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So, exactly who makes the ATT?

NVW said:
Big T, this was hashed out before. Until you swap turbos you can't say why one Sub gets better mpg than the other. No two vehicle are the same. Everyone else claims to get better mpg's with the ATT except you, are we all wrong?
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I did say it was more powerful and ran cooler. I did say I'd get another.

I don't believe your claim that everyone gets better mpg's with the ATT. There has been no rigorous tests. None. No dyno tests have ever been posted. None. Until someone does a mileage test with testing equipment, it's all seat of the pants guesswork.
 
Well, when I can go further on every tank on average with the ATT it's good enough for me. That's the same vehicle going from a GM-4 to the ATT.
 
You fund the dyno I'll run it,

As far as mpg results, I made the same trip bi-weekly same route MS to GA/FL for nearly 3 years, before ATT with the GM turbo full tank to sucking air 390 or so miles, after ATT 430-440 miles, that R&D caused me premature death of an IP, running them dry of fuel is not advised, I carried 5 gallons of fuel in a can in the bed so that when I ran out I would not be stranded.

Trip was 450 miles each way doing that every other weekend, same grades, coffee & pee breaks at same spots using cruise control is about as repeatable a condition as one can have.

Many times on phone with Slim Shady, GMCTD and a host of others to help keep me awake knew by my fuel gauge level how much longer of a trip I had or when I'd be stopping to topping it off, 26 gal tank plus another 5 gal would get me either direction and give me 2-3 days local driving in MS or GA, last 2-3 gal is hard to use as it sucks in a lot of air as the tank sloshes away from the pickup tube.

That is about as real of a test as one can do, not a seat of pant guess, actual results, fill up to the filler neck until it started stumbling for want of fuel.

Those that have installed after me have reported gains yours is only one I've seen reporting a loss, 1-3 mpg seems to be the level of gain wholly dependent on health of the vehicle, and driving style, were i able to drive at 1700-1900 rpm I suspect the mpg on mine would be better, but as Sammy Hagar says "I can't drive 55"
 
Oh in addition to funding the dyno, you'll need to send a GM turbo for comparison on the same truck, as I have gotten rid of both of mine, while not scientific my 1 time full to sucking air tank level on my burb was 840 miles mixed driving speeds highway & city for 43 gallons, I'll not be repeating that test as cost of replacement IPs is too much.

Leo is right for the test to be valid requires same truck, same configuration, same dyno/operator same atmospheric conditions, for a turbo vs turbo comparison to reflect actual changes to that truck.

Only way to know exact mpg is to fit a vehicle with a totalizer for fuel consumed vs fuel returned, I'm willing to take donations for one of those as well last time I went looking for that a good one was $3K+,.

Until then my full to empty test will have to be scientific enough, either you believe me or you don't, to me it does not matter at the end of the day, since installing the ATT my fuel bill is less, period.
 
I AM NOT SAYING MY MILEAGE DECLINED WITH THE ATT!

I am saying that it does not get better mileage than my stock '95 which has 4.10 rear vs the 3.73 in my '99 with ATT. Definitely better performance, but not better mileage. If I were to believe all the claims, then the '99 should be crushing the '95 as it has the ATT, Heath GL4 Flashing AND 3.73 rear. With no towing, I can get 640+ miles from a tank out of the '95, 620 miles out of the '99 at 70 mph.
 
Big T said:
I AM NOT SAYING MY MILEAGE DECLINED WITH THE ATT!

I am saying that it does not get better mileage than my stock '95 which has 4.10 rear vs the 3.73 in my '99 with ATT. Definitely better performance, but not better mileage. If I were to believe all the claims, then the '99 should be crushing the '95 as it has the ATT, Heath GL4 Flashing AND 3.73 rear. With no towing, I can get 640+ miles from a tank out of the '95, 620 miles out of the '99 at 70 mph.
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Exactly, you bought it that way. Maybe it got 10 mpg before the ATT.
 
Nope apples to apples comparison only way you are going to notice the difference, put the ATT on the other one and see if the mpg improves on that one or put a GM turbo back on the one that has ATT now and see if mpg declines.
 
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NVW said:
Exactly, you bought it that way. Maybe it got 10 mpg before the ATT.
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I'm with Leo here, my 98 before the ATT was getting 17-18 mpg with GL4 tune and TM on a GM-8 or 730-775 miles, after ATT it went to the 840 I stated earlier but that vehicle has 3:42 rear end & is a C1500.

Enough ATTs out there now to qualify that if you aren't getting gains you suspect you should, there is something not quite rite with your vehicle, exhaust leak, valve train, injectors, IP a whole lot of guesses one or none of which would point us in the wrong direction.
 
NVW said:
Exactly, you bought it that way. Maybe it got 10 mpg before the ATT.
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No 6.5TD got 10 mpg while not towing. There just isn't that much variability in mileage for these engines. Still looking for the real test results.:nono:
 
I'm just trying to prove a point:smile5: If you want test results you will believe, you are going to have to swap your turbos.
 
Big T said:
Still looking for the real test results.:nono:
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Now you are just being argumentative BT, I have posted gains and how I recorded them so a "Real Test" , Leo & others have posted their "real tests", you are the only one reporting no change which would tend to indicate the difference to the population results resides in some difference with your truck.

Those of us reporting improved mpg have no dog in the fight as to sale of the ATT or reason to report mpg gains we are seeing, as you know your vehicle/driving habits, we know ours, and if it takes less trips to the pump than before then that is an improvement.

As far as a 10 mpg 6.5 yes, early on was a 6.5er with mpg that low, tried a ATT to improve the mpg, it improved a little to 12-13 then they had catastrophic engine damage wholly unrelated to the ATT install.

If your engine has under lying issues the ATT because it is right at edge of being too big of a turbo any dormant problems will soon show their head. Remember without a WG you aren't artificially building boost energy on bottom end by putting a potato in the tail pipe making the turbo spool up.

From what I'm reading I suspect 2 burbs set up just like yours, with ATT or GM turbo we would see the slight difference in performance.

Out of curiosity what is the TDCO of the 2 different vehicles in your stable now ?
 
I and father in law just finished to put back on the road a 6.5.

We got several problems and had to change IP, PMD and also injectors (BOSCH marine).

Before that, we just installed the couple ATT + Kojo tune. I have to say I was a bit disappointed at first as the truck wasn't very "healthy".

Immediatly after troubles start to show : erratic from easy to hard start, stalling,reving, etc...
1st I thought the ATT and the tune did almost nothing, and then I realised that in fact, coincidence was that a bunch of problems were showing on the truck.

It took a long time to get all the parts, but finally she is back on the road, in perfect working order, and it's needless to say that the owner is now a happy owner.

We don't have any dyno here, but he says he never felt his truck like that : a night and day difference.

I know, this is not data, nothing scientific... but just to say he says " that's worth every penny I spent"

And I say : before blaming ATT and Kojo tune (I did wonder, I confess it), may be consider the source of trouble is elsewhere...

my .02
 
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My mpg around town back and forth to work didnt help with the ATT. Thats speeds up to 55mph. I would say thats because I have 3.42 gears and roll at low rpms anyway, and I already always had it tuned/set for low boost at cruise.

On the interstate at 70-85mph I had some mpg gain with the ATT.

The gain comes from being less exhaust restriction, so its going to benefit those that typically run higher rpms and high boost. This is because now they cant control the turbo with a TM that would set BOTH thier top boost AND their low boost. Now ATT just has lower boost and lower exhaust restriction in general.

Many 94/95 owners report better mpg than newer guys. It may be due to higher compression, lighter trucks, whatever, just notice that often. I think in 96 they dropped the compression from 21.5:1 to 20.5:1
 
Been down this road before. I would just about venture out to say its impossible to get worse MPG with the ATT than the GM-X, considering all else equal.

Its like saying you lost MPG's because one truck has a 4" exhaust with no Kitty, and the other truck has stock setup with kitty and the stock setup gets better mileage so it has to be the exhausts fault.

I don't even own an ATT.................. but all the facts and data are out there (here) that prove the ATT takes less engine power to create the same boost. That means it MUST increase MPG's, all else being equal.
 
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