Something i discovered today...

[Wobble]

You can use the thermostat for a 89-91 RX7 turbo 2 in your 1g or 2g with a 1g head.. it *may* fit a 2g thermostat housing but your gonna have to spend the 6 bux to find out.. because the rx7 one has a big piston...

the rx7 stat's piston has ALOT more throw then a 1g or 2g stat so it opens more and can flow more water than ours can..

give it a try

I used a STANT one from advanced autoparts..

 

[Wobble]

oh yea, it doesent have a bullber hole though, so youll have to drill one.. a trained chipmunk could do this...

 

[Wobble]

ok, make sure you dont make the bubbler hole too big, my car takes FOREVER to warm up now dammit.. make it about the size of a BB.. mine was the size of a pencil eraser.. im an idiot

 

[billdo_83]

Why would a person want to get a RX-7 Tstat over a stock one?
I'm not correlating a benefit of the extra work here.

 

[crankbender]

DUDE your here in tx. Your thermostat is gonna be stuck fully open all day every even when the car is off in a month anyway. this fall buy a new one.

Seriously i hve gone out to my car (almost black) and started it for the first time during the day and the temp was already 75% of the way to where it normally operates.

I figure it was about 150 under the hood.

 

[crankbender]

Originally posted by billdo_83
Why would a person want to get a RX-7 Tstat over a stock one?
I'm not correlating a benefit of the extra work here.

here in tx (on the coast) the hot humid air has a tendency to overheat cars even when the stock thermostat is fully open.

 

[Wobble]

if you look at the stock stat, the plunger that opens and closes doesent move very far at all, so even when fully open the stat still restricts the flow of water quite a bit.. so even if you have plenty of cool water in yer radiator the damn stat is so restrictive that you cannot move the cold in and the hot out fast enough.. the rx7 stat plunger travels AT LEAST twice as far as our stockers do..so they can outflow ours easy..

and here in TX when it can get hot.. like 100+ for days on end its easy to get hot quick..

my car runs COLD.. with the fluidyine in this cool 70 degree weather i cruise at about 185... (autometer water tempo gauge tapped just before stat on stat housing) BUT when i get on it for a hard pull.. like say sustained driving at 120ish or go ripping around my neighborhood getting on and off it on and off over and over (no lectures please) it can creep up to 200 or even a little more.. . which still isnt hot..


but after installing this rx7 stat i cruise just BELOW 180 (bubbler hole a little too big) .. i went out and did a run at WOT till i bounced off the 135 governer and then held 130 for about 1 min or so...

I got up to about 187...



so the restriction of the stocker stat definalty CAN cause you to ge a little warm when getting on it sustained because it simply cant evacuate the hot water fast enough.. thus not letting the cool water in fast enough either..


P.S. if you are using the stock gauge.. you prolly wont notice the difference.. on a 2g it reads "normal" at 135ish.. and wont start reading a little hot till 200 or so... so its pretty much just gonna sit in the middle no matter what..

 

[Defiant]

Originally posted by Wobble
if you look at the stock stat, the plunger that opens and closes doesent move very far at all, so even when fully open the stat still restricts the flow of water quite a bit.. so even if you have plenty of cool water in yer radiator the damn stat is so restrictive that you cannot move the cold in and the hot out fast enough.. the rx7 stat plunger travels AT LEAST twice as far as our stockers do..so they can outflow ours easy..

You _want_ the restriction. The engineers have figured out the optimal flow rate for the engine, and sized the open thermostat to best match.

Kind of like how they decided how big to make the weep hole, so that it doesn't take forever for the engine to heat up.

If another thermostat was better for DSMs, it'd be specified as the part number. This is not a good area for under-the-shadetree research.

 

[ITSME4G63]

I use the 180 t-stat, but still like under normal driving the temperature will go to 95 celcius which is 203 farenheit, taht like after 20 mins of driving, it stays cool for the warmup peior liek at about 88 celcius (190f), I think i'm going to get the 160 for the summer, and a huge oilcooler, if not the rx-7 one. Just my imput

 

[ITSME4G63]

Originally posted by Defiant


If another thermostat was better for DSMs, it'd be specified as the part number. This is not a good area for under-the-shadetree research.

But there are alot of parts that are better for dsms that are not listed part numbers.

 

[Wobble]

Originally posted by Defiant
You _want_ the restriction. The engineers have figured out the optimal flow rate for the engine, and sized the open thermostat to best match.

Kind of like how they decided how big to make the weep hole, so that it doesn't take forever for the engine to heat up.

If another thermostat was better for DSMs, it'd be specified as the part number. This is not a good area for under-the-shadetree research.

yea.. of course you want SOME restriction so the water can absorb the heat.. its not like im talking about not using a stat at all, but ths one does keep the engine cooler than stock under hard driving.. period..


and yea.. those engineers did design the best stat for our cars..

when they had a STOCK turbo, STOCK radiator, STOCK turbo running STOCK boost.. etc etc.. they also designed the BEST exhausts, best intake, best turbo.. for a STOCK car..

all crap that they desided is best for our cars kinda goes out the window when ya mod them all up and drive the piss outta them.

 

[ITSME4G63]

Originally posted by Wobble
yea.. of course you want SOME restriction so the water can absorb the heat.. its not like im talking about not using a stat at all, but ths one does keep the engine cooler than stock under hard driving.. period..



when they had a STOCK turbo, STOCK radiator, STOCK turbo running STOCK boost.. etc etc.. they also designed the BEST exhausts, best intake, best turbo.. for a STOCK car..

all crap that they desided is best for our cars kinda goes out the window when ya mod them all up and drive the piss outta them.

AMEN

 

[crankbender]

Actually they designed stock parts that are best for them. Look at the 2g bov there has been a big discussion on why they picked that piece of crap....

 

[set3422]

no restriction = cooler = more work on Water Pump. WP can go bye-bye pretty fast.

 

[Wobble]

how would easier flow work the water pump HARDER?.. and its belt driven anyway.. im not worried about water pump issues. my friend just replaced his water pump on his 1g GS-T when he did his timing cover.. the pump still worked and all but he did it just in case... the car had over 200k on it.

 

[MNGSX]

Slowing flow increases the time water spends in the block and radiator.

IMHO those with large aluminum replacement radiators would definately not hurt anything with the bigger thermostat.

Often times in racing where a thermostat is'nt needed an orifice plate is used to create a restriction in the thermostats place. What size do racers use? The one that decreases engine temp the most. This depends on the engine and the entire cooling system.

Since a fluidyne radiator is more efficient you can feed more GPM of coolant thru it and still get a lower outlet temp. So I'd do it.

 

[crankbender]

Slowing flow increases the time water spends in the block and radiator.

IMHO those with large aluminum replacement radiators would definately not hurt anything with the bigger thermostat.

Often times in racing where a thermostat is'nt needed an orifice plate is used to create a restriction in the thermostats place. What size do racers use? The one that decreases engine temp the most. This depends on the engine and the entire cooling system.

Since a fluidyne radiator is more efficient you can feed more GPM of coolant thru it and still get a lower outlet temp. So I'd do it.

The people who say this stuff don't often understand heat transfer. Don't think of the individual particles of water moving through the system rather think of it as 4 pieces. Lets look at it and consider no losses in the water pipes (not in the block or radiator) using a unit area.

block---X1----water-----X2-----radiator----X3-----air.

Now the ammount of energy transfered to the water from the block is dependent on a few factors
#1 convection coefficient from the block to the water
#2 conduction coefficient of the block
#3 energy input to the block
#4 temperature change from the block to the water
Increasing the water flow rate will increase the convection coefficient. We can't change the conduction of the block so it will be constant. Energy input to the block is also constant.

now the ammount of energy transfered from the water through the radiator and then to the air is also based on similar things
#1 convection coefficient from the water to the radiator
#2 conduction coefficient of the radiator
#3 thickness of radiator
#4 convection coefficient from the radiator to the air
#5 temp change of the entire system

We can combine this into a long equation using resistances to thermal transfer.
Rb-->conduction thermal resistance of the block
Rbw-->convection thermal resistance of the block-water interface
Rwr-->convection thermal resistance of the water-radiator interface
Rr-->conduction thermal resistance of the radiator
Rra-->convection thermal resistance of the radiator-air interface

the total thermal resistance of the system is
Rt-->Rb+Rbw+Rwr+Rr+Rra

the individual values are
Rb=Lb/Kb (length of the block / conduction coeff of the block)(these are constant for us)
Rbw=1/Hbw (1 / the convection coeff of the block-water interface)
Rwr=1/Hwr (1 / the convection coefficient of the water radiator interface)
Rr=L/k (radiator wall thickness / conduction coeff of the radiator)(these are constant for us)
Rra=1/Hra (1 / convection coefficient of the radiator-air interface)this is constant for us

Letting C = Rb+Rr+Rra because they are constant and will not change as we change the water velocity.

there for the total resistance Rt=

Rt=C+1/Hbw+1/Hwr

As we can see if we can increase the convection coefficient of either interface we will result in a lower interface. Now increasing the flow velocity of the water will generally increase the convection coefficient because we are dealing with rough surfaces that create turbulant flow and low velocities. Also making the flow more turbulant will increase the coefficient also.

I hope this helps yall understand why increasing the flow velocity (and therefore mass flow rate) decreases the engine temps.

 

[crankbender]

Forgot to add that
Q=the energy flow rate

Q=(Tblock-Tair)/Rt

Now your water temp gauge may read higher but since Q is constant and the temperature of the air is constant if Rt is decreased the block temperature has to decrease.

 

[Wobble]

blood is coming out of my ears....

 

[crankbender]

bwahahaha

 

[set3422]

Originally posted by Wobble
how would easier flow work the water pump HARDER?.. and its belt driven anyway.. im not worried about water pump issues. my friend just replaced his water pump on his 1g GS-T when he did his timing cover.. the pump still worked and all but he did it just in case... the car had over 200k on it.

First Law of Thermodynamics:
Total Work = Work_in - d(Work_out)/dt

Total Work is the flow passage of the block, head, and radiator that the water pump has to provide.

Work_in is the rotational energy provided by the crank to spin the wp impeller (Constant, but varies with crank speed).

Work_out is the coolant flow throughout the cross section area of the passage (Variable - step function with respect to the thermostat behavior).

Now your Work_out is constant by having no restriction to the thermostat. Opened thermostat creates more cross section area of the flow passage by flowing through the block, head, and radiator, therefore requires more pressure head to get the coolant across, larger Work_out. Closed thermostat only allows flow to go through the block and head, hence less work, smaller Work_out. If you re-arrange the first law, you will see your Work_in is always constant because of constant larger Work_out. Peace out.

 

[crankbender]

That really didn't make any sense.

the first law of thermodynamics has to do with energy and not just work.. Don't forget about the energy added and removed through thermal sources. Also you need to define your control volume.

Total Work is the flow passage of the block, head, and radiator that the water pump has to provide.

Please clarify "flow passage" and how the water pump provides "passage". Total work??? done by what on what and how?

Work_out is the coolant flow throughout the cross section area of the passage (Variable - step function with respect to the thermostat behavior).

Work has nothing to do with flow.... what are you saying?

Now your Work_out is constant by having no restriction to the thermostat.

QUE? What? huh?

flowing through the block, head, and radiator, therefore requires more pressure head to get the coolant across, larger Work_out.

Actually the flow rate increases because an increase in cross sectional area will decrease flow resistance and flow is inversly proportional to resistance....hence the term resistance...

Closed thermostat only allows flow to go through the block and head, hence less work, smaller Work_out.

Why do you equate work to flow length?

If you re-arrange the first law, you will see your Work_in is always constant because of constant larger Work_out. Peace out.

Work in is constant because of larger work out???? wtf does that mean.


Man i don't mean to be sarcastic but i don't know what the phook you are saying.

the work in is a function of fluid backpressure and pully velocity. Open up the thermostat and you get less backpressure (unless you were cavitating before which you won't be) and hence actually have a lower work in at the same velocity.

Basically the work done on the water by the pully has nothing to do with what i was talking about and doesn't effect it......

 

[Defiant]

An interesting shovel load.

Less time next to heat = less heat absorbed.

Less time in radiator = less heat radiated.

Less heat absorbed and radiated = more heat at source.

 

[Wobble]

Originally posted by Defiant
An interesting shovel load.

Less time next to heat = less heat absorbed.

Less time in radiator = less heat radiated.

Less heat absorbed and radiated = more heat at source.

Your bench mechanic reasoning makes sense on paper.. but it doesent hold true after testing.. which I have actually done...

according to your theory.. the smaller the stat the cooler the car would run right?? water would move slower right? more time to heat more time to cool right?? so i should use as small of stat as possable because my car wil run cooler right??

the situation you describe would be the case if maby you used NO thermostat..

but what you forget is that the stat opens and closes.. the water STILL stays in the block a long time but WHEN it gets hot it is evacuated quicker and replaced with cooler water quicker.. so you dont get as big of heat spike when getting on it.. if the water isnt absorbing enough heat (as you claim).. it wont be warm enough to trigger the stat to open.. and would stay put until it got hot enough to open..

 

[Enigma_Man]

Originally posted by Defiant
An interesting shovel load.

Less time next to heat = less heat absorbed.

Less time in radiator = less heat radiated.

Less heat absorbed and radiated = more heat at source.

So... according to this if I make the air flow slower through my intercooler, it'll absorb more heat?

If you throw a lot of water past the heat source very quickly, it will cool it very well.

-Jesse