Timing, boost or both??

D

Diesel Freak

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Jun 20, 2007
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So, beed driving the truck.for a year. Very happy with the streetability and power.

Note: this is a very mild build with just a HX40.

Only issue is EGT on the top end (over 3300 rpm)

On a hard 6th gear pull (or a good whack on the throttle in 3rd gear to get the back end loose in the dirt) I dont see EGTs over 1300F till 3300 rpm.

Timing is at 18 degrees, and wastgate set for 34 PSI.

Would bumping timing to 21 degrees help any? Or should I just bite the bullet and get a turbo that can feed the engine better and allow the headroom to run cooler to 4k?

Not really a complaint as the powerband that has zero EGT "issues" is 1200 to 3300-3400...would just like to be able to run harder to 4000 when screwing around offroad as the truck has decent carli/thuren goodies under it now.

Pump is a stock 215, 4k gsk, DFI mach 6 injectors, custom ground plate (kinda like a #6) stock DVs.
 
I'd bump the timing up to the mid 20's.
More time to burn the fuel in the cylinder.
 
Pick a number between 20 and 26 and go to it 😁. I ran 23 on my 12V for years.
 
If you can tell in seat of the pants, it’s gonna be a negligible amount of bottom end response.
 
I don't recall it being an issue. Drove on 600hp for a long time doing all the truck things.
 
To be honest I'm surprised you're making it to 3300 before that little turbine is a problem. I had a super HX40 on mine at 425HP(this is with a vp) and the turbine choked well before 3k rpm. This was with a 16cm housing and going bigger would not have helped; the turbine just doesn't flow. Great for towing though! I miss hearing that 40 scream! LOL
 
Marq92 said:
I would go with something like a 63/68/14.
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63/68 are great drivers. I maxed mine out racing a Duramax and killed it, but I probably oversped it turning over 3k without enough gate or housing and too much displacement.
 
mhuggler said:
To be honest I'm surprised you're making it to 3300 before that little turbine is a problem. I had a super HX40 on mine at 425HP(this is with a vp) and the turbine choked well before 3k rpm. This was with a 16cm housing and going bigger would not have helped; the turbine just doesn't flow. Great for towing though! I miss hearing that 40 scream! LOL
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Oh, the turbine is definately an issue.
I hooked up my drive pressure gauge to do some checking. Was hitting 45 psi drive at 34 psi boost above 3400 RPM.
Backed off the gate to 28-30ish, and drive pressure only hits 35ish max now. EGT is 1400 at 3300, 1500 by 3800 on a hard 5th hear pull.

Timing may help, but it really needs more tuebo
 
Raise your timing, and your drive pressure will be lower, especially at the higher rpms.
Burn the fuel in the cylinder, instead of sending the late fuel straight to the turbine.
 
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