Motorsport has always been the forefront of development in the car world. Striving for the ultimate in performance to gain an edge over rivals no matter how small; is what helps make winners out of contenders. Team Japspeed never sit still in the quest for Maxxis British Drift Championship glory. The winter saw a step up on the development programme with some Rallycross-inspired modification to both the 1JZ powered Subaru Impreza and the VH45DE TT equipped Nissan S15.
The theory behind this radical cooling system overhaul was for three reasons; to gain a better weight distribution, this will aid balance and on-the-limit handling. In an ideal world, a car should have 50/50 weight distribution to give the perfect mix of nimble road holding and stability. Besides handling, the relocation was intended to reduce the power-sapping heat soak from the engine bay. Parking on a start line with a hot engine running often saw temperatures rise. A final bonus reason besides these performance gains is that it frees up space under the bonnet to work. Making quick repairs easier for the mechanics to complete when under pressure at rounds of the Maxxis British Drift Championship. Everything for this radical swap-around was done in-house by Team Japspeed’s development crew. The Subaru and S15 both share similarities and the same principles, but with some subtle differences between the two. Here’s a quick walk through on how we did it.
The first step is a scary one. After some marking out, the floor pan was chopped to accommodate the huge cooling system. No going back now!
Things progressed with lots of measuring, offering the radiator into place and making a dummy radiator box out of cardboard, this is the easiest medium to use to make templates from. Both the S15 and Subaru run huge modified Supra Mk4 alloy radiators that are from the Japspeed product catalogue.
With the positioning of the radiator sorted out, it was time to fabricate the box out of alloy.
The air has to come in from somewhere and in this application, the rear doors were chopped about to start working out the route for all that lovely cool air.
After the route was decided and the initial vents cut in, the door panel was sealed on so that none of that lovely cool air was going to waste and pointlessly wafting around the car interior.
To channel all of this air into the car, it needed some custom scoops. It was a time consuming process, but worthwhile for the end result.
The scoops were then painstakingly crafted into the doors, things are really starting to take shape now!
The radiator box was extended internally and hooked up with cold air feeds to maximise the air into the box.
The Supra radiator is huge; nothing like a bit of over kill in motorsport, so the system was further beefed up with a large alloy reservoir/header tank. The Subaru and S15 now run between 15-18 litres in the system! Helping things circulate is a powerful electric water pump.
To ensure the best possible cooling; a pair of 14″ Kenlowe dual speed fans are fitted to draw cool air in and expel it out of the rear. The fans are controlled by the ECU for pinpoint accuracy.
To further increase the cooling potential, a Subaru bonnet vent was crafted into the roof to ram even more cold air into the radiator box.
Underneath the roof scoop the air is channelled down two additional feeds.
Which in turn are connected to the air box that is located where the rear bench once was.
The final modification was to cut imposing vents into the rear boot lid. This lets any excess hot air escape to make things as efficient as possible.
With all the design aspects finalised, the side scoops were given a finishing touch and covered in the recognisable Team Japspeed livery.
Did it work? Yes! A measurable success! Previously the car would often hit 110-112c on track, now with the radiator relocation it struggles to hit 90c. A solid 20c drop in temperature! Plus less heat soak in the engine bay and more space to work. Not forgetting the weight distribution to aid handling. Literally there’s no cooler modification than a radiator in the boot!
Check out the V8 S15 photos below: