JCH13 - Turbo Miata Build/Auto-X Prep - UPDATE 4/29/2011 MOAR VIDEO!

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JCH13

Diamond Member
Sep 14, 2010
4,981
66
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I had a big work day today. I drove the car, with my buddy Andy, to Bonky's place to do some work on it (same place where JLee and I built his dump tube).

First thing we did was to massage the exhaust a little bit. The side-pipe was kinda cool, but it'd smack into the running board occasionally, and a LOT on hard launches. So, as I mentioned before, we re-made it to dump just before the rear axle. Here is how it went...

If I had a cat, this would be the cat-back exhaust:


... and here is where it fits under the car. Note the smashed frame rail, someone tried to drop it onto a jack-stand. I think there may be Flyin' Miata frame rails in my future...



So then I sliced and diced with an abrasive chop saw, fitted, tack-welded, re-fitted, broke apart, cut with a chop saw, re-tack-welded, re-fitted again, tack welded the hanger, re-fitted, then seam-welded everything and the results are...





Boom! Done! Greatly improved ground clearance and reduced noise in the driver's left ear, though the passenger gets to enjoy a little more engine noise too. It sounds pretty great I think.

So I also needed to make a license plate bracket for the front to stay legal in NH. While crawling under the car to figure out where I could mount it, I cam across one terrible thing:



That's my front sway-bar, with no nut on the end link D: put a nut and washer on and we're off to the races...

Next I noticed another terrible thing:



The crankcase vent tube was kinked really badly. That explains why I was getting more oil in the catch tank at the dragway... LAME. How do you fix a kinked hose? I can't buy a pre-formed hose, and stores are pretty damn far away... So I did this:



Coil spring in the tube! Worked like a charm. Don't worry, it is impossible for that spring to get inside the engine.

So with two disasters averted, I worked up a license plate holder that mounts on one of the tow loops, also called the the 'baby teeth.' It bolts through and clamps on like this:



And looks like this:



Pardon all of the bugs... unavoidable this time of year in NH.

All in all it went very well, everything turned out great, and the car is legal and a lot more worry free/pleasant to drive! I spent no money on any of the parts, which was also awesome, we just salvaged everything from scrap Bonky has kicking around.

And, a new video, now with less wind noise and real spark map and better exhaust sound! Enjoy. The car doesn't sound as fast, but it feels so, so, so much better.

http://www.youtube.com/watch?v=orRqT6hkHg4
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
Ordered a 2.5" vband flange and new turbo: T3, 50 trim compressor, .48AR housing. Should help me spool a bit faster and make the car better for street/auto-x driving.
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
I decided to replace the accessory belt today because the old one was squealing and starting to crack pretty badly. While I was rummaging around under the hood, I noticed on of the bolts holding the turbo onto the manifold was gone! Not loose, just plain gone! :awe:

I bought a replacement, tightened it down, and for giggle checked the other three. Two were hand-loose.

I then noticed that one of the bolts on the down-pipe was loose and the down-pipe had backed off about a turn, wtf? I think this all has to do with driving back from the drag strip and getting that whole part of the exhaust bright red.

While my attention was around the exhaust manifold area I notice that it looked like oil was leaking out of the valve cover. I got out the torque wrench and re-tightened all of the bolts. Most needed more than 1 full turn to reach the specified torque

Hopefully these all fix the weird smells I've been smelling lately...

Also, I think the new belt is squeaking a bit, anyone know if this is normal? It's a Duralast belt if that makes a difference.
 

JCH13

Diamond Member
Sep 14, 2010
4,981
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91
Long time no update...

My new turbo is here, T3/T4, .48 AR ehxuast housing and 50 trim compressor housing. It should spool a lot faster, somewhere around 3k or 3.5k, instead of 5k.

I have decided that while I'm tearing into the exhaust/turbo guts I should replace all of the fasteners and gaskets that were cooked by my glowing-orange-hot exhaust episode. I was able to pull the turbo and exhaust manifold in less than an hour by myself. Only lost a little blood too! Woo!

Old Turbo:


Everything Pulled:


My Blood:


And I also had a hell of a time getting one of the exhaust studs out. It had been driven into the head and was bound up wicked bad. After much screwing around I just smacked the stud with a hammer a few times and it came loose. I used the double-nut stud breaking technique too, worked like a charm.

The offending stud:
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
Still sorting out exhaust bits on the new turbo, intake parts are on the way. The new turbo is on the engine and clocked in, just need to finish bolting it up, connecting oil lines, and plumbing in the intake stuff. Getting close...

Stumbled upon a 'built' 323 GTX motor on Craigslist... :\ tempting...
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
Holy neglected build thread batman...

Well, I am still alive and have been working on my Miata a little, though not as much as I once was.

I had been having issues with boost creep in my new turbo, and after much futzing with external stuff I decided I was just going to port the IWG opening. I was able to about double the flow area available in the IWG and angled the profile to be about 45deg to the exhaust flow rather than perpendicular to it.

In this picture (not my turbo, I was an idiot and forgot my camera when I did it) you can see the port I enlarged and re-angled next to the hot-side outlet. In this turbo the flapper is a bit larger than the IWG port, on my awesome china-charger the size disparity was even worse.



After porting mine out I now have no boost creep AT ALL. It was a night-and-day difference. Right now it holds wastegate sprung pressure at 8psi all the way to redline (7,200 rpm) instead of creeping to 14psi and hitting boost cut at around 5,500rpm. I was also able to tighten down the wastegate arm a bit so boost response is better. Double win! JLee has lent me a manual boost controller, so I'll get her up to 12psi or so and we'll see how silly it gets :awe:

In terms of auto-x gear I have ordered some used 15x6.5 Konig Heliums on the way. 11.4 lbs! I have some 205/50/15 100UTQG DOT-R kinda racing scrubs (some flavor of rain slicks, can't recall off-hand) to mount on them to thrash around on too, should be a good time

I have also ordered some Simpson racing gloves as the improved grip is SO NICE with a de-powered rack. It really starts to become a strength issue on hot days when my hands get sweaty and I can't hold onto my wheel. I should probably get a new wheel at some point, the original wheel is getting pretty polished in it's old age (maybe time for a new one).

A strut brace is also on the way for improved front-end response and to help with the 65mph NA shimmy.

Also replaced a dragging front caliper, brake feel is much improved without a cooking caliper. She also feels a little faster too. Slowly getting there for the next autox and autox school in two weeks!
 
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JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
Almost forgot, I also have a set of 225/45/15 RS3s on 15x7 C1M wheels on the way from TireRack. The RS3 is a heavily recommended Miata race tire (somehow it's street legal too) but is currently out of stock. Should arrive at the end of August.
 

thedarkwolf

Diamond Member
Oct 13, 1999
9,003
111
106
Almost forgot, I also have a set of 225/45/15 RS3s on 15x7 C1M wheels on the way from TireRack. The RS3 is a heavily recommended Miata race tire (somehow it's street legal too) but is currently out of stock. Should arrive at the end of August.

I've been thinking about getting those but I'm leery of putting them on my 7" wide rim. Think they would do a lot better on an 8".
 

jlee

Lifer
Sep 12, 2001
48,517
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I've been thinking about getting those but I'm leery of putting them on my 7" wide rim. Think they would do a lot better on an 8".

Maybe, but they'll certainly work. OEM '93+ MR2 rear wheels are 15x7 with a 225/50 tire.
 

JCH13

Diamond Member
Sep 14, 2010
4,981
66
91
What was the reason you didn't opt for an external wastegate?

Like JLee implied, it was cheaper. It took less than 2 hours to remove the turbo, take a die grinder with a carbide tool to it and port the IWG, then reinstall it. Seemed a lot easier and cheaper than buying a new exhaust manifold (my current one is cast iron, no way I'm welding on that sucker), EWG, buying/making a dump tube, and likely fabricating and/or buying a a down pipe. An EWG would be a bit better for performance, granted, but the money, time, and aggravation is better off spent on other things. Like the suspension which needs a lot more help than I originally thought.

Speaking of which, it's likely going to get a suspension refresh over the winter.

I've been thinking about getting those but I'm leery of putting them on my 7" wide rim. Think they would do a lot better on an 8".

=shrug= they're rated for a 7in wide rim, so they should at least do okay on one. The size/offset/color options with the C1 and C1M wheels are aggravating, so the 7in wide wheel is a compromise, but it is lighter than a 15x8. I'll write up a review when I get them too.

A budget build which has gone through four turbos? Waitaminute...

Well... they've all been china-chargers... I broke even reselling the last two that I bought (one was never installed) and the one that came on it needed a rebuild, and after I tore it down I found enough parts were permanently borked that I really just needed a new one.

Spending $900-$1200 on a turbo is for when I rebuild the 1.8L engine I have and slap it in.
 
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thedarkwolf

Diamond Member
Oct 13, 1999
9,003
111
106
My other issue is my 205s rub on my fenders now with some minor fender rolling. When I swap in my new springs I'll raise the car back up some and hopefully fix that. I'm all over the place on what tires I want to get. I'd like to just get star specs but tirerack is now the only place that sells them and they are more expensive than I would like. Have the old falken 615s now and they are about dead. This weekend's autox should finish them off.
 
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