Cat Power and MPG?

But we look COOL

 

I have a 2000 Century with a Cat C 15 that had a similiar problem. Power and mpg was lacking, there was a vibration under load, the mpg calculated by using the tank numbers was about 15% better than the number from the dash computer. Twice I had it in a shop for poor mpg and both times they did an injector cut out test and found nothing.

At 940k the engine sucked a valve and I had it rebuilt and rerated from 435 hp to 500 hp (they would not go higher and still warrenty it because it would have been too much torque for the clutch and transmission). When they did the rebuild they found that two of the injectors had cracked levers.

The injectors were supplying fuel at idle, so the cut out test failed to find anything wrong, but not their share under load. This was the cause of the vibration, low hp, low mpg and the difference between tank and dash mpg.

After the rebuild, when I drove the truck bobtail back from the shop, I thought that they had really screwed things up because the dash mpg was 10.5 mpg. They hadn't. Tank and dash mpg checked within one percent of each other.

I talked with the shop manager about the cracked lever problem, he said it was a common enough problem that shops did not want to look for. The levers get cracked because of overadjustment and pulling out and putting injectors back in is something that they want to avoid because of the risk of damage.

My advice is to get the injectors pulled out, inspected, and if possible, tested. While fuel prices are down this year, the cost of my engine rebuild was fully paid for by the increase in mpg last year.

Frenzy

 

i have an affection for IH's, I learned in a 94 with a little 350 horse cummins, 9 speed, 48" flattop. very basic, but always have fond memories of the first. the crew had 5 of em. there is one in the next town over that i wouldn't mind owning, but too bad its got a detroit...

 

What DDS is trying to tell you........is the spring in the wastegate actuator can become weak this allows the wastegate to open early. You may still maintain boost, but be less efficient.

After installing the 58's your turbo is going to be small for the job.........you're adding roughly 20% more fuel with no extra air to burn it completely.

 

If the wastegate opens early.......the engine gets sluggish........the turbo isn't working any harder, just slower to spool up and get the engine up to full power. So you waste fuel trying to get to full power.

I would say you could run the 58's with a stock turbo, but turbo life is going to be shorter. The reason is that you will over speed it trying to get the air movement the motor wants. If you leave the wastegate hooked up, then you may have issues with high exhaust temperatures. I've never seen anybody try the 58's without doing a turbo change.........so I can't say that it will work without any problems

 

Easy way to check if the wastegate is faulty... crimp the wastegate signal hose and go for a quick run with a load on, if the engine pulls heaps better then the wastegate needs attention, if there is no change in power then the wastegate actuator is working fine. With this you will always see a rise in boost pressure but more boost doesn't mean more power, just because boost goes up doesn't mean the wastegate is faulty. I wouldn't leave the wastegate crimped off for too long either or you may damage the turbo.