Making me want to build another kit. Those EFRs would be perfect on my 427. Twins are a pain compared to a single, but the big perk for me is the lower weight. I don't feel so bad hitting a pothole with a 25lb turbo on each side of the engine as I do with a single 60lb monstrosity hanging off of one head lol.

I'd share more pics but I'm not super great at documentation lol. I dug through everything and those threads have basically all of it. I ended up using whichever manifolds fit the best, which ended up being from the CTS-V twice apparently. Cast manis are my preference because they won't warp like a fabbed manifold. Beyond that its just snaking some pipes around some obstacles, but that's the fun part. I've eyeballed my GMT900 and it doesn't look any tighter than the 800 truck that Joe blew up and abandoned. Twin 3" downpipes should fit no problem.

 

Whoa Shots fired...
1. I was not even present when it was Hurt.
2. I did not abandon it... Circumstances changed and I had it stored almost 2 hours away.
3. After I repaired it, I made sure the individual that was responsible had to change his shorts when we trying to figure out how to control the boost. 24 PSI later He was an Albino after the rear end tried to pass the front end..

 

 

 

Oh boy here we go again...

 

Anyone know if there are in fact any differences in the van manifolds? It seems like there are hints there are, but I can't get a solid confirmation or find any pictures of some.

I just noticed I am getting like up to 500 rpm on the "trans slip RPM" PID during boosted 1st gear launches and it is corresponding to the rpm blips I see on the log when I launch with enough boost that it will start hoping a little. So, I need to find out if this PID is really valid and maybe try logging all the input and output speed sensors and seeing if they agree with the slip. I know +/- 25-50 RPMs or so is probably fine and just noise but when it spikes up to 100-500 rpms it starts worrying me. I pulled the transmission apart about a year or so ago to put in a new rear planetary set after it looked like something fell into it and grinded up some of the teeth, but the 1-2-3-4 looked OK to me with no burn spots but it has 270k miles on it. From my understanding of the 6L80 only the 1-2-3-4 is applied in first and the low reverse sprag holds it in first (I think the low/reverse clutch is also used to hold the sprag but only below like 5mph in drive. So, I guess I probably need to start looking for a broken/core 6L80 and start rebuilding it and unfortunately put this twin plans on hold.

 

If its persistent slip, that's an issue. But if its just during a shift you're fine.

 

I believe the Van manifolds are the same as the truck. Atleast in the GMT800...

 

So I am not sure how the trans slip PID works or if it counts it in second gear when the on coming clutch is still slipping but the RPMs are still increasing and not decreasing. But the 1-2 shift I think is different though since I believe you just have one on coming clutch (2-6 clutch) coming on and no off going clutch to handoff. But during the 1-2 shift in the logs you can see the trans slip PID start ramping up past 1000rpms right after the log says the current gear PID changes from 1st to 2nd and the RPMs are still increasing and it hasn't hit the RPM limit yet. So technically if there is just a on coming with no off going clutch I would think you would only read trans slip only once the RPMs start decreasing since in the logs the RPMs have a linear positive slope all the way up until the shift RPM and it seems if there was actual slip it wouldn't be linear.

In this log you can see the points where it slips correspond with the RPM blips, this one got up to 574 RPMs of slip:

So, this slip is occurring before it indicates the current gear is 2nd gear. It seems like most people are never worried about clutch slip during a single gear but only worried about it while shifting. During shifting it seems fine though and will meet the shift time I commanded in the cal most of the time. Sometimes randomly it will shift a little harder than usual but none of the gears seems to slip at all during the shift. My 6L80 is completely stock with what I believe to be the original transmission with 270k on it now but like I was saying I did replace the rear planetary after some of the teeth got chewed up but since all the clutches and bushings looked good so I didn't bother changing them and put them back in, I did put in a Sonnax zip kit and a Sonnax pressure regulator modified boost valve, spring, and bushing. It seemed like this didn't do much of anything though. I don't believe we really have any way of boosting the pressure on the 6L80 with HP Tuners besides faking the torque model. I am also using a LS9 ZR1 Corvette virtual torque values.

Here is another 2 psi "light" boosted launch. You can see an RPM blip and the spike in trans slip PID at the same time. What's funny is it looks like the transmission is doing this on purpose because at the exact same time it ramps down pressure control solenoid (which I believe runs the pump) to around 88 psi where it started the run at about 138 psi:


This one is also at lower RPMs and well below the 1-2 shift change indicated by the log. I know wet clutches are pretty durable and are designed to take some slip as long as you keep the heat down(especially the TCC it think which by the way I think for sure that one is starting to slip and they are of course famous for it) but I feel like this will eventually kill the clutches pretty fast. I tried to look back at my logs when it was stock and see what the trans slip was but I never logged it at the time.

 

Did you increase the MAP estimated max? If not it won't account for boost in the torque calculation. Won't react to the extra torque til its slipping.