325HP or 340HP?

[Sea N' Things]

Hey guys another topic for discussion, what does everyone think of the new 340hp Indmar with the Catalytic Converter. My understanding is that all USA boats has to be equiped with the converter starting Jan 2012 and Canada will follow commencing Jan 2013. Does it really make that much of a difference? Is the 340hp harder on fuel than the 325hp? Is the biggest difference on the top end (speed) or bottom end (power)? I had someone say that the converter produces alot more heat in the engine compartment...?

[rdlangston13]

Hey guys another topic for discussion, what does everyone think of the new 340hp Indmar with the Catalytic Converter. My understanding is that all USA boats has to be equiped with the converter starting Jan 2012 and Canada will follow commencing Jan 2013. Does it really make that much of a difference? Is the 340hp harder on fuel than the 325hp? Is the biggest difference on the top end (speed) or bottom end (power)? I had someone say that the converter produces alot more heat in the engine compartment...?


they do produce more heat. all a catalytic converter does is trapped unburned fuel particles and burn them so you dont have any hydro carbons leaving the exhaust. just an example of how hot they get. on truck in fields they have been known to start grass fires.

i wish you could get a 340 or 409 horse without cats. one more expensive ass part that can break

[Sea N' Things]

WOW that's hot. Does it make a diff with the air quality behind the boat while surfing etc...?

[rdlangston13]

it should cut down on HC and CO emissions from the tail pipe so you will have primarily H2O and CO2 coming from your exhaust. there will still be some CO but not as much as without CATS

[Ian Brantford]

I have the 340 and my buddy has the 325. We both have XLV's. The main difference is in top end, not bottom end. The 340 revs higher, but REALLY drinks gas when you use the extra capacity. So, I rarely make use of it.

[Sea N' Things]

what do you have in your boat for hp?

[sandm]

can't speak to the difference between those 2, but I do notice that when surfing behind my friends sanger w/o cats, you can get a whiff of exhaust if the wind is right. I have not ever noticed exhaust smells behind mine.

what will be interesting to see will be the first cases of having to replace them and costs associated with. would also be interested to see if gutting them like cars will produce extra hp once they do go if you decide not to replace.
granted it was force fed, but I picked up over 20whp ditching the cat on my last 2 mitsu evo's.

[Sea N' Things]

Now that is an interesting thought, but would it be madatory to replace the cats if the boat was sold with cats?

[KG's Supra24]

Now that is an interesting thought, but would it be madatory to replace the cats if the boat was sold with cats?

How would it be enforced?

I just pulled the cat out of the truck a couple weeks ago.

[Razzman]

Now that is an interesting thought, but would it be madatory to replace the cats if the boat was sold with cats?

The 340 CAT ECM is programmed for the engine and takes into account things like the cat, without one it would more than likely go into limp mode. Being as it's now required in California and soon everywhere else, dealers would not be able to modify things like the ECM by law. If caught it's a very major fine for doing so. SO in a nutshell your stuck with it. The good part is cats last a lot longer than they used to. For the record i've never had to replace one on any of my vehicles and i've had cats since they were law way back when.

[Razzman]

How would it be enforced?

I just pulled the cat out of the truck a couple weeks ago.

Depends on your state laws. In cali we have to smog test vehicles every two years whether we want to or not. No cat on a required vehicle gets you a fine as well as the cost of putting one back on. They come on motorcycles in cali now too, modify anything and it's a ticket and fine. Dealers will no longer replace exhaust on m/c's.

Now Cali wants to start checking boats, who cares it's a good thing. It WILL be nationwide soon, mark my words. They've been pushing for ALL vehicles checks nationwide for some time and will come to be. This is supposed to include all on / off road vehicles to include watercraft. They've already outlawed two stroke motors in Cali so all the people with them are hosed. It's coming and there's no way out of it.

[Sea N' Things]

The 340 CAT ECM is programmed for the engine and takes into account things like the cat, without one it would more than likely go into limp mode. Being as it's now required in California and soon everywhere else, dealers would not be able to modify things like the ECM by law. If caught it's a very major fine for doing so. SO in a nutshell your stuck with it. The good part is cats last a lot longer than they used to. For the record i've never had to replace one on any of my vehicles and i've had cats since they were law way back when.

Good point Razz, that's right the engine is programmed and tuned with the cats. It's also interesting to get feedback about hp especially on the XLV (bigger boat but only 300lbs heaver), bottom end appears to be the same between the 340 and 325 but top end does suffer a little, I guess the prop would make a hugh difference in the case on the bottom end power on the XLV.

[KG's Supra24]

That is true, it depends on the state as far as inspections. Plus you would have to retune the ECM.

Honestly though, I find it hard to believe mandatory nationwide emissions test will go into effect anytime soon, especially for on and off road vehicles. That would require alot of money from the states.

Guess Cali has the money to spend ... oh wait ... not even close :p

[Sea N' Things]

It would definitely be a massive undertaking for any town, city, state or country to enforce this reg but not impossible, perhaps the replacement parts will be more affordable as cats become more popular and their live expectancy expire.

[cham]

I'm not up to speed on boat cats but automotive cats are just platinum material in the exhaust stream that acts as a catalyst to remove the nox from the exhaust stream. There really isn't anything in there to "break" and they rarely fail.

But they also have to get very hot to start working and our exhaust streams are cooled so I'm curious as to how the boat one works.

[rdlangston13]

My mom had to replace one on her Nissan Xterra at about 75,000 miles. Good thing was emissions equipment (on cars any way) had a longer warranty than the rest of the car, I think it is about 80k miles.

I would not think the boat would go into limp mode without a cat, cars do not do that so I do not know why a boat would, doesn't make a lot of sense to me. It would for sure though a check engine light for a cat inefficiency code when the O2 sensor behind the cat reads the same as the O2 sensor in front of the cat.

[sandm]

the ones I pulled on the cars don't send it into "limp" mode, all they do is throw a code. your ecu thinks that the cats have failed, but it doesn't adjust the engine at all. buy 2 spark plug antifoulers from autozone, drill them out and presto, cel is gone.
our county does emissions checks and if no pass, no registrations. most are going to do the least amount of work possible during the day(not all, but the ones that I have run into are). all the county requires from the private testing stations is to plug into the obd2 port and read codes. clear ecu=passed emissions :) 7 years, no cats, and never had one bother to look under the car.
boats will be a very long time outside of cali before there are any inspections being performed. heck, you can still run a 1940's 2stroke oil burner on any lake.

[Sea N' Things]

True that sandm...

[rdlangston13]

Cali has a lot of weird/stupid laws. Did you know it is the only state where they average 1200 deaths a year due to construction equipment exhaust polluting the air?

All these rules are while people and businesses are leaving California in droves.

As for Cats removing NOX, I was always under the impression that NOX was formed when combustion chamber temperatures exceeded 2500 degrees F. The EGR was invented to deal with NOX, I always understood it that Cats were there for HCs or hydro carbons, becuase a modern fuel injected engine oscillates from rich to lean constantly.

Modern advances in variable valve train technology has made EGRs obsolete as well.

Soon NASCAR is going to have to have Cats on their cars when they go race at Infenion or Fontana.

[sandm]

Soon NASCAR is going to have to have Cats on their cars when they go race at Infenion or Fontana.

that's not a bad idea. all that driving in circles has to push all the engine smog into one concentrated area. no wonder that guy that won the daytona couldn't find the winners circle :)

[rdlangston13]

that's not a bad idea. all that driving in circles has to push all the engine smog into one concentrated area. no wonder that guy that won the daytona couldn't find the winners circle :)

could you imagine being in the infield of bristol if the cars exhaust exited the left side of the car??

i honestly think that being an outdoor sport the smog dissipates fairly quickly

[sandm]

so wait, they exit to the right? that explains a lot about nascar fans :)

[rdlangston13]

it does say something about NASCAR fans...that we like the smell of 98 octane race fuel! YUM!

[schuylski]

about the exhaust stream getting warm, i thought i saw that the CAT engines have the separate cooling systems and are not raw water cooled through the engine - they've got different requirements with the cooling.

[cham]

about the exhaust stream getting warm, i thought i saw that the CAT engines have the separate cooling systems and are not raw water cooled through the engine - they've got different requirements with the cooling.

I would think the exhaust would have to be cooled to be in a boat. Exhaust temps are extreme and would quickly start to cause problems in the engine compartment.

[sandm]

I know when I start mine up with the fake lake, water pours out the exhaust just like my buddies boomerang.

[schuylski]

HA! Ok oops not what I meant at all - Don't know if I'm even right, but I meant that I think the cat ext has the closed system for cooling. Water still comes out the exhaust but the raw water doesn't actually go through all the engine channels.

[sandm]

in order for you to have a closed cooling system, you must have a radiator and a heat exchanger. the extcat's are cooled by the lake/river water just like the non-cat motors unless you opt for the closed cooling system or a saltwater package. follow the hoses off your raw water pump and you will see where they dump into.

[moombabound]

Back onto the track...the real benefit of the 340 is the reduction in emissions. The difference vs the 325 is night and day. A 340 would be my recommended #1 mandatory for a Moomba. If you do any surfing, you will eat alot of CO behind a 325. The 325 w/CAT will be along in due time. CAT should be mandatory, not for environmental reasons, for participant safety. A local dealer of a competing brand does not order any Indmar 325s.
As a side benefit, you won't need to dwell on whether to struggle with installing a Fresh Air Exhaust system.

[maxpower220]

Back onto the track...the real benefit of the 340 is the reduction in emissions. The difference vs the 325 is night and day. A 340 would be my recommended #1 mandatory for a Moomba. If you do any surfing, you will eat alot of CO behind a 325. The 325 w/CAT will be along in due time. CAT should be mandatory, not for environmental reasons, for participant safety. A local dealer of a competing brand does not order any Indmar 325s.
As a side benefit, you won't need to dwell on whether to struggle with installing a Fresh Air Exhaust system.

Funny, at 34 mph I don't smell anything and doubt I am getting any CO. The "struggle" of my FAE is that I now don't have to listen to exhaust noise. Also, your dealer has a markup on engines as well.

15 hp in a 3500lb boat isn't much, The 310 hp in my 99 Malibu would walk away from the 325 in my new boat, different hull, running surface, etc.

[c.rix]

i have noticed that the cat motor is quieter also which is kinda nice too

[moombabound]

Funny, at 34 mph I don't smell anything and doubt I am getting any CO...

You surf at 34 mph? Post video.