Misleading Engine Performance Specifications in Inboard Boats

There has been a lot of confusion regarding published performance specifications in the Inboard Tow Boat segment.  Some of the engine and boat manufacturers published HP ratings that have been found to be "optimistic" when compared to scientifically derived test data. 

MasterCraft started offering Ilmor Marine engines in late 2010.  If you are not familiar with Ilmor please CLICK HERE.  Ilmor designed and built the most powerful engine to ever race in the Indy 500 and engines powering Formula 1 world champions.  With their performance heritage and talent, Ilmor told MasterCraft that whatever engine performance they wanted was available but but that performance specifications would not be overstated.

It was decided that the only way to publish real specifications and provide information that would help consumers see thru some of the misinformation from other vendors was to use data from the California Air Resources (CARB).  California has more restrictive emissions standards than the other 49 states.  All engines sold in California are tested to EPA standards for emissions and peak output in kilowatts(kw).  Kilowatts can be converted to HP by multiplying kw * 1.34.

Ilmor's GM Based 5.7 was the highest performance GM 5.7 engine from any manufacturer when tested by CARB and produced 320 HP.  PCM was claiming 343 HP from an engine that only produced 282 when tested by CARB.  Indmar's 5.7 Engines produced between 288 and 308 HP but as much as 350 HP was claimed.

We note this so new and used boat buyers can look to this data when comparing engines in boats.  We have seen customers confused when comparing actual data provided by Ilmor and CARB to data provided by a marketing department.  Here is a chart showing CARB's test data by engine family. 

Tow Boat HP from CARB.jpg

Engine torque is also very important in marine engine performance.  Indmar, the current engine provider to Supra, Moomba, Malibu, & Tige recently switched from GM to Ford based engines.  When the switch was made Indmar started marketing engine torque rather than HP.  The thing to be aware of is many boat manufacturers, dealers and sales reps represent torque output on Indmar Ford based engines as HP.  Indmar makes four versions of the 6.2L Ford engine that had been used previous versions of the Raptor Truck and can currently be found in Ford Super Duty trucks.  The different versions produce 360, 400, 440, & 575 Ft. Lbs. of torque.  Malibu chooses to call their versions of the Indmar/Ford engines with 10 additional Ft. Lbs. but they are the same engines.

The Indmar 6.2 Raptor that is the standard engine in most Moomba and Supra boats produces 350 HP and 400 Ft. Lbs. of torque.

Our advice is to use CARB's testing data when comparing engines from different manufacturers because this is the only data compiled using EPA testing standards so the playing field is level.

The link below is for the California Air Resource Bureau (CARB) web site. It takes you to reports which list the specific output of the engines CARB has authorized for sale in the state of California. Output is reported in Kilowatts (kw). To convert kw into horsepower simply multiply the kw rating by 1.34 to see the equivalent horsepower rating.

Once on the website select “Spark Ignited marine engines” and the model year depending on the model year of the boat that you are comparing, then click “browse”.

From here you can select Indmar, PCM or Ilmor engines and hit “submit” to be taken to their respective reports. Indmar shows each displacement listed separately because they “sub-brand” their engines based on the boat builder’s they supply. The actual CARB certificate has more detailed information.