P5 Puredrive vs Gaz

[Gandahar]

StressedDave said:

Grandad said:

So......if we have a naturally aspirated Mk2.5 1.8, with an LSD and as much weight as possible removed, and with lightweight (correct offset) wheels, Toyo 888s, urethane bushes, braided brake lines etc. etc., which brand/specification of suspension do we need to get round Croft in the least possible time? Absolutely no compromise needed for road use.

Are we talking about making you personally able to get around Croft in the least possible time, or getting the car round Croft in the least possible time?

If it's the former then I say getting a lot of good quality driver training (preferably not by ARDS instructors) would make the biggest difference. I've been doing a lot of work with amateur racers and normally there are whole heaps of time available just by getting them to corner efficiently - I'm talking several seconds a lap, not just tenths. Once you can consistently drive the car on the limit for lap after lap with whatever setup it has, then you can think about changing the car...

If it's the latter then:

1. Spend a few thousand pounds putting the car on a kinematics and compliance rig such as the ones at http://www.abd.uk.com
2. Spend a few tens of thousands of pounds getting the tyre parameters for the R-888s measured using a rig like the one at Calspan: http://www.calspan.com/tire.htm
3. Weigh the car
4. Take all this information to a vehicle dynamics professional who will then work out what spring and ARB rates you need. Modesty forbids, but firms like either Multimatic in Thetford or Lotus Engineering do repeatedly good work.
5. Drop 10k at either Koni or Ohlins for either 2822 dampers or TTX dampers (they are repeatable four-way adjustable monotube dampers)
6. Budget a few thousand for a data logging setup - you'll be wanting to measure suspension position at around 100 Hz minimum and those sensors aren't cheap
7. Spend a reasonable amount of time on track with a race engineer who can read the data and set the dampers accordingly

If you don't mind crunching a few numbers, then the 'Springs and Dampers' tech tips available at http://www.optimumg.com will give a very simplified insight into the sort of things you'll need to calculate just to get into the ballpark of being quick around a single circuit.

I do most of my development work at a particular proving ground which has a well designed (or read truly evil) handling circuit. Because of its design, it's not a power circuit as it's nearly all corners and no straights. Going from an OE setup on a normally aspirated Mk II with no LSD, no upgraded brake lines, no ABS and cheap 185/60 R14 tyres to a properly optimised aftermarket setup (albeit with no LSD, no upgraded brake lines, and the same crappy tyres) knocked 1.5 seconds off a 53 second lap time. If you're whole seconds away from that theoretical ideal, then all the bling suspension bits in the world aren't going to get you there.

or get better tyres. The R888 are not as good as some others for track day work.

[MG-FIDO]

Wow, someone's just found the keys to the DeLorean!

[MX-5 Lazza]

Previous reply was May 2009!!!