Rule clarification req'd

[fordy]

It says in the westfield SS regs, that those in class A (and B,C and D) need to use List 1A tyres, that have been in the blue book for the last 4 years.  

My question - Does this mean the tyre i choose has to have been on the list for all the last 4 years - or only 1 of the last 4 years - for example, could i use the a tyre that has only been on the list for the last year?

Oh, and - does anyone know if a rear diffusser is allowed in class A - says in book that silouette cannot change, does this consitute a silloette change?

many thanks

Chris

[Mark Stanton]

could i use the a tyre that has only been on the list for the last year?

yes    thats easy

does anyone know if a rear diffusser is allowed in class A - says in book that silouette cannot change, does this consitute a silloette change?

Yes you can in the SS      Its below wheel centre-lines    But it must be 100mm above ground level surface - which basically nullifies any aero dynamic effect    

Many cars use diffusers in the SS - they have very little effect, if any, at many sprints and hill venues      Your money can be better spent elsewhere in setting up your car and other mods    

[Rob Navin]

Many cars use diffusers in the SS - they have very little effect, if any

They do keep your rear suspension nece and clean though    

[Mark Stanton]

and they cook your diff if used on track days for long sessions or very long drives            but they sure do wind up your fellow competitor        

Now who's gonna bend their front number plate or fit an air-dam              

Keep it at +100mm though - they do get checked        

[Rob Navin]

Now who's gonna fit an air dam              

Could some one pass me my coat    

[Mark Stanton]

They look the mutts nuts Mr N            Anything that looks that good must work       *if only you were able to fit them less than 100mm from the ground*        

Where's my tape measure          

[fordy]

Thanks guys.

RE-the diffuser - Im not really expecting any reduced lift effect from it, more just the fact that the air wont get sucked up into the back of the bodywork - which must act like a bit of an air dam at speeds.

There is a formula that calulates the BHP required to push a flat plate of xx size at zz speed - it works out that a front number plate requires 5.5BHP at 110mph - so removing it will effectivly give you that bhp to go quicker, only a few mph, but it all makes a difference.

[Rob Navin]

Fordy.

That is the other reason that I run a full floor and diffuser to be honnest.

Now that I have gone areo and half tonnau as well the differences in the way my car performs are very noticable.

Paul did have some diffusers, or could get them done, but I have also seen them made up from ali which perform the function.  All advantages are good ones.  

Seriously though Mark is right....... the do look the muts nuts.  

[fordy]

cheers Rob.  Do you find any heat problems running a full floor?

Bit concerned about the mention of the diff getting hot on long journeys, i use my car on the road, although the longest ill drive in one go is probably 100 miles - is that long enough to cause heat problems with a full floor?

Was planning on making something out of ally - although i agree the carbon ones do look fab - might have the raid the westfield, erm i mean 'savings' account!!!

cheers

Chris

[Rob Navin]

Chris.

The full floor can be a right pain in the   to be honest.  However this is only due to how I did it.

I used one piece of ally front to rear where as what I sould have done was made the engine bay and the prop tunnel removable.  I would do this if I was going to do another.  This becomes a big issue when the sump bolts vibrate loose, it would be a simple job with a removable floor but allas its not.

Underbonnet heat is not an issue even with my engine, but I have either had exhauts wrap or now camcoat on the exhaust to help.  I also take the lip out of the nose cone hole to get as much cool air through the rad as I can.

Diffs do tend to struggle with the rear diffusers on when being pushed very hard on track days.  Mine only takes two seconds to take off though so if you were doing long hard runs you can remove it without a poroblem.

HTH

Rob

[Blatman]

My diffuser equipped car regularly does long trips in hot weather. The fuel runs out before the diff.........

[fordy]

Cheers Rob - that does help - good point about not making it all one sheet - ill bear that in mind - thanks.

Blatman - Is your prop tunnel covered - i.e is your diff getting cool air from the hole at the back of the prop tunnel - hence why it doesnt cause a problem ?

cheers

Chris

[Blatman]

Nope. I have a completely enclosed floor, except for where the sump sticks out, and there are no holes in the bonnet either.......

I imagine that just about enough air gets past the rad/engine, and into the tunnel to keep some air flowing, and that air would almost certainly be cooler than the diff..... Any air that does get down the tunnel may well be trapped above the diffuser though, so I'll bet ther are some interesting things happening, air flow/pressure wise around the edges of the diffuser, and the rear wheel arch area.......

On the plus side, as Rob has mentioned, my rear suspension and diff looks like new, despite them being around 5 years old.....

[DickieB]

Blatman

You should cut some large holes in the rear of your car to let all that air out.

Dickie

[scruffythefirst]

except for where the sump sticks out

What sump have you got on your cossie car mr B?

Scruffy