poor dyno result why?

[VW GTI]

Speaking of... When is everyone hitting the track next?

Shaneth should chuck his hand up for being the mixed event organiser in Brisbane, cos he's pretty good at organising stuff.

http://www.vwwatercooled.org.au/newforum/upload/showthread.php?t=14483

I'd do it but don't have the knowledge or the time, I am willing to get some sort of info site running (like Guy's drivegti.com).

[Flaps]

A question back on topic....

Would wheel weight have any effect on power output?

[LoriJarrod]

Heavy/larger wheels will have a negative impact, as the engine torque has to turn the wheels and the rollers. Seeing as though a chassis dyno basically measures the car's ability to spin some heavy metal tubes, having to use more power spinning a heavier wheel will have some effect.


What kind of times are Polo GTI's getting at Wakefield? I'd be interested in a punt around with no performance mods. My E9 with just pads and fluid was in the low 1.11's. But WP isn't a top-end sort of track, so I'd reckon they'd be fairly competitive. 1.15's-1.18's????

[Jarred]

A question back on topic....

Would wheel weight have any effect on power output?

Not sure about power, but it will affect torque, because the greater weight of the wheel requires greater torque to move it.

In a purely physics/maths sense, it does. In the real world, who knows, I doubt it would have that much effect (only a couple of horse probably), not enough that you would be able to feel a great difference.

Having said that, Race cars generally have lightweight wheels don't they? I geuss it's one of those small things, that adds up in the end, on a track.

[FL00DY]

Heavy/larger wheels will have a negative impact, as the engine torque has to turn the wheels and the rollers. Seeing as though a chassis dyno basically measures the car's ability to spin some heavy metal tubes, having to use more power spinning a heavier wheel will have some effect.


What kind of times are Polo GTI's getting at Wakefield? I'd be interested in a punt around with no performance mods. My E9 with just pads and fluid was in the low 1.11's. But WP isn't a top-end sort of track, so I'd reckon they'd be fairly competitive. 1.15's-1.18's????

I'm not chipped, just RSB, front strut and just Preceda 2's and my best is 1:17.8. Others like Len and Tim ar round the1:15's I think ???

[Timbo]

Wheel weight creates inertia, which affects both measured power and torque.

Race cars have lightweight wheels for this reason, but more especially to reduce the unsprung weight - a lighter wheel which readily moves in response to road bumps will have more grip when tracking over an imperfect road

My best WPR time is 1:16:1, which reflects the softwear in the seat more than anything else

[LoriJarrod]

Good times guys. I reckon the polo would be a hoot to throw around.

Do the little brakes fade dramatically?

[FL00DY]

Good times guys. I reckon the polo would be a hoot to throw around.

Do the little brakes fade dramatically?

I don't think so, I've changed pads and thats it. I think Len and Tim are using larger rotors and slotted. The Polo is the only car I have driven round Wakefield and I don't find a massive problem with the brakes, Len and Tim however have more experience round the track in RX8's I think ???

Will be very keen to see how much quicker I get with my next visit.

[GT3]

...the Polo GTI is not exactly suitable as a track car

If I was completely objective, I'd have to say that the 9N chassis is not ideally suited to high performance applications. Even with significant modifications to its handling, the 9N chassis has poor weight distribution. This is also one of the major reasons why it's difficult to get power down, the chassis simply wasn't designed for it.

[shaneth]

If I was completely objective, I'd have to say that the 9N chassis is not ideally suited to high performance applications. Even with significant modifications to its handling, the 9N chassis has poor weight distribution. This is also one of the major reasons why it's difficult to get power down, the chassis simply wasn't designed for it.

Yes down the qtr mile maybe, But if i remember rightly Guy said he was lapping a sec faster then a rs4 around QR i think. And if its one of the RS4 owners i know like the presdident of QLD Audi club i dont think he is a slow coach. And to be going faster then RS4

And i tracked my polo round QR and it was a hoot besides the conti's. No brake fade for me either.

[DUB 20V]

Yes down the qtr mile maybe, But if i remember rightly Guy said he was lapping a sec faster then a rs4 around QR i think. And if its one of the RS4 owners i know like the presdident of QLD Audi club i dont think he is a slow coach. And to be going faster then RS4

guy also upgraded the brakes i think, is it true bigger brakes later braking=faster lap times?

[shaneth]

guy also upgraded the brakes i think, is it true bigger brakes later braking=faster lap times?

Yes to a point but if he was relying on the brakeing he must have been hell fast down the straights to catch up to such be all round beast. If youo know what i mean. Brakes are only part of the equation.

[Jarred]

"Bigger" brakes are better. really you want brakes that stop you quicker, and don't fade. Ie brakes that stop/slow your car quicker than standard.

This gives you the advantage of being able to brake later, which means you spend longer periods of time at higher speeds. and yes, your lap times should come down.

Also something to note for the FWD fellas. touching the brakes lightly through corners, will help reduce understeer through the bendy bits. of course this is with your foot on the accel at the same time, so left foot braking it is. there's a reason why is works, which i can't remember enough to explain why, but it's meant to work. This is wisdom coming from my dads cousin who was a bit of a rally driver back in the day in germany. I've not tried it, cause I havn't been to a track day (yet! )

It's a bit off topic, but since you are talking about track days, I though I'd throw that in

[FL00DY]

guy also upgraded the brakes i think, is it true bigger brakes later braking=faster lap times?

lol he did a little bit more then brakes for the trackday I think you're talking bout, LSD as well I believe. Guy had practically every mod possible I believe ??? So yes with an endless amount of engineering you too can beat RS4's

[jamesatfish]

Also something to note for the FWD fellas. touching the brakes lightly through corners, will help reduce understeer through the bendy bits. of course this is with your foot on the accel at the same time, so left foot braking it is. there's a reason why is works, which i can't remember enough to explain why, but it's meant to work

I can only assume this is a weight transfer concept - touching the brakes (or indeed lifting off the throttle) moves weight to the front tyre, which gives them more grip. As understeer is effectively a lack of grip at the front (or more correctly, too much steering lock for the available front-end grip), anything that gives some more grip on the front tyres would help reduce understeer.

Haven't tried this with left-foot braking in a FWD car though - but will certainly do so next track outing just to see.