De-coded....

[DieselSlug]

Today i decided to check my boost level. It is set at about 10. I hit the throttle hard from a dead stop, there was a good puff of black smoke, and it pulled the best ever with a 208k mile tranny... I kept on the throttle while letting of for it to shift at 3500 rpm untill about 55, then as i let off the SES light came on and i got codes 47, and 78. Which are high intake air temp, and wastegate solenoid fault. Any ideas?

 

[JiFaire]

Yep, you got stock programming!

Since you're running the stock tune, it codes at sustained high boost - anything over 10 should probably set it off. The high IAT comes from being on your GM4 so hard... the little buggers aren't all that efficient.

When you upgrade your chip, the high boost code goes away and you can run your boost a little higher (14-15#), which keeps things cooler (lower EGT, lower transfer, better airflow - IAT will still climb but is a bit more manageable.)

You would need a chip - AND - an intercooler or a different turbo (think ATT) to completely avoid the IAT thing when you're really into it hard.

 

[DieselSlug]

Thanks Jim. I just dont know why the intake air would be that hot? I have the round airbox into the fender, and removed the snorkle n stuff. I would like to get a new turbo, but i cant afford to at the moment, and i really cant to an ic, due to the plow push plates being in the area where it would go. The air temp when i did it was only in the 50's....

 

[JiFaire]

The IATs get real hot from your dinky little GM4 compressing the air... it is a pretty inefficient turbo and transfers a lot of heat to the intake air.

Has little to do with ambient temps, but you should see what happens on big hills when it's 100* above! Mine was terrible when towing in the heat until I got my chip and turbomaster set properly.

 

[Big T]

The IATs get real hot from your dinky little GM4 compressing the air... it is a pretty inefficient turbo and transfers a lot of heat to the intake air.

Has little to do with ambient temps, but you should see what happens on big hills when it's 100* above! Mine was terrible when towing in the heat until I got my chip and turbomaster set properly.

Yep. My biggest fear is slow pulling long grades or mountain roads in 90 to 100 degree. You've now confirmed what I'm seeing, which is high EGT and engine coolant temps, forcing me to back off and pull off.

My question is the GM 8 better than the GM 4? If so, by how much?

 

[JiFaire]

The GM8 makes a difference to the airflow - there is a significant difference to the elbow which makes it less restricted - but if I was buying a new turbo, I sure wouldn't spend that money on a GMx... the ATT would be a better choice for your $$.


All GMx turbos really need to have intercoolers (or WMI) on them in order to make up for the high IAT thing...

I gotta tell you though, your truck can be made to pull, and pull hard, under the conditions you describe... it's a matter of doing lots of little things, rather than one big thing.

- clean rad. No, REALLY clean. Pull it out of the truck and spend 3 hrs making sure.
- Genuine ACDelco thermostat. Ignore the 180* stuff, just make sure it's a genuine ACDelco.
- either install a SD tuned fan clutch or do the fan clutch mod
- 2 bottles of water-wetter in your coolant
- do the TCC-lock mod. Your tranny puts out HUGE heat.

Then find the sweet spot (where your truck likes to settle down and pull) and drive....

I pulled a 9800# high-front 5er through the Trinity pass in N Cal (#299 from Eureka to Redding), no sweat. Also pulled through Salt lake to St George, through Vegas, to LA, then back to Sacramento. No Issues.

Before I did all those things, I overheated on a 1* grade on an 80* day...

BUT... if you want your truck to really pull, get an ATT. The guys who pull with them are very impressed, and you'll get better mileage, too.

 

[Matt Bachand]

Jifaire, why havn't you joined the ATT club yet?

 

[JiFaire]

Don't tow anymore, Matt... sold the high 5er and bought a motorhome.

Diesel, of course!

 

[Big T]

The GM8 makes a difference to the airflow - there is a significant difference to the elbow which makes it less restricted - but if I was buying a new turbo, I sure wouldn't spend that money on a GMx... the ATT would be a better choice for your $$.


All GMx turbos really need to have intercoolers (or WMI) on them in order to make up for the high IAT thing...

I gotta tell you though, your truck can be made to pull, and pull hard, under the conditions you describe... it's a matter of doing lots of little things, rather than one big thing.

- clean rad. No, REALLY clean. Pull it out of the truck and spend 3 hrs making sure.
- Genuine ACDelco thermostat. Ignore the 180* stuff, just make sure it's a genuine ACDelco.
- either install a SD tuned fan clutch or do the fan clutch mod
- 2 bottles of water-wetter in your coolant
- do the TCC-lock mod. Your tranny puts out HUGE heat.

Then find the sweet spot (where your truck likes to settle down and pull) and drive....

I pulled a 9800# high-front 5er through the Trinity pass in N Cal (#299 from Eureka to Redding), no sweat. Also pulled through Salt lake to St George, through Vegas, to LA, then back to Sacramento. No Issues.

Before I did all those things, I overheated on a 1* grade on an 80* day...

BUT... if you want your truck to really pull, get an ATT. The guys who pull with them are very impressed, and you'll get better mileage, too.

JiFaire, I am in the process of doing what you describe. Once I'm done with the cooling system, I need new injectors (and glows while I'm in there). Then it's time to chip it and decide between GM 8 or ATT.

From all that I'm reading, there really has been no definitive dyno work done on the ATT to provide factual black and white documentation of what it can do. Mostly just seat of the pants reviews and those indicate a lag on the low end rpm. There's one dyno test posted here and the ATT came in second to a GM 8, thus my interest. I tried to arrange a meet up with Rhinopkc to get a first hand impression of what it can do, but that did not happen.

 

[JiFaire]

Yep, I know.

Some people (notably on other sites) are saying that lack of dyno runs means there is no data on the ATT, and are pointing on that one test where the ATT showed up les than a GM-8.

But here's the thing... People I know and trust - Turbine Doc, Oregon Horse Tug, Buddy, Detroit Dan, guybb3, Al (Matuva) and leo (NVM) all have talked about the significant gains in pulling power, fuel mileage, and cooler IATs using the ATT.

They've all also mentioned that off the line, if spools slower. Will it produce less overall HP? Possibly... although I am not sure HP is the best indicator of anything (Alicia's Accord v6 has 271 HP, and it sure couldn't pull something what weighed 9800# like my truck did)...

Same truck, no different mods, the ATT outperforms the GMx series in a working environment... I'm convinced of that. Other guys on other sites might not have the same faith in these people I do... that's OK, too.

PS - I left Patrick and Dennis out of the above list because they muight be perceived to have a conflict of interest here...

 

[Big T]

Yep, I know.

Some people (notably on other sites) are saying that lack of dyno runs means there is no data on the ATT, and are pointing on that one test where the ATT showed up les than a GM-8.

But here's the thing... People I know and trust - Turbine Doc, Oregon Horse Tug, Buddy, Detroit Dan, guybb3, Al (Matuva) and leo (NVM) all have talked about the significant gains in pulling power, fuel mileage, and cooler IATs using the ATT.

They've all also mentioned that off the line, if spools slower. Will it produce less overall HP? Possibly... although I am not sure HP is the best indicator of anything (Alicia's Accord v6 has 271 HP, and it sure couldn't pull something what weighed 9800# like my truck did)...

Same truck, no different mods, the ATT outperforms the GMx series in a working environment... I'm convinced of that. Other guys on other sites might not have the same faith in these people I do... that's OK, too.

PS - I left Patrick and Dennis out of the above list because they muight be perceived to have a conflict of interest here...

Being that it's the internet and I'm staring at points of light which are mostly opinion to this point in time, I'm inclined to wait on the decision until I see more facts. I did talk to Bill Heath and brought up the ATT subject. He said that he has one for testing, but the jury is still out. In the meantime, I will continue my upgrade progress so that I'm ready for the move to chip and increase my boost and fuel. I'm patient. Had the truck for 11 years and 120K miles with the mods listed, so I'm real patient.

 

[JiFaire]

Yep, I understand that.

If I didn't know these guys from years on the forums, I wouldn't trust what they say, either. No problems here.

Whatever you choose, I hope it works out well for ya!

 

[DieselSlug]

I wish i had the money to do something else with mine...

 

[packratt]

One thing to keep in mind. In the only dyno test I've seen for both the GM8 and ATT they were run on different trucks with different setups. The truck with the ATT also had the TCC slipping.

 

[JiFaire]

Arrggh... sorry Packratt... forgot to add you to the list above...

 

[Matt Bachand]

Well, Big-T If you can wait till next year I'll sell you my GM-8 for cheap when I get the ATT

Efficiency is far more important to me than HP. (especially #'s coming from a Dyno).

Don't know about you, but I drive my truck for work all around cities and hills... I rarely (never) drive it on a dyno.........

Lower Temperatures = longer engine life.

Average 10% MPG Gain = efficiency

Thats all the proof I need.