Stock or aftermarket radiator?

[Tom239]

I disagree, to some extent. The NSX thermostat begins to opens at 76 to 80 C and is fully open at 90 C. There is hysteresis involved in the state change of the wax in the thermostat, but I won't go into that here. Once the thermostat opens and cooler coolant comes in from the radiator, temperatures drop somewhat, fluctuating up and down. When the outside air is very cold, there's more fluctuation than when its very hot. At some air temp, the thermostat will be fully open, the radiator working at its full heat exchange capacity, such as in Death Valley, and the temperature will begin to raise to unacceptable levels.

But to my original point, my 1984 Corvette has a digital temperature gauge, and you can see it hit the opening temp and see the temperature cycle about 5 C under cruising conditions. On my other cars, you can see the needle "wiggle" on the gauge under those conditions.

Sounds like the stock temperature gauge on the NSX gauge is damped, like how gas gauges are damped to not respond to sloshing in the tank. But damping is just low-pass filtering and doesn't have to mean the gauge is insensitive to persistent changes. A decent gas gauge is fairly sensitive and does respond to small changes in level, even if the markings are imprecise (1/4, 1/2, and 3/4 are probably not accurate figures).

When the stock temperature gauge stays at 3/8 no matter whether it's winter or summer, and no matter whether my oil temperature is 190F or 220F (consistently for more than ten minutes), I suspect that reflects the thermostat working well more than any insensitivity of the gauge. (I mean, I'm primarily interested in whether the mean temperature is maintained, not whether there's a bit of hysteresis in the thermostat.) I'd be happy to admit I'm wrong if someone has an aftermarket coolant temp gauge that shows otherwise. But just because the stock gauge is damped doesn't mean it's insensitive.

 

[liftnot]

Those who have PWR are really lucky as they were the be$$t but its no longer made:frown:
Koyo is enough for NA guys and it fits well.
If you are or plan to go FI, you should look into MASIV and get in contact with RYU as it has better heat conductivity than alum. If I were FI, I would save up and go this route otherwise you will have a cool down lap after going flat out for 4-5 laps. MASIV is heavy but you'll have a peace of mind.

 

[stuntman]

I think PWR still makes them if you contact them directly. Thats what I'll probably go with when my motor is built.

While copper does have better thermal heat transfer, the brazing processes and flux as well as the limitations in fin and tube size and shapes make them perform not as well as a good aluminum radiator. Plus they are heavier.

 

[Honcho]

Those who have PWR are really lucky as they were the be$$t but its no longer made:frown:
Koyo is enough for NA guys and it fits well.
If you are or plan to go FI, you should look into MASIV and get in contact with RYU as it has better heat conductivity than alum. If I were FI, I would save up and go this route otherwise you will have a cool down lap after going flat out for 4-5 laps. MASIV is heavy but you'll have a peace of mind.

I think PWR still makes them if you contact them directly. Thats what I'll probably go with when my motor is built.

While copper does have better thermal heat transfer, the brazing processes and flux as well as the limitations in fin and tube size and shapes make them perform not as well as a good aluminum radiator. Plus they are heavier.

The way I see it you have:

Stock --> Mishi/Koyo --> PWR/Ron Davis --> KSP

If you are a baller and want the best cooling available for the NSX, you get the KSP, which is 2 grand. The PWR and Davis are dual pass, Mishi, Koyo and stock are single pass. KSP is triple pass and designed specifically for the NSX in circuit racing in hot, humid Japanese weather.

http://kspweb.jp/shopdetail/010001000001/046/Y/page1/recommend/

 

[Albert86]

Well - as usual - got way more replies than I expected.
Thanks again for the time others took took to reply.
I think for now it will most likely be the Koyo.
My winter project list is pushing $4k for my mild mannered car,
I can spend this without too many questions from my better half.
Best keep it this way.
Al

 

[stuntman]

More passes is not better. Fin density, pitch, height, tube thickness, width, design (dimples), etc... All affect the heat transfer abilities of a radiator.

PWR offers tubes that are as wide as a common 3-row radiator, they also have tubes with internal fins and tumblers (and dimples) all to increase thermal heat transfer and surface area.

Realistically without proper testing, you can't really say or quantify one setup being better than another.

FYI you can have pwr build any heat exchanger to your specs, but they would probably recommend a setup other than a triple pass. There's a reason the top F1 and NASCAR teams use them.

But none of this means there aren't affordable systems that are fat better than stock or deliver a great value.