Thread: The FWD Mishimoto Radiator

^Do you have specs of the NISMO vs the OEM?

That's intentionally done on all cars. The point of bottle-necking the cooling system is to create higher than normal atmospheric pressure in the cooling system. Higher pressure helps raise the normal boiling point of the coolant so that it can carry more heat away from the block. Notice that the bottle-necking only occurs before the coolant re-enters the block and obviously after it has circulated through the radiator. The rest of the way, it's free-flow till the coolant ends back at where the thermostat is. The radiator cap also helps with creating higher pressure (and more so) as the spring in the radiator will not let any of the coolant move to the overflow reservoir until the cooling system reaches a certain pressure.

Now if you add the higher pressure system to a larger capacity radiator, you are enabling the coolant to spend more time in the radiator to help shed away even more of the heat it carries from the block compared to a stock cooling system.

So remember this, even if the coolant's normal boiling point may be 215* (given it's not pure water), under the pressure created in the cooling system the boiling point now would be around 220-225*, depending on how high the pressure is.

Conclusion: you want a little bit of bottle-necking and a higher-pressure capacity radiator cap so you can actually help the block get cooled better.



Extra note for newbies:

For optimal performance, the block has to stay at a certain temperature, which is why the need for the thermostat. That's why the needle on the temperature gauge shows the coolant being colder than normal when you have no thermostat in place. The various ratings of the thermostats help ensure that you reach the maximun highest temperature goal that you have in mind. And when that doesn't help, then come fans to help reach whatever highest temperature it is you want it to be at.

In essence, you want a temperature theshold where the block doesn't start melting or where the fuel is burning completely due to the cooling system not helping in maintaining that optimum temperature at all time.

I have a Nismo thermostat and rad cap, and I have an OEM two row radiator that is 1.25" thick. On daily use, I don´t have any problems, but does not work for road racing. I went to the racing track last weekend and I couldn´t do more than 7 laps, the temp went up to 240 degrees and I had to go to pits to cool down. I am running a GTi-R swap @ 15psi of boost.

JGY probably sells knock off Koyos at that price lol.

Also I don't believe you can change teh flow on teh thermostat, all you can change is the temperature it opens so I am confused at what you are saying Nate.

Here's a koyo for a great price because its in the old box!
Koyo R1440 53mm Aluminum Racing Radiator 91-99 Sentra/NX OLD BOX

Unfortunately, not for both. I might go ahead and get both though. The OEM for my NX that is running and the NISMO for my NX build.



What I am trying to say is that maybe we are over driving our thermostats (if we are just using stockers). The bore from what I can figure out of the OEM is about 1.09 inches. The max valve lift for the OEM (as stated in the FSM for a 94' Sentra) is 0.31 inch at 194 deg F (FSM also has thermostat opening at 170 deg F). So the valve area is 0.95 square inches. Unfortunately due to the valve being partially in the way of the water flow I would say we are only able to use approximately 95% of the total area putting us down to 0.9 square inches. With a higher flow, if there is one out there (NISMO? I cannot find specs), would have a larger valve bore and/or more valve lift. I would venture to believe there are different valve bore size thermostats out there because the Duralast (I know....crappy) I just put in my 200sx has a smaller valve diameter than my OEM one that I pulled out. Now if what Harris is saying is correct about the block retarding the flow more then a thermostat then what I am trying to get at may be more or less inconsequential.

I am sorry if I am being nit picky but I don't like just slapping things on my car because everyone says that is what I should do, especially when there might, just might, be an alternate better or more cost effective way of doing it. Everyone wants HP and TQ numbers for cams, headers, and other bolt ons why not be asking temperature questions about radiators and thermostats?

No, I didn't say that the block retards the flow, so I'm going to rephrase it. The thermostat housing, the thermostat, and the radiator cap contribute to the increased pressure, which then leads to a higher boiling point for the coolant.

a rad is the last thing id not want to upgrade if i was turbo.

a upgraded rad in my opinion is a must.

i have a nx and i need the fat ass koyo thats under the hood, along with my vented hood. nx's tend to run hot if they are turbo.

stratton.

I disagree thats all. No big deal. I would upgrade my brakes, which I did, before I upgraded my rad to a nx one, which is doing more then enough of a good job. My temps don't go above 200 with me beating the $hit out of it.

Now on the nx I do see more of a reason to upgrade since it has the cooling issue in the first place , but on a se-r a nx rad is perfectly fine.

Not sure what the difference is compared to the 1440 but I run Koyo R1977 53mm Aluminum Racing Radiator 91-94 Sentra SE-R