DirtyDaveW

After last weeks quick jump in 2nd took me to 17psi in second gear, I reset the manual boost controller to halfway on Saturday. Afterwards, I took the Z28 to the local Mavis Discount Tire to get the front end aligned. Once that was completed, the guy that had done the actual re-alignment gave me the motion to spin the tires. So, stupidly forgetting I hadn't tested the boost level at this new setting, I left easily in 1st but after shifting to 2nd, I watched the wide band and floored it. Well, in about a second, I heard a loud pop and then heard a small thump, I looked in the rear view and saw my charge pipe spinning the road behind me. I did an ultra quick U turn, went beside it, leaned out the door and picked it up and took off. As I drive to the nearest parking spot, I pressed the history button on my AEM Tru Boost to see what boost it had attained before it popped off the charge pipe. Gulp... 24psi. Thank goodness my motor is all forged and I'm running about 8.4 to 1 compression ratio. Good lord. I drove it home and put everything back on and reset the boost controller to minimal boost. I'll try it again next time(coming weekend).

RealQuick

No T-bolt clamps and beads on the charge pipes?

97WS6SCharged

So you turn the boost controller down and get more?

Did it break where you alumiwelded it?

CALL911

With boosted cars unfortunately you have to be more situationally aware of things.

Glad it was nothing major!

DirtyDaveW

You know better than that...

Bead rolls AND T-Bolt clamps.
24 PSI is hard to hold and the first time it's ever been that high.

DirtyDaveW

Have you ever tried the 'high boost' config that JGS shows? Line goes from compressor outlet to top port. Boost controller is between compressor outlet and bottom port.

As far as adjusting, I snuck up on it the first time and let off before anything popped. The second time, I assumed (always a bad Idea it seems) that it would be lower since I'd turned it down but I just floored it.

They call it the high boost config for good reason. I don't know what the hell that thing could go to in that config but I don't want to know. Lol...

The Alumniweld held!!!

DirtyDaveW

I reloaded my Speed Density tune and the 2 bar, having done a having done a little more reading about the Speed Density settings.
The knowledge base is so very limited on SD tuning for the LT1s. It's all experimentation. Trying to google for it gets little to nothing. And, what's there is imprecise. I'm trying to change that and documenting it with screen shots which, I think, leaves much less to the imagination than, "Oh, 2 bar Speed Density? Just cut all your tables in haif that use MAP".

One guy told me that I should just compress the columns from 20 to 100kpa into 20 thru 60kpa(use every other column from the prior table) and then zero out KPA Columns 65 thru 100. I tried that. Now knowing that the 1 bar sensor setup was 0 - 104kpa and the 2 bar sensor is 0 208kpa, you'd intuitively think that that guy was saying that the 2 bar would have all it's work done by 60kpa and the engine would be happy.
Wrong. I took her out for a drive and once the pedal got me into the 60 +Kpa, it would all but shut off and die till I let off the gas. At this point, because I was easing into it, it was in the high 3K to low 4K RPM areas.

I pulled over, set the 60KPA values into all the remaining 65 thru 100 Kpa columns, reflashed it and took another test drive. No stumbling but rather rich. I pulled over, set the inject constant from 38 to 40, reflashed and drove it. Better but still to rich. Pulled over set the injector constant to 44, reflashed and drove it. Pretty damn close to 14.3 most of the street legal speeds. Now to fine tune the boost fueling. I got into boost a little before it started raining and, with the 'low boost WG config' and the boost controller turned way down, it went 6psi. The AFR was 12.2

I was hoping to drive it to Rochester but the weather is supposed to be awful most of the week. Sigh.. more seat/tuning time next weekend.

97WS6SCharged

Glad to hear nothing got messed up and the weld didn't let go. I just found out today that the crank for my budget 6.0 street motor build is bent. Not sure if that's bad or good news.

DirtyDaveW

Well if you have the cash I guess it will be one thing you can be sure will be right going forward. Still, sorry to hear you're having this hiccup.

I've just finished analyzing my last log before I left home and reset my fuel (higher) on the 45 kpa on up. I'm having fun with this tuning.

hulettsz28

What do you spin to dirty dave? Good to hear everything internal held tight.

DirtyDaveW

Thanks
I've spun it as high as 6,500 but that was with the prior turbo (TC76) and it was really all done with power by 6,200. This new turbo (PT76GTS) should be better because of it's larger turbine(less back pressure). I'm still trying to dial in the SD tune but I may just put the 1bar and MAF tune back in so I can pound on it. So far, the limiting factor seems to be blowing off couplers. It's all bead rolled,etc but I've accidently spiked it to too high a PSI a few times.

RealQuick

Any updates Dave?

97WS6SCharged

True beads or pipe ends bent with vice grips?

RealQuick

Dave, you use that thin walled aluminum stuff from ebay? If so, might be time for thicker stuff or go with 16ga mild steel (or stainless steel) with some welds on the ends to keep the silicone/clamps on.

97WS6SCharged

There's always the Home Depot flat bar trick.