how many holes to drill in thermostat to increase cooling efficiency?

[Billzilla]

1x 8mm hole helps things a bit, just drill the little poppet valve out. will make it run a bit to cold i winter .

It can also help with the thermostat hammering, which they do occasionally - Makes the plastic tanks split.

[legend]

i use a 1/8 th drill bit

[crowncustom]

Why not try a colder thermostat?
Cheers Brett.

[brett_celicacoupe]

It can also help with the thermostat hammering, which they do occasionally - Makes the plastic tanks split.

plastic tanks? if your referring to the radiator then this radiator doesnt have plastic tanks.

stock Z12 rad is all metal construction

[Draven]

sounds like needy better radiator to me

[oldcorollas]

or just less obstructed/heated airflow....

[IN 05 NT]

have you got a thermo fan mounted of the a/c condenser? the a/c condenser can be clogged up with bugs/dirt/dust from years of driving, usually the a/c condenser will probably never come out of the car....(so will never bo overhauled/cleaned)

ive had this problem a few times now, behind the a/c condenser fan (where you cant see) has been 90% blocked (almost cant see through it.)

No such thing as flowing too fast, both with air or water. the more flow the better it cools.
but you need to keep some sort of pressure buildup on the block and rad tubes for better heat transfer and to stop air bubles from forming thus causing hot spots.


cheers
linden

water flow too fast is a problem, on alot of old big blocks they use such a large water pump that they can pump the water/coolant too fast, and thus not having a chance to cool,

cooling system pressure is controlled by the rad cap, thermostat has nothing to do with pressure, only regulating flow.

my work mate is a radiator/reco/builder veteran.

[The Real Roadrunner]

water flow too fast is a problem, on alot of old big blocks they use such a large water pump that they can pump the water/coolant too fast, and thus not having a chance to cool,

if thats the case then slow the air down that is going thru the rad and intercooler. then tell me how much cooler it runs both with water temp and air temp. simple fact is that it WILL run hotter. the water flow thru the block is exactly the same.

the thermostat is there for a few reasons,
Regulating flow
Quicker warmup
To ensure proper waterflow thru the block,

and if you actually measure the pressure between the thermostat and water pump on a JZ engine it will be lower than the rest of the system.
If you want to test that theory then let a JZ get up to temp,
release pressure from the system by purging the rad cap
remove the cap and give the engine a rev,
the resulting fountain of water comes from the waterpump trying to push all the water thru the block + rad and having the thermostat cause a restriction, any restriction will have higher pressure on one side than the other

Brett, there are probly a few reasons as to why yours runs hot but without running several tests its hard to know where to start.

Cheers
Linden

[brett_celicacoupe]

ive spoken to a couple people who have done heat and mass transfer subjects and they say that increasing fluid velocity will always increase the amount of heat transfer.


however i have put 2x 5mm holes in the thermostat and if anything its reading a fraction higher.... 1 bar on the gauge maybe.

now whether this equates to less cooling is questionable. the water may now be going faster but having a smaller temperature drop (Td) from the water inlet/outlet.

if the Td before was 10° but flowed say 10L/min and it now has a Td of 8° but a flow of 16L/min, then there will probably still be a net increase in energy dissipated through the radiator.

without accurate measurements its hard to quantify this theory

[SillyCarS]

Why don't you remove thermostat completely and see if it helps?

Easier than drilling holes

Cheers
Wilbo

+1

i ran my 18rg like this over the summer

worked a treat

then again the way i used to flog the shit out of that thing it was probly what was required

[allencr]

how many holes to drill in thermostat to increase cooling efficiency?

Zero, unless the thremo. is stuck closed or won't fully open!
Like all of the above, except for that silly old water/air 'flows too fast' BS, you've got to decrease the deficiencies first. Unclogging the radiator outside and/or inside, better before & after ducting or bigger radiator will cure it.

[thechuckster]

i'd also re-point the finger at the radiator - you have a shitload of hot air (from the other coolers) hitting a 2-core radiator.

Replace it with a 3 core asap.

[The Real Roadrunner]

3 core wont make it work any better and may actually make it worse.

the thicker the core the less airflow thru it and relying on thermos to do the job is something i wouldn't do.

Brett, can you get a viscous fan in there somehow?

[brett_celicacoupe]

Brett, can you get a viscous fan in there somehow?

no chance


as i mentioned earlier though, i was running the hydraulic fan on there for a while which was probably on par with an engine fan. i was running the hydro fan it full speed. the 'cooling' was pretty much similar to that with the twin AU thermos


maybe i could just move to a colder climate hehe

[SillyCarS]

linden. are you serious? im not calling BS or anything. i just find it interesting that in practice all my knowledge of a heat echanger is being thrown out the window here. surely just because there is extra thickness (ie another core) does not change the flow that much

just the fact that there is more metal, say surface area, improves cooling capacity

EDIT brett if its really this bad i would consider a water sprayer if you cant fit an engine fan in, i know you love your jaycar stuff so it would suit just fine