So yesterday I introduced a hardcore picture of a track R32 GT-R that uses a rear mounted radiator. Today I’ll talk more on it and also show you what I feel is the cleanest example of that modification, as done on the Top Secret Final Evolution Supra AKA the Nardo Supra.

Today’s/Tomorrow’s post since its using all of my original pictures will offer hi-res photos of everything. I kept it a minimum of 1400 res, but some of the really great shots I’ve gone as big as 2400 res for you to enjoy.

So first things first. I am many things, but an engineer I am not. I simply do not have the training or experience to be one. I’ll explain in some moderate depth why this modification exists, but I without a doubt wont be able to explain it as well as a proper engineer would. There was a suggestion in the comments earlier that I interview a great engineer and get their involvement in the blog. That did give me an idea. One of the top engineers I know is Eric Hsu. Eric started XS Engineering and then went on to be one of the top dogs at Cosworth USA. Eric’s blog is linked to mine in the blogroll (http://jdm-insider.com/Blogs/Eric/), and its my idea that we do a joint blog post on this topic…me from the design and overview perspective, and he from what he’s great at, explaining the engineering and details that go way over my head. The only problem is, I haven’t asked Eric if he’d be willing to do this…and since I’m short on time, I’m just going to make my post and then humbly ask him if he’s interested in doing a post on his blog about this topic as well, from his perspective. We’ll see if my joint blogging plan works for this topic. FYI - He and I are doing a bit of a collaboration on a Z33 350Z for SEMA. Actually he’s doing pretty much everything, I just supplied the Top Secret widebody for the build. After he see’s the two GT-Rs I’m designing for SEMA though I aim to make him regret not letting me design his Z. I want to design more cars!!! Soon people will learn to trust my taste, I hope at least.

Here is my limited perspective on this very interesting and advanced modification of moving the radiator to the trunk/rear of the car:

For track cars, especially turbocharged cars, overheating and cooling are obvious challenges to overcome if you want to enjoy reliable performance. Traditionally a turbocharged car has two cooling systems competing for the same real estate on the vehicle (the radiator and the intercooler). Often times you’ll see a front mount intercooler on a car and visually you might almost forget that a radiator is still stuck behind there because it cant be seen. If you cant see it, how can the air see it? Putting one in front of another blocks air flow and reduces the effectiveness of the radiator which relies on good steady air flow for optimum performance.

A main difference between the radiator and the intercooler when solving this problem is the concept of lag. The longer the piping is to the intercooler (the further away its positioned from the engine), the more boost lag there is. Not a huge problem for a drag car since technique can work around it, but for any other reasonable use there are a ton of downsides to boost lag. The radiator does not however suffer from this problem of lag if piping length is changed.

One of my favorite modifications for practical reasons is the anti-front mount mod, aka the V-Mount mod. The V-Mount Mod puts the intercooler and the radiator in a V formation, with the intercooler placed usually very close or in the engine bay, while the radiator is often angled  diagonally in the front bumper for maximum air flow (often with sheet metal guiding air to it). This setup is one of the best designs because it solves two problems at the same time very well. It solves the fighting over location and air flow, and it also solves turbo lag by placing the intercooler extremely close to the engine to shorten up plumbing. Despite the majority of the people who give major respect to cars with large intercoolers, I give more respect to those with V-Mounts and who are not showing off a huge intercooler occupying the front bumper.

The rear mounted radiator mod takes this concept to the next level. Of course it removes the radiator from the picture and allows flexibility in intercooler mounting and sizes. What it also does is allow entirely new options for air flow to the radiator because once you place it in the rear you can come up with all sorts of innovative ways to get air flow to it. Lastly, moving it to the rear balances out weight distribution on the car a little more since most front engine cars are front heavy and moving any components to the rear helps to regain balance in weight.

The first time I saw a rear mounted radiator it was relatively simple, it was the late 1990s and it was in an SW20 MR2 which was already a mid engined car. The cool thing about it was that the owner stripped the trunk out and made a complex sheet metal ducting system that flowed air to the radiator and helped aid in the air’s escape as well. Putting a mid engine car’s radiator in the trunk is not nearly as hard as putting a front engine car’s radiator in the trunk however. Nonetheless, it was my introduction to something I always found supremely cool and exciting.

Some cars that have done this mod very well are: Koyama-san’s Yukes/Team Orange D1 cars (Impreza and Evo), ATTKD’s GT-R, Garage Saurus’s GT-Rs, Top Secret’s Nardo Supra pictured here, and probably a lot more I’m forgetting.

It is easier to do the mod in a hard core way where implementation and finish is less important than function. Like the car I showed you yesterday as an intro, it was all function and looks didn’t matter. In that case, it made it that much more hardcore and non-compromising.

However true artistry means that no detail is overlooked and function and design work harmoniously. This Top Secret Supra is the example I want to show you of that.

This is a long post. I’ll post pictures tomorrow. Please keep all comments on this thread so we can all discuss it together in one place.

Click the thumb for hi-res.