My Reroute drawing
 

Please critique. I have most of this done already with the exception of having the heater core plumbed.
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All good to me, but where's the turbo'd coolant going too? Should be going back to the rad ideally. Mine works similar, but heater core goes back in the engine because I need it way up north in ATL. ;)

Turbo is getting fresh water from the block and the feeding into the mixing manifold the way most do it. It would be nice to send it to the rad though. Im just not sure it would get enough flow like that though. As is the water pump pulls water thru the turbo, dosen't it?
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It appears his turbo pulls coolant from the block in that port that's on the side, and then returns it to the mixing manifold/inlet of the water pump.

Overall reroute looks ok to me. I'm assuming you pull hot water to feed the heater before the thermostat, and return after the thermostat.

Correct on both.
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You have a high side and a low side on the cooling system. That is, there are two pressures. The high side is anywhere after the pump and before the thermostat. The low side is anywhere after the thermostat and before the pump, ignoring insignificant losses do to fluid flow. Odds are there is slightly more flow returning the turbo water to the inlet of the WP vs. before the radiator, but it's negligible. I would keep it the way you have it though. You don't circulate much water through the turbo anyways, so it's not adding much heat to the coolant pre-water pump. Maybe 5*F or something, but not much.

Calling Hyper, come in Hyper... *static fuzz noise* :giggle: Looks like a deal.

This is a dumb question, pardon me, but why not just come out of the head, into the heater core, and out of the heater core right into the radiator instead of that loop around the T-stat?

I understand you get a little bit of water circulation through the heater core before the T-stat opens in Levnubhins configuration but that can also be achieved with some drilled holes in the t-stat.

Instead of dumping the heater core into the return line post-thermostat, which effectively defeats the purpose of HAVING a thermostat, I would dump it back into the mixing manifold like the factory does it. The car will warm up faster and the heater will work more quickly. Other than that, looks perfect.

Would certainly be cleaner that way.

I think its a good basic reroute. I'd just retain the left side of the heater core returning to the mixing manifold. Treat the heater core like a second smaller radiator (because it is), and run it just like the main radiator. Source from head, return to mixer.

His heater will work much faster in his configuration. Remember if you have it plumbed back into the mixing manifold like i do (begi race reroute) the heater doesn't turn on till the t-stat opens. So i don't get a heater on just about all my short trips around town unless i let the car fully warm up.

Lev, are you going to plumb the feed to the heater pre or post thermostat?

it's pre.

^
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Then plumbing the heater back to the mixing manifold will be just like the stock configuration, which means you get the heater after about 90 seconds of driving.

Nick, if your heater feed is pre-thermostat, and the return is into the mixing manifold, and it doesn't work, you might have a thermostat that's stuck wide open.

I just switched the heater block to the front of the engine and put the thermostat/radiator at the rear. Your design guarantees slightly better flow for the thermostat, but I can't really see a gigantic difference in terms of performance, especially for racing.

FYI, my thermostat has no problems with failing to open (it's not on a stalk after all) and the heater core warms up normally even in subzero temps. There's also a coolant line that feeds the intake manifold from a boss that is right next to the rear thermostat housing, so you get a little flow. It's apparently enough.

Its post, Meaning it doesn't get much flow till the T-stat opens. No heater till 180* temps. I have been considering blocking off where the heater hose mates to the back of the head and putting it like the drawing above (pre t-stat) which would get me a heater much sooner yes?

Is there any downsides to doing such thing?

+1.

I see where you're going with that, taking advantage of the pressure differential across the thermostat to enforce flow through the heater core at all times. As drawn however, this system has the same fundamental flaw as the "cheap" Bell reroute, wherein coolant exiting the heater core goes into the upper radiator hose. Warmup will take forever, the engine will run too cold, rivers of blood, locusts, etc.

Apart from that, looks good.

Dogs and cats living together...mass hysteria!

It's interesting how well a conversation on a reroute can go with Hyper...

Following advice in this thread, I now have a question, I'm retaining the o/c and t/b coolant lines in my reroute (freeze plug in the front, feeding the heater core pre-thermostat, exiting heater core to mixing manifold, and sending upper radiator hose around the coldside) but looking for a place to send the coolant after the throttle body. I'm planning on running a pipe under the intake manifold to send the coolant back to the radiator, would it work ok to have an inlet in that pipe to return the coolant from the throttle body?
If my reasoning is correct, it will be like the stock setup of having the throttle body coolant running into the thermostat neck, it will just be post-thermostat now instead of pre-.

/\
All that will do is give you slightly more flow pre t-stat opening.
Which is not really a bad thing.

I did mine this way. It takes a while to heat up, but even at 35* air temp, it maintains 180* on the freeway. If you track the car, keep it how it is. If you don't then use the mixing manifold.

everything you never knew about life as a man.

With any luck, your balls will drop after reading this thread. I'll try to remember to take more pics of my motor tonight and send them to you. BEGi has lots of parts to make this happen easily.

I have a somewhat similar re-route without any loss of heater functionality and no prolonged warmup.
One small deviation, I come from the coolant port on the bottom of #4 cylinder and feed into the heater.
The post-heater feeds into the "spacer" with a 5/8 hose barb (which is after the thermostat).
The spacer is capped with a 1.6 neck which returns all coolant to the radiator.
A nice bonus with using the 5/8 hose barb: You can use the stock heater hose to the back of the head.

I use a -6AN hose and fittings for the heater "feed" line which seems to allow a little too much bypass flow for sub-summer temps. When the thermostat opens, the combination of the heater and radiator flow seems to drive the engine temp a little too low (for winter operation, probably wouldn't happen in > 50 degree weather). By a little, I mean 140ish. That's when coasting. Normal driving keeps the temps around 160 (still a little cool but that should change with warmer ambient temps)

so that when the thermostat opens, you get cool water instead of half cool half hot water. I have my reroute done like this, and I constantly get laid once the car warms up.

It's not half and half, though, since the hose to the heater core is smaller than the hose to the radiator, and if you restrict the flow to the heater core you can improve on that. It's more like 3/4 cold water, 1/4 lukewarm water (the heater still removes heat).

You can either get laid when the car warms up, or you can get laid while the car is warming up. Return the heater core to the radiator and you'll be so cold in the mornings you won't be able to physically get it up.

Both BRGRacer and I both did the OPs proposed reroute over a year ago. We both suffered from over cooling the motor. The car would take forever at idle to reach operating temp and once driving the temp would actually fall to around 140deg F and never rise higher. The only solution was to return the exhaust side heater core return pipe. Once that was added back into the system the motor would heat up normally and reach operating temp.

Isn't it nice having an intelligent conversation about a reroute? lol Thanks for all your input guys. When I do plumb the heater core back in I'll just return it back to the mixing manifold.
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Since my head is off, I decided to finally do my reroute.

I'm simply doing this:

• Freeze plug for the front outlet.
• Spacer from BEGi; machined for a thermostat, tapped for the heater core & temp sensor.
• 1.6L water neck for the radiator return

that's it. simple.

^ That's exactly what I'm doing. Except I'm keeping the smaller oil cooler and throttle body lines as well.

How much is BEGi charging you for the spacer?

I was just about to ask that. I ordered one of these, you posted this once before Scott.

AJUSA - Holley - 5 #5
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The primary purpose of water cooling the turbo center housing is to prevent oil coking during heat soakback after hot shutdown. While the engine is running, you get pretty good thermal management of the turbo center housing from oil flow. You also don't need to worry about coking then since the oil is continuously flowing through the turbo. One of the most important considerations in turbo water coolant routing is to make sure you don't have a high point vapor trap in the line. The post shutdown cooling works by siphoning fresh coolant into the turbo as the coolant boils off.

I'll be finally adding a water/oil cooler, but i have no TB lines. I'll source from the IM and dump back to the water pump inlet.


I think it was like $20 or something. You could ask them to tap it and machine it for you....

they should really make it a standard product with extra temp sensor holes and plugs to fill them as needed.

We've had like 5-attempts and no one can seem to make a reroute spacer that everyone likes. Just the spacer would be nice.

Then buy from BEGi or Moss or the Holey part linked.

But I bet if they tapped it on one side for 12mm x 1.5 and the other for 3/8 NPT, people would buy them.

86 vs. 20 dollars. why would I buy the holley part???

its just an option :P

behold!!!
http://i33.tinypic.com/2z59ile.jpg

wait a few days and ill post the same image. :P

Actually his spacer is cooler than ours. They finally started making them the way i wanted them to be made it appears :)

Well, I'll take 25% more cool water, bitch.


Also, I recommend you get a port for an aftermarket water temp sensor for future use, because after you see my Omori water gauge incorporated into my instrument cluster, you're going to wish you weren't such a homo because then you'd have a chance to see a naked woman for the first time in your pathetic life.

Anymore details on this? Very interested.

Is it sold by BEGI?

I wouldn't either. But I also didn't know Begi would sell just that part machined for a t-stat and tapped the way I want it for $20. :bang:
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The heater core probably flows 10-15% as much coolant as the radiator does when the thermostat is fully opened. The heater core is very restrictive in its design. And that % of water is only cooler if you've got your heater on all the time. If not, then all that heat is just dumped back to the motor. I don't drive around with my heater on full blast.

For most, this is fine. Most people that overheat aren't getting enough air through their heat exchangers. It's not that 10%-15% that's killing them.

And I'd love to know why every vendor on earth is afraid to put a solid reroute on the market.

lets all whore ourselves out to TravisR then.

I want: T-stat + bsp gauge + stock temp sender + GM water temp sensor with plugs for the bsp and GM until I'm ready to use them. yay.

Heres a dumb question, where is the thermostat when the car is stock? Front of the head or the back of the head? Its inside the water neck right?

Ok, it all makes sense now.

It is in the front of the head, in series with the water neck that feeds the upper radiator hose.

And that's really the #1 problem with the cooling system. The water pump is in the front of the engine. The thermostat outlet is in the front of the engine. Therefore, when the thermostat opens, a great deal of water goes from the pump, up the front of the engine, and then directly out. The consequence of this is that the volume of water circulating through the back of the engine is greatly diminished relative to the front of the engine after it warms up and the thermostat opens.

The principle objective of a good coolant re-route therefore is to relocate the thermostat and outlet to the back of the head, such that the volume of water flowing through the back of the engine does not decrease when the thermostat opens. Doing this modification alone brings the Miata cooling system roughly up to par with the original 323 design, and solves probably 95% of the problem.

This business concerning the routing of the water coming out of the heater core is entirely secondary, and of far less importance than the issue of thermostat location. After the thermostat has been relocated, then one can consider modifications to the heater core path, such as adding a restriction or returning heater water to the radiator inlet rather than the mixing manifold. These modifications will improve the overall efficiency of the system somewhat, but are totally unrelated to the primary issue of uneven front-back coolant distribution.

This is where Hyper really went wrong, incidentally. He got too hung up on these secondary concerns, and never saw the primary issue.

Aside from speculation based on observation, do we have any empirical data to show that there is more circulation between the water pump and the radiator then through the rest of the engine?

Basically what I am saying is, what if there is a restriction built into the path between the pump and the front neck to prevent over circulation of water?

I understand the re-route solves over heating issues on track cars, even though I only heard of maybe 3 such incidents on this forum. However, could it be possible that factory design of the coolant system was intended to maintain proper operating temps. While the re-route on average drops those temps?

In my mind, and I could be wrong, a properly functioning engine cooling system is the one that keeps the engine at the optimal operating temp in all driving conditions basically removing the possibility of large temperature swings.

I equate this too CPU cooling, the best heatsinks arent the one that keeps the processor the coolest, its the one that keeps the processor at its proper temperature under every load condition.

I understand the 323gtx was done differently, and it was the homologation of rally car. I can understand mimicking the reroute for race use, but wouldnt it hurt(and i use that lightly) the engine, if its driven in any other conditions with sub optimal operating temperatures.

no, I had a machinist cut the groove and tap it for $60.

Sam,

The point of moving the thermostat to the rear, and thus mimicking the original 323 design, is NOT that it causes the engine to run cooler in general. The primary goal is to cause the entire engine to run at a more uniform temperature. In the Miata design, the back of the engine has been documented to run considerably warmer than the front. Here is one page which has some good data on it: http://users.telenet.be/miata/englis...nt_reroute.htm

A secondary effect of relocating the thermostat to the rear is that the overall cooling capacity of the system is increased. This does not mean that average operating temperatures will necessarily decrease- the thermostat is still doing its job of regulating temperature and only permitting water to enter the radiator when necessary. However because the total volume of coolant passing all the way through the engine is increased significantly, the likelihood of overheating is lessened in an engine that's being pushed hard. IOW, we make the cooling system able to dissipate more heat, though it is still able to regulate the engine temperature properly.

A caveat- note how I stated earlier that this business with the heater core was secondary? If you do relocate the heater core return to the upper radiator hose, then you have essentially bypassed the thermostat and will experience over-cooling. This is true regardless of whether the thermostat is relocated to the back or left in the front. These two things (relocating the thermostat vs. changing the heater core return) are entirely separate issues and must not be confused with one another.

And there already is a restriction in the path between the water pump outlet and the water neck outlet- it's called the thermostat. But the fact that any water at all is being permitted to exit the front of the engine means that more water is passing by the #1 cylinder than the #4, and thus #4 will always run hotter than #1.

To continue your CPU analogy, relocating the thermostat to the back accomplishes essentially what you describe- it keeps the whole engine at a more uniform temperature under all operating conditions.


The rear-mounting of the thermostat is not a race-only thing, incidentally. It's how nearly ALL inline engines work, be they made by Mazda, Toyota, Chevy, Hyundai, Lada, Fiat, Caterpillar, Suzuki, etc. The Miata is the oddball, and it is the way it is because the engineers cheaped out when repackaging the engine for a RWD layout.

Many with upgraded radiators could not even get the motor up to normal operating temps in this configuration.

http://i1.fc-img.com/CTV02/Comcast_C...pg_408_209.jpg

Youre good

To summarize, the modified diagram that Brainey posted in message #31 of this thread is, in my opinion, the most optimum configuration for a street-driven car, and the one which is most similar to a "normal" inline-4 engine.

The overall maximum cooling capability could be increased slightly by adding a restrictive orifice between the pre-thermostat outlet on the back and the heater core inlet (to further bias coolant flow towards the radiator and away from the mixing manifold when the thermostat is open) and this is how I plan to do mine when ETD starts shipping their reroute kit. Doing this will not have any negative impact on warmup time or temperature stability (unlike returning the heater core to the upper radiator hose) although it will decrease coolant flow slightly while the thermostat is closed, and will increase the likelihood of pump cavitatation. I tend not to run high RPMs while cold however, so this is not a major concern.

to visualize:

http://boostedmiata.com/technical/co...ed-reroute.jpg