Pros/Cons of high pressure radiatior cap

[swaq]

Is there any advantage/disadvantage to getting a higher pressure radiator cap? I was under the impression that a high pressure radiator cap would improve cooling performance, but after doing some searches it sounded like it might be harder on the engine. What would be the reason for this?

I have a Koyo aluminum race radiator (R0171) and I bought a GReddy Type N radiator cap which didn't fit. I was thinking of trying the Type S, but now I'm not sure if I should get one at all.

 

[Jaguar_5]

I remember this was discussed before, and I remember someone really smart like Jetjock or Jdub saying this was a bad idea! IIRC it will only increase wear on the pump and chances that you will get a leak somewhere...

Wait for someone who knows actually knows what they're talking about, I just have these vague memories of a conversation :biglaugh:

 

[Wiisass]

A higher pressure cap can increase the cooling ability of the system. Water at a higher pressure will boil later and can take more heat. But Jaguar 5 said, it can bring out the weaknesses of the cooling system. But I don't think the Greddy high pressure caps are much higher pressure than the stock cap. So if you put the higher pressure cap on and there are leaks, then that just means you should've fixed them before. There are some companies that much much higher pressure cooling systems. I think C&R has a high pressure system that is something like 40-50psi or something high like that. I know it's C&R but I don't remember many of the details and don't feel like looking it up.

Tim

 

[Doward]

Don't exceed 16psi, in my opinion.

Increasing pressure in the system IS one way of increasing the amount of cooling capacity of the system (water's boiling point is increased ~3 degrees per 1 psi of pressure, IIRC).

In my opinion, though, I prefer to stick with a lower (13 psi) pressure system, and if my setup requires extra cooling, I prefer to get a radiator with higher heat rejection capacity. The reason for this, is that higher pressure puts more stress on the hoses (more likely to burst), the head gasket, the water pump, and EVERY other part of the system.

Not to mention, if you ever spring a leak in a high pressure system, you will have a much more violent de-pressurization of the system, resulting in a much higher chance of the water in the cooling jackets to instantly become steam, and higher chance of warping the aluminum head, or iron block due to extreme hot spots in the system!

 

[Supracentral]

A properly maintained cooling system is all you need, period.

I've never found ANYTHING inadequate about the stock cooling system in and of itself. The only think I dislike about the stock cooling on the MKIII is the plastic radiator endcaps. I've had two of them split on me, one of those I know was a direct result of a BHG on a 7M (over pressurizing the rad system).

If you use the stock mechanical fan, the factory cooling system in these cars is good for 99.9999% of the cars out there. I can see a few cases (over 1,000 RWHP, heavy road course or endurance, etc..) where you might need an upgrade. On a bang for the buck scale, cooling system is low. A good aftermarket oil cooler with a thermostat will do more good for your motor than a $500 radiator or an overpressure cap.

Just my $.02, ymmv.

 

[mkIIIman089]

A good aftermarket oil cooler with a thermostat will do more good for your motor than a $500 radiator or an overpressure cap.

Agreed, an upgrade oil cooling system will go much farther in improving cooling then a radiator/cap will.

Since swaq apparently already has the radiator though... wise ass ()covered it pretty well.

 

[jetjock]

Bravo. All excellent comments from people who clearly know what they're talking about. SM at it's finest

 

[dbsupra90]

in my opinion, i believe an aftermarket water temp gauge is a must if you really want to know what is going on with your coolant system.

using the stock gauge is like looking at the sun to figure out what time it is.

 

[mk3ukr]

Theoretically (as hp radiator cap makers claim) higher cooling system pressure helps to reduce steam bubbles formation in hot spots of cylinder head. These steam bubbles/pockets prevent proper contact between head surface and coolant.
There are more efficient ways to keep cylinder head cool. In addition to what mentioned above by Doward and Supracentral use Water wetter and lower antifreeze content in your coolant. Lowest possible is 25% AFAIR, not sure about that.

 

[Doward]

Just to mention - the antifreeze has a corrosion inhibitor that is also there to prevent redox reactions between the dissimilar metals.

I *highly* recommend running the appropriate formulation antifreeze/water.

 

[mkIIIman089]

using the stock gauge is like looking at the sun to figure out what time it is.

I don't know... there are people who can do that pretty accurately. LOL

 

[swaq]

Bravo. All excellent comments from people who clearly know what they're talking about. SM at it's finest

Yep Thanks for all the comments guys, this was exactly the kind of info I was looking for. I like hearing the "why" behind the "what", instead of just being told to do it one way without hearing the reasons.

in my opinion, i believe an aftermarket water temp gauge is a must if you really want to know what is going on with your coolant system.

using the stock gauge is like looking at the sun to figure out what time it is.

I have a GReddy water temp gauge.

A properly maintained cooling system is all you need, period.

I've never found ANYTHING inadequate about the stock cooling system in and of itself. The only think I dislike about the stock cooling on the MKIII is the plastic radiator endcaps. I've had two of them split on me, one of those I know was a direct result of a BHG on a 7M (over pressurizing the rad system).

If you use the stock mechanical fan, the factory cooling system in these cars is good for 99.9999% of the cars out there. I can see a few cases (over 1,000 RWHP, heavy road course or endurance, etc..) where you might need an upgrade. On a bang for the buck scale, cooling system is low. A good aftermarket oil cooler with a thermostat will do more good for your motor than a $500 radiator or an overpressure cap.

Just my $.02, ymmv.

My car has electric fans (installed by previous owner), which was the reason why I decided to upgrade the radiator. I figured it'd probably help to offset the lower air flow of electric fans. I've found that in most cases it only takes one fan running on the low speed setting to bring the temps down.

I would like to install an aftermarket oil cooler eventually.


Thanks again everyone. You saved me about $25. :biglaugh:

 

[Poodles]

I got the slightly higher pressure Greddy cap because I bought the koyo at the same time and wanted a cap that fit...

my cooling system is nearly 100% new though...

 

[suprageezer]

One bad thing about increasing the pressure of your cap is this. Radiators are made of metal, one that expands at 13psi will last longer than one that's ballooning from higher psi's. All metals radiators have so many expansion and contraction cycles before they fatigue then leak.

 

[swaq]

I got the slightly higher pressure Greddy cap because I bought the koyo at the same time and wanted a cap that fit...

my cooling system is nearly 100% new though...

Just out of curiosity, did you get the Type S cap?