Little Red Devil

[VWindahouse]

Sounds really deep and throaty, can't wait to hear it at Happy Laps

Sounds tough as bro!

Too quiet?

Gavin

Haha I blame my prehistoric recording gear. It's a tad bit louder than the clip

Irrespective of if Anth goes with a diffuser at some point, the point I was making previously was that at the expense of less drag, the addition of high velocity, positive pressure into the negative pressure wake of the car would more than likely make the rear of the car unstable and render the wing useless. What I was suggesting was that he explore the addition of a flat floor on the car, with or without a basic diffuser to eliminate the drag issues cause by the rear bumper. I've seen many a Soarer or supra lose their expensive, votex rear bumpers on drag strips due to the drag from the bumper and I've also seen how just covering that area in can solve the issue cheaply, effectively an without the cutting of holes.

Undercar aero tuning does not increase drag and is why so many exotics now no longer sport the garish wings present during the 90's. you can have highly efficient negative lift without the traditional sacrifice of drag caused by wings and spoilers.

Anth I'll try to draw my thoughts up at some stage for you.

Thanks mate, that would be great! Found a thread that goes over under panels for the Golf. It's a bit long and most of it rubbish but I think it's what you may be suggesting

aerodynamics - better feel, increased efficiency - VW GTI Forum / VW Rabbit Forum / VW R32 Forum / VW Golf Forum - Golfmkv.com

[kaanage]

Irrespective of if Anth goes with a diffuser at some point, the point I was making previously was that at the expense of less drag, the addition of high velocity, positive pressure into the negative pressure wake of the car would more than likely make the rear of the car unstable and render the wing useless. What I was suggesting was that he explore the addition of a flat floor on the car, with or without a basic diffuser to eliminate the drag issues cause by the rear bumper. I've seen many a Soarer or supra lose their expensive, votex rear bumpers on drag strips due to the drag from the bumper and I've also seen how just covering that area in can solve the issue cheaply, effectively an without the cutting of holes.

I still find this highly improbable (although everyone seems to have ignored my posts) due to the large separation between the wing and the bumper on the Polo. Look at the picture of the Civic with the massive diffuser and rear wing again - if a hatchback was liable to loose rear wing effectiveness due to repressurising of the wake, as you assert, then that car would show the effects. Anthony's car would be even less prone to be affected since his wing is mounted higher and more forward than the one on the Civic.

Soarers and Supras are completely different since the low angle of the rear window means that airflow can stay largely attached down to the boot lid which is not far above the bumper.

Horses for courses.

[VWindahouse]

Not ignoring you mate, and I agree with your comments regarding the wing completely.

[VWindahouse]

Ok so had a quick look under the car and there are two main area's of concern.

There is a large gap between the plastic panel that runs under the entire mid section of the car on left hand side and the torsion beam. This is where the exhaust snakes around and then over the bar then to the muffler. I guess VW were worried about the heat of the exhaust and left it uncovered.

Then the even bigger and higher cap between the bar and the wheel well. Everywhere else is pretty flat or a flatish transition like from the right hand side plastic underbody section to the fuel tank to the torsion beam so the air can't penetrate along the entire section.

Man I wish I had a hoist.

[gavs]

I still find this highly improbable (although everyone seems to have ignored my posts) due to the large separation between the wing and the bumper on the Polo. Look at the picture of the Civic with the massive diffuser and rear wing again - if a hatchback was liable to loose rear wing effectiveness due to repressurising of the wake, as you assert, then that car would show the effects. Anthony's car would be even less prone to be affected since his wing is mounted higher and more forward than the one on the Civic.

Soarers and Supras are completely different since the low angle of the rear window means that airflow can stay largely attached down to the boot lid which is not far above the bumper.

Horses for courses.

Sorry, I really need to learn how to be more clear in what I'm trying to say!

RE the Soarer comment, I was meaning that like Anthony mentioned earlier, the drag reduction he has performed is something that should have been done on these (much) higher powered drag cars because the air under the car was blowing out or even ripping off the rear bumpers until some bright spark thought to cover the area in with a flat piece of plastic, which is stopping the air getting behind the bumper in the first place.

I appreciate you opinion a lot mate as you know but to my mind, if these guys were seriously wanting the best package possible in a time attack car, they wouldn't have bought a civic to begin with because without undercar aero like this: then there is no hope of being able to compete with the evo's etc on an aerodynamic front. There could also be radiators etc behind there as well but to make that design better, I would have just hacked out the entire rear bumper, gone with a flat undercarriage and fitter the biggest damn diffuser I could get in there, then extended it out and lifted the lower edge of the bumper up.

I'm no aerodynamicist, far from it but what I have read countless times is in regard to the aerodynamic in-efficiencies in bluff ended vehicles every other month with what I do for a living, and how to resolve/optimize these flaws...

[seangti]

hi mate. I did renault happy laps last weekend at QR on the clubman circuit. I ran my street tyres which are new Bridgestone RE002. Even though it was happy laps and not sprints I was able to give it a reasonable run whilst not fully committed. With these tyres I was lapping in 71sec flat, with a committed lap I think a 70sec or a high 69sec is reasonable. With the semi-slicks I was mid-to-low 67sec laps. i.e. ~3sec a lap from tyres alone.

As I think you know, I break the track up into sectors almost per corner. 6 sectors on most tracks so I can compare cornering pace. Sector 1, i.e. turn one is where the biggest difference in pace was, I was 1.2 secs slower with street tyres and braking much earlier. Other corners/sectors were roughly 0.3-0.5secs quicker each. Interestingly, g-forces were only marginally higher in comparison, say 0.48g to 0.54g cornering load. Braking was much the same marginal increase. Top speed difference was 3km/h, so only a bee's whisker.

I'm yet look further at the info to compare apex, entry and exit speed to better understand where that time is coming from, but thought I'd share what I've learnt so far.

My point - we need to get some data for you You're spending time on aero, though without a base capability it's near impossible to measure the value of them.

If you're going to happy laps this weekend I can give you my gtech so we can start measuring, if you like.

[VWindahouse]

Too true mate and good idea. Appreciate the loan for sure. Also I've been wondering if we can get together to work out the best shift points for my set up?

Cheers.

[seangti]

Too true mate and good idea. Appreciate the loan for sure. Also I've been wondering if we can get together to work out the best shift points for my set up?

Cheers.

Yup sure. Just need to find a suitable location to stretch 4th gear (6000rpm would be sufficient) to get the 4th and 5th gear over lap. Lakeside could be sufficient, though would need to be 2-up to do that. 2nd and 3rd gear can be done elsewhere and best ran from 2k rpm.

[seangti]

I had the privilege of having a good steer of Anthony's car at Lakeside over the weekend, did about 18 laps. Yikes, insert multiple profanity here...

What a beast, still having a chuckle today. Mighty impressed with it; power, cornering and those brakes. The power is addictive though needs to be balanced as it spins through 3rd at half throttle, haha, the cornering is balanced with some understeer (which I found reasuring given the speed), and the brakes, it just keeps teasing to dive later and later. My car with standard sized rotors averages a maximum of around -0.7g's under braking, these brembo's were over -0.9 with a few -1g dives, and still easily had more in it.

I lapped mostly in 4th and 5th gear, which if doing a committed lap would probably run 4th a lot further down the straight. I did a best 1:08.16s lap, I reckon I could do 1:06's with a clean and committed lap. Much beyond that I wouldn't have pears big enough, haha.

Thanks again Anthony, I owe you

[VWindahouse]

Not at all mate, glad you enjoyed it And I really appreciate the driver tuition. Can't wait to properly try your preferred lines and tip in points.

I thought we were faster than 1:08 but then again you had a 70 odd kilogram weight penalty to cart around