What is the difference, other than H.O. between ETC and ETH??? I just bought a 04 2500 HD 4x4 and I was told that I have the ETH engine. I know the ETH is the high-performance version but what is the difference?

 

I believe that the major differences are different tuning, and the HO engines have oil cooled pistons.

 

The ETH is the 04.5 model with as you know more horsepower and torque. They also have a Cat in the exhuast system and 3 injection events. The 3 injection events add to the quietness of the engine. The Cat of course cleans up the exhaust. The ETH has a 4 inch exhaust system from turbo all the way out. They reportedly get slightly lower mileage than the ETC. IMO either makes a good choice.

 

Check the "advertised hp" number on the white sticker on the driver's side of the valve cover. It'll either be 305 or 325. The 305 hp engine was 305hp/555tq. The other would be 325/600. If you can, you can also get the CPL number (Control Parts List) off the sticker and find out all you need to know by decoding that number. It'll be a 4 digit number like 8344.

 

We all have piston cooling nozzles.