2008 cummins ISL 425

[garybtt]

Is there anyone out there with this new engine that can report on performance? This engine is availble on Horizons and Vectras.

[garybtt]

Is there anyone out there with this new engine that can report on performance? This engine is availble on Horizons and Vectras.

[Route 66]

I took a test drive Friday with a 2008 Dutch Star here at the Newmar factory.

It has the 425HP ULSD engine.

On part of the test drive, the factory rep had me floor it from about 5 MPH until we reached 65 MPH.

There is no performance problem with this engine in normal driving or hard acceleration.

I found no real difference between the 2008 425 HP engine and my 2007 400 HP engine. I didn't expect the additional 25 HP to make much difference, and it didn't. The torque is the same.

I would not hesitate to buy a RV with a ULSD engine.

[Cruzer]

The power graph between the 370 ISL, 400 ISL, and 425 ISL is very similar. Basically it's nice and fat until it get's up to the higher revs, then the extra power comes in. The only time that you'll see those extra 25 ponies is when you are climbing a real steep grade and the engine is wound up in excess of 1900 RPM. For 95% of your driving it'll feel the same as the 400 ISL.

The new engines aren't out there that much yet because most people in the market jumped the gun and bought one of the earlier engines to eliminate any hassles with ULSD. Still, they are starting to filter into owners' hands now.

An RVer recently bought a new 2008 Allegro Bus with the 425 ISL on a Freightliner chassis. The Bus is available with your choice of Freightliner, Spartan, or Tiffin's own Powerglide chassis. Previous Freightliner XC units with the 400 ISL and side radiator had a marginal cooling system and had a tendancy to run hot and overheat on steep grades. Freightliner has changed the cooling system on the new ULSD spec chassis (I believe they are even using two fans now) and the owner reported much cooler temperatures compared to the older XC chassis and was happy with the engine for the first 1,400 miles.

However, once he hooked up his toad he melted three Remco lube pumps and there were various other signs of heat damage on the toad. The exhaust from the DPF gets much hotter than the older engines and can reach temps of 1,200 degrees inside the DPF before being exhausted. Unlike Spartan and Powerglide, who direct their tailpipes out the side, Freightliner has chosen to direct their tailpipe straight out the back. This heat is basically melting the toad like a giant flamethrower. Freightliner has stated that they can't go out the side because the frame is now in the way so now they have a problem on their hands.

So, this is something to be aware of if you are looking at a new 425 ISL on a Freightliner chassis. Apparently the engines are running fine but the direction of the exhaust is a problem for anything behind the coach. I'm sure they're going to have to come up with something to remedy this. Exhaust stacks maybe?

[jimandsue60]

Cruzer, I think that issue has already been addressed. Here are a couple of pictures of a 425HP Vectra on display at the Winnebago Visitor Center in Forest City. The exhaust is coming out the left side in a fluted type exhaust pipe. The air cleaner has been turned horizontal front to rear.

Jim

[jimandsue60]

Maybe it is a Winnebago mod and not freightliner?

Jim

[Cruzer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jimandsue60:
Maybe it is a Winnebago mod and not freightliner?

Jim </div></BLOCKQUOTE>

I bet you're right. I see the steel shielding around the fiberglass opening too. That's a good idea to prevent the fiberglass from burning.

[jimandsue60]

The exhaust pipe underneath was also wrapped with some type of protective cloth.

Jim

[Thudman]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">The exhaust is coming out the left side in a fluted type exhaust pipe. </div></BLOCKQUOTE>

Appears to me to be a dust-maker in dry, non-hard surfaced roads/campgrounds.

Thudman

[garybtt]

I was told it is fluted as the exhaust is very hot due to the combustion of the solids in the converter.