Engine Undertray Purpose

[Charles89]

Hi guys,

I recently just bought an OEM plastic engine under tray for my GTT, but I was wondering the actual purpose of it.

I've been told that it helps cool the engine?...

Anyone knows what exactly it's for? Apart from keeping water from the road out of engine bay.

Cheers!

[89CAL]

Alot of times it creates more efficient air flow through the radiator by removing a high pressure area at the rear below the radiator.

That is air from below the radiator at the back has something spltopping it from going upwards. With the cover air goes straight under the car and through the radiator. I don't think it matters a great deal but should help with the under tray in

If its already off might be a good time to do a test. With and without the undertray

[ARTZ]

i thini its purpose is to be a PITA everytime you want to work under your car....just another thing in the way

[Charles89]

Well yeah that makes sense. The tray is off the car at the moment, since I haven't installed it yet. Have had the car for like 4 years and it never had the tray.

So maybe I'll put it on and see if it effects any of the temperature at all.

And yeah it would be pretty annoying to take off every time I change the oil lol.

Thanks mate

[GTR-N1]

I thought that aerodynamically, items like wings, diffusers, canards and undertrays are to help your car remain more fixed to the ground at high speed.

But the way an undertray works, is to help create negative pressure between your car and the road. That's what I've been told.

[hardsteppa]

on R33 the tray has cutouts for engine oil, radiator drain, imagine R34 would be same? So no need to be removing it for every little thing.

[89CAL]

I thought that aerodynamically, items like wings, diffusers, canards and undertrays are to help your car remain more fixed to the ground at high speed.

But the way an undertray works, is to help create negative pressure between your car and the road. That's what I've been told.

In a way yes, but its not its primary purpose on the GTT + GTST's. The GTR might be different but because I havent seen the undertrays on them.

anyway, they will probably provide a slight Aerodynamic benefit but as far as I'm aware (and I'm happy to be proven wrong) their main purpose is keeping rocks/objects/some water out of the engine bay as well as removing turbulant air from the engine bay. Thinking about it like this I'd say your probably right and it would provide an Aerodynamic benefit, but hard to say really how much. The main reason for keeping turbulant air out of there is for cooling efficency im pretty sure

[dkbcleaner]

Yes i think the tray does have a cut out to drain fluids. I dont think you will notice any difference areodynamic wise as the mechanical grip of the car far exceeds the aero grip of it

[skylinecouple]

I made one some time ago which covers from front leading edge of the bumper to the subframe and out the sides to suspension arms. Much less wind noise on the Highway. Cooling is better when working the car hard up mountains. Less drag based on even the most basic of aerodynamics. For me it was the improvement in noise.

[89CAL]

I made one some time ago which covers from front leading edge of the bumper to the subframe and out the sides to suspension arms. Much less wind noise on the Highway. Cooling is better when working the car hard up mountains. Less drag based on even the most basic of aerodynamics. For me it was the improvement in noise.

Photos?

I've always thought about doing something like this but never have the time to plan it etc

[Victory]

One of the main functions of the undertray is to create a low pressure area in the engine bay which helps to suck air through the radiator.

I remember talking to Sydneykid about this with his R32 GTS-T track car and it ran about 5 degrees cooler with it on in race conditions so he put it back on the car. The gain would not be as defined in a street car due to the slower speeds and reduced heat levels but anything to reduce heat in a RB engine bay has to be good.

[sonicz]

I wonder if it improves the drag coefficient of the car? Compared to my previous car, My R33 stops like a plastic bag when I pop the car in neutral at high speeds.

I might around look for one, as mine didnt come with it.

[Dobz]

Definitely helps with cooling. I made a small one for my r31 rb25/30, it's the width of my stock radiator and it extends from my radiator to the start of my sump. After some hard mountain driving I noticed my water temp definitely stayed lower than usual.

As has already been said before it also helps with down force, reducing drag and stopping wind noise.

Though they're just another thing to remove when doing major work it's well worth keeping it.

[Charles89]

It's good to know all these benefits but I tried to fit the tray on yesterday, it was hitting my front mount pipings...So it didn't fit...

Maybe I'll have to modify it to fit, because the benefits do sound good lol

[skylinecouple]

Why buy one when an aluminum supplier will give you a cutoff for nothing or close to it. Make a cardboard template, poke holes through where bolts go and it's done. If it's show your after then get a $10 buffing wheel and use your drill to polish. And if somebody thinks this is going to come lose and fly off taking someone's head with it that just won't happen. Bolts and lock-tight.

[sonicz]

Can anyone give me some info if having a 33 GTR front kit on a 33 gtst will affect the way you can fiit one?

[skylinecouple]

Comes down to the bumper. There are so many different types. Mine is standard so had to make a custom undertray otherwise I would have just bought a carbon one for a GTR. If you have the M-spec front bar then perhaps, being lower, it may fit. Just make one. One hour tops.