C38-81 + 70mm pulley on stock internals

[fishsticks]

What's the verdict on this? Mods in profile. Motor is higher mileage but still gives good compression on all 6. I'm using a 75mm pulley now and the stage 2/80lb injector calibration.

After the last round of mods, VE improved and it feels like my power band has shifted upwards a bit. I'm looking for more area "under the curve" in the 3-4K range. I have U-tune, but I'm resistant to adding timing since I travel a LOT and fuel quality can vary sometimes. I figure just squeezing a little more air in there will get me what I want.

I have plenty of fueling and the MK3 intercooler does a fine job of keeping IATs down. The truck errs on the rich side under power already (black tailpipe, 11-10 AFR on the gauge under heavy load). I'd work on tuning that out but the UCON is quite different from the GM ECUs I'm used to. Plus I'm told it adjusts for most things on its own. There's no VE table to adjust the sensed AFR to match commanded, so I don't even know where to start.

Anyway, this got longer than I wanted it to. Your experience/suggestions appreciated. G is busy enough as it is so I didn't want to bother him via email.

 

[Torspd]

What will that rise the boost level to, and what is your elevation?

 

[fishsticks]

What will that rise the boost level to, and what is your elevation?

The 70mm pulley is a 7% increase in compressor RPM. Assuming efficiency stays roughly the same(and that CFM output follows RPM linearly), I should never exceed 11psi with it.

I am at sea level most of the time.

 

[Gadget]

70mm will approach 15PSI at 6200 RPM.

Should limit RPM to 5700 unless running race gas.

Don't jack with the configuration files. They have been developed over years of experience with the engine and supercharger system. People do, brake stuff, then blame the equipment and not their jacking with stuff.

G

 

[fishsticks]

70mm will approach 15PSI at 6200 RPM.

Should limit RPM to 5700 unless running race gas.

Wow my math is off then, or I just haven't been watching the boost gauge closely enough. This thing sees redline so infrequently that reducing it wouldn't hurt my feelings.

Don't jack with the configuration files. They have been developed over years of experience with the engine and supercharger system. People do, brake stuff, then blame the equipment and not their jacking with stuff.

G

This is precisely why I'm still using the tune you emailed me. I'm assuming the really rich tune up top is just a safety measure though? I get black smoke on occasion (not a lot) and am cleaning the exhaust tip off pretty regularly.

What's the difference in Stage 2 vs Stage 3 calibrations? Mostly timing?

 

[Gadget]

The only difference between S2 and S3 is that S3 runs the additional injector. This is good for the TRD system, but for the URD a better choice is the S2_800cc config.

G

 

[fishsticks]

The only difference between S2 and S3 is that S3 runs the additional injector. This is good for the TRD system, but for the URD a better choice is the S2_800cc config.

G

I thought about that right after I hit send... :laugh:

 

[Torspd]

So which size injectors are you currently running? Seems that S2_800 file is needed with that new pulley.

 

[fishsticks]

So which size injectors are you currently running? Seems that S2_800 file is needed with that new pulley.

I run the 80lb/hr Siemens injectors URD sells. I run the S2_800 calibration already.

 

[Torspd]

Ah. Gotcha.

 

[shane881510]

Yeap I've seen 15/16 psi on my 70 mm pulley. I run mine to 6400rpm tho.