bbundy

Yea the thermostat is a 180 +- 10 so say it has to see 190 before its fully closed. I don’t know how much temperature drops across the heater core with the heat off but it wouldn’t surprise me if it is 30 or 40 degrees compared to where a standard radiator thermostat and temperature sender is located. So it may not close fully until the engine is hotter than Id like it if it is after the core.

I run a 180 degree main thermostat in the back of the head for the main radiator. With the heater core thermostat placed before the heater core it should start shutting flow down about the same time as the flow starts going to the radiator. when I took the valve apart and fiddled with it I could still blow through it with the path shut so there is always some flow going to the heater core just a significantly reduced amount.

So yea I think a 160-170 thermostat placed after the heater core would be better. The only thing I have found so far is this.
http://www.summitracing.com/parts/EAR-501ERL/
I think some OEM’s BMW? are setup this way I wonder what there heater thermostats look like.

Bob

jacob300zx

Bob, your bay looks amazing.

sr20ser

iTrader: (1)

I am pretty sure that copper is better for thermal transfer.

fooger03

iTrader: (2)

Indeed, copper has a significantly greater thermal conductivity per surface area.

But you've completely missed the point.

wayne_curr

iTrader: (8)

Here is one kinda bad picture of it.



Trying to find another.

Edit: After a bit of reading it looks like they implemented that back in the 80s as a recall to try and eliminate some coolant system over pressurization that was causing heater cores to explode and scalding drivers' legs.

chpmnsws6

iTrader: (12)

They also put restrictors into the HC inlet pipes to slow that down. I was talking to our local hotrod radiator shop and they suggested doing that to my stock HC since the OEM Mazda cap was only 13psi, where we have an 18-20psi (can't remember the exact) cap on it now. They said it actually takes very little coolant flow to keep the cabin warm.

bbundy

Yea that is my theory that full flow needed to warm things up in the cabin starting from cold. Once the cabin is warm and the engine is warm it dosn't take much flow to keep it that way. Pretty small air space in the cabin of a miata. It also dosn't get very cold in this part of the country. The themostat I am using dosnt close entirely it just reduces flow quite a bit.

Bob

bbundy

Interesting I took the thing apart wondering if I could just find something to replace the wax thingy with and it is stamped 77C / 171F. The wax plug part looks the same shape and dimensions as some other thermostats I got maybe I can just take one out of a 160F standard thermostat.

Maybe it was working correctly with it after the core if it was a 171F stat I just don’t know for sure what the temp drop is like across the heater core. That is actually how I had it prior I must say it seemed to work but I didn’t record actual data to prove it. I can certainly re plum it back that way again.

Bob

JasonC SBB

I kinda disagree, I lived with a 1/4 NPT tap / 1/2" hose in the back of my head as a heater source for a while, and it was a bit wimpy. And I live in CA.

bbundy

Update I found a 160 Motorad thermostat at O-Riley’s had the same wax pellet dimensions as the True Cool oil cooler thermostat.

I put the thermostat assembly in a pot on the stove.

With the 171F pellet it came with it was fully closed at ~195 F
With the 160F pellet it was fully closed at ~175 F.

So if I put this in post core it means it won’t allow much flow through it if the heater core unless it can reject enough heat to get it below 175 F thus somewhat preventing it from possibly being a short circuit of the radiator while still allowing it to resonably function well as a heater when needed for heat.

Any Idea what the temp would typically be at the outlet of the main radiator if say it was 210-220F where it left the head? I havent found where anybody measured it yet. and Im too lazy to measure it myself.

Bob

JasonC SBB

LOL you're such a stud...

When the t-stat is wide open, it depends on RPM (and thus water flow rate) and airflow through the rad. Circa 10-15*C drop across the rad at like 50 mph on a steep mt. road doing ~4000 RPM, fans running, on a hot day. At higher RPMs the deltaT will be a bit lower. If the t-stat is partially closed, it'll climb to 30*C delta or more.

bbundy

Ok that sounds about right then. With it at coming out of the heater core and headed back to the engine at a regulated maximum of 175F then that path won’t return coolant to the engine any hotter if any than what the radiator will do. Thus the total heat transfer from the radiator and the heater core together should be about maximized.

Important if you want to drive the **** out a car making 3X stock hp and have it maintain temp.

Bob

dgmorr

iTrader: (4)

That looks great. How did you connect the AN fitting to the water pipe under the manifold?

curly

iTrader: (25)

I'm using a hose barb and hose clamp, but I've drilled and tapped my mixing manifold for a 1/2" NPT. Or 3/8" NPT, I forget. Anyways a NPT to -AN fitting could obviously be screwed in to connect a hose on.

bbundy

I welded a steel AN fitting to it.

More bling. note: all the turbo lines are AN fittings. Custom fabricated inlet to the water pump to work with my turbo location. I finished it off to look like it was cast like that.

Bob

bbundy

Update,

I changed the installation a bit. Moved the heater thermostat to the other side of the firewall and cleaned up the engine bay. Also have it installed after the heater core with the lower temp wax pellet I ripped out of a different thermostat.

Bob

freedomgli

This is great stuff! It’s getting my own creative juices flowing. I want to do a hot side coolant reroute and I need to do something clever like this with the heater core feed and return lines.

matrussell122

iTrader: (1)

So I want your reasoning on bumping a thread on 9 years ago.

Tran

Fairly major thread necro there.

But I did find it useful. I asked about using a thermostatic valve on the heater line in the cooling system thread and it didn't sound like anyone had tried it. The implementation post heater matrix looks like just what I was thinking of.

freedomgli

Because **** you. Is that good enough?