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Discussion Starter #1 (Edited)
At 10 and 15 pounds of boost, the water temperature stays at a constant 170 degrees (I have the 170 degree thermostat). But once you bump the boost up to 20 pounds and run hard through 3-4 gears, the water temperature will raise up to around 205 to 210 degrees...and then it will work its way back down shortly after you let off. Everything seems to be working fine, but I am wondering if this is a typical situation for high horsepower MR2's.? FYI: The car is making 326 rwhp at 15 pounds of boost and 377 rwhp at 20 pounds of boost. I just replaced the radiator, flushed the system completely, added the 170 degree thermostat, and filled 1/2 & 1/2 Toyota Anti-Freeze with water.

My set-up is as follows:

Brand new motor (complete rebuild) 4,000 miles on it

HKS 264/272 Cam Combo

HKS Cam Gears

TTE Headgasket

65lb Valve Springs

JE forged Pistons 8.5:1 swain coated

ARP Head Studs

Greddy TD-06, 20G Turbo :smile:

Greddy Intercooler w/ 7.5" Spal Fan

3" Downpipe

Accel DFI, Gen. VII EMS

Supra Fuel Pump

TFFR 83lb Injectors

Aeromotive FPR w/ fuel gauge

MSD Ignition

Tial 40mm External Wastegate

Richardson's Intake Manifold

TRD Spark Plug Wires

Aquamist Water Injection

Garage Fukui Departure 52mm Exhaust

Turbo XS Blow-off Valve

Manjit Intercooler Shroud

Alamo Twin-entry Fuel Rail

Greddy Profec-B Spec II EBC

Clutch Masters FX400 Clutch

Filled Motor Mounts
 

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not sure about your specific problem, my car is stock and i bled the air out (guess i need to bleed it more) and the temp guage goes very high sometimes. What seems to help it go to normal is turning the AC on to high and super cold and that sometimes brings the water temp down.
 

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mr2mch said:
But once you bump the boost up to 20 pounds and run hard through 3-4 gears, the water temperature will raise up to around 205 to 210 degrees...and then it will work its way back down shortly after you let off.
Does it really surprise you that when you push the engine to make more power, it also makes more heat?

What you are seeing is perfectly normal.

bill
 

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Discussion Starter #4 (Edited)
billwot said:
Does it really surprise you that when you push the engine to make more power, it also makes more heat?

What you are seeing is perfectly normal.

bill
Doesn't surprise me at all that it heats up, I'm just wondering what other MR2 owners who are making some big power numbers are experiencing. My water temperature is climbing 40-50 degrees after a hard run at high boost. Just wondering if this is typical. I would love to reduce how high the temperature climbs if there is an easy way to do so. It could just be fear talking, after all, I don't want to f*** up this new engine!!!

So Bill, you are saying this is very normal, thanks. Anyone else? I would love to hear from those who are making big numbers!

Scott Richardson has done all the work to the car at this point, and is the soul reason it hauls ass! He has built a great motor, and has tuned the car conservatively. Scott has the opinion that this 40-50 degree increase in temperature is a bit much. He experiences temp increases after a hard run in the 10-20 degree range, and he is making huge numbers. He is also basing his opinion on other customers cars who are making big numbers and don't have the temp increases I have.
 

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What Bill says is true.

Make sure you don't have rust in your cooling system. You need to change your fluid frequently enough to keep it rust-free. I change mine every 2 years. When pushing more power, you need to maintain your car better than you otherwise would.

Make sure your cooling system is properly bled of air.

Lastly, make sure your head gasket is okay. A leakdown test can help with this.
 

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Do you have an EGT probe? If so what kind of numbers are you getting? You must be running an EMS with those kinds of numbers. How is your knock?
 

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How high does it raise? Do you overheat? Put a catch can under your overflow. I was having the same issue. I was blowing out coolant when I hit boost. Put the catch can (a soda can or something) with the overflow tube running into it, and hit some boost for awhile, then pour it out, see if you're blowing out coolant. It could be signs of an improperly torqued or blown headgasket.
 

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Wait, hold on... you are exactly what I had. 4000 miles, ARP, TTE. Go retorque your headstuds and watch the miracle of good torque =D.
 

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What torque level are you using on your ARP's? You can AIM or MSN or Yahoo me if you feel the need fora little information. You might have a hard time getting to one of the stud's since you're using aftermaket cams.
 

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PsychoSquirrel said:
not sure about your specific problem, my car is stock and i bled the air out (guess i need to bleed it more) and the temp guage goes very high sometimes. What seems to help it go to normal is turning the AC on to high and super cold and that sometimes brings the water temp down.
Turning the AC on does not cool down the temp. By turning the AC on, you are producing more coldness (correct), but how>? You are working the cooling system to also produce that coldness which then shoots up your temp(UP UP UP). If you drive on the highway, and turn on the AC, you can feel the loss in power. IF you turn on the heater, you can feel a difference in power increment.
It is vise-versa.
 

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Turning on the A/C INCREASES the heat load.

1) It increases engine drag, and

2) it pumps hot refrigerant into the cindensor, which is in front of the radiator.

bill
 

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My friend has a built motor like yours, he had a similar problem...turned out to be the head gasket, which was a high end one...would not hold the boost and caused air pockets which lead to extreme overheating after hard running. They replaced it with a different brand and cured the problem
 
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