Glider Kit CAT OR Detroit

For the Detroit 515 hp model, max torque is up to 1500 rpm and it drops to 1600 foot pounds at 1600 rpm. 1600 is a pretty good happy medium but it gets max horse at 1800 rpm with 1503 foot pounds of torque.

http://internal.fdda.com/uploads/products/brochures/4.pdf

On the cat chart, it depends on the model but most find a happy medium at 1500ish. The 455hp finds its happy spot at 1400. For the 455, 1400 rpm is just before the torque drops off and your almost at max hp. This is probably the motor I drove. The 500hp motors seem to loose torque after 1500 rpms so 1500 would probably be best although i have no idea if the extra power is worth the fuel.

http://www.ciar.org/ttk/mbt/engine.cat.c15.pdf

 

guess it depends on the year, because this shows something completely different for the cat power curve. http://australia.cat.com/cda/files/2990003/7/P20454_Melbourne_C15ADR_Engine_Spec_Sheet_Rev2.pdf

 

It does depend on the year. He's talking about using a 2000 year model, and the curves are different now. But ok, look at the shape of the current HP curves. On a Detroit it climbs continuously to peak and drops off. Look at how the Cat peaks 200 rpm sooner and stays there for nearly 500 rpm. And don't discount that 200 lb-ft of torque, that's what drives the acceleration and makes a truck feel more powerful. What it means is that where you need to operate the truck for fuel mileage, the Cat (or a Cummins for that matter,) has far more available power. Yes, you can downshift the Detroit to make power, but then your fuel mileage goes right out the window. You just can't beat that extra torque, it let's you stay in high gear far longer, and means the engine has to produce a far lower percentage of it's total power to maintain road speed in cruise.

In the real world, a 475 Cat (or a 500 Cummins) will run off and hide from a 515 Detroit. Trust me on this, I've run with enough of my buddies to know. Can I stay a little closer by revving the dickens out of the Detroit? Yes, I can. But I'm not ever going to out pull one of them, no matter what I do, they just keep pulling away. I'm not saying the Detroit's not a good engine, it is. But you can't give up that much torque and expect equivalent performance.

 

1600-2100 is within 15 hp of peek HP Detroit
1400-1900 is within 15 hp of peek HP on Cat (first link)

Both have 500 rpm ranges. Now the graphs arn't supper clear, but they both are pretty similar. just 200 rpms off.

If you spec your rear end right you wont need to down shift. Not to mention I still get great mpg one gear down. The specs I posted show the same max torque so what are you talking about? Unless you go for the 550 with the 1850 torque, but from what i have read, that didn't come out until after 2000 and EGR which may or may not be available on a glider. All set and done, i challenge any one with a 500 hp cat to beet my 490 Detroit off the line or up a hill with the same weight load. Actually you may get off the line quicker, but that's cuz i got a 13 speed trans that got one leg in the grave....but ill def beet a cat up a hill.

the op says he's interested in short haul, 80,000 or less, ad MPG is important.

With 80,000 or less you don't want more then 500 hp because its just a waste. You will never use more then 500hp if you want good fuel economy for 80k or less. We all know the Detroit gets better MPG. OP never said anything about raceing up hill (even if you do think the cats better although we will have to agree to disagree). The best motor for his truck is clearly a cheaper to buy, cheaper to fix, more fuel efficient motor.

 

You go suuuppper trucker, whoop and ride

 

I am so glad you are here to school us.

 

If you think a 490 driptoit will stay with a 475 6nz on any hill pass me what you're smokin

 

who cares how fast you make it up a hill all that matters is it gets the job done and makes $$ i run with a lot of guys running cats and yeah they outpull me on the hills but when we have compaired fuel millage im 1.5-2mpg better than they are. i still run the same number of loads a day and run the same miles the difference in speed up the hills may make a 15 min difference at the end of the day. and thats if your running a lot of hard pulls. yeah it may hurt your ego to not be the first to the top of the hills but one look in my wallet and feel much better.

 

If your going to keep the truck for the next 10+ years Detroit seems good for your specs. If I were to build one out of pure resale value I would do the cat.

 

Well said.