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Impressive to me ATS 6.2 turbo

dually man

dually man

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Sandpoint, Idaho
I got my k5 blazer swapped over to a 6.2 that has a Ats turbo on it. No egt gauge on her yet argggg. I do have a boost gauge:rolleyes5:. Engine is a stock gm goodwrench with a db2 pump turned up 1 flat of an allen wrech. timing is advanced by an unknowen amount:eek:. the consern, or should I not be conserned is my boost pressure. This turbo builds boost FAST, like hit the throttle halfway and she is pullen 8 to 10 psi boost, today I had it up to 12 and the boost gauge was still climbing fast, but I let off the go pedal in fear of meltdown like I did to the last 6.2 that I smoked with this turbo when it spiked to 17 psi. I do not tow anything with rig, its just a get to work and hunten rig. at 60 mph with 3.42 gears 33-12.50 tires and turbo 400 auto I am pullen 3 to 4 psi boost crusing, It dont take anything to hit 10 psi when trying to pass someone.
So my main question about boost is alot of people talk about boost #'s as a figure that includes continuious duty load such as pulling a trailer up grade. But in my application I only need spurts of power to pass or take off from a stop, while never pulling a load other than passengers and a elk if I ever get one LOL. So what kind of boost pressure is a safe assumption:rolleyes5: for my ride and driving style, oh and by the way I might get in a wreck someday cause my eyes are glued to that damn boost gauge all the time LOL
 
no backpressure from the exhaust but I wonder how much the turbo might be choking it to boost that fast and high. about the same numbers as with a gmx wired shut. Back to your original ? supposedly the 6.2s headgaskets weren't as robust as the 6.5 turboed ones, but having said that I'd probably run 10-12 max
 
I dont know if this is wierd or not but the 6.2 pulls ok under 10 psi boost, but above 12 it really gets with the program, I mean it really goes... I know a little about thermal dynamics and how boost on 6.2's cause too much heat from boost so it limits power, but how does this thing pull better than my wifes truck running at 12 psi boost with a 6.5 turbo gm4? My blazer curb weight 4750, wifes 97 is 6125 curb, BUT the 97 has better gearing with a 4l80e and 4.10 gears, all I got is 3.42 gears and th400 auto. Oh I see, I make more black smoke than her truck LOLOLOL
 
too burned out on wrenchen right now, that engine would have to come out to do head studs ARGGGG. sounds like a good summer project
 
guys have done them in the rig, put the studs in the heads with the nuts on top and a spacer to keep it from hanging below the head. only need to do that with the hard ones
 
well, this might get a bit confusing so hold on to your hat; boost doesn't increase EGT's, it lowers them.

Boost actually lowers combustion temperatures because it leans the mixture.

If there is a corresponding increase in fuel, then EGT increase stays linear to boost increase.

Where you run into increased EGT's with boost is where you begin to run the compressor out of it's efficiency curve on the turbo map (IE: too much boost). While a turbo always imparts heat to the compressed air, it gets much worse once it's out of it's range.

To make it worse, the exhaust section has a "choke point" on it's map as well. This is where the turbine section becomes a restriction in the exhaust path. This has the effect of increasing EGT's because the exhaust cannot carry away the exhaust/heat fast enough. It lingers and combines with the next exhaust pulse, which drives the egt's even higher.

With the ATS unit, I can't tell you where this is because I'm not familiar with it nor have I ever seen a turbo map for it.

You could be fine running at 12-13 psi and not hitting a choke point. Or you could be well above it.

Until you get an EGT gauge on there, you just won't know what is going on.

But, I'd limit your runs into the boost at no more than a 13 psi spike. Most 6.5 TD's only run around there, although some guys crank the TM and run them higher. Not a lot of point in that if you don't have the extra fuel going in to take advantage of it and the GMx series hits a choke point real soon after 13 psi. My 98 maxes out at 13 psi and then the TM is full open. I'm not willing to push it higher than that because I want my 7 thousand dollar engine to live a long and happy life.Where it runs normally is pretty much dependent on my throttle position because I have a TM and not the vac boost control system.

A 6.2 that wasn't intended for boost shouldn't run higher than a 12-13 psi spike IMHO. The head gaskets, block, etc may take the higher cylinder pressures, it may not. I can't tell you for sure either way but I'd err on the side of caution...
 
If my memory serves me correctly ...:cool: the ats 6.2 turbo is a Borg Warner S-200 based turbo which is barely better than the Gmx turbos ! So i definately would not go over 12 psi of boost .
 
Remember a 6.2 doesn't have the coated pistons from the factory like the 6.5 does. Banks themselves recommends no more than 10 psi sustained and ~1000*F EGT maximum.

I can tell you with the Banks/Garrett T04B it's near impossible in my situation(due to 3.08 gears) to get it over 5-6 psi and 700*F pre-turbo. That turbo really is over-sized IMO but it also limits boost in a round-about way. Been debating swapping to a TE06H that Banks used in their 6.9/7.3 IDI kits if one fell into my lap that is.


5 lbs of boost really makes that truck scoot though. I'd hate to see what enough fuel to crack 10 psi would do besides scare me and blow the headgaskets to the moon. I know it's got the fuel to do it too, which means i know i'll be into that engine for headgaskets/studs at some point.
 
Dave, I think we can put the uncoated 6.2 piston concern to rest. (The 6.2 pistons are thicker crowns than the coated 6.5 pistons to keep the weight the same.) I am running two 6.2 bottom ends with non-coated pistons and I have done bad things to them. Very bad things. I know for a fact that there is simply no way to run a 6.2 continuously harder than I have because I have tried everything without getting expensive add ons. I have run EGT's to 1500 sustained with black smoke due to a manifold warp caused exhaust leak. I have run 1400 smoke free sustained and have no damage. I have pulled the engine down due to the screw clamp one 6.2 ate, my fault, and everything looked fine except for the damage from the screw clamp. No adverse affects to the non-coated pistons from high EGT's. Timing and ECT among other things determine what EGT you can get away with.

IMO Glow plugs and injectors suffer first from extreme EGT. I have seen weirdness with glowplugs, like surface rust texture while being shiny, and my injectors were sticking open at 30K from rebuild with unknown nozzles.

I share the high boost concern with TTY head bolts and 6.2 head gaskets. Several places recommend putting 6.5 head gaskets on for turbo charging a 6.2. I have always used ARP's and they paid for themselves with the number of times I have had the heads off. With ARP's I don't have to worry about blowing head gaskets. Even after I ate a screw and pounded it into a piston it did not lift the heads like TTY bolts could have - so we were able to drive it home and save a tow bill. (I said I did bad things right?) Yes, it is easier to pull the engine to convert to ARP's for the 1990's body style. Your body style is easy to add studs.

At 60,000 miles give or take on my 1986 6.2 that was rebuilt in the past, well this makes the block unknown miles. 1) We assume after the rebuild the it was crack free. 2) We assume it had less than 30K per the military surplus seller's claims. 3) It had 30K on it from me. With my extreme use of WOT and 14 PSI boost towing trailers up 6-10% grades during the 30K I used it for. That said it had 2 cracks in 2 main bearing block webs. I am still using the block and now with an A Team Turbo I am pushing 18 PSI of boost. I turned the timing back to cut down smoke and help it live a little from what was an extreme advance that really work it up more than it is now.

Yes, one day I will have to pick up the crankshaft off the road and get it towed.

Banks recommends a 1/4 turn on the 6.2 pump. Having used both a 6.2 and a 6.5 pump on my engine the 6.5 pump puts out more fuel. Your one flat turn is almost nothing. I run 1/2 to 1/3 turn...

IMO, second to manufacture's data a good way to see if the turbo is choking is watch Intake Air Temps. 270 degrees at 70 outside with 17 PSI of boost is not choking with an ATT. Over 300 I would say is choking the turbo where they produce more heat than boost.

6.2 Precups will hit a wall somewhere around 17 PSI unless you change them to turbo precups. This may be dependent on the turbo, but it is a factor. Wall = more fuel and timing won't clear the smoke.

With all this said I suggest you turn down the fuel until you change the head gaskets over - that would be my only concern.
 
I sure wish I could find more info on the elusive ATS turbo setup, I called ATS and they know nothing about it cause they were bought out after those 6.2 turbos were discontinued. I think you fellows for the detailed info, it helps me and others also understand better.
 
WAG: Your ATS may pull better than the GM4 due to lower backpressure than the GM4 at the same boost.
 
There's more than one flat on my pump. I'm sure of it. I had it tested and calibrated by Accurate Diesel and i told him to give it plenty of fuel. He asked what plenty was and i said that i wanted a good bit more than Banks recommends and that was that.

I'm sure there's at least a 1/2 a turn change judging by how much it smokes when i lay into it. Just wish the turbo spooled faster so the smoke would clear up. That's my only complaint.
 
I was goingto ask if an A-Team Turbo might not be a good option here, and if anyone had done it. Then I saw Warwagon has. Seems like the larger flow and lower intake temps that the ATT is know for might correct the choke point issue, wouldn't it? I don't know how you'd control where the boost is set, it being such a different turbo and non-wastegated, but I guess it's timing and fuel. Of course, the large volume, cooler turbo isn't going to do much to save the heads and gaskets from the pressures, but at least it should run cooler EGTs and IATs. Pressure will be another issue to address, that's all.
Warwagon, how did you get so much boost from your ATT? I noticed in your sig you're running the 6.2 with a computer tune, so apparently the motor thinks it's a 6.5 anyway. My 97 with ATT and tune only ran around 10-11, with an occasional spike to 12-13. It's been a while, but I can't remember any higher than that. So I really didn't get much more boost than stock turbo, just more volume.
 
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