So I've driven the Duramax for a couple of weeks.. driving impressions.

[OrangeCrush]

I've been asked by a few members on here to post my impressions. I wanted to drive the truck for a couple of weeks before I said anything.

First, I got the truck back from Travis and he did EVERYTHING he said he would. My biggest fear was that I'd get back my truck and it would be jerry rigged. (ie. missing clamps, zip ties holding stuff together, different size or missing bolts, etc, etc)

Nothing ruins a job IMO more than a sloppy half ass attempt to pull something off like this transformation. He did an excellent job. I can't find anything sloppy about his work. VERY, VERY PLEASED!


When I had my 6.0, I installed a supercharger on it. It helps, but the supercharger just never pulled the most unaerodynamic truck ever built like it should have.

And like most of you, I even had 4.56 gears to make up for the bigger tires. The truck simply didn't have the umphh it should have had. On the highway if I tried to tow anything (we all know the H2 isn't the best towing vehicle... not too bad when stock but liftkit and bigger tires....)


Drivetrain: When Travis did the conversion, he told me to just buy an entire truck. I bought a 2007.5 HD2500 Duramax truck that had been rolled. The truck had 49K miles on it. I didn't realize how many things he needed from that truck, it wasn't just drivetrain.

The engine was left stock. I did add a PPE tuner which has like 10 different power levels but I plan on only using the first 4. At this moment, I'm only running the 3rd level.

The Duramax puts out like 320HP, 630TQ from the factory so you can see what is added on at the 4th level.

Power Level HP Increase Torque Increase
1 40 97
2 90 160
3 160 240
4 225 335

When using the 4th level, the truck will be over 500HP and 900FT LBS of torque.

Everything I have read says that anything over 90-100 HP increase will shred the stock allison transmission so I had this guy Mike L's transmissions build a tranny for me with new converter. He said it was good for 800-1000 HP.


Driving impressions.

The truck drives like a stock HD 2500. There is less than a second waiting for the glow plug light to go off so you can start it almost immediately when it's cold. Once it's been driven, I have yet to see the light during the day. I'm sure many of you already knew that but I hadn't driven a diesel in a while.

The power is ridiculous. When I leave my house, in a few miles I get onto I-485 where the speed limit is 65. Most people are cruising in the morning between 75-80. So, as you merge on to the highway (it's uphill for at least 2 miles) you end up stepping on the gas to merge with traffic at the right speed.

When I had the supercharged 6.0, I had two choices.... I could either step on the gas hard enough to keep up with traffic which meant the poor transmission was coming out of overdrive and my gas mileage was 5-6 mpg until I reached the top of the hill

or

I could not let it get out of overdrive but only maintain a mid 60's speed and hope there was no other traffic tooling along at 75+.

Now, I can run 85-90 going up that hill AND NEVER LEAVE OVERDRIVE. The allison transmission is a 6 speed and the extra gear helps.

The same thing when towing.... two weekends ago, I was pulling a 4K pound load and the truck never even flinched.... never left overdrive and still averaged 13 mpg.

13mpg seems to be the average in the city whether or not I have a trailer. I tend to have a heavy foot, if I drive it nice, I can pull mid 14's around town.

In the 70's mph range, I can get 15-16 mpg on the highway. Not quite what I was looking for, I honestly thought I could get closer to 19-20 since the more HP you make, the leaner a diesel gets... the leaner a diesel gets, the better the gas mileage.

I still have to put the tuner to the 4th level, maybe it will increase a little. Of course, maybe I tend to have a heavy foot because I like to play with the power.

Wednesday night as I was pulling out of my shop, a loud ass Mustang GT (2000 bodystyle) with a huge scoop on it revved his engine as he drove past me.

I don't know what the attraction is but I always seem to attract the Ricky Racer's with the H2... I don't get it, why would you do that to an 7000lb 4WD truck???

Anyway, as I'm going up the road running about 50-55, I get within 3-4 car lengths behind him and he punches it...

So of course, so do I.... in less than a 1/4 mile up the road I'm 3-4 car lengths in front of him. When we get to the next light, the look on his face was priceless... he had the most confused, bewildered look on him like "what the fuk just happened?"

Anyway, the entire process took longer than I expected but I told Travis in the beginning, I don't care how long it takes, I just want it right. Kudos to Travis for staying with it. Even when he got frustrated with the wiring, he stepped up to the plate, took it to Predator and made it right.

Travis even drove the truck back from CA for me. I figured two things...

A) what better person to have it break down on if it were to happen? I mean, seriously, at least he's familiar with it.

and B) what better test drive?? I'd like to think if in 3K miles it doesn't break, blow up or leak, it should be pretty reliable, don't ya think?? LOL.

Overall, it was worth it. I got what I wanted, the truck is done to my satisfaction and best of all, I can PULL A DAMN trailer!!!!


Mark

[twr]

Hi Mark, sounds like you got what you were looking for now. I said when you started that the wiring would be the most time consuming part of the whole job. I think Travis has a handle on the conversion now. Also it should just as dependable as any gm dmax truck now and go for many many miles. Also thanks for updating us the whole time your truck was gone. Better get a big Diesel sticker for the fuel cap.

[BACKNBLACK]

Mark, excellent story! What was the cost start to finish including the build donor? I would like to see a video with the start up and rev of the new ride. I bet it sounds awesome. Congrats and good luck with the way an H2 should of been built .

[OrangeCrush]

Originally Posted by twr

Hi Mark, sounds like you got what you were looking for now. I said when you started that the wiring would be the most time consuming part of the whole job. I think Travis has a handle on the conversion now. Also it should just as dependable as any gm dmax truck now and go for many many miles. Also thanks for updating us the whole time your truck was gone. Better get a big Diesel sticker for the fuel cap.

Yes, definitely the most time consuming part. The part I haven't figured out is the amount of time it took Predator to fix the wiring. It spent almost 2 months at their shop. I think mostly because my H2 got kicked to the curb because of their schedule. I mean, if they can do a whole conversion in 2-3 weeks, why would it have taken them almost 2 months just to go over the wiring.

As far as the diesel sticker, Travis even went so far as to use a OEM bright green gas cap that has diesel written on it.

Speaking of letting someone know it's a diesel, of course, I ordered a personalized tag that says:

DIESEL'D

[twr]

Hi your right it, your truck got put to the side because predator would do their conv. jobs frist. Wish i could order a deisel plate to, but i don't have time to do a DMAX in my truck and my shop is full.

[OrangeCrush]

Originally Posted by twr

Hi your right it, your truck got put to the side because predator would do their conv. jobs frist. Wish i could order a deisel plate to, but i don't have time to do a DMAX in my truck and my shop is full.

You know, I thought about doing the conversion myself in the beginning. The part that scared me was the wiring... and now that I've seen what little bit I've seen, I'm glad I didn't attempt the conversion at all.

I know my weak points and I would have been lost with the wiring.... waaay out of my league.

Mark

[HUMMERICH23]

i know you have prob mentioned in another thread about the build out, but did you have to beef up your suspension for the added weight of the duramax? can you tell a major difference in the ride and turning with the heavier motor up front?

[OrangeCrush]

Originally Posted by HUMMERICH23

i know you have prob mentioned in another thread about the build out, but did you have to beef up your suspension for the added weight of the duramax? can you tell a major difference in the ride and turning with the heavier motor up front?

No, I didn't do anything for the different engine. When Travis brought the truck back, he did bring back the HD2500 torsion bars in case I needed them.

I haven't installed them since the truck drives fine and I honestly can't tell a difference.


Mark


PS. Having said that, I can tell you that the truck, though level, has no room for adjustment to crank up the torsion bars that are on it now. If I had to raise it up, I'd have to change bars.

[ssgharkness020147]

I've got an LMM truck too mark. They make 365 hp 660 lb/tq, so you are not quite to 700 hp. Yet....

A good friend of mine has run a PPE hot tune on his Duramax for years, its a hell of a program. I still think I'll go EFI live, especially if I do twins down the road.

[OrangeCrush]

Originally Posted by ssgharkness020147

I've got an LMM truck too mark. They make 365 hp 660 lb/tq, so you are not quite to 700 hp. Yet....

A good friend of mine has run a PPE hot tune on his Duramax for years, its a hell of a program. I still think I'll go EFI live, especially if I do twins down the road.

LOL, I'm so sorry... I went back and looked at my original post... I posted 520 HP... I meant 320 HP.



With the 225 tune, it should be almost 550 HP... not 700

Thanks for pointing that out... not quite sure why I had 520 as base HP (wishful thinking I guess...lol)

Thanks bud,

Mark