Ten Pounds of Shit in a Five Pound Bag - Twin Turbo LS3/DCT Daily Driver

[shainiac]

Can you get the flexplate machined and rebalanced?  Great to see you getting closer to driving it

I'm not even sure it was balanced tbh. It's SFI rated and "high inertia", but I don't see any balancing marks. I had considered just grinding the welds down. The ring gear is welded on both sides so should be fine.
For now, I chose to just put my old flywheel back in. I looked back at an old video and the 6.2 does seem to rev snappier than the 5.3, both with the same heavy flywheel.
But DAMN did that light flex plate sound nuts. It sounded like a race car. That could also mean that it'd drive like one too lol

[freeskier7791]

Can you get the flexplate machined and rebalanced?  Great to see you getting closer to driving it

I'm not even sure it was balanced tbh. It's SFI rated and "high inertia", but I don't see any balancing marks. I had considered just grinding the welds down. The ring gear is welded on both sides so should be fine.
For now, I chose to just put my old flywheel back in. I looked back at an old video and the 6.2 does seem to rev snappier than the 5.3, both with the same heavy flywheel.
But DAMN did that light flex plate sound nuts. It sounded like a race car. That could also mean that it'd drive like one too lol

I would definitely want to try that 8lb flywheel, but like you said it probably would suck to drive in traffic.

[shainiac]

DBW can tame down a lot. I already have the DBW mapped so that at low speeds 50% pedal position is only 25% TPS. It blends gradually to be 1:1 by 60mph, but it makes cruising around a parking lot easier. It also helps that I have a small cam. The one in the LS3 is 225/234 but on a wide 115* LSA. It idles very mild. Tuning the first gear take-up in the DCT might be tricky, since when the clutch grabs, it'll try to drag down the idle more than before.

Worst-case scenario, I can swap the flex plate in about 2HRs if the car is already on jack stands.

[shainiac]

Coolant leak is fixed!
I put crush washers and pipe dope on the turbo coolant plugs and all seems good now. The coolant-saturated turbo blankets did smell terrible on startup, though lol.
The car is still on jack stands while I button everything up, but it has over an hour of run time now and seems healthy. Hot oil pressure is 40psi at 850rpm with 5w30.
Fans and rad keep coolant temps at 185F.

After swapping to larger 1500cc Bosch injectors, it looks like my old VE map is going to get thrown out the window. The car wants to idle at 14.5:1 at ~50-55VE, where my old engine idled at 35VE. Not that either are probably 100% accurate, but just everything in the map needs redone. Same for accel enrichment. It goes 20:1 on heavy throttle tip in lol.

I wired/plumbed the exhaust cutout and set it up in the ECU. One of my CAN keypad buttons is set to have 2 modes. Mode1 closes the cutout below 50% TPS. Mode2 keeps it open all the time. I may throw a needle valve on the solenoid line because it opens/closes the valve rather agressively.

Using a cheap decibel meter, the valve drops the sound volume by 5db measured 5' behind the muffler. I still need to weld the exhaust tip on the car, but I want to get the car on the ground before I figure out how I want it to look and fit.

Exhaust cutout video:
https://imgur.com/1uTAxHF

Engine idle video:
https://imgur.com/M0pyIE5

[shainiac]

Saturday I was finally able to have a first drive on the new setup. The car backed out of the garage under it’s own power, but the transmission controller lost its brain when I connected the laptop up for a first drive.
I wasted 5 hours trying to get it fixed on the nicest day of the fall and finally got it working 30 minutes before dark. It did make a quick trip around the block and to the grocery store, though.
 
The closed-loop learning on the transmission requires you slowly work up on how much load you apply, or you’ll end up slipping the clutches. I was able to make one pull to 6000rpm and the engine only made a little over 1psi of boost. I only have 3psi springs, but that seemed weird to me. It was also very late to make boost.
Yesterday I hooked up the boost leak checker to see if I had a leaky coupler that was causing my issues. What I discovered was all 8 injectors were pissing air at the intake manifold. Long story short, Gen4 injectors/intakes have a slightly larger lower o-ring than Gen3. New o-rings should be here today.

When reinstalling the rails, I managed to drop a stainless bolt and washer down the injector hole into the intake port. I should buy a lotto ticket, because that intake valve happened to be closed. Being stainless, I couldn’t fish them out with a magnet, but I did have one of those weird claw tools that I’d never used. Gotta love when random tools you’re too much of a pack rat to throw out save the day!

It's going to be cold and rainy the next few days, but hopefully I can get some miles on the car next weekend. With the new engine and injectors/data, the whole VE map needs some TLC. The extra 0.9L of displacement are noticeable, but the turbos are nowhere near as snappy as the EFRs. Hopefully most of that boils down to the boost leaks.

[kinger]

You gave me a heart attack on the dropped bolt, I can't imagine how you felt!! 

Weird on the GCU, are you switching away from that soon?  You are on Maxx ECU but still using the HTG TCU right?

[shainiac]

Lol, it seemed to happen in slow motion. I even thought about putting a towel down first and couldn't be bothered to walk the 8' to my work bench. Lessons learned I guess.

Yes I'm planning on switching soon. Maybe over the winter. I have a spare DCT, but I sold the mechatronics (OEM computer inside the trans) to recoupe some costs. My logic was that I could always swap my modified mechatronics over to another trans if I ever had mechanical issues. What I sold it for is about 2/3 of what they cost used now lol. It'd honestly be more cost effective to just buy another transmission and I'll still have a spare for parts if I need it. I'm planning on selling the whole setup complete. Adapter, trans, GCU, harness, cooler/line/thermostat. 

The GCU is still an option for someone who wants a DCT but is on a different ECU. I kinda wish I'd just paid the $600 and had the HTG owner remote setup everything at this point. Most of the issues they've helped me with, they were able to fix remotely, but it's hard to troubleshoot yourself with their lack of documentation. Apparently that's something they're working on.

[shainiac]

I finally got the car driving on the latest HTG firmware. Since the car's been down for 10 months, I was 2 updates behind. HTG had changed how they do torque modeling in those newer updates and I was missing some data inputs that is required. I've put maybe 20 miles on the new firmware and closed-loop DCT adaptations and it drives really nice. HTG has a closed-loop clutch takeup that learns your clutch bite point through some automated tests. It basically pulses the clutch pressure until the car moves smoothly. The problem I have with this is that it requires a flat parking lot with decent amount of space. My driveway is sloped up, so the clutches it learns are usually too aggressive for normal driving.
After a bit of driving, I switched it to Open Loop for take-up only and it drives really nice now. Took a bit of tuning, but not bad at all.

I've gotten the car into boost a few times and the big 50mm wastegates and 0.2bar springs don't really make much boost. Maybe 0.1bar at 6k.
I think this is mostly due to the small turbos having some backpressure and pushing the gates open. Adding 0.1bar of dome pressure brought boost back up to the target of 0.2 spring pressure. The car on 0.2 bar is surprisingly quick. Much quicker than the 5.3 on 0.3 bar.

The only thing that is mildly concerning to me is oil temps. With my 5.3, the oil temps would maybe get to 215F in normal driving on a 70F day.
The LS3 and new turbo kit will get up to 230F or so. Still not danger zone, but that's not even really beating on the car. My thoughts are that the tighter bearing clearances might add more shear to the oil. And the turbos are cast iron rather than aluminum on my old EFRs. I think the aluminum EFR CHRAs would suck more heat out of the oil with coolant.
 

[kinger]

Do you think the turbo positions so close to the oil pan is heating up the oil via radiant heat?  Did you put any insulation between the block and turbos?

[shainiac]

I don't think the turbos would be heating the oil radiantly. I have blankets on the turbines and the downpipes are wrapped and have heatshields.
The sensor is only a couple inches from the downpipe, though. I'm also using a different oil temp sensor than before, so that could also be an issue. I switched from the standard 3/8"NPT GM liquid temp sensor to a 1/8" NPT GM temp sensor that's commonly found on 90s Saturns. Both are supposed to have the same scaling.

[Esser]

More cubes usually equates to more heat. Especially since oil volume has remained constant between both setups.

Big oil cooler is the only answer, but i would beat on it before making any changes. 230 is far from danger zone, we don't know if it will sit there or shoot past it.

[shainiac]

Good point on displacement. I have most of the parts for a whole new cooling package I want to build over the winter. Howe 27*19 instead of 27*16 radiator with a large oil heat exchanger, large laminova cooler for the lower rad hose, and brushless Spal C7Z fan. I was planning on running the DCT to the rad oil HX, but I may use that for engine oil instead. That's a lot of load on the cooling system, though. It'll be a challenge getting the cooler lines past the turbo and the the front of the car lol

[Esser]

With your setup, you can always go to the back area of the car. I wouldn't go all the way back because that is a lot of line length (oil pressure), but you should be able to place a cooler in the floor area before the diff section, and get a fan on it. Just getting oil out of the main system will help temps, so the cooler with a fan should help significantly.

[shainiac]

,

[Exidous]

And here I am with my lowly 7.2L and oil never goes over 93C. Haha I've not taken it to the track with this motor yet though. Pretty sure I'll find out I need more cooler.