1st posting.....

[Lynchy]

And the winner is............Lynchy

I managed to be the first Queenslander posting!!

what's the prize?

Lynchy

[DON NOBLE]

And the winner is............Lynchy

I managed to be the first Queenslander posting!!

what's the prize?

Lynchy

um none ... 1st formal appearance was supposed to be Mr Bob Ellis in his lovely red dress

[BOB ELLIS]

Lynchy , check out the previous Qld page set up by Don, and you will see "I BEET YA, (Nah nah nah)" Cheers ,Bob #66 C/GCC.

[BOB ELLIS]

I put this on the Original Qld page , but Don got Greg Wapling to set up our own thingy, So ,again , I've entered the Nostalgia's on the 19th Aug (Willowbank) in the bucket.Also , on the 18th Aug, there is a super swap at Willowbank , and am looking to see if any members are interested in assisting to flog some DLRA stuff,we got heaps of 2007 shirts , posters etc.Will be sent up from HQ (Vic).We had a great response from the Bris hotrod show , so lets keep the momentum going! Cheers , Bob , #66 C/GCC.

[momec]

Sorry Bob
I'll be south of the border at Oran park the weekend of the 19th A.
But any saltlake fans at Qld Raceway this weekend drop by the WPS/WOW Racing pits and I'll show you around A.
Chris

[David Leikvold]

Bob, at this stage I think I'm available for 18 and/or 19 August, so put me down as a probable for at least one day.
And Chris, what are the chances of showing a group of us the WPS/WOW workshop sometime? I didn't go to QR today because I'm saving up for the bits I'll need for my car. Yes, I'm finally building a car. I found an '86 Celica and a '93 Camry V6 in a cheapies yard, total cost for the pair $2k. Have spent the last two weeks stripping the Celica and scraping sheets of tar sound deadener out of it. I'll be very glad when that's all gone! The Celica will get the 3VZ-FE V6 (obviously!) and a turbo and probably nitrous too, so it will run F/BGALT and F/BFALT. If I also fit a full belly pan I'm in F/BGCC and F/BFCC. Only 32 weeks to go. Gotta build a trailer too.

[Dr Goggles]

Hey Dave ,
I was thinking once about belly pans and wondered if anyone had ever tried putting their car on a hoist and using a dumpy or laser level to get reference points on the underside of the car. You could then build a flat frame on which you could set up the "negative" of those measurement and build a full size bellypan on that , anyone????

[Lynchy]

Dr G

We will be building a full 'pan for the Jag so will let you know what happens for us. We need to learn a bit more about bellypan theory though....

OK - it's important to have a smooth pan and it's important to have a sloping pan going from low at the front to higher at the rear. It's also important to reduce the amount of air entering through the front of the car. That air must also get out somewhere.......

So, do you louvre the pan / cut a hole up front to let the air out? This is what I've heard + the exit opening must be larger than the inlet opening... is this generally agreed???

Also - at the rear of the car we have a LARGE area formed by the rear clip that the diff sits inside of. Should this area be sealed up as good as we can or should it be ventilated to prevent a high pressure build up under the rear of the car??

Anyone got any ideas? I might also move this thread to the Tech area.

Lynchy

[David Leikvold]

Doc, I think your idea is great, shame I don't have a hoist. I don't even have a shed, both my cars are out in the weather. Lucky they're already junk. My wife is so, so impressed!
I'll work out some way of getting under it to accurately measure up for a frame for the pan. Maybe I'll build the trailer next, that would do it.
And the frame would be a perfect spot to put lead ballast.
I think a belly pan would be about right if it went from bumper to bumper, sill to sill and just left room for the tyres to poke through. With a very low splitter at the front to minimise the air getting in there in the first place and most importantly, had a slight ground effect curve built into it, that is, closer to the ground near the middle than at either end. You wouldn't need much of a bend in it, just enough to increase the air speed under the car and lower the air pressure a bit. Semi-rigid skirts attached to the sills would help tidy the airflow too. Too much ground effect would just suck salt off the surface, it wouldn't generate any downforce. You would also need very hard suspension to maintain a fairly constant ride height, but most fast cars would already have that. Fairings behind the rear wheels would also help tidy the airflow. Check out pictures of Ferrari road cars and any road cars that race at Le Mans. On the Shaguar they wouldn't need to be big because the car is already so low. Venting the pan should probably be under the engine where lift is most likely and most unwanted. And the rules want drain holes too, so that would solve both problems. Perhaps active venting with flexible tubes leading up to the front mudguards behind the wheels like an XU1 or the new Commodore.
That's enough, I have tar to melt. At least the heat gun keeps me warm at night!

[Dr Goggles]

I have tar to melt. At least the heat gun keeps me warm at night!

you can of course go the other way and sit dry ice , or even wet ice(?) on the deadener and then chip it off with a scraper or chisel.

The idea with the belly pan ( now I've got a little time) was that I'd figured it would make it lot easier to make the attachments points if you knew the "lie of the land" underneath the car . If you knew where you wanted to attach it you could attach vertical "posts" , mark them all with a laser level and then measure from that point up to where the pan would be attached. It's a similar way to how foundations for a house are set up , ( "A" Bob, )By establishing a "negative " I meant that if the pan were to be contoured ,with this method you could work out what limited the amount of contour and then subtract that from the measurements you have .Obviously measurements would need to be taken with the car on the ground as well in order to get the rake right .Seems complicated but if you did it right it would take a lot of the guess work out of it , and allow you to design the shape of the pan .

[Reverend Hedgash]

Rather than measuring all the differing heights for the belly pan supports and cutting them accordingly and trying to attach them accurately, I would just attach them all in the right place but too long.

Then using the laser leveler mark them and cut them back to the right height in place. Seems simpler and faster.



The following are some thoughts regarding belly pan aero that we have learnt in our studies for our tank, not experts but have been considering this stuff for a while.

In relation to belly pan angle our aero book says around six degrees is a general ideal to allow for the expanding boundary layer, etc under the car to best reduce drag.

The greatest 'downwards' force on the belly pan is at its thinnest (closest to ground) before it expands as this is where the air is accelerating the most to get to the bigger space at the back. (pressure is reduced as air is faster- Benouli effect) You really want this as close to the rear wheels as possible for it to be most useful.

So keep your pan low until you hit the rear clip then go up after it.
A sketch of the section would help understand a bit more of your predicament here...

Not sure what you mean about having louvers in the belly pan, it really should be sealed to the underside of the car.

(Note: care must be made when looking at cars such as a Ferrari F1 diffuser as it is NOT designed for the best effect possible, rather it has been limited by regulations in its shape as to when it starts and ends in relation to the rear axle and a lot of the turning vanes, shape etc is the response to make the most out of of a poor situation)

The skirts stop the air rolling around the side of the car and then being sucked under the car thereby reducing the potential downforce generated.
Some cars have a bulge sideways instead which stops the air from going under by causing it to vortice away.

The skirts on the early F1's could move up and down to allow more suspension travel (not really required on the salt) and were banned because of their tendency to sometimes get stuck in the up position causing some very high speed accidents at curves. This again not a problem for the salt as there are no curves.

Care must be taken to not upset the balance of the car still with the rear diffuser and a splitter may help here. The splitter works by not allowing the air hitting the front of the car and going downwards due to the shape of the front of the car (eg under the front bumper) to go under the car but rather around to the side. This not only reduces the air going under the car but also creates a downwards force at the front end helping to balance the rear similar to a front wing. (An air dam is different as it does not have this downward component.)

Yes these items all produce downforce which helps traction, but they also cause drag which lowers your top speed possible (especially if you use a a rear wing to help pull the air out of the diffuser). How much you go for one over the other is the real can of worms and we are going to make our decisions based on real world data with our car.

Essentially the thing to keep in mind is that you want to separate the air cleanly as you travel and then put it back together as cleanly as possible as you can as it leaves you.

The major advantage of the belly pan is of course removing all the turbulence and drag caused by the mess of stuff under the car first. Downforce is a secondary assist possible.

There are also some interesting ideas about dumping your exhaust into your diffuser too can assist in extra horsepower and improved airflow but I have waffled enough!

Actual height plays a huge factor too but there are posts at length elsewhere on this.

Reverend H+

ps we bought a polishing wheel this weekend... I think I am going to polish everything I find in the house...

[David Leikvold]

Doc, I thought about the dry ice idea but I'm doing this very much on the cheap. Even though I don't like buying cheap tools I figured $20 for a heat gun that might even last longer than this job was better than watching my money evaporate and choke me with the CO2.
And it's been so cold here at night lately that the tar sheets are already frozen at night and are rock hard. The heat gun works really well with an old paint scraper and I'm now wiping away the dregs with petrol on rags. The floor is virtually unmarked so I'm happy. And when I stop for a breather I can think about the roll cage.

[Dr Goggles]

Rather than measuring all the differing heights for the belly pan supports and cutting them accordingly and trying to attach them accurately, I would just attach them all in the right place but too long.
.

You missed the point there my liturgical friend.If you wanted to put a perfectly flat pan on that could well be the way , however the underside of a production car being what it is taking measurement would allow you to design something that could be a flusher fit and allow a lower ride height .

We'll argue about this on the weekend , five bucks?

[momec]

Dave, regards the shop tour l work at the engine shop and build the engines for both cars. This is a separate shop to the race cars. One or two person tours of the engine shop are always possible for DLRA members, just PM me if interested and we can work out a time. This needs to be in business hours.
The race car shop is on the Gold Coast and they don't incourage tourists so that parts unlikely.
Chris