2008 isx how do they pull

Been there, but I don't really want to go back. I remember driving an old Detroit 671 with a Spicer 7 speed and Eaton 3-speed tandem (anyone remeber those?) in a GMC Astro. It was an ol' Schlumberger truck and we still have it--out back! Talk about a slow POS! Took almost two miles to get to 55mph on flat ground. However, it did pave the way for newer and better things, and it did get the job done.

I now have the ISX-600 in a 2009 389. So far, it's been a good engine, and certainly less complicated than the twin turbo offerings. However, 600hp is total overkill in my opinion. I was dead set on the 600 and really didn't think it over before I ordered the truck. If you drive conservatively--keeping your rpms less than 1500 under normal conditions--I think you're better off with a 525 in the family 3, or a 485 or 500 in the family 2. They will be producing roughly the same power as the 600 in the lower RPMs. You only reach those advertised 600 horses above 1700rpm--I don't drive like that.

FWIW, my next order will likely be the 455ST. There are tradeoffs though. It's a family 2 engine, uprateable 'as-is' to only 500 and 550 outside of warranty. The family 3 adds scissor-style gears with a different turbo, lube cooler, injectors, and cam. However, anything under 460hp on the Cummins extended warranty plans is considerably cheaper, not to mention the engine itself being considerably less expensive. Considering the fact that I got along just fine with a 350 BCIV w/1200lbs-ft # 1300rpm pulling at times over 80,000lbs., the 455ST w/1550-1750lbs-ft # 1200rpm ought to do just fine. I won't lose my pride if someone passes me. I'll likely pull up right beside them at the next red light.

 

Problem is how hard it is to compare pre and post DPF age engines and ECMs. Its hard to beat a pre '07 CAT engine in anything but emissions. Which of course is pretty much the reason CAT is leaving the business. Look at the hot side of a post '07 CAT and compare it to the cummins and you see why the life-time repair costs are so much different.

There are huge differences between the way CAT and Cummins do progressive-shift and driver inducement. The cummins ECM starts cutting torque much more aggressively than a CAT does. So its really hard to compare one ISX to another without looking at parameters much less comparing it to a pre-'07 CAT.

 

Cummins only starts cutting the torque back on certain calibrations that certain companies want. That way the company still has a decent truck after 300,000 miles with a new driver in the seat.

 

I've also seen many differences on the ISX engines, even on the same order of 50 trucks, for the same company. Even just the intake piping alone from the CAC to the intake manifold. Some were pinched down to almost 2" in diameter, and the others were still the same size as what came off of the CAC hump hose. Same 530hp rating as well.

 

The company I drive for has a few isx and a bunch of C15s (bridged and non bridged) and the ISX spanks them in MPG and the hills.

I run a bridged with a Fuel temp wire only. On wed I was grossing about 97,000 and was running with another driver that was running an ISX. He grosses a tad over 100,000 and he passed me in the hills and got better then 2 mpg better then I did for the day. We both left from the same place, went to the same warehouse and unloaded at the same plant. About 540 miles round trip.