O2 Sensors - Is Dry Over The Transom the only option?

**FormulaZR** · 10-10-2011, 12:13 PM

Ok, Here's a quick question. Right now I have water injected through transom headers and I'm wanting to add EFI to my boat. I'd also like to utilize factory type and wideband O2 sensors...

Can I do that with water JACKETED through transom headers...or do they still run too cool and still have too much moisture?

Are dry over-the-transom headers the only option?

Also - how would one accurately install EGT sensors?

**Grand Illusion** · 10-10-2011, 12:18 PM

It can be done with jacketed through transom headers but to be safe I would make them fully jacketed all the way to the tip and make sure the tips are above the waterline

**FormulaZR** · 10-10-2011, 02:23 PM

Originally Posted by Grand Illusion

It can be done with jacketed through transom headers but to be safe I would make them fully jacketed all the way to the tip and make sure the tips are above the waterline

That's sort of what I figured would be the answer; my exhaust is already just below the waterline...so I'm thinking the "safest" thing is to go over the transom...

**Sleeper CP** · 10-10-2011, 02:47 PM

Originally Posted by FormulaZR

That's sort of what I figured would be the answer; my exhaust is already just below the waterline...so I'm thinking the "safest" thing is to go over the transom...

Is this for a 1 time tuning experience or something you want to keep in the boat for a gizmo?

do you want to put an egt probe in each cly or just a lean one?

S CP

**steveo143** · 10-10-2011, 04:47 PM

I have probes mounted 8" after turbos and less than 2' from merge to water with double jacketed tubes going to thruhull outlets with Salisbury flaps, never had a problem with moisture on the sensors!

**slow67** · 10-10-2011, 05:56 PM

Originally Posted by steveo143

I have probes mounted 8" after turbos and less than 2' from merge to water with double jacketed tubes going to thruhull outlets with Salisbury flaps, never had a problem with moisture on the sensors!

Right, but turbos pretty much kill any pulses from the exhaust. The pulses make it a much more dynamic environment.

**FormulaZR** · 10-11-2011, 04:47 AM

Originally Posted by Sleeper CP

Is this for a 1 time tuning experience or something you want to keep in the boat for a gizmo?

do you want to put an egt probe in each cly or just a lean one?

S CP

Probably wouldn't do 8 EGT probes...but to be honest, I'm pretty new to the EGT thing...

I would like to keep the O2's on the boat all the time. If I'm only using it for initial tuning then I have it "all figured out".

Originally Posted by steveo143

I have probes mounted 8" after turbos and less than 2' from merge to water with double jacketed tubes going to thruhull outlets with Salisbury flaps, never had a problem with moisture on the sensors!

2 feet, or 2 inches? I don't think I have that much exhaust...

I would like to see your exhaust setup, though - I do eventually plan to go turbo...but not yet.

Originally Posted by slow67

Right, but turbos pretty much kill any pulses from the exhaust. The pulses make it a much more dynamic environment.

I think I already have a marginally "safe" cam for water injected headers...

**MACHINEHEAD1** · 10-11-2011, 08:39 PM

I agree with thread #2. Even if your exhaust is below or slightly below water line. All that really happens is the O2s get fuzzed up and screw your tune and you will know about it. Im sure your 5 wires are heated, that helps. Eliminate the water for the mean time and make it fire up nice and quick (base map tuning). This will help keep the O2s clean if it just fires looking at the switch. Once its lit, with your small cam , the O2s will last. If you are planning on idleing around a lot., dont.

**skav** · 10-19-2011, 07:12 PM

Originally Posted by slow67

Right, but turbos pretty much kill any pulses from the exhaust. The pulses make it a much more dynamic environment.

So I guess that a sc engine would still have exhaust pulses?

**Outlaw** · 10-19-2011, 08:11 PM

What exhaust do you have now?
I added O2 bungs to my Imco's
They exit under water at idle
And blend 18" after the sensors
I have a wide band on one side and a narrow on the other
No problems so far
Let's see what you have

Sent from my iPhone

**FormulaZR** · 10-20-2011, 04:53 AM

Outlaw - below is some pics of my current exhaust setup. Do you run water jacketed, or dry, or what?

**Outlaw** · 10-20-2011, 06:57 AM

I'm running a jacketed exhaust, I'm not sure what might be available for your engine, I'm guessing you want to reinstall the EFI??

**FormulaZR** · 10-20-2011, 09:05 AM

Originally Posted by Outlaw

I'm running a jacketed exhaust, I'm not sure what might be available for your engine, I'm guessing you want to reinstall the EFI??

Yes - you are correct. Lightning says they make LS1 jacketed headers...but I haven't priced them yet.

Been seriously considering going to a twin turbo setup...in which case I'd still probably need to do over-the-transom exhaust...

**Unchained** · 10-20-2011, 02:03 PM

Formula ZR,

That looks like a mercruiser heat exchanger, how has that been working for you ?
It looks like that same size unit that's on the 4 cylinder 470 mercruiser engine in my son in laws boat.

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O2 Sensors - Is Dry Over The Transom the only option?

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