Does anyone use a big NASCAR style radiator in there FD. I can get a 4 to 6 inch thick radiator that come out of stock cars really cheap. They go for around 700 new and nothing is wrong with them. I know during the summer alot of people have trouble with running hot so I would think somebody has tried this. I have looked and it seems like it would be easy to make them fit. What do you guys think?

 

My personal feeling is that it might be too thick. The radiator needs air flow to cool the coolant/water running through it. On a core that thick, air flow might be a bit more difficult to accomplish - especially at low speeds.

Most people these days have cooling under control. A regular Fluidyne or Koyo works great provided its ducted/sealed and the rest of the cooling system is in good shape and there isn't any air in the system.

Do some further research in the cooling system threads in the FAQ thread. Lots of good info in there.

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/
https://www.rx7club.com/3rd-generation-specific-1993-2002-16/cooling-system-flush-info-441967/

 

I'd have to second the thought of it being too thick for the application.

I had a custom 4" thick unit built for my Suburban and I was surprised at how much the airflow thru it was reduced compared to the 2.5" stock unit.

 

Did your coolant temps go up or down?

 

If you drive your FD at a sustained 100mph, you might generate enough flow to make that radiator perform the way it's designed. I would like to, but I'm sure my FD spends less than .1% of it's time going that fast. Will it cool the engine, probably yes. But all that extra bulk probably won't help you at all.

I would stick with an FD-sized radiator. They mount nicely, provide appropriate cooling for street to track applications, and even have resale value.

Dave