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Garrett Powermax Stage 2 GT3782R Install/Review

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Tom told me that the Stage III uses a 64. 5, but he also said all he modifies is the turbine housing, and not the comp wheel. The 3788R is a 63. 5x88, and the 4088R uses the same 63. 5x88 wheel, with a larger turbine than the 3788R. All 3 stages have the same turbine.



Ah OK, must have been misinformation I read on Comp Diesel :rolleyes: It could have been a custom setup he did for someone. What you say makes sense since the prices Tom quoted were close to or less than what other vendors were selling the same series of turbos for.



Next upgrade- new clutch :p
 
I am ordering the clutch today!

Tom certainly knows his Garrett's but he did tell me originally that the Stage 2 had a 59. 1mm comp wheel, and CompD was supporting this. I called Tom and asked him to verify it, as the literature states 61. 4 and the MAP looks like the 3582 wheel. . He pulled out the calipers and 61. 4 is what he found... Just goes to show how careful you have to be with internet info!
 
45 is well above the MAP, did you set it there?



I am trying to get my WG dialed in (how I slipped my clutch) and want it set for 35 (What Tom recommends).



When I bought it, Tom ask me what I wanted it set at and I said 40. I had a time installing that thing. (There is an old thread about my experience. ) It was one of Garrett's earlier kits and it had a funky thing for the electronic waste gate solenoid on the compressor elbow and it just flat out didn't fit. I ended up getting what i think is the current compressor elbow that is just a plain elbow. I re-clocked and relocated the waste-gate actuator what seems like a dozen times trying to get the supplied elbow to work. Anyway, after fooling with it I ended up at 45. Was really intentional, I was just tired of messing with it. Haven't been beyond 35 yet.
 
looking at these install photos I see no wastegate solenoid. I installed this turbo on my 05 with the solenoid. should I remove it and put the plug back on?
 
My WG solenoid is on the shelf and I installed a WG fooler. I don't ever really run the stock tune, and even if I did I haven't hit enough boost yet to throw a overboost code so I am not worried about it.

How much boost are you making?
 
before the Garrett install I had bare/broken wires on the wastegate solenoid. The damage was too close to the unit to repair,so I got a new solenoid. I also had a jumper plug from ATS I was going to use to make the service engine light go away prior to the new solenoid. That being said,I could delete the wastegate solenoid,connect the jumper plug and see if I get a boost.
 
That's not a lot of boost, I would check the WG and the connections for leaks, you should be able to pull at least 30 with stock fueling.

The WG is probably opening mechanically, little to do with the solenoid. I just left if off for a cleaner install.
 
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 18K 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°.
 
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Thanks for the update... looks like you have found a turbo well matched for trucks with lightly modified fueling loads.

I will definitely consider this turbo after I pass my 100k warranty !!
 
I just got a smarty jr and have played with it a little. Also noticed that egt was lower on sw2 then on sw1 ... have not tried sw3 yet and am not sure i will. Thank you for your write up been looking at those turbos for a while and wondering how well they work.
 
Good write up, with scientific specs. Some info is above my head tho!:)



I would like to know your axle ratio and tire size, just some basics, lol.



Also how are you arriving at an estimate of power levels? If you can pull 18/19k gcw in 6th on a 6% grade, I would guess your estimate is low.



Just for comparison, my '01 in my sig. will pull 16k on a 6% grade in 6th but 18k makes me drop a gear. This is with 3. 55 gears and 265/16 tires. Average dyno is 330hp/840tq.



Nick
 
I am running 3. 73's and 265/70/17's right now, I have considerably less 6th pulling power with my winter 255/80/17's.

I dyno'd 386/712 before the cam/turbo upgrade but I am running the same amount of fueling now that I was then. I need to re-dyno the truck one of these days.

The weight and grade was just a guess, a lot would also depend on the trailer. I doubt I could do that with a TT, but a lower drag trailer like an enclosed trailer would be easier. I'll have to get some heavier loads and report back, but there was plenty of pedal and EGT left at 15K and 6%. 18K is probably a better estimate. If I can run 67-68 in 6th I have more power and run cooler than 65, 2,000's seems to have a big impact on the tuning.
 
When you say rear axle was 130*, I assume you mean rear differential temp? Mine gets to 190* when towing on level ground at 65. Is 190 high, or is 130 low???
 
When you say rear axle was 130*, I assume you mean rear differential temp? Mine gets to 190* when towing on level ground at 65. Is 190 high, or is 130 low???



I would say you are right on both counts. My test was a short run of 28 miles at 75* ambient, with the first 12 miles slightly down hill, the next 12 miles was uphill, then 4 miles of down hill. Not a very good test for oil temps. As I do more hauling, longer distances, I can get better numbers. I would think 190* is a little warm and yes the temp was shot at the diff.



Nick
 
I agree, but aren't the 600 engines made to take 1350 sustained and 1450 peak pre-turbo?? My personal limit is 1250 per-turbo.



Only on stock timing, advance the timing and that number needs to drop.



I use 1250° as my continuous and 1300° as my momentary. . thou I haven't hit either yet with this turbo.
 
Update: Just hauled a heavier load (24,500 gcw) on the same road as before. Set the cruise at 60 mph in 5th, 2300 rpm on the same 6% grade, I pulled down to 55 and 2100 same 28 psi boost and 950 egt. post. It pulled harder at lower rpm and egt. so next time I will set it for 55 and try again.



Looks like Cummins and 2100 is like bread and butter:)



Nick
 
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