sasquatch

iTrader: (2)

nice build, looks great

underdog

iTrader: (6)

Hey everyone!

Thanks to old man winter and the voices in my car guy head, I convinced myself that my internal wastegate was no longer cutting it. It never really sat well with me, as I've always run externals on my other turbo cars. The housing was OK for controlling boost, but didn't look like something that flowed too well. Plus, external wastegates are just an all-around better decision. They offer more precise boost control, faster spool, proof that you are indeed a man, etc. Oh and my digicam died right before I started wrenching, so apologies in advance for the phone pics.

So here's the wastegate setup that I got rid of. Not a bad design, but not built for 'manifold danger' levels of boost and horsepower either.


Now that's more like it! The Tial 38mm MVS wastegate in all of it's v-bandy goodness. I love Tial everything. From the packaging to the beautiful design, I would buy a Tial toilet brush if they made such a thing.


Time in the garage is precious for an old dude with a bunch of kids, so I attacked the exhaust manifold as if it recently insulted my momma. I used my step drill bit, then a carbide burr bit to open it up the rest of the way.


Once the hole was the right size, I shaped a short section of pipe to match the contour of the manifold. This was the best mounting location that I could come up with, given the tight dimensions of this "log-style" manifold. Once I welded this up, I then welded the Tial v-band fitting to the end of the short pipe. I welded the pipe to the manifold on the inside and outside of the pipe.


Here's the setup before I shot some high-temp paint on the pipe and welds. These are by far the ugliest doo-doo welds that I've ever shat out. Let's just say that welding high quality steel to sketchy quality chinese cast iron is tricky. It seems that I got good penetration though. (That's what she said?)


Once I had that squared away, I focused on the dump tube. I started with this 1.5" O.D. u-bend from Summit Racing.


I cut the pipe down the middle of the bend and use the longer end as a starting point. Then I welded on the Tial v-band outlet fitting.


Here's the dump tube before I shortened it a bit, painted it and wrapped it.


And here's how it all ended up! As y'all likely figured out, I am going with an external dump, but may route it back in if I get sick of it. I've always ran external dumps, but have always ran off of either the collector or 02 housing, which usually sounds better. We'll see I guess!


Thanks for reading y'all. I'm waiting on some parts that should be here today, then I can wrap this up. I've got a new turbo inlet gasket, an exhaust flange, and a new silicone oil drain hose coming. The NAPA high temp hose is OK for oil drain purposes, but got brittle where it pushed onto the turbo oil drain fitting.

flier129

iTrader: (7)

Looking good, as always.

Have you ever thought about autocrossing it?

PatrickB

iTrader: (1)

underdog been awhile since i have seen you!

old 4g61t member here had a 89 mirage GT silver on that board big turbo fmic injectors almost he same setup as you minus the cams.

9671111

iTrader: (10)

Are you going to brace that dump tube?

underdog

iTrader: (6)

Thanks for the comments fellas!

flier129: Thanks! Yes, I would love to autocross it this spring/summer! I've never been to one, so I'm really looking forward to it.

PatrickB: Small world eh? I spent TONS of time on that board back in the day. Do you still have your Mirage?

rccote Yes, I was checking out what I could brace it to this evening. I think there is a spot on the block that I'll end up welding a tab to from the pipe.

PatrickB

iTrader: (1)

Nope sold it 7 years ago.

underdog

iTrader: (6)

Allright! My parts came so I decided to knock this out.

Here's the internal wastegate block off flange and gasket from ATP Turbo. The flange is a 1/2" thick which means no warping! It's way nicer than the crappy Ebay ones out there. The little step makes welding up a 2.5" O.D. pipe a breeze too.


I still wanted to keep my V-band downpipe setup that I had before, so I made this little adapter and welded it to the exhaust flange.


Voila! Here's the new exhaust flange setup mated up to the downpipe.


With the heat shield in place, you gotta look pretty hard to see the wastegate tucked under there!




I hope to take it for a spin this weekend, I'll let y'all know how it performs!

flier129

iTrader: (7)

First local event is March 5h, a saturday. The car that I'm codriving this year isn't going to be together just yet and my car isn't really prepped (I need r-comps for e-stock)

I would be happy to show you the ropes, pay your entry fee, and co-drive your car .

Your car would fall into the local STM class. Its a class that is to catch streetcars with lots of things done to them. Anything goes, you just need 140 treadwear tires. So your car would actually be pretty competitive in it.

underdog

iTrader: (6)

Hey everyone!

Thankfully, the weather has been great here, which allowed me to drive the Miata the last few days. I've really been beating the heck out of it to make sure my new external wastegate setup is going to hold. Well, so far it's going great! The car feels better on the top end, and the boost control is rock solid.

Here's a quick video of what the external dump sounds like from outside the car. I like it, as you only hear it if you're going full tilt. Let me know what you think!

viperormiata

iTrader: (24)

wow.....sounds insane.


I know what I'm doing this weekend.

soadrules1989

dude i came and i cant get up.. lol
been following the build and its just pure hardcore sex.

underdog

iTrader: (6)

Thanks! Now go clean up, will ya?

redeagle

Like this thread (informative+lot of pic's).Yellow colour looks cool as well the 6UL under it.
Two questions: Do you still run stock 1.6 open diff? Fitting those 225\45 tyres caused any clearance problems with fenders (turning wheels out for example) etc or no issues at all?

leatherface24

iTrader: (10)

I love the sound of a dumped to atmosphere wastegate

Braineack

iTrader: (62)

do you use some silly Apple software to make those nice captions in your videos?

underdog

iTrader: (6)

Thanks for the comments and support everyone! I appreciate it. To answer your questions:

redeagle: Thanks! I do still run the 1.6 diff, although the window sticker states it is an LSD, for what it's worth. Speaking of rear diffs, I need a numerically lower gear in this thing bad. The short gearing just doesn't match the turbo powerband in my opinion. My old 4G61 (1.6L) Turbo mirage gearing was nice and tall, which felt great under all driving conditions. Second, I haven't experienced any fender clearance problems with the 6UL/225 combo so far.

leatherface24: Me too! The sound was much better than I expected and one I look forward to hearing, vs. some other "non collector" dumps I've heard before that sounded farty, for lack of a better term.

Braineack: Yes, I use iMovie '10 and went a little overboard with the captions this time. The best thing is that it took me less than 15 minutes to download the video from my old Sony camcorder, put this together and post it to YouTube. That's really the only reason I got a Mac - I like the ability to easily capture, sort and organize my photos and videos, then whip up projects like this. I am a PC guy, but could never get that sort of stuff working in symphony, which drove me bonkers.

In other Apple news, last year for our wedding anniversary, I made my wife a book of a trip we took to NY a few years back. Honestly it looked like something you'd buy in a bookstore and was very easy to make in iPhoto. Sheesh, now I sound like a fanboi.


FYI - so the plan for the car over the coming months is to drive it a bunch when the weather improves, head back to the dragstrip, go to the dyno and go to my first autocross. C'mon spring!

redeagle

Then it means you must have VLSD type diff. I've heard they are not best ones when it comes to reliability, but in other hand it could be that most people don't maintain them properly (correct oil etc). Exchaust sounds are awesome(quiet on cruise, but when needed bites), need to build one for mine

PatrickB

iTrader: (1)

I did the same thing with my honeymoon takes like 10 seconds and looks pro.

underdog

iTrader: (6)

Yes, the factory diff is tiny and on borrowed time. I use Redline Heavy Shockproof gear oil in there, so maybe that is helping with the reliability.