Hyper re-route?

No no, none of it is hot side.

Just looks like the "Racer" re-route is teed into the upper radiator hose. So this is the "engine rebuilder's special?"

Conjecture and speculation is abound. Anyone besides Lars have actual results?

Because I do. I have had the reroute on my car for the past... I dunno 6 years or so.
Comes to temp just fine on a spring or summer day. I have no winter data, car sits in a nice garage when it's not nice outside.

Frankly, I would not have installed it myself (due to the previously mentioned conjecture and speculation), but the turbo parts were installed by BEGi. I picked up the car that way. I have since installed an aluminum 55mm radiator and removed the "air scooper". In fact, the air scooper came off like day 2. I also have autometer coolant temp and oil temp gauges in the car, and my temps are fine and my engine is fine. It's 100°F+ here in the summer.

So the fact of the matter is your world won't end with the reroute.

Well I only have a 37mm koyo and the car struggles to get over 140F on thr highway. Drove it to work yesterday and on my 25 minute commute it never broke 120F.

It IS cold here right now but the car is definitely overcooling for some reason to the point i'm suspicious that it's staying in cold start/warmup mode.

Suppose I should check to make sure it has a tstat before I tear the re-route out.

The racer re-route will lead to overcooling if you drive it on the street. I had this issue when I first did it to my car. On track, cooling was fine. Never got over 200*F. Now have the normal reroute (thermostat and spacer at the rear of the head). Heats up normally during daily driving.

I was just on the phone with Stephanie yesterday and we were speaking about this as I needed to purchase a water bypass system (Racer re-route comes included depending)

She stated it would take much longer to get up to temperature on the street.

For a track car or a car with a Honda civic radiator...this could be a useful mod, but speculation on here is probably correct for a daily driven vehicle...especially this time of year.

What i don't understand is.... i could see it taking longer to get up to temp, but wouldn't it still eventually get there, even in winter? I mean, it will hit 180-190F if i just let it idle or i'm sitting in traffic.

But as soon as i get on the highway again, it drops FAST back down to 120-140F range.

I guess i'm not seeing how this is truly adding additional cooling, rather it just seems to bring the whole system up to temp at once, instead of just part of it.

Or maybe i'm way off base.

Maybe diagram out the coolant routing as installed. If it is the BEGI racer reroute, shouldn't the front radiator hose not be there anymore? Maybe you've got an incorrectly installed or partial system.

Anyways, if the outlet from your heater core T's into OEM upper radiator hose, that means the water flow going through that T ALWAYS goes through the radiator -- whether or not your T-stat is closed.

Again, a sketch of what you have would sure help visualize because I'm really confused on what you have.

I'm confused, too. It looks like it's installed the way that BeGi intended...

It's sitting in my upper radiator hose, and the line that's going into it/from it/whatever is going to somewhere near the back of the engine compartment.

That metal piece in the middle of my front/upper radiator hose is the "re-route."


What i'm struggling to grasp is how this could do anything but cause a car to warm up slower. I don't understand how a car could reach operating temps, then go WAY below them again the first time it's moving, just because of this part.


If it's still daylight when i get home, i'll open the hood up and see exactly what it gets into, maybe get some better pictures.

That's what I understand it is hornetball.

It never gets up to temp because all the coolant is going through the rad and it's 6°F right now, so of course it's never gonna reach temp.

As a stopgap measure, you could probably do the socket trick if you have an extra one. Maybe a 1/4" one will keep flow through the heater core down enough to let the car warm up. But even still it will be cold going back in the engine because it's all going through the rad, so I'm not sure how much it will help. I'd try that AND block off part of the rad too. Worst case your heater doesn't work great and the thermostat still opens to keep the car from overheating.

Heatsoaking the rad. Not much heat is exchanged so it starts to warm up when you're stopped, but once you start moving ALL the coolant is going through the rad whether the thermostat is open or not (making it useless) so it cools right off.

This is a BEGI bungle (of which there were many in my kit).
Routed to the upper radiator hose it causes coolant heat up to be so slow that it will consistently cause a CEL (thermostat stuck open) on a NB2 (2001-2005).
Ok if routed to the bottom radiator hose.

Ok so what you're saying is that if you have this installed in the upper radiator hose, it's basically the same as not having a thermostat. Awesome.

Yep, in a stock coolant system, thermostat closed = coolant through heater core and into mixing manifold. Thermostat open = coolant into upper rad hose and into heater core (though less into the heater core obviously since it's a greater restriction). You are just going around the thermostat in your scenario, the only difference between thermostat open and thermostat closed with the 'racer reroute' is that when it's closed it's only taking coolant from the back of the head instead of the front.

And this is the "re-route" portion of it.

Got it.

This sounds like AIDS.

BEGI's rear spacer along with a KIA waterneck and GM truck hose works really, really well though. Exactly like a FWD 323! You just have to know which BEGI parts to buy I guess.

Seriously, if you take the time to sketch what you have, I think the problem (and solution) will become clear.

The proper way to fix that is to remove the tee from the upper radiator hose and move it down to the lower radiator hose.

I just felt like drawing
 

Popped out Visio and drew away. Picture is worth a thousand words.

First, let's start with OEM:

https://www.miataturbo.net/attachmen...1&d=1393514555

Mazda's dilemna was fitting a FWD transverse engine to a RWD chassis. To preserve maintainability, they wanted the thermostat in the front. They had room to fit a large radiator, so why not?

Note that with the OEM configuration, the maximum flow of water through the engine is with the thermostat closed. As the thermostat opens, part of the flow from the water pump is diverted away from the engine and to the radiator. Obviously, this is compromised operation. In addition, it means that the radiator never sees full flow no matter how open the thermostat is (some, thankfully, always goes through the engine). That means radiator efficiency is also compromised -- which is one reason our radiator is more than twice as large as a Civic's.

So, the Mazda engineers paid a heavy price for that front thermostat. But they weren't dumb. They sized the components so that the engine retained adequate cooling water (at OEM power levels) with the thermostat fully open in hot conditions.

Alas, who among us is happy at OEM power levels? #4 gets awfully hot when you bump it up. Hence . . . the reroute:

https://www.miataturbo.net/attachmen...1&d=1393514555

Since we're men and don't fear blood on our knuckles, the traditional and best way to reroute is to restore the flow of coolant to the FWD transverse configuration. This is really the optimum configuration. Every molecule of water from the water pump goes through the engine first and through a heat exchanger (either heater core or radiator) second before returning to the water pump. Doesn't get much simpler or effective than this. On my cars, I do this with a BEGI spacer, KIA waterneck, GM truck hose and TSE waterneck block-off. BAM!! (Relatively cheap too).

The above seems so obvious. So, what might be this BEGI "Racer" reroute I'm reading about? Went to BEGI's website (where they recommend T'ing into the top hose) to check it out. Aaaannnddd . . . here it is in all it's glory:

https://www.miataturbo.net/attachmen...1&d=1393514555

In this setup, all water always goes through the radiator with some of it going through the heater core as well. And you wonder why you run cold on the highway. LOL. Plus, the deficiency with water flow through the engine remains. WAIT!!! Actually . . . it's worse!!! How can that be?

Look carefully. The highest pressure point in the system is the water pump outlet. Likewise the lowest pressure point in the system is the water pump inlet. The water pump belt provides the mechanical power to make this happen. Now, with the OEM system the flow through the motor is:
1. pump outlet
2. motor
3. heater core
4. pump inlet

But, with this system, the flow through the motor is:
1. pump outlet
2. motor
3. heater core
4. radiator
5. pump inlet

I said in an earlier post that this was the dumbest thing I've ever seen. I think now it's worse than that. The fact that it "works" at all is one heck of a testament to the way Mazda overbuilds cars. Try this with a BMW or MB . . . I dare you. LOL.

So, let's "fix it" and put the T into the lower hose. Here's what that looks like:

https://www.miataturbo.net/attachmen...1&d=1393514555

Bears an uncanny resemblance to the OEM system, doesn't it? LOL. At least it's better than a T in the top hose.

My recommendation . . . pull that trash and sell it over at CR.net.

Oh, BTW, I run an OEM plastic-tanked radiator on a 200HP car on track in TX in August. I don't overheat. That is how effective a traditional reroute is. That is also how large our OEM radiator actually is and how effective the stock air guide/undertray is. I don't run an intercooler in front of the radiator though -- I'm sure it would impact cooling if I did.

Excellent this all makes perfect sense now. Thank you!

Now to read up on the cheap bastard DIY re-route.

Ok so since this one is my thread...

BeGi "real" re-route vs. M-Tuned re-route vs. homebrew.


Fight!