Changing turbo setup

PureHybrid

Isuzu Shakes IT
Feb 15, 2012
3,492
472
83
Central OH
How's the front end set up? Looks like it still pulled you around. With that lift gate over the back end you could probably run 2wd LOL
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
296
83
Boise, ID, USA
How's the front end set up? Looks like it still pulled you around. With that lift gate over the back end you could probably run 2wd LOL
Torsion bars are set to stock ride height (stock keys). Can't really turn it down without the 35" tires murdering the cab.
I have a front ARB Air Locker, but I haven't used it on the pavement yet, so it was open diff for that video.

Steering setup is:
  • Stock centerlink (20k miles)
  • DHD centerlink stabilizer (6k miles)
  • Rare Parts tie rods (20k miles)
  • Kryptonite idler, Rare Parts idler arm, weld-in idler support gusset (6k miles)
  • Steering box varies week by week as I blow them up. My PSC has a bunch of internal play, but the brand new RedHead leaked the second it was installed, so it came right back off with 0 miles. Trying again next week...
  • Pitman arm varies with box. PSC uses a 4-spline Moog (200 miles), RedHead uses a 3-spline Rare Parts (0 miles)
Exact weights:
  • Steer axle: 4,460 (55%)
  • Drive axle: 3,560 (45%)
  • Total: 8,020 w/o driver
It murders the tires if I try and boost launch in 2WD. I am running BFG All Terrain KO2, so not the stickiest of tires :p
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,661
5,808
113
Phoenix Az
Torsion bars are set to stock ride height (stock keys). Can't really turn it down without the 35" tires murdering the cab.
I have a front ARB Air Locker, but I haven't used it on the pavement yet, so it was open diff for that video.

Steering setup is:
  • Stock centerlink (20k miles)
  • DHD centerlink stabilizer (6k miles)
  • Rare Parts tie rods (20k miles)
  • Kryptonite idler, Rare Parts idler arm, weld-in idler support gusset (6k miles)
  • Steering box varies week by week as I blow them up. My PSC has a bunch of internal play, but the brand new RedHead leaked the second it was installed, so it came right back off with 0 miles. Trying again next week...
  • Pitman arm varies with box. PSC uses a 4-spline Moog (200 miles), RedHead uses a 3-spline Rare Parts (0 miles)
Exact weights:
  • Steer axle: 4,460 (55%)
  • Drive axle: 3,560 (45%)
  • Total: 8,020 w/o driver
It murders the tires if I try and boost launch in 2WD. I am running BFG All Terrain KO2, so not the stickiest of tires :p

You just have a lot of toe in due to the awesome gm suspension geometry and lack of rebound control. Don’t use the locker till you correct that lol. It will really be a fight.

Toe it out an inch and it will be a different animal at launch
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
296
83
Boise, ID, USA
Went down to the Northwest Dyno Cicruit event in Jerome, ID yesterday to see what the new turbo setup does. Running 2000 μs pulse, but timing is just a best guess, so there may be more on the table. With the current setup, my SAC75 injectors are the limit now.

It put down 789 HP and ~1150 lb-ft. Not sure they had calibrated the RPM, so torque might be off some. 2nd pull did 787 HP, so nice and consistent. It was crazy seeing so many high-HP trucks.

I need to get some sort of cold air intake because on the street, especially in traffic, I see intake temps of 170-200+ °F, and the smoke output is almost Cummins level bad.
 

ZeroGravity58

Well-known member
Mar 23, 2008
1,401
51
48
38
Maryland
I know this doesn't help you. Wondering how you changed the shifts. I'm running a empire stg 3 cam in my new build with a 366/488, 14 mil with 250 overs and it is nothing but smoke. I piss everyone off at anything but lazily leaving a red light. I have a feeling it's my cam selection also, it rips above 2k rpm.
 

2004LB7

Well-known member
Dec 15, 2010
6,957
2,136
113
Norcal
I know this doesn't help you. Wondering how you changed the shifts. I'm running a empire stg 3 cam in my new build with a 366/488, 14 mil with 250 overs and it is nothing but smoke. I piss everyone off at anything but lazily leaving a red light. I have a feeling it's my cam selection also, it rips above 2k rpm.
Sounds like the converter is too tight for your setup
 

DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
296
83
Boise, ID, USA
Their printer was broken, but I grabbed a snapshot of the dyno graph. Since HP is measured, and torque gets back-calculated, I believe it is pretty straightforward to back-calculate the true torque since I know the claimed and true RPM for the run. The graph showed me revving out to 4150, but the log shows 3620 RPM.

So on the 789 HP run the actual peak torque was 1318 lb-ft.

I also attached the tune I ran and the log if anyone is curious. Finally, I forgot the video last time:
 

Attachments

  • Dyno Log and Tune.zip
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DAVe3283

Heavy & Slow
Sep 3, 2009
3,727
296
83
Boise, ID, USA
Hit the last day of the season at Firebird Raceway, and now that the rough edges of the tune are worked out, put down a new personal best: 12.609 @ 111 MPH

This was with a full tank of fuel, tow hitch, tools, etc. Probably right at 8,200 lb with me in it.

I could launch a bit harder, but chickened out since I was at the track alone and wouldn't be able to fix anything that broke. Starting to be pretty happy with this setup as I dial in the tuning.
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