay in here regarding performace.

As for a Three way Cat. It is looking for a the switching we do above and below that stoichiometric mark. In a sense we are pump air in to the cat to keep it lit.

you need to look at ben perfected post to really understand what is happening. the optimal fuel map for any motor is a function of what power it makes at what temps and atm press. thats going to give you egts that are repeatable and mapable on the dyno and will translate to af ratios at YOUR 02 sensor ON your exhaust on the dyno at the SAME time...

so now you throw the motor in your boat and the af ratio is all screwed up and you need dif jets.... HMMMMMM why do you think that is ? has the motor materially changed since it left the builder ? NO

what has changed is the air the motor is breathing in your engine compartment... HOT contaminated air... which makes your AF meter scream at you that it needs to be leaner... so fix the BREATHING of the boat and get the power you built ... DON'T re jet just because you have 140 deg air going in the motor...

the notion that you can tune w/ a wide band meter that has NOT been calibrated on the dyno is absurd. the numbers are, for all intents and purposes no better than pulling a plug and looking at them...

hmmmm at 12. 2 the plugs are nice and tan... REALLY ? and do you figure thats good, bad or indifferent ?... and why ? if tan is safe and good then why use the meter in the first place ? and are you aware that the color in the plugs is often a function of the addative package in that particular fuel... and if they were snow white and your meter said 10 : 1 would you lean it further ?

the meters are perfectly good serviceable instruments ASSUMING the numbers have been validated in an controlled environment... but if you are just plugging them in and basing your conclusions on some theoretical base line , then , with all due respect, you are kidding yourselves.

Steve,
The heat and humidity in the summer on the water and in the bilge is what it is. I have dyno'ed in 3 separate marine based engine shops since 2002; each time generally jetting for peak power. Duplicating the boat engine loads on the dyno isn't a perfect science. All I can tell you as each time the dyno jetting process has led me to a rich condition with black plugs and transom.
My point is that a wide band O2 sensor used in my actual boat and conditions got me a better result than in an engine shop.