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Old 08-30-2002, 01:00 AM   #1
Wheelman
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Default drilling holes in the thermostat??

i read something here about an article in tpis insider hints about drilling holes in your thermostat, could somebody explain the theory behind this and tell me where to drill the holes?

thanks
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Old 08-30-2002, 01:08 AM   #2
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Default Re: drilling holes in the thermostat?? (Wheelman)

The entire story from TPIS for the stat in an L98 is as follows.

First plug the water pump bypass in the right side of the pump boss with some RTV.

Then drill four .200" holes around the edge of the 160 deg stat, for summer use; and four .080" holes around the edge of the 185 deg stat, for winter use.
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Old 08-30-2002, 02:45 AM   #3
95Purple
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Default Re: drilling holes in the thermostat?? (Wheelman)

Why not just remove the stat? Once its open it never closes again anyway, at least my car never gets below 160 while driving. I never drive it in the winter so whats the point.
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Old 08-30-2002, 05:03 AM   #4
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Default Re: drilling holes in the thermostat?? (95Purple)

:nono: Never, never, never remove the thermostat. Even when fully open it restricts coolant flow out of the engine which gives the water pump something to push against and build pressure in the block. This pressure is necessary to prevent coolant from boiling around the combustion chambers and forming gas pockets.

Drilling the holes in the thermostat alway allows some coolant flow, and provides an escape path for any air bubbles in the block.
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Old 08-30-2002, 07:52 AM   #5
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Default Re: drilling holes in the thermostat?? (gcrouse)

Another reason...sometimes with high flow water pumps, the thermostat cannot open against the flow/pressure of the high flow pump.

My 82 Vette has a Weiend Team-G pump, and unless I remove pressure from the stat by opening the heater valve by sliding the temp lever on the dash to hot, the thermostat wii NOT open, and the temps just climb.

I need to pull the thermostat cover and drill the 3 or 4 small holes for the 82.

The 86 has the holes drilled...because it was done second.

Tom Melton
82 CE
86 Z51 Coupe
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Old 08-30-2002, 08:26 AM   #6
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Default Re: drilling holes in the thermostat?? (tommelton)

The water also needs time to slow down going through the radiator so the radiator can do its cooling job. Without some restriction by the thermostat that won't happen. Without the thermostat I'd guess the 'hole' where the water flowed is probably 4 times larger. BTW an old racing trick on oval track cars was to not use thermostats but a washer with a hole drilled in it (3/4", 1", whatever worked best). Of course that would really mess up totay's modern electronic controlled engines)
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Old 08-30-2002, 09:10 AM   #7
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Default Re: drilling holes in the thermostat?? (DaveD)

Moroso came out with those washers to hepl those of us that were putting them in our race motors........... they're in the catalog............ but on the street it would give a very slow warm up :seeya
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Old 08-30-2002, 09:46 AM   #8
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Default Re: drilling holes in the thermostat?? (Wheelman)

I had an interesting telecon with rep at Motorrad, who makes thermostats inluding the 160 sold by Hypertech. He said thermostats should be replaced like every 5years, 50,000 miles because "they get lazy" and stop opening fully which will cause a motor to start running warmer due to reduced water flow. The telecon prompted me to try the TPIS suggestion. I actually drilled 6 3/16" holes in the flange of my 160 stat before the trip to Carlisle. The car for the first time ran in the 160's & a few times dropped as low as 157 on the long downhill mountain runs. The drawback was definitely longer warmup time. It appears to me the thermostats in LT4 place a limit on maximum cooling. Depending on how you drive the car the TPIS suggestion seems like a good one to me. I would not do it if I drove the car in cold weather due to slower warm up times.
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Old 08-30-2002, 09:53 AM   #9
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Default Re: drilling holes in the thermostat?? (LT4BUD)

Sounds like we need two different stats.......a winter and a summer one.... :seeya
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Old 08-30-2002, 10:04 AM   #10
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Default Re: drilling holes in the thermostat?? (vettmech)

I played with my old 160 stat in a pan of hot water on the kitchen stove and a thermometer. It started to open at 160 ok but it was at least 180 or more before it opened fully. You could clearly see the restriction it was placing in coolant flow even when fully opened but especially below about 180. What we really need is a good 160 stat that goes fully open more rapidly. This would give us the best of both worlds, fast warmup & cooler operating temps. By the way my heater worked just fine with the 160 stat in cold weather.
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Old 08-30-2002, 10:13 AM   #11
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Default Re: drilling holes in the thermostat?? (LT4BUD)

My heater works well also in cold weather with the 160 stat.......... and I have been in some very cold climates with the car :seeya
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Old 08-30-2002, 10:27 AM   #12
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http://www.stewartcomponents.com/htm...t/techtip3.asp
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Old 08-30-2002, 12:27 PM   #13
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Default Re: drilling holes in the thermostat?? (tommelton)

Quote:
sometimes with high flow water pumps, the thermostat cannot open against the flow/pressure of the high flow pump.
Hey TomMelton- you need to switch to a "balanced" thermostat which has a reverse-opening poppet; it doesn't have to open against water pump pressure. They're made by RobertShaw and Autozone carries them. The above link to Stewart Components has a picture of it; as well as showing where to drill the holes. :cheers:
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Old 08-30-2002, 12:39 PM   #14
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Default Re: drilling holes in the thermostat?? (LT4BUD)

Quote:
I drilled 6 3/16" holes in the flange of my 160 stat before the trip to Carlisle. The car for the first time ran in the 160's & a few times dropped as low as 157 on the long downhill mountain runs.
That's too many holes; 2 or 3 is all you need. And I would never want my engine running below 170-180F as cylinder bore wear is greatly increased.


Quote:
I played with my old 160 stat in a pan of hot water on the kitchen stove and a thermometer. It started to open at 160 ok but it was at least 180 or more before it opened fully.
That's exactly how it's supposed to work; the temp rating of a themostat is when it starts to open. It's fully open 15-20F above that.

Some of you guys are really obsessing on these low temperatures; the optimum operating temp for lowest engine wear, combustion efficiency, and performance is right at 180-185F. If you care about polluting the air, the optimum temp is above 215F; which is why the cars originally had 195 stats and fans that go on at 225F.

I think you're confusing engine temp with intake air temp; if you really want to increase the charge density, put a cold air induction on, or one of those ice packs on the plenum.
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Old 08-30-2002, 06:27 PM   #15
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Default Re: drilling holes in the thermostat?? (gcrouse)

Quote:
Some of you guys are really obsessing on these low temperatures; the optimum operating temp for lowest engine wear, combustion efficiency, and performance is right at 180-185F. If you care about polluting the air, the optimum temp is above 215F; which is why the cars originally had 195 stats and fans that go on at 225F.

I think you're confusing engine temp with intake air temp; if you really want to increase the charge density, put a cold air induction on, or one of those ice packs on the plenum.
Click the image to open in full size.
For street use, you want the engine to warm up as rapidly as possible to operating temps. According to a seminar by Doug Rippie, you will generate more HP at 160 than 200, but only a couple. So, unless you are going for a national championship, why bother. He was very happy to race at 200-210 degrees.

Also, you want the oil in the 215-220 range to drive the condensation and volitiles out.
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Old 08-30-2002, 07:06 PM   #16
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Default Re: drilling holes in the thermostat?? (John Row)

:yesnod:
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Old 08-30-2002, 07:31 PM   #17
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Default Re: (PeteL)

PeteL this is a very informative link. Do they make a thermostat for LT4 application??? It doesn't appear that they do.
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Old 08-31-2002, 04:03 AM   #18
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Default Re: drilling holes in the thermostat?? (DaveD)

Quote:
The water also needs time to slow down going through the radiator so the radiator can do its cooling job. Without some restriction by the thermostat that won't happen.
This is a common misconception about cooling systems. Increasing the flow rate of coolant through the radiator increases the rate of cooling. That is what high flow water pumps do. A high flow waterpump will increase the rate of coolant flow through the radiator because the size of the passages in the radiator and engine do not change when you put a higher flowing waterpump. The higher flow rate also takes more heat out of the engine by passing more coolant past the cooling surfaces in the block and heads.

Thermostats only purpose is to keep the engine above a minimum temperature under all operating conditons.
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Old 08-31-2002, 04:03 AM
 
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