SOOT4BRAINS

A few months ago I had a nice long conversation with Tom down at turbo resource about the feasibility of running a ball bearing turbo on a first gen and what size would work best for my needs. We decided the GT3788R would be a decent size single and make a bit more air than my current s300 while also gaining spoolup and drivability. This is the same turbo as the the "stage 3" kits for the newer trucks. Here is the compressor map.
http://www.turbobygarrett.com/turbob...mapCummins.pdf
64.5mm compressor wheel
72.5mm exhaust wheel
.89 a/r housing
Its quite a bit different than the box stock 3788r and has a much higher pressure ratio capability and flows a bit more but it makes the stage 3 prone to surging. The surging issue is usually overcome by head porting or a camshaft and I have a camshaft so I decided to risk it and so far no surging at all.

As far as installation, it fits pretty well. The turbo is a smidge longer than the s300 but the diameter is a lot smaller. Tom sent me some water lines for a 24v truck and I was able to modify them to work. One of the main obstacles is getting water for the turbo. The lines are set up to run off the heater hose lines but the factory cut off valve would cut the water off. I found a 4 way heater bypass valve that closes off the heater core but still flows water through the lines. Hopefully this may also help keep more heat out with the A/C on in the summer.

Being water cooled, the turbo needs much less oil than normal. It comes with a restrictor to slow down the oil flow to be just enough the keep it lubricated but too much oil slows the shaft down. The hole in this is only .035 inches

SOOT4BRAINS

After figuring out what type of fittings this would need it was just easier to get a new oil line for a 24 valve and be done with it. The newer line fits right on and it uses o-rings instead of compression fittings and seals up great. The oil drain does not line up perfectly with the block fitting but its close enough the flex line will take up the offset without issue. You can see the new oil line and one of the water lines in this pic. It connects using large 18mm banjo bolts and copper washers. This is all there is really room for.

There is less than 1/16 between this inner water line banjo and the flange nut.

Here it is all ready to fire up.

The manifold and hot side of the turbo are painted with POR15 cast iron grey brush on paint. Cold side is clear coated with engine paint. Makes the rest of the engine bay look like crap. I also got all new silicone heater hose and got rid of the factory hard lines. The turbo return replaces one of them and other one won't work with the new heater bypass valve.

SOOT4BRAINS

Now for the good part. Performance is better than the s300. Not a huge difference but its very noticeable. It starts spooling up sooner and the pump comes on slower because its starting earlier. The s300 would come on really fast and hit you hard but it was at a higher rpm. The Garrett takes less fuel for the same amount of boost and feels much smoother. The afc tuning really shines with this turbo. Spoolup smoke on the street is down even more. Top end feels less restricted and the temps get to 1400+ but it gets there slow. From a dead stop it will hit 1200 at the top of 4th gear and climbs a bit more in 5th gear. Boost gets to 45psi which is where the wastegate is set at. So overall I would say its better low end, better top end and streetability is great. Plus the whistle is INSANE!!! It sounds different from any other turbo I have heard. Even at idle it sounds like I'm hiding a small turbine in my stacks. I am hoping to get to the dyno soon. I have not changed anything but the turbo so I can get some real results on what the turbo gained me. Seat of the pants gained some for sure.

nasty01cummims

Definantly impressive soot4brains. That POR looks good an their as well. Really dresses up the engine bay. And I've heard those BB turbos all have insane spool up givin the right application. I hope it works out well for ya.

KD93

SWEEEEEETTT!!!! Very nice Soot!!! Can't wait to see the next set of numbers.

archer39

Sweet, i was wondering about ball bearing turbos for these trucks. I have ran a few different turbo setup on a car (srt-4) that I had before the truck and the double ball bearing turbos blew everything else away.

If you don't mind me asking what did it run you?

mhuppertz

Really nice job. Can't wait to see the dyno numbers!

fatt

Nice writeup, I vote for sticky for how to install a Garrett. Will be waiting for dyno numbers.


Edit: This is soggy posting, fatty was signed in and I didn't realize til too late

JBradley500

i think interesting is the best word... i like that youre trying things you dont see much, it opens up new things to be done by guys who want to be different.

GLHS

I have talked to Tom in the past about this but, they want to steer me away due to the possible surging issue.

What size S300 did you have and what is your elevation?
Does it run hotter or cooler when run flat out?

93flatbed

VIDEO WITH SOUND.......PLEASE? Glad you got it all fixed up, hope it goes well with that big 14mm!!!

SOOT4BRAINS

For now till I get permission from Tom to post the prices, I'll pm them to those who ask.

JBradley500, Thats exactly what my goal for this truck is. Want it to be different and quick (for a first gen) and still keep some of its street manners.

GLHS, It runs a little cooler than the s300 flat out. The s300 kept it pretty cool but would climb towards the upper rpm range pretty quick where the Garrett gets there slower. Total max egt is down at least 100 degrees or so. Its hard to watch the gauges when your are accelerating that fast. I just glance at them when I think about it. Tom said to plug the wastegate and see what that does for temps and boost. Not good for my head gasket but I may do one run on the dyno with it plugged. 24 valves have seen 550+ hp from these turbos although I know this pump isn't near that, there may be a little more air in it with the gate closed. The s300 is a 62/65/12 and Phoenix is 1100-1200 feet. Tom does not recommend the stage 3 without a cam or head porting because of the surging but the stage 1 or 2 would be fine but below the power level I was looking for. Most of the problems you hear of surging are with 24 valves but there are only a handful (that I could find) that have even done a Garrett on a 12 valve and I found no info on one on a first gen.

93 flatbed, SMKHZRD tried to take a video in the truck and all you hear is the stacks roaring and see the camera shaking all over the place and banging back and forth every shift......... I'm going to try to rig the camera in the back of the bed like Richie did in his video of his turnout stacks. Just driving around below 5 psi you get quite a bit of whistle from the exhaust and above that the compressor sings to you. Maybe I could just tape the camera to the air filter for you??

GLHS

To say it spools quicker than that series s300 is impressive!

Who exactly made 550+ with one of these?

If it's who I'm thinking.....................

whereswaldo250

Hey Aaron, that thing looks sweet man! SMKHZRD told me you installed it. I bet it is a blast to drive!

SOOT4BRAINS

This is the thread I found. I would say at 575 it was pretty hot and stressing that turbo pretty hard to do that. https://www.dieseltruckresource.com/...highlight=3788
But that's third gen stuff and they seem to make better numbers for the same turbo than a 12 valve. And who knows what kind of correction that run has on it.

Ben, you can see it in person on Saturday at the show. Maybe I'll take you and Justin for a quick ride, but you guys get to argue who gets to squeeze into the little fold down kiddie seat in the back.