Cummins Big Cam HP Questions - Page 2 - Competition Diesel.Com

fld · 12-18-2013, 06:04 PM

You're right it's being in the dark. And something like this, I like to learn as much about as possible.

And thank you , that makes alot of sense and that is exactly what I will do.

I think what snedge wrote above is a really good basic target for turning it up. Of my math is correct, that's a little over 20% increase that probably puts you somewhere between 475 and 500.

I would think that hp perfectly safe, and that pressure perfectly safe also, driven properly. We'll see about mileage.

I got to tell you guys, I really like the idea of this engine. I have never driven anything that I enjoyed more than this engine. I like the mechanical simplicity of it, I like that the jake brake stops me dead in my tracks, I like that it is very simple to alter the hp, I like that I can work on it myself, and I like that parts are pretty reasonable. And it is fun to drive.

Joesixpack · 12-18-2013, 06:13 PM

They are a great engine, have a few around. Your not likely going to get to that pressure by just drilling the tamper ball out of the throttle shaft and backing out the screw.

You start pulling hills or accelerating with 215+ rail, you will use more fuel. Guaranteed.

We always install a pressure gauge in the cab and watch rail, gives you a really good idea of load and a visual indicator to minimize it to gain economy.

RockinRam96 · 12-18-2013, 07:49 PM

When I sent my pump in to be rebuild I was told that it was set at 160 psi of rail pressure. I got it rebuilt and the shop set it at 200 psi. Now it's up to around 290 at WOT before free rev. No idea what mileage is like.

My 855 is the first big diesel I've owned. I've always been a Cat guy and known about Cats because that's all my father has owned. I really like this motor, too. I am really looking forward to messing with it more and trying to make the power I've been told by many that I can't make, with a small cam.

FLD, just remember that there's motors may be rated at 400 hp from the factory, but that is flywheel horsepower. You should figure about 25% driveline loss in power. So, 500 hp at the wheels is a lot different than 500 hp at the flywheel.

12-18-2013, 06:04 PM	#21
fld Name: fld Title: Rookie Status: Not Here Join Date: Dec 2013 Member`s Gallery Posts: 9	You're right it's being in the dark. And something like this, I like to learn as much about as possible. And thank you , that makes alot of sense and that is exactly what I will do. I think what snedge wrote above is a really good basic target for turning it up. Of my math is correct, that's a little over 20% increase that probably puts you somewhere between 475 and 500. I would think that hp perfectly safe, and that pressure perfectly safe also, driven properly. We'll see about mileage. I got to tell you guys, I really like the idea of this engine. I have never driven anything that I enjoyed more than this engine. I like the mechanical simplicity of it, I like that the jake brake stops me dead in my tracks, I like that it is very simple to alter the hp, I like that I can work on it myself, and I like that parts are pretty reasonable. And it is fun to drive. Last edited by fld; 12-18-2013 at 06:11 PM.

12-18-2013, 06:13 PM	#22
Joesixpack Name: Joesixpack Title: Pull'n it. Status: Not Here Join Date: Apr 2008 Member`s Gallery Posts: 4,118	They are a great engine, have a few around. Your not likely going to get to that pressure by just drilling the tamper ball out of the throttle shaft and backing out the screw. You start pulling hills or accelerating with 215+ rail, you will use more fuel. Guaranteed. We always install a pressure gauge in the cab and watch rail, gives you a really good idea of load and a visual indicator to minimize it to gain economy. __________________ Basically stock if I would have built it at the factory.....

12-18-2013, 07:49 PM	#23
RockinRam96 Name: RockinRam96 Title: Too Much Time Status: Not Here Join Date: Sep 2011 Location: Shortsville, NY Member`s Gallery Posts: 2,699	When I sent my pump in to be rebuild I was told that it was set at 160 psi of rail pressure. I got it rebuilt and the shop set it at 200 psi. Now it's up to around 290 at WOT before free rev. No idea what mileage is like. My 855 is the first big diesel I've owned. I've always been a Cat guy and known about Cats because that's all my father has owned. I really like this motor, too. I am really looking forward to messing with it more and trying to make the power I've been told by many that I can't make, with a small cam. FLD, just remember that there's motors may be rated at 400 hp from the factory, but that is flywheel horsepower. You should figure about 25% driveline loss in power. So, 500 hp at the wheels is a lot different than 500 hp at the flywheel. __________________ 05 Jeep Liberty CRD 11 Dodge 1986 Freightliner Cat 425