Holes in rear bumper

[Iain]

The mk2 rear bumper looks like it traps a fair bit of air behind it. Am I right in saying a few strategically placed holes will benefit it?

If so, any pics?

[Iain]

Just found one in a recent track car pics thread, hope you don't mind me nicking this for here Toymex!

http://i367.photobucket.com/albums/oo114/toymex/016.jpg

Any pics of something a little more subtle?

[scott.parker]

Try looking for Oli DHdev's old one, I'll be doing mine shortly, keep your eyes pealed and don't do it till you see what I'm planing, you may wish to do the same;)

[calibra-keith]

Try looking for Oli DHdev's old one, I'll be doing mine shortly, keep your eyes pealed and don't do it till you see what I'm planing, you may wish to do the same;)

planning on doing my rear bumper soon, so be interesting to see what your doing now.

[mowgli]

Has it still got a wheel well? You could fit a filler sheet from just behind the rear beam to the bumper, this will smooth the air out. I once read about fitting an upside down gurney flap in an arrow shape under the floor un front of the back wheels, with the centre near the gearstick. This apparently creates a negative pressure zone behind it, thus pulling the backdown.

If it hasn't got a wheel well, then a diffuser could be made, and it will look cool too

[Edd]

A nova ain't a F1 car tho lol surely its going to make no difference? ?

[Jack]

Every little helps lol

The easy answer would be to swap for a Mk1 skinny bumper though?

[scott.parker]

A nova ain't a F1 car tho lol surely its going to make no difference? ?


Well said, i know a lad called Colin who races a mk2 golf I'll try grab a pic, and he works for a touring car team, he knows his stuff, and said unless your building a real race car rear diffusers are useless if you don't know what your doing, and they wont work on the type of cars we build as the speed they come into affect is way to high to obtain etc, he told me a big splitter made from ply and a big rear wing as far back as possible is the easy and best option for my type of car, he's going to give me some help setting the geometry on it too.

Scott

EDIT: said golf, poor pics i know. His bonnet/boot/spoiler are made from carbon fiber, so strong yet very light.

http://img716.imageshack.us/img716/7912/photo0771s.jpg

http://a6.sphotos.ak.fbcdn.net/hphotos-ak-ash4/270623_10150718356240714_558620713_19954882_391439 5_n.jpg

pmsl a pic i stole of olis of FB.

http://a1.sphotos.ak.fbcdn.net/photos-ak-ash1/v300/29/45/558620713/n558620713_3841449_2775.jpg

[Iain]

Scott I'm busy prepping my new bumpers currently so tell me what you're doing so I can do it before I paint them lol I agree with what you're saying tho, attempting to design a rear diffuser with no knowledge of the subject sounds hit and miss, this just looks like a quick win to reduce some drag. Front splitter to reduce air going under the car should help too.

It's either holes like the above, or cut the part that folds under the car so it doesn't "scoop" the air up, this might not even spoil the looks of the rear end too

Mowgli I've had a look at doing that, for it to work it would have to come all the way to in front of the fuel tank or it'd be at an angle and the air would hit it and try and push the rear up? Yeah still got a wheel well.

[scott.parker]

PM'd

[mowgli]

With the wheel well in place, i don't think there will be much air getting jammed up in there... Fitting smaller mirrors would be more of a benefit

[Iain]

It looks a bit scoopy still behind the wheel well

Got some small mirrors actually, but they look horrific for vision!

[Edd]

Surely for the holes to make a difference you'll have to cut away the lower bit of the rear panel as that will be in the way?

[scott.parker]

Surely for the holes to make a difference you'll have to cut away the lower bit of the rear panel as that will be in the way?

With the wheel well in there still Edd the air at the speeds were assuming make this difference wont go back into the small gap and be "jammed" against the rear panel, the only time you would cut that out is if the wheels wells gone, but then you need to know what your doing and add a full flat floor/rear diffuser etc and have a very well set up car to utilise it all, tbf were talking about fricking NOVA'S! lol

IF you were making a race car, with flat floor and diffuser you would not use a car with a horrid heavy rear beam thats going to create lots of drag, as in theory you need to be using a independent suspension system so you could have flat floor/diffusers clean through and out the back etc

[Edd]

That's my point really, by cutting holes in the bumper all your going to be doing is making it look crap as the holes wont do anything

[scott.parker]

Cut outs and such will aid to less air being caught in the bumper and creating less un stableness, Have you ever seen a mk2 mondeo on the motorway, crazy how there rear bumpers flap about like mad! anything flapping like that is not good for small stability really, but again, were just guessing, and tying to do things to "help" aid the car on track, it's never going to make them into a R8 killing machine.

Scott

[Edd]

Mondeo bumpers are dangerous lol

I can see the thinking behind the holes for sure, just not convinced on the gains that's all

[scott.parker]

I understand mate, but it's a cost effective mod that cant hurt to try really.

[MK999]

IF you were making a race car, with flat floor and diffuser you would not use a car with a horrid heavy rear beam thats going to create lots of drag, as in theory you need to be using a independent suspension system so you could have flat floor/diffusers clean through and out the back etc

Nova's aren't independent rear suspension? No one told me that... lol