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Discussion Starter #1
First, my car loves me: it waited to blow the aft-most coolant line until I was literally pulling into a parking space at work. I have some good friends with big trucks and even bigger trailers that'll get it 22miles back home for me.

So I jumped around and decided that the OEM hoses will probably be fine for my DD needs, however I also found the TDR coolant reroute kit. The explanation and theory sound solid. The question I have is whether it would be worth it for my application. My knee-jerk reaction is to do it, but I'm concerned this adds complication to an already complicated cooling routing (thus more potential leak points). I will be leaving for a trip from TX to VA and back next month, so I have to get this done soon.

Description of use for my car: Daily driver, 5x per week, 22 miles at 70-85mph constant highway. High summer heat (not uncommon for 2-3mo of 90F plus days). I also do more limited driving (common 16-20 miles 2-3x per week in slightly more suburban driving).

On the other hand, the car has been surviving the Tx weather for 16 years, and the hoses may be the originals; in which case I have to think that for my needs, maybe it isn't necessary.

Give me some pros and cons and recommendations.
 

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It'll allow your car to run cooler so the stock ecu senses the temp diff and supposedly gives you a better map for more power.

Also looks better
And I haven't heard of any coolant re routes gone bad unless its installer error.
 

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It'll allow your car to run cooler so the stock ecu senses the temp diff and supposedly gives you a better map for more power.
This is not the case, the only thing I can possibly think of the car doing is if you had a super low temp thermostat and an incredibly efficient radiator, the car would never warm up and you'd just run pig rich all the time. There is no switch in timing based on coolant temp, at least for NAs. The main improvement of the reroute is an even temperature gradient across all cylinders (cyl 4 runs hotter with the OEM route).

With a near-stock power NA that isn't seeing track duty, I'd just buy the OEM hoses and be done with it unless you have some other reason aside from functionality that makes you want the reroute. I thought about the same thing since I was going FI over the winter and decided that a completely refreshed (replaced all hoses, thermostat, slightly thicker OEM-style rad, etc) OEM system was perfectly fine for my purpose, which is occasional autocross and street use.
 

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From 949;

Simple, bolt-in installation
Benefits of a coolant reroute for the B series Mazda Miata engine

Lower and more stable coolant temps - factory ECU runs in standard temp map (not hot enriched) for more power
Fans will only turn on at idle, cycling on and off on the warm days - less alternator load means more power
Cooler CHT's raise detonation threshold so timing can be advanced - more power
Much faster warm up
On most mildly boosted engines a 55mm radiator is no longer needed, a lighter 37mm is plenty
Neater appearance at front of motor - front outlet can be removed entirely if you wish
Why the Miata has a built in problem
 

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Hmmph, that's news to me, but if it's Emilio talking I'll believe it. I suspect that at normal operating temperature I doubt there will be a timing difference.
 

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From my understanding, if you're willing to swing it the reroute should be an upgrade even at stock power, but you really don't need it until you're tracking and/or FI.
 

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Yeah if your just daily driving it a coolant reroute might be overkill. A kit like that is for cars that are gonna be absolutely abused. I would just do a 160 thermostat and oem hoses. All the hoses and just live your life worry free.
 

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From 949;

Simple, bolt-in installation
Benefits of a coolant reroute for the B series Mazda Miata engine

Lower and more stable coolant temps - factory ECU runs in standard temp map (not hot enriched) for more power Does anyone know at what temperature these changes are at? For example, the "HOT ENRICHED" @ 202 * F? There is typically (in my experience w/ OBDII cars) more ignition setting at cold temps, to help raise ECT, and less at higher ECTs.
Fans will only turn on at idle, cycling on and off on the warm days - less alternator load means more power IIRC, it's at 212*F, verified with my aftermarket water temp gauge, before I pulled the fanswitch when I went with a reroute.
Cooler CHT's raise detonation threshold so timing can be advanced - more power Though too cold can cause more wear and tear. I had a 160Tstat pre-reroute, 180Tstat pre and post-reroute, both ran very cool, particularly at night. I now have a 192Tstat and still relatively cool-- I DO have a 37mm alum rad and proper ducting though on a bone stock 1.6L @ 11*BTDC on 87 CA fuel.
Much faster warm up It was about the same, if not a minute or so quicker once I did the reroute on my setup.
On most mildly boosted engines a 55mm radiator is no longer needed, a lighter 37mm is plenty
Neater appearance at front of motor - front outlet can be removed entirely if you wish
Why the Miata has a built in problem
^
 

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Don't ever use a 160* thermo. Get an OEM Mazda thermo with the secondary (little) thermo on it. That's the only thermo a miata will ever need, ever ever ever ever ever ever
 

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Spite, I think the 2 valve thermo is for NA's only. Or that's what I found out after talking to the friendly folks at m.net. I belive the NB is a one valve thermostat.

Now for everyone above, Running a better map: I think etikoner's source was refering to how the back of the engine is around 10degrees hotter, so the fuel map is usually not ideal for the whole engine. Once the reroute is in place it evens out the temp differences and the ecu has a better understanding of what's going on. AKA a stock ecu will add more timing/fuel and the engine will run better most of the time.

As for the warm up time. Using an aftermarket ecu, I tried, I was running leaner than the stock ecu. Around 14-16 in the first minutes vs the stock 12.9-14.3. And it did warm up in 3-4mins vs the stock 6. So that 1 minute better is nill. Dont worry about it. It will marginally help you. IF anything put that money towards better things, but if your the type that's happy with those 1-3hp butt dyno stuff then go ahead, its just a steep price for almost no gain. If anything you should chose the begi one as it has the thermostat closer to the block.

OH and the 160* thermostat people. The thremostat regulates how warm the engine runs, not how cold. That is the radiator's job.
Using a 160* thermostat means as soon as your engine touches 160* you will have no way of keeping/controlling the engine warm past 160*. Bronto says it well, so I will quote him
160 degree thermostat is great if all you want to do is make your car harder to warm up in the morning and use more fuel
Now, your engine probably is happier running at stock temps 180+ as that's what the thermostats of the 90's did. So clearances were calculated on how the metals of your engine expand. If your running 160-170* your clearances are larger meaning wear, then your oil will fill up with gas vapors and humidity and pretty soon you'll have a worn engine.
 

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Discussion Starter #14
The biggest reason for me to consider the reroute is to keep the engine at a more common temprature across all the cylinders to promote longer life; I have zero expectations or interest in this somehow giving me more power.
 

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Discussion Starter #16
^Only once, but she was REALLY hot!

Hold on... what? I was... ummm...

How 'bout dem Bears?
 

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Spite, I think the 2 valve thermo is for NA's only. Or that's what I found out after talking to the friendly folks at m.net. I belive the NB is a one valve thermostat.
False. Bought an OEM thermo for my reroute the other day and it is a two valve
 

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If its not a track car of a turbo car dont both. Dealing with the re-route is a fucking pain in the ****. Mazda engineers had a good reason to compromise cooling on a daily driven car to make working on the damn thing significantly easier.
 

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Stock ECU starts to pull timing between 202~212° depending on year. It will also gradually add fuel as it gets hot. If you are skeptical about this try recording power levels of a bone stock engine, recording AFR and advance, over 3° increments from say 190 to 215°. we have done this and shared info with Oscar Jackson a few years ago. Between us both, we covered just about every year/ ECU combo. Running cooler makes more power, even with a stock ECU. With a programmable ECU you can delay the clt temp corrections but we still find the BP's make best power close to 200° clt regardless of map.

This is why we set up the cooling system on our race cars to run a specific temperature then make sure our ECU maps are not pulling timing or running fat within those ranges. Whatever power we make on the dyno is exactly what we get on track when we pull out to pass someone. Using a sealed and ducted crossflow rad, reroute, full undertray, we can hold 195° clt temps in 100° ambient race conditions.

If you are paying for power making hardware, don't flush it away because your car is always running 15° too hot.

_______

To the OP:

Reroute not absolutely necessary in your case but it will improve mileage, power and engine longevity a bit. Main thing is to make sure the system is healthy. Fresh rad cap, distilled water, oversize rad (37m if no AC, 55mm with AC), undertray in place. Cheap bonus points are sealing the radiator off to insure all the air entering the bumper opening is forced through the rad and not leaking around the edges. Home Depot pipe insulation works like a charm here. If you are concerned, get a real clt temp gauge. Warning though, you won't like what you see.
 
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