Garrett Powermax Stage 2 GT3782R Install/Review

[AH64ID]

I recently installed a Garrett Powermax Stage 2 turbo, which is a GT3782R. It’s a 62/64/.89 turbo. The comp wheel is a 61.4x82mm 6 blade wheel, and is normally found in the GT3582R turbo. The turbine wheel is a 72.5x64mm 10 blade wheel, and is normally found in a GT3788R. The center section is a GT37R water cooled ball-bearing unit. The exhaust housing is a .89 a/r divided and internally gated unit that has the HE351 4.4” outlet on it. This combo is designed specifically for the 3rd gen Cummins.

The kit is a well designed and was quite easy to install. I spent about 5 hours doing the install which included a new (to-me) exhaust manifold. The only issue I had was with one of the bolts required for bolting the turbo to the manifold. It was too long and hit the turbine housing. I had to get another at the parts store. The rest of the kit fit perfectly, the intake, exhaust, coolant, and oil lines all attached easily and no adjustment was required.

Prior to putting the turbo on the manifold you need to attach the inlet coolant line. I had to disconnect the WG rod to get the allen wrench into the banjo bolt.

Turbo ready for install

Manifold ready for the turbo.

Bolted in place.

Where the inlet for the coolant connects to the OEM heater core return.

Where the coolant return goes into the water pump.

To pre-oil the turbo I used one of my kids medicine syringe’s in the oil feed line. It worked quite well, it took about 2 ounces before there was resistance on the oil feed line.

Completed install, wrapped in Turbo Performance blankets.

Impressions:

During the initial idle is was apparent the tone of the exhaust had changed, it is much deeper and there is a faint hint of the turbine wheel. It sounds like a bigger I-6, and reminds me a marine 3406 with an 8” stack. I think that both the manifold and turbine housing are responsible for the change in the tone. The turbo also spins for a few seconds after you shut the motor off, which I think is awesome.

On the first drive around the block I thought my boost/DP gauges had come unhooked because at no load there is no boost/DP, unlike the stock setup. I did another leak check, reinstalled the finder liner and went for a drive.

The turbo howls! From about 2-7 psi is has a howl, which I gather is a characteristic of the Garrett comp wheels. It was different at first, but I love it now. I took it easy for the first 50 or so miles. After the easy miles I got on it a few times. It’s pretty quiet from 7-15 psi then it starts to sing! It’s a very different whistle than the stock turbo made, but the comp wheels are very different in design. My 4 year old will mimic the turbo sound, which I find much funnier than my wife does. It’s only really noticeable at low boost and low speed, it passes the wife test, but the 4 year was told to be quieter…

Despite lower boost at low-no load the engine is much more responsive and revs easier than with the stock turbo. I also noticed that it takes a lot less pedal to get the rpms to 2200-2400.

Under normal DD driving the boost is much lower than stock, as expected, but there is no lag, less smoke, better acceleration, and best of all less timing rattle.

When I get on it the boost builds very very fast. From 0-10 psi from 1,000 rpms in 6th the boost builds about the same as stock, maybe a touch slower. From 10-25 its much faster than stock, and a little slower from 25+. That’s all what I expected, under normal acceleration, not lugging, the turbo is much faster than stock. Even thou the boost is a hair slower to reach 10 in that test the smoke clears much sooner than it did stock. Boost and Drive are nearly 1:1 under all acceleration and cruise. The only time I have seen greater than 1:1 is WOT above 2500 rpms, the DP climbs slightly faster than boost but based on the 3rd event that is to be expected as well, and I am rarely ever above 2400. Even at its worst is better than stock was at its best. Cruise at 80 is 1:1, where stock was 1.5:1. Below is a no load chart of what I get.

The main reason I wanted a turbo upgrade was the DP when towing, it was nearly always 1.5:1 or greater with the stock turbo and the Smarty Jr.

Towing!

I have about 225 miles on it towing and it’s a great towing setup. Around town acceleration in 2nd-4th gears it runs about 100-200° cooler than my stock turbo did, gets to 800-900 normally and stays there, regardless of light acceleration or heavy acceleration. 5th and 6th it will get to 1000 ± 50 and stay there, light or heavy acceleration. If I short shift it and start off in the next gear at 1300-1400 rpms the EGT's are a little higher but not over 1100°-1150°, but that's driver error and did it stock as well.

6th gear (255/80/17's and 3.73's) at 60 mph it will get to 1225° WOT on a grade, which is what it did stock as well, but the truck has more power than it did stock for the same fueling. There is a grade that I do at 60 in 5th becuase stock it wouldn't hold speed in 6th, I pulled it easily in 6th today at the same speed as always.. still 95-100% throttle but never slowed, rpms were 1700.

I can easily tow in 6th at 60-65 with a TT and a 25 mph headwind and not get too hot on the EGT's.

Where we went this past weekend we go often and there is 1 good sized hill that is 60 mph in 5th, stock turbo would run 1150° at the bottom and 1225° at the top, the new turbo ran 1050° most the way and the last steep part where the truck is at 75-80% load I saw about 1150°.

Boost is slightly lower across the board but EGTs are generally down and power seems to be slightly up.

IAT's are up to 25° lower on long grades with similar boost (+25° vs +45°), so the turbo is much more efficient than the stock HE351. Cruising in 6th at 60-65 mph with the a/c on the IAT’s were +10° with this turbo, where stock would have been approx +20°. I attribute that to the efficiency of the compressor wheel and less heat in the engine bay from the manifold/turbo blanket, but at highway speeds it’s mainly the compressor wheel.

Drive pressure, what drive pressure?? I never saw more than a +2 psi difference on drive pressure over boost for the entire tow. When I hit a grade drive will get about 2 psi ahead of boost and hold there until boost stabilizes, then it will drop to about 0 to -2 psi, which is amazing if you ask me. Even at 2400 rpms, 75% load in 5th gear DP would drop to 2 below boost; where with the stock turbo it would have been +12 at the lowest.

Slow speed is an absolute joy. I did about 70 miles of 20-30 mph towing mostly in 3rd, but 2nd -4th were used. The truck responds better than stock and has all the air I need at low rpms and low speed. I never saw over 650° in all those miles, not many hills but some small ones.

The truck is also much smoother at higher rpms. At 2000-2500 rpms the truck drives like it did at 1500-2000 with the stock turbo. Downshifting is easier and does slow the truck as much. Cruising at 5th at 2200 rpms the motor is much quieter than it was, and the boost builds and drops off easier and makes for a more constant speed and smoother operation.. I know I used the word smooth a lot, but it really is quite amazing.

My low boost “Smarty signature” smoke is 90% gone. I still see a minor haze right at the shift, but its nearly gone. If I try I can still roll some black, but normal driving the difference is huge.

Normal driving in lower gears keeps the turbo ahead of the air demand, and shifting so that your at 1500-1600 rpms after the shift is perfect in upper gears, which is where you should be shifting anyways to stay above peak tq rpm.

My mileage seems to be a hair better for the driving I have been doing, but time will tell on that.

All in all I am very happy with the turbo. I have yet to experience a situation where the stock turbo was superior. In the 350-400 rwhp range this turbo seems to do it all with ease!

The last I have noticed that I didn’t expect is oil pressure is a 2-4 psi higher all the time. I figure this is from less oil going to the turbo and more to the block. The BB turbo’s use very little oil and have a restriction built into the inlet fitting.

More to follow as I put some miles on the truck.

[dorkweed]

Great write up!!!!:thumb1:Why is this new turbo water-cooled??? The stocker isn't. In my world, that's just another seal/gasket/washer to eventually pop a leak. Not arguing, just saying. I guess I don't understand the need for it. The way you describe it, it should'nt get as hot as the stocker because DP is lower. Help a simpleton out here!!!:duh:Also, what's the purpose of the manifold blanket???? In frigid climates, I understand, but, I wouldn't think your part of Idaho needs it. Again, not arguing, just saying!!!

[AH64ID]

There are a couple of reasons for a water-cooled turbo. The main reason is BB turbo's use very little oil so there is less cooling from the oil, the second is that the temperature is more stable and more heat can be removed with coolant, providing for better turbo bearing life. The stock turbo on 6.7's is water cooled, as are many larger industrial turbos.The blankets actually have nothing to do with cold climates. There are several benefits to them. With the exhaust heat retained in the manifold you get less heat rejection which translates to quicker turbo spool, but the main reason I went with the blankets is to decrease under hood temps. I do lots of slow speed towing where EGT's are 600-800 (1000 even on some grades) at 20-30 mph, with little air movement that makes for a very hot engine bay. The blankets will keep that from happening. Immediately upon shutdown I can put my hand on the blankets and they are only warm, not even hot. I also plan to wrap the first few feet of the exhaust to keep the heat away from the trans in similar circumstances.

[dorkweed]

I do a lot of slow speed towing also. Very rarely do I ever see over 700* at 20-30mph. I'm usually in in 3rd or 4th gear at those speeds. On the rare occasion that I'm in 5th at those speeds, and give her, she'll get warm, but not as warm as yours does!!!! At least according to my gauge!!! I believe it to still be accurate, because it would read almost the same as the J w/A monitor when I still had it connected!!I almost cannot get my EGT's that high except in 5th or 6th gear. There's just too much "low end" torque in these bad boys. Let me preface this last sentence..................there's "too much" low end torque to get hot in 1st thru 4th gear...........at least the way I drive. There's never "too much" torque per se!!!!!:lmao2:Not arguing, just saying!!! Is your truck auto or manual???

[AH64ID]

Those temps are not my normal temps, but there are some places we go camping where the grades are STEEP and you start above 5K feet, and it can be over 90* out... I too can't hardly get over 700* on 90% of slow speed tows, but there still is very little airflow as the coolant isn't normally hot enough the fan is on (only had the fan kick on once at slow speed towing in 3+ years), so the under-hood temps climb, which makes IAT's climb, which makes EGT's climb, etc... This past weekend I did 70+ miles under 30 mph and never broke 650*, that's more normal.. but again it all depends on where we are headed and what were hauling. Big difference in slow speed towing, and climbing switchback steep mountain roads on a hot day and towing, espeicially when we start just under 3K feet and go up.. My truck is a manual.I can't think of a single draw-back to having cooler under hood temps.

[dorkweed]

10-4 Bud........just needed some clarification...............just for my trucks' sake!!! I was thinking my truck wasn't normal!!!! I know, too much thinking!!!

[AH64ID]

Sounds normal.. it's not often I get to those instances where EGT's are high in lower gears but it does happen... It is really nice opening the hood and not getting a heat blast thou!

[AH64ID]

I have had the turbo on the truck for about 3500 miles now, with about 1525 of those miles towing, some hwy, fwy, and FS roads. About 1100 miles of empty fwy/hwy cruising and the rest is around town and FS roads. Here is my updated overall impression. I still feel the turbo is superior to stock in every form. The hottest I have seen is still the ~1225° WOT in 6th at 1600 rpms with a trailer on a hill, and that was on SW1 on the SJR, SW3 peaks about 1190° as there is more boost from the increased exhaust flow. DP is nearly always 1:1 or better. Empty cruise with EGT’s below 900° its about 1-1.5 psi higher than boost , and WOT acceleration above 2500 rpms will give about a 1.2:1. Towing at constant rpms its right at 1:1 95% of the time. If the EGT’s are at 1100° or above the drive pressure can get as low as .8:1 on a grade (I have noted more than once 24-25 psi of boost with 20-22 psi of drive on a grade). This is one efficient turbo!I have been running SW3 on the SJR and the EGT’s reported here on on that setting (SW3 TM2 TQ2 PoD99.. uncorr 386/712 without any of the bolt on mods). EGT’s are generally 600-800° in 1-4th gears, but can hit 1000° with a big hill and load. 5th and 6th gears run 700-900°cruiseing around here with the elevation changes, and big mountain passes will see approx 1050°max when empty and 8-12 psi of boost. If I had to pick the turbo’s favorite EGT is would be 1000°, towing or empty that seems to be where the turbine starts to gets it’s peak efficiency at, the EGT’s will climb quick to near 1000° and then only slowly go up from there. When towing in 6th gear it runs between 900-1100° except on the biggest of hills where is will slowly climb to a peak of 1190°, I have yet to break 1200° except where noted earlier. If I drop to 60 in 5th it generally runs at about 800-1100° depending on the grade, but it takes over 70% load to get the EGT’s above 1050°. I recently pulled rye-grass hill (I-90) at 50 in 5th at 7spi and 800° (was slowing for the u-haul following me) at about 15K GCW. I think with my current power setting the turbo is well matched for the fuel, I am not sure I would get above my personal limits of 1250° continuous/1300° momentary above 2000 rpms in any gear, but especially 6th. Based on what I have seen I can probably pull just about any mountain pass (curves aside) in 6th up to 18-19K GCW and have the power/EGT’s to do so. Fuel Efficiency is really much harder to quantify an increase/decrease than most want to think, but I would say that I have seen about a 10% increase in cruise economy, and probably 5% in slow speed towing. I recently got an average of just above 14 towing a 7x16’ enclose trailer at an estimated 15K GCW from Bozeman to Seattle, normal flats speeds were 65 and hills were 45-60 depending on curves. Then returning from Seattle to Boise I got right around 19 (had some mixed towing but the math points to 19 flat on the last 500 miles), with a bed full of furniture and appliances at an average speed of 66, my previous best on that trip with an empty bed was 17.25 with more timing.Towing or empty the IAT’s seem to hold 6-10° (a/c off) and 9-12° (a/c on) above ambient unless pulling grades, then +30° is still the hottest I recall seeing at 25psi of boost. The compressor is very efficient. Oil pressure is still holding a few psi higher than it ever was with the stock turbo and doesn’t drop as much pulling grades, the higher oil flow thru the stock turbo must have heated the oil more than I thought. Coolant temps seem to run a little cooler as well. I am not sure what is causing the lower coolant temps, if it’s the lower drive pressure and thus better flow thru the cylinders so lower cylinder temps, or if it’s from lower heat soak from the wrapped manifold/turbo, or what.. but I have yet to break 198° this year in the last 1525 miles of towing, and the thermostat isn’t even fully open until 207°.

[AH64ID]

I have had 2 or 3 tows where I am doing 25-30 and EGT's are 900-1000° on grades. The blankets work awesome! The coolant temp stays lower as do the IAT's. When I get to where I am going the few times I have popped the hood the under hood temp is noticeably lower than without.

[AH64ID]

Went on a great camping trip this weekend, coming home on Monday it was HOT and I decided to take some notes on a decent local hill. It's about 5.6 miles long and goes from 2650' to 4250', so an average grade of 5.4%, with spots as low at 1% and as high as 9%. At the bottom yesterday it was 93° and 88° at the top with 92° being the most prevalent. I weighed 15,220 at the bottom (scale was 1 mile prior) and towing my TT which has an 18" receiver and produces LOTS of drag.

The hill starts in a 35 mph zone, while accelerating up the initial 5-8% grade to 55 mph I didn't go over 1100°. Coolant temps went from 190° to 207° in the first mile or so, then slowly went to 213° and never got any higher.

I pulled the hill in 5th at 55 mph, which works out to be roughly 2250 rpms. Rail pressure was 18K ± 200 psi for 90% of the pull. Intake air temps were pulled from the MAP sensor, the IAT sensor in the pre-turbo intake tube showed air temps +8° from ambient for the pull.

Looking at the map below you can see my 3 markers, here are the stats.

1) 24 psi of boost, 22 psi of drive pressure, 1190° EGT's, 92° ambient, 117° Intake temps, 65% load, 3,000.

2) 25 psi of boost, 23 psi of drive pressure, 1210° EGT's, 92° ambient, 119° Intake temps, 71% load, 3300 feet. (this was the peak EGT/Boost for the pull)

3) 23 psi of boost, 20 psi of drive pressure, 1175° EGT's, 90° ambient, 123° Intake temps, 60% load, 4,000 feet.

I am very happy with how the truck pulls, every time I drive it I like it more. The only time I have pulled that grade with the same ambient temps I was running the stock cam/turbo and ran about 220-225° on the coolant and 1200-1250° on the EGT's for the entire thing, and IIRC was at 50 mph.

[JOHNFAK]

hey man was just going back over thisI want your turbo, your manifold, your blankets ...... so how much for this truck ??? When can I pick it upYou mentioned stock cam - are you running stock or aftermarket - if aftermarket - whats your 411 review of it ??

[AH64ID]

hey man was just going back over this

I want your turbo, your manifold, your blankets ......

so how much for this truck ??? When can I pick it up

You mentioned stock cam - are you running stock or aftermarket - if aftermarket - whats your 411 review of it ??

What's a '11 with deletes, studs, HE451, and a clutch cost? :lol:

I am running a Colt Cams Stage 1 and LOVE it. It's one of the milder cams out there, designed for improved efficiency (especially over the 3rd gen cam) and bottom end tq. It drives like it should have stock, especially with the cam/turbo combo.

--- Update to the previous post...

The cam moves a bit more air, but so much that the feel is different. You can see how much more air it moved than the stock cam in the little spreadsheet I attached. Boost is up, but lb/min per a given psi was also up. So an increase of 2 psi at 3000 rpms was more air than a 2 psi increase with the stock cam..

That's similar to how I now move similar air with the Garrett at 28-30 psi than I did with the stocker at 33-35 psi.

You get that 351 installed yet?

[AH64ID]

I did a 670 mile trip this weekend where 640 miles were towing my TT. I am guessing about 16.5K on the trip down and 16K on the trip back. With my extended shank my TT is not windage friendly, and on the flats takes as much power to maintain 60 as the 15K lb dump trailers I have towed. For the most part cruise was set at 70-71. Elevation ranged from 2800 to 7000. There were a couple of short 9% grades, but mainly in the 5-6% range when pulling hills. Temps were 70-97°.Boost ran from 5 psi on the flats to 30 psi on some of the long grades (drive never went over 25 that I saw). EGT's were from 800-1100° except on the longer grades. EGT's didn't break 1200° except the one grade that went to 7000 feet. They peaked about 1300° at 71 mph which was 2100ish rpms. I am not sure I can complain about that, 7000 feet at 70-75° ambient is not EGT friendly when pulling 5-6% grades in 6th, which took up to 92% load on a 400 rwhp tune. I was harder on the truck that I have been on that trip in past years (weight and speed) and got better mileage on the trip down than I have ever gotten and roughly the same on the way home, but drove a good 5-10 mph faster on average.

[AH64ID]

I noticed that Garrett re-did their website and the hp rating on my turbo has changed to 510, but that's flywheel hp with the standard 15% loss that's about 435 rwhp, which is pretty close to where I am and I would say that's very accurate. I can just touch 1200° WOT on a 80°+ day, and below that its 1150-1175° when empty and towing I can touch 1300° at 2K rpms in OD up a 6% grade at 7K feet on a 75° day at 17K GCW, near WOT..

[Prowelder]

Nice read man!!! I'm looking into one of these for my next truck since Black Magic got wrecked... Stepping up to a Common Rail!!

[AH64ID]

Went camping this weekend, and pulling up the grade from the river was STEEP! I was thinking of dorkweed's comments last year about EGT's in 3rd gear. The pull is a little more than a mile, but the last .6 miles is where the fun is. It starts off slow, but about 1/4 mile in your at 8% and then it jumps to 10 and all the way to a 20% grade at the top. The average is 17.4%. It's low, 2100 at the bottom and 3000 at the top and the temps were in teh 60's. I did the steep part in 3rd gear, 2200 rpms, 15 psi of boost and 1000°-1100°. I have never worked my truck that hard in 3rd gear. I figure were had a GCW of 16.5K (need to get the new camper on a scale). It's times like that I am really glad I have the blankets on the manifold/turbo becuase otherwise the enigne bay would have been a LOT hotter. It was also cool to hit the 20% section and give it some go juice (75% at most), the boost went up to 30, the EGT's peaked at 1150° and she shot to redline in a blink of an eye.

[dorkweed]

20% grade!!!!! Wow; that's gotta seem like you're sitting in the space shuttle on the launching pad!!!

[AH64ID]

Yeah it's steep there for a little bit.

[AH64ID]

I pulled the same hill in post #10 this weekend. I looked at the grade on the updated version of the software that I did a screen shot of, and there are several 10% grade sections. This trip it was 104° at the bottom and 99° at the top, with 102° appearing on the temp gauge the most. GCW was 17,300 lbs, or about 2,000 lbs heavier than last year. Intake air temps got up to about 132°, with 117° pre-turbo. EGT's hit 1225° in one corner for about 3 seconds, but the rest of the time 1200° is the most I saw. Coolant got up to 217°. Boost was about 24-25 peak, drive never broke 20. Load was up to 79% in some stretches. I did the bottom half at 55 mph, 2250 rpms, and the top half at 60 mph, 2450 rpms. I am running a different tune this year, and think I have a hair more timing that I did last year. All in all for a 100°+ day at nearly 18K lbs I am quite happy with the performance.

[JOHNFAK]

All in all for a 100°+ day at nearly 18K lbs I am quite happy with the performance.

Nice stuff bossman Still happy with your turbo and manifold blankets ?