I know this sounds silly, but I have talked to a few diff people, said to run 02 sensors.. I wasn't sure of the whole 02 sensor thing so i assumed they meant for keeping a eye on AFR( 02 stlye sensor), so you know when or if it goe's lean.. It will be kinda hard to get a 02 sensor in a pipe that has water running through it, but if it needs to be done, I can find a dry spot in the pipe.. What are you all running as far as additional gauges?? I am running boost, afr, FP in my truck, but boost isn't a essential gauge needed in a boat... I am good with the autos on whats need, but not to much on boats as this will be my first boosted boat...Thanks for the help

John Jr

My pipes are also water jacketed. You have to through the pipe a little bit bigger then the bung and then weld the inside and out side of the pipe around the bung to seal it. So you have to place the bung in a location so you can get to it to weld inside the pipe. Water will flow around the bung.

That is kinda what I figured. What all gauges do you run on it( as far for the blowers), your only getting AFR from 1 bank, not 2 correct??



John jr

Are you running headers? you want to install the o2 18'' back from where the water blends with the exhaust,starboard side if your only running one o2 and it has to be on top or 10* on port or starboard,no more or the o2's heater element will fry out..if your using a ss riser then you can drill a hole through the riser tube making the outer pipe bigger so the inner pipe can be welded to the lower part of the bung,then you can close off the top side of the bung by welding It to the outer pipe..make sure you have a good welder do it.

I am running a decent set of EMI's but they are wet pipes, might go to dry tops, but not this year.. I am going to be putting a procharger on the boat. As far as the welding part, we can do that, not a problem.. So again, the AFR is the main one. I am aware that afr will go stupid if FP drops off, am not worried about egts. So the main THING IS AFR, correct.. Thanks again

John Jr

I really wouldn't recommend running an O2 sensor all the time. They are highly allergic to water and they will eventually get wet since there is a mist of water constantly in the pipes. It will take its toll on the sensor eventually. I am constantly using them for tuning and they fail. I go through a few a year. Once the engine is tuned, you don't need the O2 and you must rely on your gauges. You should have (on top of the normal gauges) boost, fuel pressure, and oil temp.
When tuning you must monitor both banks. One bank is always leaner than the other. You have to tune on the lean bank. They can vary by 2 full points or more, depending on distribution. You could have one bank at 10:1 and the other at 12:1. If you are only reading the richer (10:1) bank, then while tuning you will lean the engine to the point where the leaner bank will be far to lean and hurt parts. You can run the boat with the sensor in each bank and determine which is the leaner one and tune on that one if you only have one sensor. I use a unit from FAST that has 2 sensors going at once. It runs about $425.00.
As for the bung, drill a hole through both the inner and outer pipe. Then put the rounded portion of a ball pein hammer on the outer pipe. Hit it with another hammer so that the outer pipe caves in just a bit so that it closes the gap between the pipes. When the gap is tight enough, weld up the gap between the pipes. You have just sealed off the water. Now place the bung on top of the pipe and weld it in. You do not have to weld the inside of the pipe now. Been doing it this way for years and it works great. Some pipes you can not get to the inside to weld, so we needed to come up with a better plan. Place the bung in your riser in the turn where it heads back to the transom. Place it about 2-3" behind (above) your water fitting in the riser. Hope this helps.
Eddie

I have bungs in all 4 banks. They were put in for tunining only and plugged after jetted. I use an Innovate LM1 handheld AFR.