I have done the old wicked wheel a couple years ago and also switched to gearhead tunes. The truck pulls pretty decent but for example this weekend. I was toeing around 12k. On some 6-8% grade if I couldn't get over 25-2600 rpms at the bottom i would lose speed and start to surge and have to downshift to 3rd. Is there anyway to get rid of this? I wanted to go to the rebuild with the ww2 on my stock turbo, would this help? I don't drive the truck enough to warrant spending big bucks on a new turbo such as a 38r. So is this how I'll have to drive the truck or can I finally rid the truck of turn surge. Thanks

 

I may be wrong but my impression is that turbo surge occurs when you are mashing on the motor and the truck upshifts. When that happens engine RPM's drop but the turbo is still spinning a little fast and the turbo makes noise until it slows down. Probably from trying to push air that's not moving and backed up at that point. The conditions that you are describing are not the same.

When you say that your turbo is surging, what are your symptoms?

 

On my E99 the turbo came with the old style cast WW1 compressor wheel so I was not experiencing any surge even with a chip installed and pushing 24lb of boost. I will say that installing the billet WW2 was definitely an upgrade. The turbo lit faster and boost went up to about 30 psi. The seat of the pants dyno said there was a bump in power.

My current 2000 had the SD wheel in it and after the chip was installed, I did experience some surge when towing. I rebuilt the turbo with a 360* kit and installed a billet wheel and have not seen any surge in any condition towing 13K lbs.

Hope this helps,
Good luck!

 

Well I have a six speed so I may have it in 4th coming down a hill say 45-50 mph and I'll try to get on it to start on the hill and If I can't get the rpms high enough like 2600 then itl start to fall off and do what you described and start to surge. Then I'm stuck downshifting and losing speed.

 

There is something not right (mechanical or driving style) because if I am running at 45-50 MPH in 4th gear in my truck I can pull up a grade just fine. Now, if the ascending speed is sub 40 MPH, you will be bogging the engine down in 4th and need to downshift into 3rd.

Normally I don't even shift out of 5th gear unless the ascending grade is long enough to bleed the speed off to bog down the engine. Each grade is going to be a bit different and a choice should be made at the bottom of the grade in regards to downshifting or maintaining gear and speed.

The RPM's must not go below 2200 or so when climbing a grade or you will drop speed like a rock in the ocean. Really, I prefer to have the RPM's up near 2800-3000 when ascending a grade and then level them out at the top and come back down to around 1800-2000 which is cruising RPM for me.

The ZF6 7.3 will run all day long at 3000 RPM and be happy about it... Bogging this engine is the worst thing you can do for it. I learned that lesson on a 10K mile trip cross country from GA to Seattle towing a 10K lbs travel trailer.

 

Your experiences are going to be a little different than mine as I'm running an automatic. However, I can tell you that the WW will not cure all surge. And it's possible to surge virtually any turbo under the right circumstances. That being said, the one thing that finally helped me was installing a ported compressor housing. I can tell you that I tried the WW first, no difference at all. Then I swapped to a van turbo. I tried it with both the ported housing and without, and it surged without the housing, so I put the housing back on. I have since added one of the billet wheels for ported housings. Honestly it didn't really aid in spool up or anything on my van turbo as I had hoped. But it still doesn't surge so I've just left it in there.

Edited to add : I wouldn't recommend running the WW and ported compressor housing together unless you and your passengers are immune to the obnoxiously loud whine/whistle. They both make increased noise, and one doesn't cancel out the other.

 

I guess first off when saying what gear I'm in I'm not counting low. If counting low it would be 5th while decending. Now sometimes I could be wrong in the fact of not deciding to use 4th at the bottom and start out by lugging it a bit at the bottom but there are times where I would get the rpms up to 25 and still lose speed. I guess I may need to change my driving habit on top of it because I rarely ever hit 26-27 rpms because most times I don't feel the need to.

 

Unless I'm on really flat ground, I have learned to just let the truck live in it's happy place between 2500-3000 rpms when I'm towing heavy. It's less stressful on me, and from what everyone says it's easier on the truck, too. I know the EGTs reflect that.

 

Let me give you another example. I don't even shift into 5th gear (towing or not) unless I am going 65 MPH or higher. 4th gear has the range and power to make the engine very happy at anything below 63 MPH or so. When towing on state highways at 58 MPH or so, cruise control and 4th gear is the sweet spot. If I approach a grade that I think 4th gear may have a problem, I rev match and down shift to 3rd. Normally though 4th gear is good to go on its own.

I thought the same thing on the trip I mentioned earlier, that I should keep the truck below 2500 RPM or so because I thought that is what it liked. Not true on a 7.3 diesel. Lugging the engine is so much worse on performance than boosting it and running it up near 3000 RPM.

As Bob said, EGT's and smoothness of the RPM will reflect what is making the truck happy at the given situation.

I had a lot to learn as this was my first diesel truck. Heck, even learning to drive the ZF6 was a bit of a challenge for me because of the torque involved.