IJ. said:
Exactly, so if drilled, cooler coolant could rise from the block into the head above cylinder 6, instead of using the coolant thats already hot from above cylinder 5.
extra head cooling #6 cyl!!!!!
- Thread starter quake
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Exactly, so if drilled, cooler coolant could rise from the block into the head above cylinder 6, instead of using the coolant thats already hot from above cylinder 5.
And where is this "cooler coolant" coming from exactly? (keeping in mind it's already flowed past 5 cylinders on it's way to the back of the motor)
Cya said:
So this whole apparent issue exists because of the heater router (which is for heating the car?) as in Australia I doubt there'd ever be a day when you would require a heater if that's the case.
vas85 said:
no its not the heater core. im not sure exactly why the #6 gets so hot, but i do know that adding another path from the hot spot (#6) to the radiator (the cool spot) will help with cooling. Seeing as how all you have to do is turn two valves for more cooling, and drilling seems to cool the block but hurt when you need the heater I see this as a more feesable option.
IJ. said:
Up from the block. threw the new found passages.
Quick drawing because i cant describe it good enough. i figure the coolant in the block is cooler then the coolant in the head because its further away from combustion and its iron so it doesn't conduct heat as fast either. If thats true then it would allow that cooler coolant in the block to rise into the head from the bottom of cylinder six to the top of cylinder six as it does for all the other cylinders.
Unless thats not how it would work or it already has been heated in the block to the point where it doesnt matter much.....
Cya said:
Colder thermostats delay getting the coolant up to the 176 deg F temp the stock ECU uses to switch from warm-up enrichment to normal run mode. A 160 deg thermo could easily delay getting the coolant up to ops temp a long time, especially if it's cold outside, by opening the path to the radiator well before the coolant gets warmed up. In warm climates, a 180 deg thermo is ok and will help get "ahead" of the heat in a place like Phoenix. For most climates though, the stock 190 deg thermo is what you want to run.
so essential what should be done from what im gathering is get a hotter thermostat (200 in winter 180 in summer) and add more coolant after drilling the block so that you heater will remain of use. Does this make sence?
nosechunks said:Up from the block. threw the new found passages.
Quick drawing because i cant describe it good enough. i figure the coolant in the block is cooler then the coolant in the head because its further away from combustion and its iron so it doesn't conduct heat as fast either. If thats true then it would allow that cooler coolant in the block to rise into the head from the bottom of cylinder six to the top of cylinder six as it does for all the other cylinders.
Unless thats not how it would work or it already has been heated in the block to the point where it doesnt matter much.....
There's only a single hole being drilled for #6 right at the back the 2 ports on either side of #6 are already open.
Sorry I just can't see how drilling that hole will be of any benefit at all.
If someone can provide solid proof/evidence ie: 6 x egt probes or even a run on a dyno shooting the head with a laser temp gun I'll do it until then it's just another Supra Myth.. :nono: (nice drawing even if it's inaccurate)
Um yup, i just looked back at the post made by zooloo and now i see that i was thinking of it wrong. Its the smaller hole in the back not the holes on the side.
For some reason i was thinking about the holes on the sides of each cylinder being the ones that were drilled out.
for some reason this:
Looked like it was this:
I had a spell of confusion and made several posts in this thread completely about the wrong thing. Whoops. :3d_frown:
For some reason i was thinking about the holes on the sides of each cylinder being the ones that were drilled out.
for some reason this:
Looked like it was this:
I had a spell of confusion and made several posts in this thread completely about the wrong thing. Whoops. :3d_frown:
Cya said:
Nope...doesn't work that way. Unless you live in a hot climate, use the stock 190 deg thermostat...it was designed for *most* driving conditions. The problem with using a 200 deg stat it the ECU will pull timing over 210 deg F. So what you have here is a coolant temp range the ECU "wants" to see is between 176 to 210 deg F. Using a higher temp stat over stock is worse than using a 160 deg.
IMO, the only time to use a 180 deg stat is when you live in a hot climate and all it will do is open the path to the rad a bit earlier. It will "catch" the coolant during a fairly rapid rise in temp due to running the car at a high OAT.
IMO, drilling those holes is of little or no use. The coolant flow through the block/head and the way heat transfer works to a fluid does not support this contention. I'm with IJ...me thinks it's another "supra myth".
Glad I'm not mistaken on this 
(when you actually sit down and think it though it just doesn't do anything, I can't even see how it could affect the Heater circuit)
(when you actually sit down and think it though it just doesn't do anything, I can't even see how it could affect the Heater circuit)
Might work well if you could cap off the waterpump outlet and divert it to in between #3 and #4 low on the block (Right where the Turbo sits of course)
Doing this would more or less equalise the temps but you'd need a central outlet on the head as well for it to work.
Doing this would more or less equalise the temps but you'd need a central outlet on the head as well for it to work.
And the pressure on that line would have to be greater than the pressure inside the block, otherwise insignificant flow. Capping off the stock water pump outlet and diverting all flow to the middle of the block would do this...you couldn't divert coolant and feed, say the drain hole at the back
Drilling the holes is not going to hurt anything from what I can tell...I damn sure wouldn't go to any extra effort to drill them though
Drilling the holes is not going to hurt anything from what I can tell...I damn sure wouldn't go to any extra effort to drill them though
Actually drilling the rear passage was discussed on supras.com back in '99-'00 and was originated by Lance Wolken back in the mid 90's on his blue '87T. My personal results are, nothing. Heat still works like it did before. If anything it does seem easier to bleed. With the stock t-stat (always), operating temp averages that of the t-stat temp as measured with an aftermarket gauge.
Also a few of us back then worked on running a line from a T in the heater hose up to the front side of the t-stat (drilled out one of the blanks). I never did this mod myself but those that did reported as expected - took longer to warm up. Most had to undo the mod in winter. Unfortunately nobody who did this mod back then had an accurate temp gauge.
Also a few of us back then worked on running a line from a T in the heater hose up to the front side of the t-stat (drilled out one of the blanks). I never did this mod myself but those that did reported as expected - took longer to warm up. Most had to undo the mod in winter. Unfortunately nobody who did this mod back then had an accurate temp gauge.
jdub said:Just don't see how it can help IJ...there is no flow of "cooler coolant"
I identified my confusion, i was mistakin'....
IJ. said:John: Nah I mean cap off the stock in/out and replace them with centre block/head in/outs
Exactly...we're saying the same thing. I can't see a way to add flow to the back of the block (at least not easily).