To ATT or not part II Technical Discussion Only ?

[tazz]

That is the question that I have. I'm in the need for a new turbo as the one I have now is on the verge of failing, it's developing quite a bit of play in the shaft and I noticed recently that the waste gate is starting to fail/stick. I'll try to give as much info as I have. First let me tell you what I have done to my truck, I have the basic mods done to the truck as in my signature, older Heath tune, Turbo Master set to 15psi @wot, 4" SSD exhaust, AFE CAI, newer stock injectors and -1.94 injection timing on a newer pump. The truck has 214,000 or so miles on it with the orig. GM5 turbo. I have also replaced the heads on the truck. All these mods were done at around 164,000 miles. The truck is a five speed with 4:10 gears and I'm running BFG 235x85x16 mud terrains. I'm also running a dump body in the truck.

I don't plan on doing a lot of towing with it but I do occasionally haul a car trailer. I do load the dump body though and I try to get the most out of it, usually I'll load a ton or more on it. I notice now with the turbo going bad that my EGT's are running higher than normal and on some small grades they get to the 1,100 mark before I have to let off on the throttle and this is with running empty on the highway usually around 70 mph. Normal temps are around 550-600 when cruising but now they are around 750-800. I haven't hauled anything yet with it in this condition as I'm not comfortable with these temps. The other thing is with my boost is usually around 6-8 on the highway empty and is now only around 3-4 psi.

So will I benefit from putting on an ATT or should I just stick with a GM5? If I go with the ATT will I have to redo my Heath tune?

Thanks,
Dan

 

[Chief915]

I would say definately go with the ATT!!!! With what you do with your truck, the ATT would be the best option for replacing your worn out GM-5. You won't regret upgrading to the ATT at all. I had an ATT on the 95 in my sig and will definately get one for the Suburban in my sig too, as soon as the GM-8 gives up.

On the tune.... I wouldn't say that you MUST redo the heath tune because you changed to an ATT. If you did, you would most likely see more benifits as far as slightly better drivability or acceleration. But that's not to say you will have problems without a new tune either.

I ran an ATT with an older Heath Max-E-Tork tune and didn't have any issues at all. Could it have been better with a tune designed to run best with an ATT, yea probably.... But it was just fine the way it was too.

 

[tazz]

I did not remember the tune that I have but you just jogged my memory, it is a Max-E-Torque tune and the truck runs great with it but now with the turbo on it's way out it's running like a dog. I had wanted to take my time with this and do it over the summer or before winter as it also needs glow plugs and a new harness but my luck (no luck at all) is terrible these days, I have a 2004 Impala that blew the engine the other day and that is going to cost me considerably more to fix. Hopefully I'll get some better fuel mileage out of the truck with a new turbo seeing as I can seem to only get 13.9 on its best day.

 

[Chief915]

You should be getting better MPG than that..... My 95, 2WD dually with 4.10's averaged 14.7 around town and idling quite a bit. On the highway with the cruise set on 75 it would average 17.5 mpg.

But a worn out turbo will definately kill MPG and power

 

[tazz]

That mpg is combined highway and city still I do most of my driving on the highway. I think putting on the bigger mud terrains killed some of my mpg although they are taller than what was on there, stock were 30" and these are 32" so I am using less rpm's to go the same speed, maybe it's just a wash for that. Also the majority of my highway trips are from home to work, 56 miles one way so I don't really know if that's a good comparison.

 

[buddy]

What kind of fabricating, welding or whatever skills do you have or access to good friends with them? If you do then you could consider something else. Although I think you would do well with the ATT. Otherwise, if there was a cheap HX35 or there are knockoff HX40WII turbos on ebay for cheap. Not saying the same quality and definately not as simple installation as the ATT though.

 

[6.2 turbo]

I just listed a GM-1 in the classifieds .

 

[Edzzed]

What kind of fabricating, welding or whatever skills do you have or access to good friends with them? If you do then you could consider something else. Although I think you would do well with the ATT. Otherwise, if there was a cheap HX35 or there are knockoff HX40WII turbos on ebay for cheap. Not saying the same quality and definately not as simple installation as the ATT though.

I'm not prejudiced one way or the other but would perhaps agree with buddy. had I the skills I might very well have gone holset with the good things I have heard. having an ATT myself I have nothing but good tings to say. My belief is I could have gone ATT as I did or for the same money had someone fab up a holset for the same price I paid for the ATT installed. bear in mind I paid for the install. Not as cheap as it could have been but also not as bad as it could have also been. Ed

 

[tazz]

Well I have a decent welder, metal bandsaw, drill press and a South Bend lathe so I'm not so bad at fabricating although not the best but not bad. I'll have to see whats involved for that type of swap. I can't tie up the truck for more than a day as this is my daily driver now as I don't have any plans soon to get my car back on the road, I have to choose the lesser of two evils, the truck is going to cost alot less to fix than the car.

 

[Chief915]

I'll have to see whats involved for that type of swap. I can't tie up the truck for more than a day as this is my daily driver now as I don't have any plans soon to get my car back on the road

If you need your truck back on the road quick, the ATT is basically a "bolt on" replacement for the GM-X turbo. It comes with great instructions, but the short story is this. You will need to cut an inch or two out of your stock oil drain line and cut 6" or so off your upper intake. Other than that fabricating....it is a straight bolt on.

 

[buddy]

The fabricating for the HX35 or HX40WII would be to get the turbo elbow onto the downpipe, or making a turbo elbow, so exhaust work primarily. Others already have the HX35 and could comment on what intake elbows would be needed.

 

[tazz]

I did a little reasearch on some past threads and I see that making an exhaust would not be to difficult but what about where the inlet size and clearence to the battery? I also noticed that a lot of people think you should use intercooler and as far as boost goes what should I be running for that? I currently have my GM5 set to 15psi and just till recently I had it set to 18psi with out a problem but I never hauled anything with it set that high. So just a bunch of question that I have about this. I know that with the ATT I can have the truck up and running within 3 hours and thats with replacing my glow plugs and harness, I might as well do that upgrade while I'm in there as I know that the harness is shot anyways.

 

[WarWagon]

The ATT for a bolt on, once you get it spooled up, makes you think you have a new truck. The engine has power over 2100 RPM where the factory turbo is just blah up there. With a tune anyway. 4" exhaust you have already. I would get a different intake connector 'orange tube' then the one supplied - although the ATT folks are working on a better one.

I would also recommend the turbo heat shield and header wrap for the downpipe to keep things cooler. Wrap just past the bend to clear the cab as my 4" exhaust burned the cab paint in the 3" downpipe section...

 

[Paveltolz]

Tazz, with the larger tires, your odometer may not be recording all the miles you are actually driving. With my 33" I'm about 3% under actual miles driven. Checked with two GPS units to be certain.
Once "on plane" the ATT does pull like an SOB up to my cowardice settings (especially with the performance tune I had on there for a few months). The GM-5 boosts quick at lower RPM but falls off as described around 70-75mph. Since I'm fickle, I like them both for their strengths and dislike their weak points. There has to be a happy medium but you're in a hurry so either rebuild the GM-5 or jump up to the ATT, you won't be disappointed either way.

 

[tazz]

Tazz, with the larger tires, your odometer may not be recording all the miles you are actually driving. With my 33" I'm about 3% under actual miles driven. Checked with two GPS units to be certain.
Once "on plane" the ATT does pull like an SOB up to my cowardice settings (especially with the performance tune I had on there for a few months). The GM-5 boosts quick at lower RPM but falls off as described around 70-75mph. Since I'm fickle, I like them both for their strengths and dislike their weak points. There has to be a happy medium but you're in a hurry so either rebuild the GM-5 or jump up to the ATT, you won't be disappointed either way.

I am taking my milage from my GPS as my speedometer is off, for example when on the highway speedo reads 64mph and the GPS reads 70mph. By the way, how do I adjust that on an OBDII truck?

As far as the GM5 to ATT I think you hit the nail on the head and that is why I am asking to ATT or not. I have not had the pleasure of driving in a rig with an ATT so I don't really know how they perform. I am getting all of my info from this site and what other members say about it which is mostly towing larger trailers and such. I don't plan on hauling trailers for long distances maybe an occasional trip with a car trailer but that's about it. As I said before I have a dump insert in the truck and haul that way. As for the GM5 you are right it certainly does pull nicley off the line with or with out a load. Being that the cost for a new turbo be it an ATT or a GM is the same is the reason I am asking this question. As far as puttiing an HX35 on the truck I am not going to go that route so it is going to be between these two. I'm just looking for opnions.

 

[Big T]

Taz, it would help if you narrowed down your location. Then maybe one of us might show up with an ATT rig for a demo.

 

[tazz]

I'm in Springfield, MA and I work in Middletown, CT. I know that there is a bunch of guys on this site from CT so I'm allways driving RT 91, really anywhere in CT-Western MA is close. Heck even some parts of NY state are pretty close to me.

 

[buddy]

I think you'll be happy with the ATT, just understanding it has a slight lag compared to the GM5. Since you already have the AFE air filter and 4" exhaust it should work well.

 

[Slim Shady]

Ok lets define what "LAG" is.

1. Momentary lose of power nothing happens when hitting the accelerator. or no action when the accelerator is pressed then all of a sudden the power comes in in a big way. Most people
consider this "LAG"
2. The truck does not have the seat of the pants snappy "quick response" feeling the gm turbo gives the accelerator right off of idle, Not the fact the truck does not respond to the accelerator.


LAG is a subjective word when you are dealing with someone's definition. I have not noticed a "LAG". BUT on second note the truck is not that much different than the stock configuration.

It is most definitely not a off the line turbo, but get the turbo to 1400 and there is boost, that keeps on pulling up to 3500 with out any problem. Small area to give up for such a wide band of useful power.

SO PLEASE lets be specific when throwing the word "LAG" around. ALSO I WOULD CALL PM OR TALK DIRECTLY WITH someone that has owned one and get a few opinions. MAKE an informed choice. SORRY JUST TIRED OF HEARING LAG associated with the turbo.

Also a good tune will minimize this so called less responsive pedal feel. So there are changes that can enhance the truck and get you the best of both worlds. A bad tune will make any truck run poorly. I STAND behind the turbo, it is a solid product.

Respectfully Slim Shady

 

[NVW]

I don't notice much if any lag, if I WOT from a stop I get a puff of smoke then it clears up.