3126 Turbo Upgrade?

[Mavcaster]

I didn’t see any other topics related but I’m sure it’s been discussed before.

I just pulled the turbo on my 1088 and the compressor wheel is a bit chewed up with a little more play than I’m comfortable with. Just curious if anyone has replaced their turbo with a different PN adding a little more power maybe? I get it, go fast parts usually are paid for in reliability so not trying to improve my 1/4 mile here but if there’s a better option, figured you guys would know.

 

[simp5782]

I didn’t see any other topics related but I’m sure it’s been discussed before.

I just pulled the turbo on my 1088 and the compressor wheel is a bit chewed up with a little more play than I’m comfortable with. Just curious if anyone has replaced their turbo with a different PN adding a little more power maybe? I get it, go fast parts usually are paid for in reliability so not trying to improve my 1/4 mile here but if there’s a better option, figured you guys would know.

PDI makes a Big Boss turbo if you want something bigger and you will need to get into the ecm

A Borg Warner S300SX-E which is basically a little bit better turbo and a direct replacement

 

[GeneralDisorder]

With computerized fuel injection the ECM is the gatekeeper to all potential upgrades. It regulates boost pressure and supplies the correct amount of fuel to go along with the additional air being delivered - and since these engines have no closed loop fuel control the engine computer has ZERO ability to compensate for any mechanical changes that have been made without reprogramming it.

Someone out there might be capable of hacking the ECM's ROM code and "tuning" the fuel mapping for a larger turbocharger and/or more boost pressure but I haven't run across anyone doing it. On the civilian vehicle side it's highly illegal and the EPA is actively, currently, and aggressively pursuing shops that do this sort of tuning and the inevitable emissions equipment deletes that go hand-in-hand with it. A shop on the other side of town from me just got hit last week and accused of illegally tuning 245 diesel trucks and is being accused of profiting over $400,000 from it. They will be facing federal charges and fines that would make your head spin - possibly including jail time.

Consequently you are not likely to find anyone willing to even discuss it - then there's the obvious challenge of putting an FMTV on a chassis dyno - which isn't going to happen BTW. So it would be a "street tune" with a lot of data acquisition equipment attached.

Ultimately it's not going to happen. But you could potentially and rather easily swap in a C7 and run the factory CAT tune that's 370 HP and 931 TQ. From reprogramming these ECM's and knowing how the wiring is configured - it should be REALLY simple actually.

 

[Mavcaster]

A Borg Warner S300SX-E which is basically a little bit better turbo and a direct replacement

Perfect thank you, I’ll look into that one.

Ultimately it's not going to happen. But you could potentially and rather easily swap in a C7 and run the factory CAT tune that's 370 HP and 931 TQ. From reprogramming these ECM's and knowing how the wiring is configured - it should be REALLY simple actually.

Ahh yeah that’s what I kinda figured anyway. Here you’re talking about swapping in a C7 engine though right? not just the turbo

 

[Ronmar]

What General said… the programming is based on the flow thru the engine provided by known components. You alter that flow by changing parts, the programming has no way of knowing this(no mass airflow, no O2 or even EGT feedback.

kinda reminds me of hacking early toyota EFI…

 

[Mavcaster]

What General said… the programming is based on the flow thru the engine provided by known components. You alter that flow by changing parts, the programming has no way of knowing this(no mass airflow, no O2 or even EGT feedback.

kinda reminds me of hacking early toyota EFI…

Ah yes good point, lightyears from the duramax I’m used to working on.

 

[GeneralDisorder]

Ahh yeah that’s what I kinda figured anyway. Here you’re talking about swapping in a C7 engine though right? not just the turbo

The 3126b and the C7 are almost the same engine. They use essentially the same turbocharger (same size, etc) for both the 275 HP and 330 HP variants. Indeed even the 370 HP C7 used in the M-ATV is the same size - it just has a water cooled CHRA to prevent engine oil coking under extreme operating conditions - I recommend the use of high quality synthetic oil on any truck that I've flashed to 370/931 since the synthetics can handle higher temps and thus mitigate the need for the water cooled CHRA.

The issue with getting the 3126b up to 370/931 is that there does not exist a flash file from CAT for that rating on the 3126b ECM. The highest HP map from CAT is 330/860.

The C7 should be pretty much a direct swap for the 3126b. They are virtually identical on the vehicle side of the wiring harness. Even using the same chassis side harness plug and AFAIK the same pinout. There are some sending units for gauges that would need to be swapped over on the 3126b chassis because it doesn't used the MMDC like the C7 chassis that get's much of it's data from the J1939 bus. But other than a few minor things like that - it should be a bolt-in upgrade for 40 HP and 71 TQ.