Turned it to 2 turns from fully closed. It definitely lost some bottom end compared to fully closed or 1 turn from closed. This is the recommended starting point from DPS. I am going to keep it like that for this trip. It is still substantially better than the old, fixed exhaust housing and is "safer" until I get the pushrods and valve springs in. After that, I will go back to fully closed or 1 turn from closed.

It appears to drop 2 psi of backpressure at 2500 rpm each turn.

Lastly, Cruise control is working!!! What are the thoughts of cruise control while towing? Is it a hazard? I thought I read somewhere that someone melted down a 7.3 due to cruise control? I may be off my rocker, maybe I am not. I cant seem to remember, I know these trucks have weird nuisances sometimes, so I wanted to check.

 

It depends if towing causes your EGTs to go nuts. If your EGTs stay at a reasonable margin below the point of meltdown, cruise control on a long, straight and flat road should be okay. I wouldn’t use cruise control towing in the hills though.

 

When you do valve springs, if you plan to measure seat height, I’d suggest the tool from CNC or similar. Made it so much quicker. My CNC fab springs all required the same shim which was reassuring. I can send you a picture of what it is if you’d like. Heck if you want to use it I can ship it too you.

 

I use cruise towing with mine. Just keep eye on egt obviously.

 

There is a switch on the master cylinder that is used to deactivate cruise control. The original harness was prone to short and catch fire, was recalled, and many of the trucks got a new updated harness with fusible links in the harness. My '99 has the updated harness with the tag on it saying it contains fusible links, if you have that, then you are fine.

 

I am successfully home from my 1800 mile road trip. The new VGT Turbo is AMAZING. It allows me to hold overdrive so much longer not because I lacked power but because I lacked EGT control. I could honestly almost throw my EGT gauge out the window and it would be fine. At 2k rpm I would literally burn the motor to the ground up a hill, so I would downshift to keep rpms up and now I can cruise at 2k rpm up hills at 1000 EGT near 30 lbs of boost. I could lay into it more but didnt as I am playing it safe from a valvetrain perspective.

For about 1500 miles of that trip I was around 20k gross. The other 300 miles I was just under 27k gross.



Since I am neurotic I didn't even push the VGT harder. If I saw 38 lbs of backpressure steady (Id let it hit 40-45 for a quick spike) I wouldn't push it further. I am really ready to get my pushrods and valve springs in now to push it harder.

I even got to use 4wd to its full capability. When I was looking for camp, I kept going further and further out and staying on main dirt roads, but I pulled a corner a tad tight into some soft sand and SUNK immediately, it doesn't take much when you're at 27k lbs and 110 psi in the tires. I was able to disconnect the trailer, then hammer it back and forth on the throttle and inched my way out by going back and forth about 40 times, just enough to get the Hummer off the back, then the truck came out under its own power.




I also was at 399,997 so I drove around the block a few times.



The exhaust made the drive much more enjoyable and I used the cruise on flat roads and downhills. Overall it went well!

 

Good report! Sounds like you got your combo right. What fuel mileage were you pulling?

 

That is an awesome report @Hvyhaulr . It just goes to show how much potentiala VGT has for our 7.3s. It’s just too bad it was a half-assed product when launched that took considerable development on our part to get it to run right.

 

Honestly, I did not check on this trip, it has been so consistent I stopped checking. All almost all previous trips, I get 7.5-8mpg no matter the load (20-30k gross) and at 12.5k gross (unloaded) I end up at 10 mpg. The 4.88s kill mpg at 70+ mph. I need to reevaluate this with the new turbo.

Right?!? Honestly, this is modern tech that the new trucks get, and now you can apply it to the dinosaurs which I am grateful for. If you pair this with a 6 speed auto I wonder how it would pull.

I would love to refine it more. I wish I could get an 11+0 wheel for it, brokstroke claimed that picked up more low end, and got rid of the swoooshing noise that breaks shafts. I am happy where the truck is at right now but plan to refine it more.

 

Good to hear on the egts, I have never ran one with my vgt.

 

Most people carry a spare tire in the back of the truck. This dude carries a spare truck in the back of the truck!

 

Ok, sometimes things take an unexpected turn in a build, and you just go with it.

So, the VGT has transformed the truck. Modern trucks kick *** due to modern technology and while this truck will never be modern certain modern additions can lessen the gap.

The next modern addition is a US Gear Dual Range Overdrive. 4 speeds suck, there is a reason 6-8-10 speeds are a thing in 2025. I have contemplated every scenario possible.

I have a spicer 7041 aux trans. I bought it years ago. I wasn't 100% sold on that setup. For certain trucks I think it is the answer. My truck is heavy and adding another 350 lbs to it seemed unnecessary for the downsides I would have. Guys can shift an aux trans with an auto but it is not as easy as a truck with a manual so I figure any gains I would have in rpm options I would lose in slow shifting. This would be a badass unit in a manual truck, especially if you drive around unloaded a lot, low rpm, great mpg. I never drive unloaded.

Gear vendors....I have talked to them numerous times. They have told me I will kill a gear vendors unit quickly and wouldn't even want to sell me one. Idk how they hold up to 3000 hp but I guess TQ and weight kills em.

Allison 1000 6 speed. It is a reliable proven option numerous 7.3 guys have done but the cost is astronomical. 15k from CA Conversions. I am not spending that much money on a trans conversion for my old ****box I use less than 6 times a year.

I had dreams that I would rock the 4R100 for a few more years and assume a ZF Powerline 8AT would work with time. The 8HP70 swap has taken the world by storm and I would imagine they use similar electronics. The have SAE bellhousings and I imagine it is a viable swap one day....and maybe one day that will happen. Honestly, I wanted to swap an 8HP70 in my H3 behind my LS a few years back but the 8HP wasnt really a big swap yet and now the aftermarket is around. I imagine this Powerline will be a go to in the future.

Lastly, the US Gear Dual Range overdrive. It is a heavy duty gear vendors (to a degree, they don't function the same but execution is similar.) They have a GCWR of 35k lbs. They can be used forward, back, towing, unloaded, any speed, etc. unlike a GV. I have seen plenty of positive reviews of them but of course US Gear got bought out then the new owner discontinued the product. I thought it was a solid option but I never thought I would find one, the few times I have found them on marketplace they get snatched up immediately or if I find one its not the right spline count.

Anyways, I found one on marketplace. It was listed for a couple hours, he is 4.5 hours away and I told him I can't pick it up immediately, but I am not a scammer, I gave him my # and asked him to call me. He did and he said he has a guy coming tonight to buy it for $200 under asking. We had a good conversation and he realized I wasnt a flake, scammer or "is this still available" idiot. So I gave him $200 to hold it and am paying full price. Just need to pick it up next week.

https://www.dieselwarden.net/temp/us...e%20manual.pdf

It is 31 spline and for a 4x4 but it is for a manual. I believe the spline depth is longer on the manual, that is an easy fix.

Ratios go from
2.71
1.54
1:1
.71
to


Will it shift as quick as a 6R140, 6 speed allison, 8AT or 10R140? Does it have the deep 1st gear ratios the new trucks have? Hell no, but it will lessen the spread and I hope for less than $1000 it will work just fine.

How it works is I am on throttle, hit the button, wait 2 seconds (still on same throttle input during those 2 seconds) lessen throttle input (don't need to let off all the way) then apply to same throttle input and it shifts.

Lastly, I am not worried about bearings, seals, the shift motor, there's a group of us gear overdrive enthusiasts that have all the part #'s for replacements, the only thing you can't get are gears but those don't fail from what I hear.

 

that sounds like the way a very old inline six International semi tractor shifted when I needed to shift the two-speed axle.

Shift and wait, let off and klunk, push throttle and go.

 

This gonna be awesome.

 

I believe the motor on the unit is a 2 speed rear end motor.

Going from 1 OD to 2 direct will be interesting