Need some Duramax info

[andydew]

Does your pcm know that the dpf has been removed?

Yah,

I had to buy the edge programmer when I found out...that the computer found out... I unbolted the dpf

That's good to hear DF, I was always told the turbos would start frying bearings past 1200. That's when I always back out of it.

And yah, I never had a guage before when I pulled the boat up to mead; I'm curious what she'll run on the hills. Sounds like it'll be more than I thought was safe.

[wingnut]

Sounding like these temps are common on pickups. It baffles me a bit though why they run that hot. One idea I had was rigs run vertical stacks; maybe the heat rising evacuates the heat away from the turbo quicker, than the pickups down and out flow?

Thanks for the link, I'll check out some feedback for removing the cat for a free flowing exh. on there.

Sorry, if I got a little :rainbow1:, just always trying to learn up on the diesel stuff

Running stacks wont reduce egt's. Big Rigs run stacks because the exhaust has no where else it can be routed.

Fuel causes heat. The more fuel the higher the heat. That's why programmers and tuners raise egt's. Higher line pressure and more fuel. Stock turbos are one of the biggest issues for heat. If you want to reduce egt's there are several things you can do. Bigger intercooler, bigger intake elbow, bigger manifold(s) bigger turbo water/meth injection. If your an unfortunate one that has a corked up truck do to emmisions equipment you can delete those(egr, dpf cat). Then you will have warranty issues, though.

Edited June 30, 2010 by wingnut

[andydew]

Running stacks wont reduce egt's. Big Rigs run stacks because the exhaust has no where else it can be routed.Fuel causes heat. The more fuel the higher the heat. That's why programmers and tuners raise egt's. Higher line pressure and more fuel. Stock turbos are one of the biggest issues for heat. If you want to reduce egt's there are several things you can do. Bigger intercooler, bigger intake elbow, bigger manifold(s) bigger turbo water/meth injection. If your an unfortunate one that has a corked up truck do to emmisions equipment you can delete those(egr, dpf cat). Then you will have warranty issues, though.

Nah, I don't want stacks on my pickup...just thinkin out loud.

I built a rig with 7" weed burner pipes, so it CAN go elsewhwere, btw. The jakes were a kick in the teeth for other motorists :rainbow1: However, My current rig is running twin 8" straight pipes( no muffler, no restriction, straight up). The exh. temps drop to 300 seconds after lifting from the throtlle.

Maybe I'm just comparing apples to oranges...I suppose these pickup motors would respond similialy if I spent some cash on the suggestions you mentioned...Sounds kinda spendy for me right now, though. And I certainly don't need any more power; I was thinking just a few hundred bucks for a 4" pipe from the turbo back, removing the cat, might help evacuate more heat, and hopefully increase my mpg. Mine is an '09, so it's all "corked up", or was. It currently dumps out a turn down behind the cat; no more dpf, no more muffler. And NO, no sawzall's were used in these mods...I've planned on having to reinstall stock exh. for things like smog tests, dealer visits , etc.

Thanks for the input. Gonna roll the dice on the warranty issues. It's a chevy , so I've got good odds :assrock:

[eli]

People worry too much about EGT's. Wanna know why? Because they put a gauge on it. Raptoroy put a gauge on his bone stock 07 LMN DMax. He wanted to see what his EGT's got up to when pulling his hauler with it bone stock. Guess, what...if you pretty much keep your foot in it you will see 1600+ with a bone stock Dmax.

I keep mine under 1450-1500 (under extreme conditions in short spurts). These motors can take it. I wouldn't go much more than that though. You could crack or melt a piston if held there and pushed hard enough.

Hey Pete I've got a question for you. I'm told that you can't hold a Dmax back going downhill by dropping gears preferably before you start down. True or False? I've driven a lot that doesn't hold back much but never driven anything that didn't hold back at all. Except of course my RZR if I don't keep a little gas on to keep the clutch locked up.

Guy that told me this rides his brakes all the way down and refuses to use the tranny. All I know is I'm going to continue following him down the hills and half expect to see a lot of brake smoke just before a big ole crash some day.

Eli

[sanddunesaddict]

^^^your guy doesnt have a clue.

thats why the truck has the tow haul mode built in.

[bp-guy]

Mine doesn't even need to be in the Tow/Haul mode. After a few seconds of riding the brake it downshifts a gear.

[andydew]

Hey Pete I've got a question for you. I'm told that you can't hold a Dmax back going downhill by dropping gears preferably before you start down. True or False? I've driven a lot that doesn't hold back much but never driven anything that didn't hold back at all. Except of course my RZR if I don't keep a little gas on to keep the clutch locked up.

Guy that told me this rides his brakes all the way down and refuses to use the tranny. All I know is I'm going to continue following him down the hills and half expect to see a lot of brake smoke just before a big ole crash some day.

Eli

I'd use the "tranny".

In trucking, were required to use the motor to slow us down. Those gravel run a way ramps are there for guys who don't :rainbow1:

The compression of the motor slows you down, thus saving the life of the brakes, and more importantly, keepin you, your passengers, and everyone else on the road safe. And like it has already been said; with an allison trans, if you have the tow/haul button in, it downshifts on a downhill automatically, after a few seconds on the brakes.

[eli]

In trucking, were required to use the motor to slow us down. Those gravel run a way ramps are there for guys who don't :rainbow1:

Been up and down a hill or two in a big ole truck. Many with over weight permit loads. My idea of heavy starts at 80,000 and goes up from there. Never been in an escape ramp and don't intend to start by putting a toy hauler in one.

This guy insists I don't know what I'm talking about and says Dmax are different. Never been down a hill in a 1 ton Dmax so I asked but still not planning on getting ahead of this guy on a hill:(

Eli

[dunefreak]

Never heard of anything like that Eli. Dmax's aren't any different. You are very wise...don't get in front of that clown. :rainbow1:

[andydew]

Been up and down a hill or two in a big ole truck. Many with over weight permit loads. My idea of heavy starts at 80,000 and goes up from there. Never been in an escape ramp and don't intend to start by putting a toy hauler in one.

This guy insists I don't know what I'm talking about and says Dmax are different. Never been down a hill in a 1 ton Dmax so I asked but still not planning on getting ahead of this guy on a hill:(

Eli

Right on;

I got a 16 tire expando lowbed, so I've seen some permit loads myself.

The dmax and allison is why I bought my pickup; I absolutely love the auto downshift feature. Next best thing to jakes.

I haven't run a gravel pit yet, but I've seen it a few times :ahhhhh: Lately, I saw a lowbed hauling an earthmover northbound going down the grapevine. He Musta been doin 90 :praying: He was all the way up top at the end of the ramp(and that's the steep,long one).Scary.

Your bud must be misinformed, to be nice about it.

always let the motor hold you back, with light and steady braking when necessary

[andydew]

I hear ya,

I only run setting 3 on my edge, or else I'll be up in bearing frying territory as well. I was just wondering why it gets so dang hot? My big caterpillars runs 1600+ ft.lbs. full throttle, and sees maybe 900 degrees. I'm thinking the catalytic converter is blocking up some flow

I thought I'd dig this thread out for an update:

I went and bought the 4" turbo back exhaust, to remove my catalytic converter too. I haven't seen much difference in fuel economy, or exh. temps, compared to when I removed just the DPF. I might have wasted $400 buying this, but I just had to find out for myself. I do notice the diesel smell A LOT MORE...Especially parking it in the garage;...Oh well.

I'm still getting around 12-13 mpg in town. (I'm considering full tank averages, not a short "feather footing spurt" of 25mpg.) I have yet to see if it''l improve on the highway. I was getting around 14 hwy. bone stock, and I got about 16-17hwy. with the DPF removed. I'll repost after I know for sure, in case anybody else is dealing with this emissions garbage.

As for the temps, I've still pegged 1450 next to, and then in front of, a loud "vacuum cleaner" ricer. I haven't seen any significant drop with the removal of my catalytic conv. Perplexed at the comparison of the big Caterpillar engines, I studied the exhaust and discovered the reason they're showing cooler exh. temps: I believe it's due to the location of the pyrometer bung/sensor. The big Cats have it after the turbo, where my duramax has it before the turbo. I think this would explain the almost instant drop in temps(at the gauge) when I let off in the rig.

Either way, One benefit to the turbo back pipe is the smoke!

I turned up the setting on the programmer for fun, and holy cow! I might've beat that ricer simply because he couldn't see the road