Archive for August, 2009

Components layout

To better understand how the Nissan GT500 will be built when it comes to its components, I did a couple of simple drawings to illustrate how the airflow (air intakes/outlets), oil system, fuel system, electrical system and exhaust will be built.

These are just simple drawings, not a final design. But an illustration of the major positioning and layout of some core components of the car. I’ll try my best to explain the different layouts in the text next to the pictures, if you don’t understand – don’t worry! It will be much more understandable when the build progresses. ;)

The main goal is to place all components as low as possible, all while trying to fit as much as possible between the front and the rear wheels of the car to get a low and car-centered CGH. This also gives me a more free design space for the chassis and suspension, without the engine or anything else getting in the way of the suspension design.

Exhaust layout

Exhaust layout

Due to the engine placement and planned aerodynamics, there isn’t much options for the exhaust system.

The turbo will be placed in front of the engine instead of beside it, to give some legroom for the driver as well as taking away some of the heat from the drivers feet. The exhaust manifold will probably not be the most well designed manifold, but there will always be compromises when everything about this car needs to fight over small areas of free space.

The exhaust system will then be routed past the engine on the passenger side and go all the way back between the seats before connection to the catalytic converter will be made. All the time keeping the exhaust as low as possible (as close to the belly pan/undercarriage as possible).

After the catalytic converter the exhaust will divide in to a “Y-pipe” and routed through two separated silencers behind each seat (still behind the rear firewall/bulk head).

Finally the exhaust will exit in “flat” outlets in each side skirt, just in front of the rear wheels.

Electrical layout

Electrical layout

The main goal of the electrical system is to keep it as compact as possible. Few components, short cable distances and keep everything easy accessible is the key values that I’ll try to achieve.

The battery will be placed behind the passenger seat (behind the firewall/bulk head). The engine ECU and the fuse box will be positioned between the seats against the rear firewall/bulk head.

A large single harness will go from the ECU/fuse box to the switch panel (which will hold all switches for fans, pumps, etc.) mounted between the seats. From the switch panel the harness will go on to the main engine plug/outlet and the dash.

When the main engine plug is disconnected all electrical cables going to and from the engine will be disconnected and the engine can then be unmounted from the car without the hassle of disconnecting each and every cable.

The dash will be able to display everything that I need to observe during driving. No other gauges will be used.

Some small harnesses will run to the front and rear of the car providing power to the lights and various sensors throughout the car.

Airflow layout

Airflow layout

This drawing is intended to illustrate the purpose of the air intakes and outlets, but it isn’t easy to describe with simple drawings exactly how the airflow is planned. This illustration does not cover the planned aerodynamics and ground effects, just the air going in and out of the car. The chassis will determine the final routing of the air intakes and outlets, but this illustration gives you an idea of how the final solution will be like.

The dark yellow/orange colored fields is for the brake cooling. the two huge holes in the front will lead cold air to the center of the front brake discs and the intakes in the rear wheel arches will do the same for the rear brake discs. The hot air will hopefully then evacuate through the rear of the arches, same principle for both the front and the rear of the car.

The green colored fields are the air intake for the water- & intercooler. The big intake in the middle of the front will lead air into a duct, through the coolers and then divide into two separate outlets, each leading the hot air out in the back of the front wheel arches.

And finally the probably most interesting airflow through the car, the light red field. The intake between each front headlight will lead air through a duct and via a large electric fan pushing air through the engine compartment, past the exhaust, gearbox and differential where another electrical fan will help lead the air out in the huge box placed on top of the rear diffuser. Hopefully that made some sense… ;)

The purpose of this airflow (the red field) is to try to keep the main heat away from the inside of the car and keeping the engine, gearbox, exhaust and differential at a decent temperature. Together with some basic insulation around the exhaust and engine compartment I hope that this solution will do the job of keeping thinks cool, but most likely this will be an area that needs modification after the car has been test-driven under hard conditions.

(And yes, the big box on top of the diffuser has nothing to do with the ground effects, it’s just the outlet for the main airflow through the car.)

Oil & fuel layout

Oil & fuel layout

The oil & fuel system will be quite basic.

An oil tank for the dry sump pump will be placed behind the drivers seat (behind the firewall/bulk head). One of the caps in the left rear window of the car will be the oil fill. Since the rear firewall will cover the tank entirely, accessing it won’t that easy. So an oil change will be done by detaching the  drive belt to the dry sump pump, detaching some oil hoses and using a screwdriver to turn the pump around. Thereby emptying the engine and thank from oil and refilling oil trough the cap in the rear window. There will also be a small catch tank mounted for the crankcase ventilation.

The fuel tank will be placed after the differential, still as low as possible without disturbing the rear diffuser. Which fuel pump(s) and if I should use separate catch tank or a built in one is still undecided.

The fuel- and oil-lines will go separate containers (basically metal tubes protecting the lines from the exhaust heat)  through the the engine compartment, keeping the lines as short as possible.

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And that is basically the main components of the Nissan GT500 (other than the chassis, body, wheels, brakes, etc.). No power steering, no ESP, but hopefully a car with good control, awesome grip and power ;)

(But wait a second… where is the air filter and the engine oil cooler? Well, their position and airflow will be determined after the chassis has been built.)

When more drawings of other layouts are added, you’ll be able to see them in their own gallery here.

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Sculpting the body – stage 1

Since the body is to be made in carbon fiber the first thing to tackle is to sculpt the new shapes. When the sculpting is done a mold of the entire body is to be made and finally a carbon fiber casting inside the mold, but first things first.

To make the sculpting easier I made a wooden floor that was leveled and bolted to the garage concrete floor. Before the body was stripped of all unnecessary metal and bolted to the wooden floor I welded in some basic support structure so that it wouldn’t collapse. The body was then cut down in height by cutting of the bottom, giving the body an approximately height of 990mm. The body was then placed in the correct height and position on the wooden floor and securely bolted in place.

(You’ll have to excuse the perspective in the pictures, but due to the claustrophobic area (22 square meters) that is my garage I simply can’t take photos in any good angle without tearing down a wall… ;) )

Body under sculpting

Here you see the wooden floor that is bolted to the garage floor. The body is stripped of unnecessary metal, cut to height and bolted to the wooden floor. You’ll also see the drivers seat temporary mounted, the wooden floor also acts as a measure-table to see that everything fits as planned.

Rear arches in the first stage of sculpting

Now the doors are cut to the right height and new side skirts are built out of plywood.A support structure for the rear wheel arches are built and spot welded to the body to ensure that the body is exactly 2000mm wide and that the arches are kept at the same distance from the body. I started out with some polyurethane foam to give the structure some rigidity. This will be done in sections and by constantly creating new support structure to ensure that the arches doesn’t move out of position.

If you look to the left of the picture you could also see the engine placement.

Rear arches in the first stage of sculpting

Now the foam has been sculpted in to a basic shape of the arch.

Next step is to relocate the support structure for the rear wheel arches and mount the side windows. Then the doors need to be aligned properly and I’ll continue working from the rear to the front sculpting the new shapes of the body.

See the rest of the pictures in the gallery.

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