rotarygod

Who are you directing that at? I do think outside the box. I preach it more than anyone else here.

yiksing

Not you rotarygod, thanks for pointing out the stuff that you did, I meant PUR_NRG. Sometimes its just not enough to consider individual item on a car no matter how much the theory behind it is valid or not. My point is simply upgrading items that help to lose heat faster meant more capacity to transfer heat away from the other parts of the engine. It might not have been mentioned in articles or theories but by common sense they do contribute. That's why you have controversial issue like decreasing port size for increase power in inline engines also, it definitely sounds like BS to me but after considering how it will affect the rest of the system, it works (at least in my opinion). Thinking outside the box helps.

PUR NRG

To me, "the box" is the ricer "bigger is always better" mentality, be that bigger turbos, injectors or even radiators. So now that you've rejoined this conversation let's consider the salient facts:

1. Rotary engines have an optimal temperature range. According to Racing Beat, on 13B engines that was around 210F in daily driving. Above 220F was a concern. I don't know how this applies to the Renesis engine but since it's proven there's an optimal temp range for a 13B, inductive logic will say there's an optimal temp for the Renesis as well.
2. We also know cars have temp control systems to reduce cooling capacity on startup in order to bring the engine up to operating temp more quickly. That temp control system is also used in cold weather to keep the engine warm.

Now we get to the interesting bit. You said, "Anything associated with heat if upgraded will always be good for a force induction". Why? If a turbo car is not overheating then what benefit is a larger radiator? In that scenario I can see a larger radiator as a drawback since you're carrying more radiator fluid means more weight without any additional benefit.

You also said, "Helping the car lose heat through radiator... lets the turbo... operate at lower temperature". Once again, why? If the engine is not overheating then adding a bigger radiator will not reduce engine temps. If it doesn't reduce engine temps then it doesn't reduce oil temps and therefore doesn't make the turbo run cooler.

You're challenging me to "think outside the box" using Mototune's "smaller intake ports are better" as an example. I find that ironic since I'm the one saying a smaller (stock) radiator is better than a larger one. I also find it ironic because like MotoMan, I've been trying to utilize critical thinking and inductive logic to support my contention that your claim sounds bogus.

So here's a direct challenge: can you find any flaws in the logical arguments I presented above? If you can not, how can you argue your two statements I quoted are true? Please note that by "argue" I mean provide rational and logical arguments that support your position, not simply repeating your original hypothesis over and over.
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Extreme Q

PUR NRG

No argument there. The point I was making (and yiksing repeatedly ignores) is if the turbod car is not overheating, how does a bigger radiator cool the turbo?

MadDog

This isn't exactly true, is it? The thermostat on the 8 begins to open between 176 and 183. Its fully open at 203. So there is a range of operating temps between 176 and 220 where the car isn't overheating, coolant is flowing to the radiator, and a radiator with more cooling capacity will reduce the normal operating temperature. The radiator doesn't come into play during overheating only.

I guess my point is that a bigger radiator will reduce engine temps, and therefore turbo temps. The coolant system and oil system, while not directly coupled for efficient heat transfer, are not totally insulated from eachother. It may not be a very efficient way to cool the turbo. But, since the car is a fininte power source, if the radiator dissipates more power, then there is less available energy to be stored in the form of heat in all parts of the engine. It would probably be much more efficient to put an oil cooler in the system if you want to reduce turbo temps.

PUR NRG

I'll assume for the moment that you have good references to support those numbers. They sound reasonable so I'll use them in this discussion.

Inductive logic bit #1: The Renesis has an ideal operating temp range. The stock radiator should be designed with some excess cooling capacity in order to stay within that range despite ambient temp and other factors.

Inductive logic bit #2: As long as the Renesis is within that operating temp range it doesn't matter where in the range it is.

Inductive logic bit #3: If we assume #1 is true, the Renesis temp range is around 180F - 190F. Any colder and the radiator shuts off to maintain heat. Any hotter and the radiator opens up more to keep temps down. Given my aftermarket radiator temp gauge stays around 190F in normal driving I'd say that's a pretty fair guess regarding top end of normal operating temp range. If anyone knows what the Renesis operating temp range is (and can cite credible sources) then I'd really like to know. Likewise with the thermostat numbers MadDog mentioned.

This part I'd disagree. Instead I'd say a radiator with more cooling capacity will reduce the current operating temperature to the lower end of the normal temp range.

As mentioned in the "intercooler upsets the car's handling" thread, while there may be a measureable difference the real question is whether there is a performance difference.

If you assume a 1F change in radiator temp results in a 1F change in oil temp, is engine oil that's 10F cooler a significant difference? My uninformed opinion is probably not. I say this because of two things:

• the flash point of engine oil is more than twice as high as the temps we're talking about so oil volatility isn't a concern
• the turbo itself is exposed to exhaust temps of at least 1300F so even a 10F delta seems trivial

So to bring this all back to where we started, we have the following two claims made by yiksing:

• Anything associated with heat if upgraded will always be good for a force induction
• Helping the car lose heat through radiator... lets the turbo... operate at lower temperature

Given everything we've both said, do you think either statement really has any merit?
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Problems with avandia

yiksing

Thank you MadDog, that's why I couldn't be bothered arguing. By the way "bigger is always" does applied to turbo-charged cars as long as you keep turbo lag in consideration. I kept repeating "higher capacity to dissipate heat" but somehow PURNRG simply can't get it and keep your insult to yourself.

PUR NRG

Here's one example where bigger is worse for turbo kits: vacuum hoses. Blow-off valves would be another example where past a certain point bigger valves buy you nothing.

I was driving the RX-8 last night and noted the following numbers: cruising on the freeway my oil temp was 133, water temp was 189. In stop and go traffic the numbers changed to 172 for oil and 197 for water. Once traffic cleared the water temps went back down in less than a minute but it took much, much longer for oil temps to fall.

Based on that evidence it seems the water temp (8F change) has very little if any practical effect upon oil temps (39F change). I stand by my claim that unless you're overheating, a larger water radiator isn't going to help cool the turbo.
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Public store

MadDog

Interesting post. It really emphasizes the amount of heat carried by the oil. Oil temps went up by 29%, water by 4%. I think that oil has roughly half the specific heat of water, though. Also emphasizes the total inefficiency of the stock oil coolers. My water temps are about 212 in traffic. Are you turbo'd?

PUR NRG

I have one but all this is at 3K RPM or lower. Actually I think it points out why the radiator has a fan to blow air through it at low/no speeds. The oil coolers work fine once they get air blowing through them but not at low speeds. The interesting thing (for this thread at least) is that even though water temps were fairly constant (8F change) the oil temp is highly dependant on air flowing past the oil coolers. It doesn't really matter what the water temp is when it comes to oil temp.
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UHWH