Lets do it again! - GRM $2007 Turbocharged Miata Build!

kcbhiw

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64 Valves, 16 Cylinders, 7.2L, 622 HP
How time flies. It's already been over a year since I started my second build/rebuild of the GRM Challenge Miata. It's time to get things rolling for this years build and I'm already way behind.

Many of you are already familiar with my previous builds in which I have improved the performance of my built-on-the-cheap turbocharged Miata. It's time to take this car and win with it. In the $2005 challenge, I placed 18/59. In 2006, I took 6/63. I'm in for all the marbles this year. As they say, the third time is a charm :D.

The first build thread can be found HERE
And the second build is HERE

Information on the $2007 Grassroots Motorsports Challenge is Over there.

Purchased as:
miata_SM.jpg


The $2005 challenge resulted in this:
turbo_miata_SM.jpg


For the $2006 challenge, she matured into this:
DSCN4486.jpg


This year's build will improve upon what's already existing. The car has proven to function well, so it's time time to refine the weaker areas.

The current high-end goals are listed breifly as follows:
-Repaint hood and trunk lid
-Fabricate new downpipe
-Replace Clutch
-Replace OE ECU and RRFPR with Megasquirt ECU incorporating launch control, dual maps (auto-x/drag), knock sense, and whatever other feature that strikes my fancy.
-Metallic clearcoat
-Less oversteer (the budget bites hard on this one)

As I have peformed in the past, I will chronicle the build process in this thread for those that are interested and hopefully some usuful information will be provided to others :).
 
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I've been quite busy before even starting this post, so a number of things have already been started/completed.

The first order of business was to repair the wastegate actuator mounting. The angle of the mounting bracket in relation to the actuator rod was causing a few boost spike/sag issues. Furthermore, it kept coming loose. To remedy the problem, I manufactured a small spacer from part of Phil's old oil pan to space the WG properly. This is nothing noteworthy, but I thought that the fact that it's part of another [failed] challenge car was kinda cool. Thanks, Phil! ;)

The next step was to re-incorporate the thermoswitch (temperature switch that controls the cooling fan). In the previous build, I used a t-stat housing from a second gen 626 to orient the direction of the radiator hose properly. However, the orientation of the thermoswitch boss didn't allow the switch to be installed and it was therefore omitted and the boss plugged. I was forced to use a switch on the dashboard to turn on/off the cooling fan. Obviously, this wasn't an ideal situation.

I stumbled across a t-stat housing at the junk yard from an '87 626 that worked perfectly, so I snatched it up and fitted it to the car. Problem 2 solved.
 

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The downpipe that has been employed on the challenger has been more or less a detriment to its performance and is one of the last remaining "rigged" parts on the car. It falls back to the original build where I was lacking options, experience, and overall knowledge of how these things worked. This year, I am correcting that and am constructing a new downpipe that incorporates a divorced wastegate setup. Furthermore, the massive restriction found in the main tube of old hybrid downpipe will be non-existant.

It's currenlty ~95% complete as it is lacking an outlet flange, a bit of bracing, and heat wrap. Below is the pipe in its current stage of completion. Obviously, I still need a lot of practice in welding, heh.

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Lucky number 3. It's time to install the third clutch into this car. 2005 yielded a burnt stocker and 2006 yielded a burnt Centerforce Dual Friction clutch. To put things into perspective, I've put about 150 [very hard] miles on the car since I purchased it. That's not a good track record. I attribute the second failure to the lack of proper break in. The clutch system has been a bane to this car's existence.

This year, I'm going to try a Gripforce 6-puck style clutch. This is a $140 "E-bay special". 9/10 reviews I have read on other forums have been quite postitive, so why not give it a go, especially when considering budget constraints.

Tonight, I brought myself to finally remove the transmission to begin the swap process. I don't know if it's because I've done this before or if it was just a good day, but the transmission was laying next to the car in about 1.25 hours. Strangely, the CF clutch showed a lot less wear that I'd expected, but it was obvious where it was slipping. The pictures below depict the new (blue) and old clutches (orange). I'll wrap it up the clutch install Sunday hopefully.

Side note and short term goal: I hope to have the clutch installed, downpipe completed, and a catalytic converter installed so that I can pass emissions and register the Miata for street use within the next couple of weeks. For the first time ever, I hope to be driving this car, at least temporarily, as a daily driver to A) break in the clutch and B) feel the car in all it's livery on a regular basis. Wish me luck!

Below is the car in it's current stage with the clutch swap:
 

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so how does that work from year to year if you use the same car.. can you spend $2007 more dollars on your car this year?
 
nope, you can spend $1 more ;) However, there are rules about selling and recouping value on parts that you can use to tweak the budget.
 
I have a couple hundred dollars still in the budget left over from the previous year. The overall total carries over year to year. Parts that I'll be removing, such as the RRFPR, will be deducted from my budget, penny for penny.

Christian, keep an eye on this thread for results of the Gripforce as I'll definately be posting them.
 
My friend here with a 240sx with a KA-T uses one of the $200 ebay clutches in his car. He's had it in over two years. It has seen extreme use, as his car is used for drag, auto-x, and drifting. It has held up perfectly fine so far. Nice job on the downpipe, too.
 
Gaboost said:
My friend here with a 240sx with a KA-T uses one of the $200 ebay clutches in his car. He's had it in over two years. It has seen extreme use, as his car is used for drag, auto-x, and drifting. It has held up perfectly fine so far. Nice job on the downpipe, too.

That's great news!

And thanks! :)
 
dang. I wish I had a garage so I could just park the Miada and work on it too...

Good luck Kevin!

[OT] is that you in the DIYAutotune ad in the last GRM?
 
MiaTurbo said:
dang. I wish I had a garage so I could just park the Miada and work on it too...

Good luck Kevin!

[OT] is that you in the DIYAutotune ad in the last GRM?

Yup! That's me. :)
 
If you're talking about the one I think you're talking about, yes, that's him.

I was too slow.
 
Page 2 - Update 2

Progress has been made and it's time to post some pics.

The clutch has been installed and everything went smoothly. The flywheel looked good and using a straight edge and feeler gauge, I confirmed that the surface was flat and measured less than .002" (IIRC) of runout. I scuffed it with a bit of sand paper to remove any glazing, cleaned things up, and assembled everything. The entire process took about 4 hours.

A problem that has been looming since the intial build was that the heater core to coolant by-pass tube hose has always been very close to the downpipe. I was able to move it far enough away last year using a couple of rubber hoses and a peice of copper tubing. However, with the divorced waste gate piping that I'm implementing this go around, the clearance was once again shot. Therefore, I modifed the coolant bypass tube to significantly increase the distance between the two. The second image depicts an unmodified pipe compared to the one that has been modified.
 

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Wrapping up the down pipe

I have finally completed the downpipe. The outlet flange has been mounted with respect to the catalytic converter piping that I will be using, lower bracing has been added, and a heat sheild bracket has been added. I'd assume that I've put roughly 30-40 hours into this thing. Sadly, it's far from perfect. Hopefully it'll suffice.

A lower brace was added this time to secure the lower portion of the pipe to the transmission in a similar manner to what is found in a stock Miata. This will siginificantly reduce vibration induced stressing and cracking (hopefully). Furthermore, I added a second mounting point for the heatshield on the top side. Due to the changes that have been made, my previous heat sheild won't fit properly. I'll construct a new one sometime in the coming weeks.

To further reduce the amount of heat in the engine bay as well as heat transmission to surrounding objects, I wrapped the pipe with header wrap. This worked well for the previous pipe, so it was only wise to do the same with this one. Additionally, the finished pipe was coated in 1500* paint to minimize rust. I've used this paint on various exhaust bits in the past, and it has held up surprisingly well.
 

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It'll probably crack.

The attached pictures compare the previous junky downpipe to the new unit. It's definately an improvment, if I do say so myself. The last 3 are a few shots of the pipe installed. I've had this thing in and out of the car no less than 30 times, I'd say, at various assembly and fitment stages. It's nice to finally bolt it up and leave it there. :)
 

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re: coolant bypass hose

Kevin, have you seen how Corky's new turbo kits use a different bypass? Perhaps you can rig something like that?...
 
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