Indmar’s ETX CAT Manifold w/ Data

While many said it couldn’t be done, Indmar said it could. And as the data confirms, they were right. We understand there is some apprehension towards the new EXT CAT system, but hopefully this article will help to dispel those thoughts. We’ll start with a quick overview of a CAT system, then relay some test data and stats gathered during testing of the new CAT system. At the bottom of this article is a link to an article printed in Boating Magazine. It is pretty informative and is written independently of Malibu or Indmar.

For those just tuning in (ETX= Extreme Tuned Exhaust, Get it?), let me explain what a catalyst is and its purpose in life. A catalyst is a substance that affects the rate of a chemical reaction, but does not get consumed by the reaction. That seems pretty straight forward, so we’ll define a catalytic converter. A catalytic converter is a chemical filter connected to the exhaust of an engine and designed to react with the fumes so as to reduce air pollution.

As you can imagine, this was not a simple “plug and play” application. Several other changes had to be made to allow this system to work. With the introduction of this system, the ETX manifolds were going to run warmer than they have in the past. To compensate for that, the flow of the cooling system has been rerouted to cool the added temperature of the exhaust manifolds. The CAT manifolds will run at temperatures less than 200F. As a precaution, Indmar recommends that you Let engine temp “normalize” before shutting down the motor, and run bilge blower both before start-up and after shutdown. Indmar also recommends you replace the impeller at least every other season.

The fuel system was also changed to a closed loop fuel system. A closed loop system uses oxygen sensors to adjust the fuel to match the air flow through the engine. By adjusting the fuel ratio using data collected from the oxygen sensor, fuel burn is more efficient with the catalyst left to burn the rest. At 4200 RPMs, the fuel system goes out of closed loop. What does this mean to you? Better fuel efficiency than the 2006 Monsoon with the EXT Manifolds. 6-10% better fuel efficiency to be exact.

What is the impact to the environment and to your family? A realized reduction in harmful exhaust emissions. Specifically, a reduction in Hydrocarbons (HC) and Oxides of Nitrogen (NOx) to less than 5 grams per KW-hr combined. The 2006 model lineup reported a 11.74 grams per KW-hr combined. Carbon Monoxide (CO) levels are also reduced to negligible levels. While there is currently no regulation for CO levels, the added safety should put Mom’s mind at ease when the kids are out wakesurfing.

Now let’s take a look at some performance data. Indmar took a motor installed in a boat with a conventional exhaust system and did some base line testing. Indmar then took that same engine in the same boat and converted it to use the new ETX CAT exhaust system. While a little over-propped in the first example, you can clearly see the performance data speaks for itself. Further below, you’ll see some more trials, performed in the same manner, but with a boat propped correctly. Sorry about the image quality.

Propped 4850 rpm – Peak Speed .02 mph FASTER
Acceleration:
0-20 mph: .45 seconds, 6.47 feet FASTER
0-30 mph: .35 seconds, 3.13 feet FASTER
0-200 feet: .28 seconds FASTER

Propped 5250 rpm – Peak Speed 1.29 mph FASTER
Acceleration:
0-20 mph: .41 seconds, 7.08 feet FASTER
0-30 mph: .82 seconds, 22.8 feet FASTER
0-200 feet: .37 seconds FASTER

To read more about the new ETX CAT Manifolds, check out an article in Boating Magazine found here.

You can also check out Indmar’s site for additional information.