Rear difusser undertray

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sonic

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Building: Dax Rush Fiireblade

posted on 21/1/09 at 10:27 PM

Rear difusser undertray

Has anybody made one or has one fitted

It fits under the back of the car and has fins to direct airflow.
I have seen one fitted to an MK but i cannot remember where

bigrich

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Building: a new life on my own

posted on 21/1/09 at 10:31 PM

I think Hellfire has a diffuser on their MK

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MkII

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posted on 21/1/09 at 10:33 PM

ive got plans to make one for my striker but its a way down the upgrades list at the moment.m.

Dangle_kt

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posted on 21/1/09 at 10:39 PM

dont you have to have a completely flat floor (inc engine bay) for it to do much? most (but not all) cars on here will have the engine below the chassis rails I'd guess.

omega0684

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posted on 21/1/09 at 10:40 PM

i have one fitted to the back of my rush

[Edited on 21/1/09 by omega0684]

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posted on 21/1/09 at 10:47 PM

Hellfire have one fitted I believe

PAUL FISHER

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Building: 2 MK Indys 929 blade and a zx10r now a Westy V8

posted on 21/1/09 at 11:22 PM

Steve Keenan had one fitted to his Indy at Oulton park last weekend.

[Edited on 19/05/04 by PAUL FISHER]

Rescued attachment steve oulton.jpg

Steve Hignett

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Building: Z650 Cafe Racer, ZX9R Front, Triumph Daytona Rear

posted on 21/1/09 at 11:33 PM

I fitted one to my old worX

Here's a pic of Danny's at Oulton last week!

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Building: Z650 Cafe Racer, ZX9R Front, Triumph Daytona Rear

posted on 21/1/09 at 11:35 PM

And here's a pic of mine...

I thought I had a better pic than this, but maybe not!

rick q

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Building: Fraser Clubman

posted on 21/1/09 at 11:42 PM

I've made one up out of aluminium sheet - not difficult but can be fiddly. See :- http://www.locostbuilders.co.uk/viewthread.php?tid=82829 />
It's now so efficient on the highway that I have to turn the engine off - otherwise it just gets away from me!! In truth, running it with a front undertray as well certainly smooths the airflow under the car - but any differences in "feel" seem to be very subtle

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Building: Rebuilding FR 2.0 which I crashed

posted on 22/1/09 at 01:07 AM

Who cares if it does anything, it looks very cool. That's enough for most of us.

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posted on 22/1/09 at 07:31 AM

quote:
Originally posted by rick q
I've made one up out of aluminium sheet - not difficult but can be fiddly. See :- http://www.locostbuilders.co.uk/viewthread.php?tid=82829 />
It's now so efficient on the highway that I have to turn the engine off - otherwise it just gets away from me!! In truth, running it with a front undertray as well certainly smooths the airflow under the car - but any differences in "feel" seem to be very subtle

Corrected linky

procomp

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posted on 22/1/09 at 08:26 AM

Hi

It has to be said though that a majority of the ones fitted and sold do nothing at all and actualy slow the car down.

It would seem that the Kitcar scene is slowly becoming like the boy racers scene where it doesnt matter as long as it's got enough BS to go with it.

Cheers Matt

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Building: Built-Indy Blade & Fisher Fury R1.

posted on 22/1/09 at 08:36 AM

what about on a fisher fury, do these things work ?.

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http://www.locostbuilders.co.uk/forum/23/viewthread.php?tid=172301

Back on with the Fisher Fury R1

marco

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posted on 22/1/09 at 08:52 AM

Made a couple of these....

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Building: MNR VortX RTR Hayabusa

posted on 22/1/09 at 09:34 AM

Marc at MNR is making one specifically for the VortX. Ordered mine when I placed my order. According to Marc's last post on it it should be ready around now (but may be delayed while they put up their new workshop building).

[Edited on 22/1/09 by sucksqueezebangblow]

andrew-theasby

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posted on 22/1/09 at 11:35 AM

im on with making one at the mo but havent got any pics just yet. remember not to leave any sharp edges if you havent passed SVA yet.

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Building: Rebuilding FR 2.0 which I crashed

posted on 22/1/09 at 03:55 PM

Please explain how on earth blocking a great big space, under the car slows it down? Obviously, that space is creating drag by reducing the flow of air. All we want is an increase in smooth airflow.

I have a background in aviation and know full well the implications of lift (or downforce) vs. drag, angles of attack etc. so that argument is not valid here. We know that there is no downforce without corresponding drag. We are not talking about large wings.

But to be accused of being a boy racer? Sure, whatever. Better than being an old racer.

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Building: Driving Supercharged Zetec Indy

posted on 22/1/09 at 04:06 PM

This might be more effective....

Rob Palin

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posted on 22/1/09 at 06:06 PM

quote:
Originally posted by RK
Please explain how on earth blocking a great big space, under the car slows it down? Obviously, that space is creating drag by reducing the flow of air. All we want is an increase in smooth airflow.

Not wanting to tread on Matt's toes, I think he means more that many of the diffuser panels fitted to 7-style vehicles are not fitted with a flush leading edge and kind of 'dangle down' into the airflow, rather than providing a truly continuous lower vehicle surface. It then acts as an impediment to smooth airflow, rather than an assitance to it.

It's also fair to say though that if the trajectory of the air coming past the diff / axle / rear suspension travels naturally below the rear bodywork edge then it doesn't make a whole lot of difference whether you panel that area or not (c.f. 'open' vs 'closed' cavity flow regimes).

procomp

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posted on 23/1/09 at 09:10 AM

Hi

As Rob has said the way in which most are attached and the angles that most get mounted at and the fact that most have not panneled the other areas on the floor of the car. Means they do nothing for actual performance. I shall not try to tread on Robs Toes in the Aero department and actual wind tunnel testing. But in actual driving 7 type cars round circuits at speeds up to around 135 mph. What you start to find out is that when adding such things as diffusers rear wings front splitters is that in a majority of cases they do little to increase actual performance / handling but do take a significant amount of speed off the car. For instance on this pic below the rear spoiler dropped the speed by a whole 6 mph whith no noticeable gain in handling etc.

Description [/img]

And although the front spoiler did add a little grip at the front on the fast corners it also took a significant chunk of speed off the car hence the prototype snout to try and do somthing to regain some of the speed.

Description [/img]

All in all if diffusers etc are done with some research and thought they can be of benefit. But the majority of them fitted are doing nothing for actual performance gains and in some cases will actualy be a deficit to performance. But on a road car at road speeds they are fitted purely for there looks.

Cheers Matt

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