JCH13 - Turbo Miata Rehab Thread

[PseudoSport]

I was running a 14B turbo off a DSM with a different manifold and exhaust. I just found that the EBC was a little more sensitive to temp changes over the manual controller but over all it was pretty solid when daily driving the car. The only time it really bugged me was when I’d tune car at home where it was in the mid 40’s at night then head to the GRM challenge in Florida where it was 98 degree the last year the car was there. Still the quicker spool and smoothness made it worth it once duty cycle was dialed in properly.

Boost had always hit like a hammer with 15 psi coming on at 3500 RPMs with the 14B and EBC. The T3 50 trim felt a little lazy in comparison and didn’t have the same top end. I always assumed it had to do with lack of timing advance down low. I even messed with the EBC so try and soften the hit by having a slower ramp from 10 to 15 psi. It felt smoother but I liked having the power sooner and it was more predictable.

 

[JCH13]

I was running a 14B turbo off a DSM with a different manifold and exhaust. I just found that the EBC was a little more sensitive to temp changes over the manual controller but over all it was pretty solid when daily driving the car. The only time it really bugged me was when I’d tune car at home where it was in the mid 40’s at night then head to the GRM challenge in Florida where it was 98 degree the last year the car was there. Still the quicker spool and smoothness made it worth it once duty cycle was dialed in properly.

Boost had always hit like a hammer with 15 psi coming on at 3500 RPMs with the 14B and EBC. The T3 50 trim felt a little lazy in comparison and didn’t have the same top end. I always assumed it had to do with lack of timing advance down low. I even messed with the EBC so try and soften the hit by having a slower ramp from 10 to 15 psi. It felt smoother but I liked having the power sooner and it was more predictable.

That is some pretty amazing boost response with a 14B. I can't find any comparable build threads right now... but I think I'm at best getting 10psi by 3500rpm. It might be worth revisiting my turbo choice to improve boost response now that I'm refocusing my efforts on autox performance.

 

[JCH13]

Holy thread necro batman!

Now that various winter commitments have expired I am starting work on my Miata again. Given my wedding this summer time and money are both limited, so I am only focusing on two smaller projects compared to what I've done in the past: a coolant re-route and a 2.5in ID stainless steel v-band downpipe.

The downpipe is the only part of the exhaust system I haven't completely replaced, so it's about time. A larger diameter downpipe will help improve turbo spool and top-end power, and making it out of stainless steel will help reduce under-hood temperatures. I got the needed bends and v-band fittings from amazon for less than $100 with prime shipping, winning.

My first focus though: a coolant re-route on the cheap. A little history lesson: the Miata's Engine, B6ZE, is a slight variant of the Mazda 323 GTX engine, the B6T. The B6T was an E-W engine fitting into a fwd car. In the E-W configuration there is a coolant inlet near the bottom of cylinder 1, and a coolant exit (and thermostat) near the top of cylinder 4. This provided nice uniform cooling for all the cylinders. However, when the engine was flipped N-S for the Miata, this cooling layout was no longer practical. In the stock configuration the coolant inlet is near the bottom of cylinder 1, the exit is near the top of cylinder 1, and there is an always-flowing bypass through the heater core from the top of cylinder 4 to the bottom of cylinder 1. This configuration is not ideal, but in the Miata the B6ZE was only producing 115hp, so it was sufficient.

However, when a turbocharger, racing conditions, or both, are introduced the cooling system starts to show deficiencies. So, the solution is to re-route the cooling system such that it performs as originally intended.

It's a well known concern, with many OTS kits available:
http://www.bellengineering.net/product_info.php?products_id=300
http://949racing.com/miata-coolant-reroute-system.aspx
https://www.flyinmiata.com/index.php?deptid=4532&parentid=0&stocknumber=09-60000 1990-93

But all of the OTS solutions are fairly expensive and, IMO, leave a lot to be desired. Each one introduces several, if not many, new failure points to the Miata's cooling system and cost too much damn money for what they are.

So, I didn't do a coolant re-route for a while. It was never a serious problem in Autox where the engine never really has a chance to heat-soak. Then enter the 'coolant reoute easy button': an upper radiator hose from a 2002 Cadillac Escalade fits the miata almost perfectly. Now there is a decent option to do a coolant reroute without spending an inordinate amount of money, the hose is a whopping $17. I figured 'why not?' at the very least it will open up the option of driving my Miata at a serious track day.
http://revlimiter.net/blog/2011/06/coolant-re-route-2/
Not sure if I'm going to need the second hose suggested in this thread, but it's only $10 if I do.

Now the second part of a coolant re-route is the fitting on the back of the engine's head. Most people need to buy a Kia t-stat housing because it's outlet is slightly different from a Miata's and that lets it get around the coil pack. Fortunately, I have a COP conversion, so I can just re-use a Miata t-stat housing, which I have an extra of because of the spare engine(s) I have lying around. I also have an extra heater core and thermometer fitting too. So, I set to work to turn those two extra parts into one part that would (a) house a thermostat, (b) fit on the back of my engine, and (c) have enough room to keep the coolant temperature sender in place.

The first thing I did was start to clean up the old fittings. Hooray wire wheels on bench grinders!

Then I got a little creative with the bandsaw to get the two chunks to fit together.

A little something like this...

And there is still plenty of room inside each bit for the thermostat and coolant temperature sender.

The next step will be to fine-tune their fit-up, add chamfers to improve weldability, run them through an ultrasonic cleaner, and then TIG them together. TIG welding cast aluminum can be very tricky, but I've done it before, so I am optimistic that I can get them stuck together and water-tight.

Here goes nothing!

 

[exdeath]

How much filler is needed for welding cast aluminum? I bet it shrinks down pretty good.

 

[JCH13]

How much filler is needed for welding cast aluminum? I bet it shrinks down pretty good.

Maybe a tiny bit more than normal. When the base material melts it doesn't shrink away a little because it's porous. The issue with cast aluminum's porosity is (more so) any shit that it's absorbed over the years comes out of the base material and into the weld. This is why I run a welding arc over everything on a high cleaning setting before I actually start welding.

 

[FuzzyDunlop]

thats cool. Wish I had the know how to build custom parts like that. Really opens the door of possibilities for you.
Jelly.

 

[JCH13]

thats cool. Wish I had the know how to build custom parts like that. Really opens the door of possibilities for you.
Jelly.

If only there was a place on the internet where like-minded people could meet and discuss their projects and seek advice from one another... :awe:

There's not much of a secret sauce. I just have a bit of experience and a small measure of common sense. All the equipment helps a lot though... I can't lie. I bet you'd be surprised what you could come up with if you immediately nixed any OTS solutions.

 

[JCH13]

Hooray progress!

Welded the franken-fitting together. Disclaimer: welding cast aluminum is the shittiest welding ever, especially stuff that's spent the last 24 years soaked in oil and coolant. However, I think they're stuck together pretty well.

And I made a good bit of progress on a new stainless downpipe. The old one was made by the previous owner, and while it was functional I had modified it a bunch to work. It was rusting at each weld and didn't fit quite the way I wanted it to. Starting from whole cloth is nice, the new downpipe is going to fit the FM downpipe brace I have, taking a lot of stress off of the turbo and manifold.

I realized I didn't have enough pipe to finish the new downpipe, and that I didn't have a flex section, so I ordered a stainless steel flex section. It should arrive later this week or early next week.

 

[jlee]

Fancy.

So, you should move to Phoenix. :awe:

 

[slag]

How deep are your pockets?

:awe:



http://www.stovebolt.com/techtips/rust/electrolytic_derusting.htm

This site says "use cleaning soda" and a number of write-ups say "don't use baking soda" but a number of other write-ups say "use baking soda." My understanding of battery chemistry says that any salt will work.

Warnings (not a comprehensive list):

DO NOT use table salt. It will make chlorine gas in addition to hydrogen gas. Chlorine gas is poisonous. When Chlorine and hydroden react you'll get hydrochloric acid, which will make you a sad panda when it dissolves the parts you're trying to de-rust, then melt your hand when you try to get them out.

DO NOT use a stainless steel electrode. It will release hexavalent chromium and kill you, and anyone around you, through your lungs. You will then explode at your funeral and kill everyone who ever loved you. So just don't do it.

It will produce hydrogen gas and oxygen. Be well ventilated.

I use arm and hammer washing soda with a 1-5 amp variable battery charger and it works pretty well. I use it to clean off items I have found metal detecting.

 

[JCH13]

Downpipe is done and seamed up! Hooray!

Might have to do some massaging to get it to not rattle against the transmission tunnel.

And by massage I mean hit shit with a big-ass hammer.

 

[JCH13]

Rigged up a compressed air blast and coolant mist on my router. Made it a lot easier to cut aluminum. Designed and made a block-off plate for the coolant reroute effort.

Fits the gasket quite well.

 

[Zargon]

nice!

 

[JCH13]

A Miata owner on another forum asked me to make a blocker plate for him, without a hole in it (because race car). So I obliged, and practiced doing engine turning.

Motor mounts for mine came in, and I expect the tap I need to finish my blocker plate tomorrow. Soon the coolant reroute will be mine!

nice!

Thanks!

 

[FuzzyDunlop]

engine turning! You should try to program your CNC machine to do it! Perfect swirlage.

 

[JCH13]

engine turning! You should try to program your CNC machine to do it! Perfect swirlage.

I know, right?

Might also be fun to spell things and/or make non-traditional patterns.

Oh the possibilities...

 

[JCH13]

So, on the docket for this weekend:

Coolant re-route.

And improving steering feel by removing the power steering seals and welding up the pinion gear splines.


Ambitious, we'll see what happens.

 

[jlee]

Moar pics!

 

[JCH13]

Didn't get around to doing the Coolant re-route, spent too much time screwing around with steering. However, the steering took a phenomenal step forward in ease and responsiveness.

The steering was one of the few systems on my Miata that I hadn't torn into until this weekend, and I'm really glad I did. The passenger side steering rack mount was only finger tight! Not so good, definitely contributing to steering sloppiness, and it could have made life REALLY suck if it ever came loose.

So, here is the whole steering rack assembly out of the car and ready for surgery.

I cut the lines out and crimped them, took everything apart and greased the rack up, readjusted the rack preload tension, took out all of the power steering valving, and cut off the power steering seal. I notched it on two sides with a cutoff wheel, and then split it with a chisel. No damage to the steering rack!

Then I welded up the steering pinion shaft. As one might expect, ductility of this weld is paramount. It's unlikely that strength will be an issue (as the only torque it will see will be from the steering wheel) so I braze-welded it with silicon bronze filler. Turned out pretty well I think.

And here is the whole assembly ready to go back into the car. I didn't have extra wire to re-tie the inner tie-rod boots back on, so I used 1/16th aluminum welding rod. Worked like a charm.

You can see all the lines are gone (hooray!) and after a bunch of futzing around I got it back in and re-aligned the car. I think I'm going to have to fine-tune the alignment a little bit more, I don't think the rack is as centered in its travel as I would like.

All-in-all a ridiculous amount of improvement in steering drag, feel, and responsiveness compared to a simple by-pass de-powered steering.

 

[FuzzyDunlop]

gah, you make such pretty welds.

A shame that most of them are hidden in the depths of your car where no one will see them.

 

[JCH13]

gah, you make such pretty welds.

A shame that most of them are hidden in the depths of your car where no one will see them.

:$

 

[JCH13]

I ordered this laser line in order to do a more precise alignment on my Miata using FM's alignment hubs.

The hope is to put a laser line down the center-line of the chassis. The self-leveling laser should be more accurate than string, and If I can anchor the laser line to the car itself I won't have to worry about the car shifting when I am tightening and loosening fasteners.

We'll see what happens.

 

[JCH13]

Okay, I'm going to state the obvious: lasers are WAY better than strings. By all of it.

I measured and marked a centerpoint on each subframe to establish a center line. I used the laser aligned to these two marks to cast the center line down onto the tape measures attached to the alignment hubs. This let me easily set thrust angles on each wheel and made it really obvious when I accidentally shifted the car when tightening a bolt (which happened way more than I thought it would). Huge improvement in how easy it was to do an alignment.

Final alignment specs-

Front
4.8deg caster
-2.2 to -2.3deg camber
1/16in toe out each side

Rear
-1.55 to -1.6deg camber
1/16in toe in each side

Was raining last night so I didn't take it for a test drive, but I will update once I am able to do so.

View from under the car while aligning the rear axle.

The alignment hub, camber gauge, and tape measures all attached to the front passenger hub.

The laser cast across the tape measures on the front axle.

 

[jlee]

Very cool.

 

[FuzzyDunlop]

Frick-en Laser Beams!