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Old 06-07-2011, 03:23 PM   #1
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Default Heater Core bypass q' restrictor needed?

Hey all the title says it all, i couldnt find a specific search answer to this but here it is:

This is an IT car thats racing in the honda edmonton indy this year, i didtched the heavy heater core with all the wiring associated in it. I bypassed the heater core with a peice of tube i had laying around, do i need a restrictor in place on that line? and what could i use for a restrictor?

Also, i plan on doing a coolant reroute in the near future, is it possible to use the 1.6 water neck on the back of the block, and then plug off the hard line that goes under the header since im not running a heater any more?

I can draw a diagram when i get home on paint or something if i sound confusing

thx for your help.
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Old 06-07-2011, 03:44 PM   #2
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You can run a line back to the water pump. I did this with my spec miata a while back. Having a picture of what you are thinking about doing would be of great help.

Have a great day,
Jared
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Old 06-07-2011, 07:45 PM   #3
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You can run a line back to the water pump. I did this with my spec miata a while back. Having a picture of what you are thinking about doing would be of great help.

Have a great day,
Jared
Ill draw a diagram when i get home, hopefully it will make sense, all i did was connect a hose connecting the two hard lines, one passing under the factory header and one going into the back of the head, but i read somewhere that there needs to be a restrictor
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Old 06-08-2011, 12:54 AM   #4
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I do run a restrictor (just a hose inside heater hose) with coolant reroute. that's what the kit recommends.

but I've never ran a restrictor with my SM. w/o reroute, I am not sure that's a good idea. where does all the hot coolant go after it passes through the block if you restrict it ?
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Old 06-08-2011, 04:06 AM   #5
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I run a restrictor on both the turbo and the SM.
Sum lik diz:
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Old 06-08-2011, 05:03 AM   #6
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Originally Posted by bellwilliam View Post
I do run a restrictor (just a hose inside heater hose) with coolant reroute. that's what the kit recommends.

but I've never ran a restrictor with my SM. w/o reroute, I am not sure that's a good idea. where does all the hot coolant go after it passes through the block if you restrict it ?
It goes through the radiator, ideally

The idea is to get the same restriction that the heater core provided, without the heater core. It can be as simple as sticking an appropriately-sized socket in the hose.

It doesn't matter what you do, as long as you have some flow through the system before the thermostat opens. (Or just gut the thermostat, like I did on the black car)
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Old 06-08-2011, 11:19 PM   #7
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It goes through the radiator, ideally

The idea is to get the same restriction that the heater core provided, without the heater core. It can be as simple as sticking an appropriately-sized socket in the hose.

It doesn't matter what you do, as long as you have some flow through the system before the thermostat opens. (Or just gut the thermostat, like I did on the black car)
haha the T stat removal world war.... i removed mine on my ford festiva race car and never had an issue, but i have had people get really angry hearing that saying its a bad idea and the coolant system does not work well like that :S

anyways heres my coolant reroute concept, forgive the noobness im an accountant and not an engineer!
Name:  miatacoolentreroutewtf.png
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Size:  15.0 KB

would this work?
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Old 06-08-2011, 11:47 PM   #8
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or you could just stick the thermostat in the back of the head and use the front water neck. Instead of using an inline thermostat.
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Old 06-08-2011, 11:50 PM   #9
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Quote:
Originally Posted by Savington View Post
It goes through the radiator, ideally

The idea is to get the same restriction that the heater core provided, without the heater core. It can be as simple as sticking an appropriately-sized socket in the hose.

It doesn't matter what you do, as long as you have some flow through the system before the thermostat opens. (Or just gut the thermostat, like I did on the black car)
Would it get hot if a restrictor wasn't used? My car would do a few laps at the last event before the temps would go up. I thought it was due to my new bumper, but I forgot I had also removed my heater core and I didn't use any kind of restrictor.
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Old 06-09-2011, 05:12 PM   #10
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haha the T stat removal world war.... i removed mine on my ford festiva race car and never had an issue, but i have had people get really angry hearing that saying its a bad idea and the coolant system does not work well like that :S

anyways heres my coolant reroute concept, forgive the noobness im an accountant and not an engineer!


would this work?
what happens before thermostat opens ?
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Old 06-09-2011, 05:32 PM   #11
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Theoretically the hose jumping the heater core without a restricter is probably better than one with a restricter as you will get more cooling to the back of the engine. A good waterpump will throw enough water through a clean radiator to give you good cooling after the thermostat opens and there would be a better chance of maintaining the flow to the rear with no restricter back there.

Your coolant reroute will work OK as long as you drill at least a 3/16 hole in the thermostat flange so that you have flow before the thermostat opens.
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Old 06-09-2011, 05:32 PM   #12
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Originally Posted by spoolin2bars View Post
Would it get hot if a restrictor wasn't used? My car would do a few laps at the last event before the temps would go up. I thought it was due to my new bumper, but I forgot I had also removed my heater core and I didn't use any kind of restrictor.
My car was fine without a restrictor, except at idle/slow speeds when the car would overheat. At low RPMs the water pump doesn't seem to build enough pressure to force any significant water through the radiator. Once I was driving the car would sit right at the thermostat temp. Certainly wouldn't hurt to have some restriction in there though, any restriction you have is going to force more water through the radiator.
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Old 06-10-2011, 03:13 PM   #13
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Theoretically the hose jumping the heater core without a restricter is probably better than one with a restricter as you will get more cooling to the back of the engine. A good waterpump will throw enough water through a clean radiator to give you good cooling after the thermostat opens and there would be a better chance of maintaining the flow to the rear with no restricter back there.

Your coolant reroute will work OK as long as you drill at least a 3/16 hole in the thermostat flange so that you have flow before the thermostat opens.
yah i forgot to mention that in, either that or just gut the thermostat completley and not run one... the cars never going to see the street and will get warmed up before each race... so i guess it is that simple of a coolent reroute!


Also i was going to ask if there was a lower water neck i could just swap in without plugging or welding shut the stock hardline going under the header?
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Old 06-10-2011, 04:04 PM   #14
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Quote:
Originally Posted by miata39 View Post
yah i forgot to mention that in, either that or just gut the thermostat completley and not run one... the cars never going to see the street and will get warmed up before each race... so i guess it is that simple of a coolent reroute!


Also i was going to ask if there was a lower water neck i could just swap in without plugging or welding shut the stock hardline going under the header?
I believe the stock 1.8 thermostat waterneck will work to feed the waterpump from the radiator.

It will take a lot of warming up to reach operating temps unless you go out and run a couple laps to do so.
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Old 06-13-2011, 01:52 AM   #15
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Thx for all the help everyone, i thought my way would have have to be wayyyy to easy to be true but i geuss it wasnt!
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Old 06-13-2011, 02:54 AM   #16
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Theoretically the hose jumping the heater core without a restricter is probably better than one with a restricter as you will get more cooling to the back of the engine. .
Sure, and compromise the entire system in the process. If you're getting more coolant to the back of the motor via increased flow, you are putting less coolant through the radiator, and the overall CLTs go up. Exactly what you DON'T want.

The heater core is a restriction - you just need to mirror that restriction. That's it.

Removing the thermostat is a bad idea, BTW - I said gutted thermostat. The restriction of the thermostat promotes a pressure differential across it, which helps to carry water from the engine to the radiator. My "gutted" thermostat is just a brass plate with a hole in the middle - exactly what a thermostat would be without any of the spring/center pieces.
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Old 06-13-2011, 01:08 PM   #17
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Quote:
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Sure, and compromise the entire system in the process. If you're getting more coolant to the back of the motor via increased flow, you are putting less coolant through the radiator, and the overall CLTs go up. Exactly what you DON'T want.

The heater core is a restriction - you just need to mirror that restriction. That's it.
Don't want to get into a pissing match, but the restriction caused by the OEM back plate and nipple feeding the heater is more than in the heater core and hoses; unless the heater is clogged up.

OP is leaving this in place, which is why I recommended no additional restriction.

Further, the thermostat is there to keep the engine at a relatively stable temperature under all conditions, recommending it be gutted and left as a restriction is not in the best interests of a reliable setup.
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Old 06-14-2011, 06:11 PM   #18
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let the pissing match commense.. (jk)

im just going to stick a nut of some sort in the line, and see if that helps..

the highest my water temps ever got were 190F. It was also +36 and the race was an hour and 20 mins non stop.. That was without the restrictor.
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Old 04-12-2012, 04:13 PM   #19
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Bringing this back since I have the motor out of the car and my heater core hasn't worked for 6 months anyways, might as well button this up now.

My understanding is that if I loop the heater core out, I could cap the heater inlet pipe from the coolant outlet neck and the heater outlet to the water pump inlet. Then I would need to either gut my thermostat, which would make it run basically open all the time, or drill holes in the thermostat to allow enough water through the system to stop overheating while not on the racetrack.

Does that kind of sum things up? Also, one question, does drilling holes in the thermostat have any benefit over gutting in per Sav's instructions?
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Old 04-17-2012, 01:36 PM   #20
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Nobody?
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