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Discussion Starter #1 (Edited)
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.
 

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Nice review. I just put a 4094r on my truck. Very pleased with it so far. Still trying to get a few other bugs worked out to see what it is really capable of.
 

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Great write up, and great review.
 

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Nice write up
 
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Nice job John!
What kinda manifold is that? What's the deal with wrapping it? Isn't there any danger of cracking it or something since the heat can't dissipate as much?

I know nothing about turbos, how does the 62/64/.89 compare to the stocker? Less max boost than stock?
 

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Nice write up! I'm glad to see a different brand being tested.
 

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This is awesome. By far the best turbo review I have seen on here, backed up with quantitative data and everything. Do you ever plan to go to compounds? I'd really like to see how that turbo pairs with one of the larger GTX wheel Garretts.
 

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Nice job John!
What kinda manifold is that? What's the deal with wrapping it? Isn't there any danger of cracking it or something since the heat can't dissipate as much?

I know nothing about turbos, how does the 62/64/.89 compare to the stocker? Less max boost than stock?
Buy wraping the exhaust. Lowers the heat under the hood and keeps the heat in the exhaust. Heat is energy the more heat that stays in the exhaust gases the beter the turbo will preform.
 

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Where did you get the blanket and nice job.

I had an 88mm Garrett on my Ford and I loved it. It also had a 6spd. I wish they had that one out when I started building this truck. Or if it was out, I wish I would have known about it. My set up works great, but I miss the sound of the ball bearing turbo. Plus the water cooling would be cool.

It sounds like you tow a lot as do I. Have you done anything else to get the heat out of the engine bay? I always remove the insulation that is on the hood and any where else except for on the firewall. It seems to help. It would be nice to get some cool air flow from the inner fender wells or something. On the Ford there were factory holes packed with insulation for sound that you could remove. They were pretty high up. Then cool air would come in from the inner fender well. When the engine was running you could feel the air flow if you put your had in the wheel well.

Looks like a great set up for towing. Are you going to add some small injectors? 50 or 90's? Or anything else in the future?

Thanks for the info.
 
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Thanks for the write up! Now we WANT a couple videos!!! Now!! hahahaha
 
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Discussion Starter #13 (Edited)
Nice job John!
What kinda manifold is that? What's the deal with wrapping it? Isn't there any danger of cracking it or something since the heat can't dissipate as much?

I know nothing about turbos, how does the 62/64/.89 compare to the stocker? Less max boost than stock?
The manifold is an ATS 2-piece. The main reason I wrapped was to keep the underhood temps down when towing at low speeds, and it WORKS! The other benefit is that you get less heat rejection out of the exhaust which puts more energy into spinning the turbo. I have been told blankets can help spool the turbo by a 100 rpms or so, but I never tested it. At low airflow I think it increases the EGT's in the manifold a little, but again I never tested it.

Stock is a 60/60/9cm (9 cm is about a .60 a/r). I am currently making less boost than I did with the stocker.. but as you know I am clutch shopping and can't tune the WG until that's in.

The stock comp wheel is a 60x82, and the stock turbine wheel is a 68x60. The comp wheels flow similar air, Stage 2 is slightly higher, but the main reason for my upgrade was a better turbine wheel.

This is awesome. By far the best turbo review I have seen on here, backed up with quantitative data and everything. Do you ever plan to go to compounds? I'd really like to see how that turbo pairs with one of the larger GTX wheel Garretts.
No real plans for twins, but I can dream about a GT3782R/GTX4202R twins set thou!

Where did you get the blanket and nice job.

Have you done anything else to get the heat out of the engine bay?

Looks like a great set up for towing. Are you going to add some small injectors? 50 or 90's? Or anything else in the future?
Turbo Performance Products makes the blankets and I highly recommend his products! Turbo Performance Products

I did wrap the down-pipe last weekend, but that's more for heat soak of the trans than the engine bay. The blankets are all I have done in the bay and they work great I am not sure I need to do anything else.

I would like a set of 50's, but that's a ways off I think... I was going to do a set when I did the turbo but had to put them on hold.

Thanks for the write up! Now we WANT a couple videos!!! Now!! hahahaha
All you would see in the vid's right now is a slipping OEM clutch! I was trying to tune the WG and found out the harder fueling from more boost in the mid range is more tq than the stocker can hold.

I was only getting about 27 psi so I turned the rod and got 30, and some slippage.. but I turned the rod some more and still only get 30, but more slipping at 1600-1900 in 6th. So once I get a clutch I'll mess with the WG some more.

For now I am back to timing only and stock tq management, well see how it does towing on stock fueling this weekend.
 

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Nice review bud, lots of good info there! You are still moving more air even though your boost is lower!
 

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Discussion Starter #15
The air is a LOT cooler as well.
 

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Thanks for the info. I had a BB on my 2nd gen and loved it...

I have a Jacobs exhaust brake on the elbow and love it and have been looking for an upgrade that keeps the stock elbow. I think I have found it. Wanted to go 90 hp sticks later... do you think that this turbo will keep them cool or should I go with 50s?

what other turbos will keep the stock elbow? can I go bigger? Would love twins, but???

AH you are the man for info... thanks so much
 

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Discussion Starter #17
There are quite a few options for the stock elbow.

With 90's I would run the Stage 3 with a .89 housing from Tom at Turbo resource.
 

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My 66 uses the stock exhaust elbow!
 

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AH64ID, Thanks for such a great write up.

I love to see real testing and numbers, I wish more of us would do this.

I did a BD IC test and wish I would have had more sensors and gauges like you.

I cant help but think your fuel mileage has gone up just from the lower DP, keep us posted.

Thanks again
 

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AH, did you run it on the dyno before the turbo? Before and after numbers would be good to see.
 
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