Radiator Cooling suggestions

BGTV8

If you are not running an aftermarket radiator, can I suggest that with a S/C kit, you might just be taking the demands on the cooling system outside the OEM design capability.

Running around town/down the highway could be fine because you only need cooling for <100hp - that's all the demand on the engine (and cooling system) needed for that sort of speed.

Running WOT for 10-15 seconds is a whole different ball-game., because you need to cool 500hp or more (I'm guessing you are at least 400+rwhp so that is close to 500 at the crank and that is what needs to be cooled).

The OEM radiator is a thin little sucker and an extra row will increase heat absorption by a minimum of 35%, but you will also need to look at air-flow thru the rad.

I have to cool 540hp in my race car (not a Z34, but comparable) with a radiator that is 19" across and 21" deep (because that is the only space I have to fit a radiator in). I had PWR design a radiator and specify a water pump specifically for the application - it is not a simple set of calculations to do, because you do not want to over-cool the engine and nor do you want it to overheat. PWR do sell a Z34 radiator, but it is specific to the Fairlady Z race car and can only be ordered thru Nissan Motorsport in the US. There are other uprated after-market rad's but I have no experience of them.

The 3 middle dots in the temperature gauge cover the best part of 40 degrees F - you really need to log exact temps and you can get that from the OBD II port and an app if your are not already doing this.

It is also worth monitoring your peak temps where the water exits the radiator as well as where is enters the radiator, to see how efficient the rad actually is.

If your track does not have a lot of part or off throttle time in a lap, that is certainly going to cause heat to build up when you are running boost.

You should not under estimate the impact of oil cooling on engine heat as well. The biggest oil cooler you can find is probably a good idea.

With the intercooler in front, it is also reasonable to fabricate some ducting to make sure that air heated by the inter-cooler is not going thru the radiator - especially as at WOT, the cooling demand from the inter-cooler circuit is also significant and that hot air can only go straight thru the radiator.