Julian's '91 200 20vt

[PRY4SNO]

Good thing about pie cuts is (with full penetration welds) they're stronger than mandrel bends because they don't thin out in the neck of the bend.

And infinitely customizable.

[88a5tq]

I like how mine looks like drier duct right now (pre-welding)

[88a5tq]

It's been too long. This warning for coolant temp has been squawking at me I'm the 5000 from the moment it starts running. Isn't this triggered by the sensor in the bottom of the coolant reservoir?

20160318_175337.jpg (2.08 MiB) Viewed 31193 times

Sorry about quality. Tough taking a pic through the steering wheel while navigating busy city streets lol

[88a5tq]

That 996 axle-back is easily worth at least another hundred than their sticker price of $4200 :l

[loxxrider]

Good thing about pie cuts is (with full penetration welds) they're stronger than mandrel bends because they don't thin out in the neck of the bend.

And infinitely customizable.

Not so fast there... that is not true in a general sense.

First of all, when talking about exhaust applications, have you ever seen an exhaust fail at a mandrel bend? No, because exhausts are not subject to high loading. The thickness of the material is not important in most cases for that reason (we're talking normal, properly designed exhaust system piping here).

However, they (exhausts) are subject to both thermal and mechanical fatigue. For that reason, the ductility of the metal is paramount. IF Julian is using an Austentitic stainless steel like 304L, then he doesn't have much to worry about here, but pie cuts in carbon steel are significantly less resistant to fatigue when welded, and in AL they will significantly reduce the actual yield and tensile strength of the material (not just fatigue).

[88a5tq]

Just so happens it is 304L

[loxxrider]

I figured. That's one of the big reasons why 304L is one of the most commonly used alloy steels. That, and the fact that it doesn't lose corrosion resistance when welding like regular 304 and a lot of other "higher" carbon alloy metals would.

[PRY4SNO]

"Properly designed system" being assumed here.

On a further metallurgical note, any benefit to going 316L in an exhaust over 304L?

I'm going to assume Hank's old manifold that I bought is 304L (he didn't reply when I asked).

Sent from my SM-G900W8 using Tapatalk

[PRY4SNO]

Gonna answer my own question a bit here; but only to further the discussion. Emphasis is my own.

As American AISI basic grades, the only practical difference between 304 or 316 and 304L or 316L is carbon content.
The carbon ranges are 0.08% maximum for 304 and 316 and 0.030% maximum for the 304L and 316L types.

The lower carbon 'variants' (316L) were established as alternatives to the 'standards' (316) carbon range grade to overcome the risk of intercrystalline corrosion (weld decay), which was identified as a problem in the early days of the application of these steels. This can result if the steel is held in a temperature range 450 to 850°C for periods of several minutes, depending on the temperature and subsequently exposed to aggressive corrosive environments. Corrosion then takes place next to grain boundaries.

If the carbon level is below 0.030% then this intercrystalline corrosion does not take place following exposure to these temperatures, especially for the sort of times normally experienced in the heat affected zone of welds in 'thick' sections of steel.

link

[88a5tq]

Finished product. Tada!

[themagellan]

It's wonderful. You should be really proud! Coming together very nicely.

[88a5tq]

Thanks very much for the kind words
I give ALL the credit to the excellent welder. He designed and did the whole thing start to finish in 2 days! Great guy with 28 yrs welding under his belt.

[PRY4SNO]

Keep that man happy.

Beers, steaks... whatever the cost.

[88a5tq]

Lol or 550 cash
Said he was "tickled" that I was impressed and happy with it

[loxxrider]

Lol I love that phrase. Way to git r done!

[88a5tq]

I'm glad you're on Chris. I don't quite know where I should take vacuum from on this hog. My k&n has a rubber top that I could tap into with a large fitting for my CCV/catch can setup. That's the only place I could find tho! I think I may tap the n75 into that area as well

[loxxrider]

Why not just tee into one of the lines at the back of the intake manifold?

[88a5tq]

I have the one line on the n75 coming from there but I need a vac source for the catch can for sure

Well I guess I could just pipe it under the car or something. Or I could actually attempt to weld a pipe into the exhaust at the same angle as a WG dump in order to pull vacuum on the CCV system

[loxxrider]

Oh, yeah you don't need to do that. You can just vent it to atmosphere. The downpipe idea works fine too as long as there isn't pressure there (a very real possibility). Before the turbo would work, but isn't necessary. You probably aren't getting that much negative pressure in front of the turbo anyway if you have a very free-flowing filter on it. I'm sure there is some, but it's not a crazy amount or anything. Any little bit helps though.

[Aktapod]

This is coming along nicely, Julian! I'm excited to see you play with the big boys. Any chance you'll be coming out to Carlisle, seeing as you're in PA?

[DE80q]

That looks great! Glad to see it together again. As for Carlisle, I keep bugging him about it...

[88a5tq]

Bahaha oh god I'm never gonna hear the end of this Carlisle bit! I don't know tbh. Never road tripped this bucket of bolts before.
Thanks Sven, a big turbo build has been on my bucket list for awhile
Dave, seeing as you're the only other real welder I know, it must be well done seeing you say that about the quality.
On a scary note I keep spiking to low 20s boost so I'm about to change the WG spring and remove all the freakin shims. I can't even keep boost under 20 psi atm with my foot in it. I find it hard to believe that this 38mm WG doesn't flow enough to reign in the holset beast master. Gotta be the crap I jammed inside the WG cap hah

[Aktapod]

Your 200 will make it! probably. Plus, of all places to break down, Carlisle has got to rank among the most convenient places to do so.

edit: Do you know what the cracking pressure of the wastegate is? You might on the right track if the preload is too high.

[88a5tq]

"So youre sayin theres a chance." Lol thanks
It came with 4 shims and 3 springs of unknown ratings. I went for the super max.

[loxxrider]

Lol you on Stock wastegate? I feel like either I missed a lot of details here or you never posted them.

And yeah, the wastegate should have no problem handling the holset. My 38 didn't.