6.2L A.T.S Turbo Boost Questions?

[mrbornery21]

I have a 1989 4X4 GMC Jimmy 6.2L, Equiped with an A.T.S Turbo Kit , Turbo long style injectors, Heavyduty injection pump, 700r4 rebuilt Trans, 3:42 gears, 31inch B.F.G mud tires. Truck does 75-80mph, on freeway, Up a mountain, not a hill, unloaded, 3rd gear, W.O.T, 10-12psi boost. Egts 1,000-1,150. The Turbo is made by Garret its a T04, non-wategated, .60 A/R cold,.96 A/R Airesearch "P" Trim "on-center" T4 flang 4 bolt Exaust housing, Ball Bearing, oil cooled.:cool:

Questions?:confused:

1. If I keep my fuel pump adjusted to where its currently at, and go with a smaller turbine housing with an A/R of .81 or .69 will this lower my Egts?

2. What psi of boost will the above A/R's give me between 1600-3600rpm?

3. A guy that sells turbos suggested that of instead of going with an .81 A/R turbine housing go with a .69 A/R housing. He said i would get better boost from 1600-3600rpm. What housing do you think will be a better choice?

4. Will I Need to run a wastegate with these housings?

5. What is the absolute maximum Turbo psi boost a stock 6.2L can handle without coming apart ? Banks recomends 10 P.S.I max, I Think there just scared. I think these engines can handle 14-15 P.S.I max:D . Am I stupid? what do you think?

6. Diesel fuel controls engine speed and power not air right?. So if I took a stock 6.2L diesel engine and didnt turn up the fuel, left it alone. And put a turbo that produce about 15-20psi of boost would this harm the engine and create dangerous compression? As far as i can tell I would just be supplying more than enough air for a clean burn and lower egts. Because the combusting fuel creates the pressure in the cylinder.

7. Basic same question! if a cylinder has a compression of 300psi N/A and you supply it with 15psi of intake air does it raise the compression of the cylinder and if so by how much?

[mrbornery21]

:confused: Anyone! Please help me

[More Power]

Based on the boost pressures and exhaust temperatures you're seeing, it appears to me that the turbo was correctly sized for your application. IMO - Boost pressure and EGT are both exactly where you want them.

Raising boost pressure, like you propose, won't in and of itself affect engine durability. It's when you then add fuel to take advantage of that extra boost pressure that you may be pushing the durability limits of the 6.2L diesel. If this were a 2001 or newer AM General engine or one built using splayed main caps, you could build for more power without risking as much.

Adding boost pressure also adds turbine drive pressure, which affects engine efficiency to some degree. So, more boost "could" reduce fuel economy, and more boost would increase the need for an intercooler.

Jim

[mrbornery21]

;) Your input on this matter is very helpful, Thanks again man. Just trying to sort of educate myself and gain some knowledge! Its like they want to keep this stuff a secret, E-mailed Banks on what size turbine A/R they use on there banks sidewinder setup, E-mailed Garret the part# and serial# off of my turbo and asked them for some specs on the turbo and a rebuild kit or part# for rebuild kit, because the turbo shaft has some up and down play! not rubbing on housing yet but give it another 20-30k and it might, and guess what no reply! Guess Ill have to take the turbo apart and measure the compressor wheel and the turbine wheel to find out what the trim is. And I dont think ill be able to find a rebuild kit for the unit very easy! But anyway thanks again for the reply:D

[mstockton]

The main thing here, is as was stated above, more boost pressure does not increase pressures inside the chamber in a significant way. While a healthy engine will be cranking at 300+psi, the combustion pressures are many times higher. The boom is what will blow the engine apart. Simply adding more air will not increase combustion pressure by itself. You have to combust more fuel to generate more heat, more pressure, etc to cause damage.

Just something I've been seeing some people wonder about,

Martin

[mrbornery21]

Thanks for your reply martin, very helpful . It was something that was a burning question in my mind. Because I belive too that the psi of air wont harm my engine its when I add the extra fuel too go with it that its going to take its toll on my engine. just wanted to check will some people.

[DmaxMaverick]

There's a problem with this scenario. Wanting boost and getting it are two entirely different things. Even if you had a turbo that will produce 20 PSI, you won't get near that w/o fuel. You can't just "turn up the boost". What makes boost? Exhaust pressure. It is the exhaust gasses that spin the turbine, and the turbine spins the compressor. The compressor output is dependent on turbine input. Any amount of air over what is needed for efficient combustion will be a waste of energy, which means you will cross the ROI (return on investment) line. Meaning, the power level will drop due to the increased demand on the exhaust pressure, requiring more fuel to keep up, until it can't. What you will end up with is a turbo/fuel system operating outside of their effective envolopes. This translates into wasted fuel, additional heat, and an impractical/unusable power range.

RJ can explain it better, but increasing boost isn't always the only answer.

[Robyn]

In reading your post you stated that the EGT is running at 1000F to 1150F

These are max absolutes now.
If you are going to even think about more ooooomph from the little beast you need an aftercooler to cool off the intake charge.

To go for more HP on this little engine is asking for a big splat in the road someplace thats not going to be handy.

As Jim mentioned the new AMG Engines would be a great choice for such a project.

The 6.2 can produce some good reliable power even when turboed but just a little too far and they turn into a grenade.
I have the remnants of one here now that a fellow pushed too hard.

What generally happens other than the lower ends cracking is the pistons will crack in the recardo bowl area and then you will lose that cylinder and if it happens at night where you cant see the exhaust , aside from running sour the engine will blow out all the crankcase oil due to the broken piston and then things really get interesting.

The one I have here was being asked to pull 15-18 K trailer up a 7% grade and the number 4 piston cracked and then the engine consumed all its own oil leading to loss of oil pressure and Poof all gone.

IMHO get your current setup working as good as it can and install a monster exhaust on it. 3-1/2-4 inch and sit back and be happy.

Any real push beyond where you are currently is going to take you to downtown Meltville.

Not what you really wanted to hear I know but never the less a safe recomendation.

If you want a good comparison, look at an older Ford 6.9 or 7.3 engine.
The block, crank and heads are a lot beefier than the 6.2 and will tolerate far more in the way of abuse.

An engine not only has to produce power but also has to do several other things. It has to be able to reject heat well, tollerate the stresses placed on its internal structures for a long period of time and of course be reasonably efficient.

The 6.2 if run within its design window will do all these things and be a happy little camper.
Push the envelope and the first areas that show problems are the structural integrity and the ability to reject heat.
The 6.9/7.3 Ford will allow the envelope to be pushed far further without any issues.

Just a comparison


Best to ya

Robyn

[john8662]

After actually having an ATS setup I can throw in a few pointers here (can be seen in the photo album).

My setup had the .81 turbine housing.

It was just as you described.

T4 Turbonetics or Garrett turbo
On center (verses Tan)
60:1 compressor
P-trim wheel

The .96 and .81 ratios were the two combinations used with the early ATS setup (that fits your body style truck, and mine).

Banks uses (no secret, it's on the turbine housing) a 1.00 A/R turbine with the same p-trim wheel (actually large turbine wheel).

IMHO, the .96 is still fine, for a 4x4.

The .6 a/r ratio turbine housing you're quoted is TOO small for a 6.2. The .81 is on the bleeding edge of being small enough to require some kind of internal or external wastegate.

The .81 was more suited for a light truck (1/2 ton 2WD like i had), but the manifold doesn't fit 2WD 1/2 tons well, thus, I have a Banks now.

Looking for a better turbine for my Banks setup now.

10-12psi is right on the money.

How fast does it make the boost, and how many psi do you see on a flat cruise?

J

[mrbornery21]

with the .96 A/R turbine housing on a flat cruise at 55mph in overdrive 0-1psi of boost, egts 600*. maintaining overdrive at 55mph on any small grade hill egts would rise to 800* boost would be about 5psi. pushing overdrive on this hill to speed up boost would go to 7psi cant remember egts but pretty sure they were 1000* I put the .69 A/R housing on and the difference is night and day truck seemed to run smoother and truck has way more power feels like I gained 100Hp its more like about 50Hp, but it will put you back in the seat on takeoffs, response is instant feels like im driving my bro inlaws 1996 3/4 ton 454 suburban egts went down buy a remarkable 100* no lie.
leaving a stop light boost spikes at 13psi. no matter what speed im driving i have an easy 10psi on tap no problem. going down the freeway up a decent hill trying to maintain overdrive at 75mph without kickin the truck down in 3rd
boost would hit 9psi max and egts were maxed at 1,150* now with the .69 A/R housing i can do 85mph max up the same hill in overdrive boost 13psi egts at a sweet 990* alls I can say is im very impressed and all of this just cause I changed the size of my A/R turbine housing I havent even tried to turn the fuel up and dont think i want to probably not safe without lowering the compression ratio . got a little crazy and kicked the truck down in 3rd on the freeway at 75mph and boost is unknown as my gauge only goes to 15psi. I would not recommend you do this two your truck without running a waste gate. I love the response of this housing feels great for towing and around town driving trucks way fun to drive now. want to buy a .81 housing and test it I shouldnt have to run a waste gate with the .81 but i think if everything works out im gona stick with the .69

[Robyn]

With the changes in the turbo you probably have just the right amount of fuel to spin the thing and build the boost up and not an excess that will build high EGT..

Generally with boost numbers where you say they are you would be needing a charge cooler.

I think you have found a sweet spot that is just right.

Sometimes these things happen, and its a good thing :D

I would leave it alone and be sure and document what you did and or are doing so it could be repeated.