How to properly tune for egts?

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dodgediesel59

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Sep 20, 2009
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Well i got my truck going but holy $%@^ i can get my egts up to 16-1800 degrees on a zero to 40 run. When i did the project i put in a stage 2 regrind from colt cams. Had my 125HP vp injectors reset to P7100 pressures. For the pump i put in a 4gsk, made my own 0 fuel plate with a little tail at the bottom to cut down on low end fuel a touch, and put in 191 d/vs. I put the plate and afc housing both about in the middle of the road when i assembled. I also put a garrett gt3788 on with the new set up and have it wastegated at 38psi. What can i do to get this tuned in good and still use the truck without melting a piston into the block? Also i set timing at 22* when i put the pump on using the bluepoint timing kit.
 
whats the size of the garrett...not really familiar with the garrett sizes. Any idea how many CC's your pump flows? Also check for a boost leak, clogged air filter...etc...
 
Not a clue what the pump flows, it was a bone stock 160 horse pump off a 96 freightshaker with the mods in my sig. Air filter is new. I was told not to run these past 40 lbs of boost or bad things might happen, any truth in that? Not sure the exact specs on the turbo but it is the gt3788r. I got the stage 3 kit which they claim will handle 600 horse or so.
 
Yea thats the other part of it too. I dont have the money to put studs in at the moment. I got a few too many dollars tied up in this swap at the moment. :nail:
 
45psi is perfectly fine on stock bolts at stock torque. Just let the tstat open before hitting full boost.
 
Thats hard for me, i have a heavy foot. :doh: So how much does sliding the fuel plate back help things out? When i had it out i set it back about dead in the middle. Also, what affect does sliding the whole afc housing have?
 
The Garrett is a 63.5/88 compressor. They have small major diameters compared to BW turbos. I remember posts from Hammer a long time ago not being able to crack 500hp with his 3788. That was on a 12v, mind you.

Pulling the plate back will reduce max fuel, which should in turn reduce max EGT's. Moving the AFC back will reduce fuel in relation to boost, which should also help temps, but at the sacrifice of bottom/mid power.

What housing is on the turbo? I know both .89 and .99 housings were available at one point.
 
I beleive its a .99 I slid the plate and housing all the way back and i can still bring the temps up pretty quick off the line. They came down alot and stabalized in overdrive now though. Everybody told me that garrett would be a good fit and said i would have problems spooling that. Now i have an expensive turbo that still doesnt move enough air. Would that work good with some twins maybe? I mean short of downsizing injectors or putting the 131 dvs back in i really cant defuel it too much more than where i am at right now right? I suppose i could put a different plate in it.
 
Twin it up then. I'm running 3782R over a 4202R. I can still peg the pyro, but I am running a 1.0 v-band TiAl exhaust housing on the primary, and I think thats hurting me right now. I should say though, that I built this set for 600hp, and I am pretty sure I am over that as I sit right now. It will be fun on my 12v, I'll be moving to a 64 over an 80 for the dually next.
 
So where can i get a good understanding of setting up twins? There are 2 different ways to run them right? And how the hell do you make all the piping? Mount the chargers? I understand the theory for the most part but would like to spend some time researching it. You think my 3788 would make a good small turbo though for twins?
 
Does the 3788 only wastegate 1 side? If so, that should be changed if you are going to change. Keep in mind that 125hp injectors on a VP and 125 on a p-pump are 2 different things. I made about 400hp with my RV275's and a Dodgezilla turbo(it ran much hotter that way than it does now at twice the power). You may need to ask yourself what power level you are looking for and adjust accordingly. Twins are a pain the first time around, but make the truck far more enjoyable to own because the egt issues go away( although if you keep screwing with the power level they eventually come back). If it isn't too expensive, you might try backing off on the injector size for now.
 
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Hey ron could you explain what you mean by only wastegated on one side? I am not quiete sure what you mean by that. Well, i know me, and i always want more power. I will be ok with my setup for awhile and then i will think gee maybe i should put bigger injectors in. Maybe i should o ring the head and put studs in. I think for me, twins would be good down the road because i can have the power and still use it for towing from what i have heard.
 
If your exhaust housing is a divided housing(2 ports going into scroll) and your wastegate only vents 1 side, that's what i was referring to.
 
My 3782 only wastegates one side, I can't see any of the other 'Cummins' Garrett turbos being different.
 
Yea, thats what it does. I pulled my gooseneck and skid loader today which grosses about 12K and it did alright, i just gotta drive by pyro. I was thinking of putting water injection in with a boost switch for towing. Anybody have inputs on this? The sole purpose of me doing it is just for comfort while towing. I know that it has a very positive effect on egts. Thanks for trying to help me out guys.
 
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