Indmar catalytic converters -- thumbs up or down?

Trying to get an idea of how well the Indmar catalytic converters have worked out so far. Are people having issues with them? Are they insanely expensive to replace?

Also, for the MC folks, is it only the MCX that has them? Is there such a thing as a closed cooling/closed loop cooling ETX/CAT setup? (Not that clear from the catalogue/build-a boat)

Gracias.

(Message edited by fbroen on October 09, 2007)

For MC yes for 2007 only the 350 MCX has the Cat. For 2008 though I think all their engines have them. Don't know about the closed cooling setup?
I think the CAT system is relatively new so not sure if anyone has had to replace them yet. No issues with the CAT.

My boat only has 65 hours on it ( new indmar 340) no issues with the catalytics.

closed cooling is closed only for the block. The pump in the engine circulates antifreze in the block, thermostat and an extra heat exchanger and river water is pulled up from raw water pump and passes through this heat exchanger (used like a car's radiator in this setup) and exits through the exhaust just like raw water cooled engines. The ETX cat would see the same conditions whether it is normal or closed cooling.

I could be wrong, but I thought that there was an option to have the ETXs closed loop cooled as well?

That is, the raw water would only go to the heat exchanger and back out (not thru the exhaust). Maybe I am smoking something?

The Crusader Marine engines do offer the freshwater cooled manifolds. Indmar doesn't?

http://www.crusaderengines.com/NewFiles/5057specs.pdf

MC isnt using Crusader anymore for 08. Indmar has a true saltwater engine now. The EXTCAT in my 07 is a lot stronger than my 06 was. No complaints here. I think the MCX is the only one to have Cats in MC's lineup for 08.

Been reading that all new engines will have to have cat's come 2009. At least in CA. It will be interesting to see what's up with the Indmar engines when more and more hours are put on.

Nothing but great things to say at 135 hours in my Supra 22SSV. Now when I get in a boat without it the smell is annoying, I would never go back. I think the fuel economy is a little better too.

cant see a cat which restricts the motors ability to breath allowing for better fuel economy?

In order to protect the cat, they have to control the fuel metering more precisely than an open loop air density system can do, so he is correct in saying they will get better fuel economy, but not by much.

FWIW a cat does not restrict the motors ability to breath if it is the correct size. In fact some back pressure is desired to improve bottom end. Hence why headers and minimal exhaust systems suck for low end torque.

My 07 MCX has it-Love it!. No exhaust smell at all and more enviromentally responsible.

'Hence why headers and minimal exhaust systems suck for low end torque'

Only if the wrong size/length tubing is used. Headers come in all different sizes and lengths. The trick is to properly size the headers to the application. I would say most people don't do this, and then complain about low end torque...

^Then you lose top end. Trade off is the key word, but that was not my point. We care more about torque than peak RPM HP, with a wakeboarding boat.

I still say bull. Cats are not designed to be more effiecent economy whise, thats the job of a FUEL INJECTION system. Cats are for enviromental cleanliness.

show me some documentation that supports that theory of efiencey and closed loop open loop? and ill buy what your sellin. I could be wrong.

I can see the benefit of it burning cleaner.

until it plugs up and you have to replace it how much do they cost to replace? (cats dont last for ever)

Whenever I am behind or even relatively close to an older car w/o a cat, it really stinks. I can't imagine what it was like in traffic b4 cars has cats.

Cars w/ cats have almost no exhaust smell, if we can get boats that way, I'm all for it. This would be one of very few reasons that I would consider buying a new newer boat.

I do not claim to know the answer, but according to Boating Magazine's test, fuel economy is improved:

"Fuel economy, however, was significantly improved by the ETX/CAT system. We measured an 8 percent gain at 30 mph, a 12 percent gain at 20 mph, and a 28 percent gain at idle. The boost in economy occurs because this closed-loop system uses an oxygen sensor to control fuel delivery with more precision than on a standard EFI system."

http://www.boatingmag.com/article.asp?section_id=8&article_id=858

Yeah !! take that.

great article!

28% better at idle. THAT SHOULD make for a much cleaner burning motor. I like the use of the 02 sensor. my biggest concern would be what the longevity of this system will be in 8 - 10 years down the road? could be a troubleshooting nightmare for a boat that is old and not being serviced by the dealer any more.

Indmar claims to be fasing out all motors that do not use this system by the time the CARBS deadline is enforced.

the future is clear its clean burning low enviro impact motors. It will maybe create a new industry too. SMOG for boats! imagine if dealers can charge money to smog your boat as well!

"show me some documentation that supports that theory of efiencey and closed loop open loop? and ill buy what your sellin. I could be wrong."

If you will really buy what I am selling, then I will take the time to explain long term and short term fuel trims, along with how a modern fuel injected system works. After all I help people acquire expensive equipment and software, and could always use another sale.

To simplify it look here
http://en.wikipedia.org/wiki/Air-fuel_ratio

Oh and your wrong

A properly set up cat will not take power away, and they will last a long time if the engine runs correctly. Any misfires will begin damaging a cat in a matter of minutes.

FWIW if anyone ever needs a cat for their car, do not buy the cheap crap as they will not last. Purchase an OEM cat for $$$. The after markets for half the cost have 1/4 of the bed inside of them.

yes he did i read it, you got me peter

I am well aware of how a fuel injection system works. ASE certified mechanic circa 1996.


better fuel economy but at wakeboard speed its 12% not a huge gain, id say biggest advantage is cleanliness!

the cat does not have anything to do with the effiency that is the job of the o2 sensor which is part of the fuel injection system. the article clearly states the abiltiy to run an 02 element that is capable of withstanding moisture and will hold up in a marine enviroment.

awesome idea really

but dont think for a second those manifolds are going to be cheap to replace. its on a boat! and we all know what boats are! crap the exhaust manifolds on them now is $$$

I def agree with you on the aftermarket cats though.