Alfonze

It seems that my info was incorrect for the final drive ratio, but about the traction off the line, its pure physics, let me see some videos where you take off with both wheels spinning for more then couple of seconds, and when moving off. I tried to get a decent start with mine last year, and couldnt... With quaife there is no problems ofcourse, and just got my brand new Michelin pilot sport 285 rears, so the drag should be fun. The only problem is automatic transmission stall-speed (i hold the car with break till about 1500-1700 rpm). I try to aim low 14 or maybe a bit under, but its really difficult, because dragraces here are on old airfields, wich have concrete and burned street tire crap all over it, its like riding on plastic:-(

craigm1841

i dont do burnouts often, but if i do, it is usually a last second decision to act foolish in my car. i dont think i actually have the motivation to charge my camera, set it on a street somewhere and do a burnout, go back, get the camera, upload it to my computer. first time i did it, i had a friend in from out of town, i told was complaining about the car costing as much as it did and not having a good rear setup. he didnt believe me, i turned off DTS/DSC, power braked and left probably 60 foot stretch of rubber and kept going. he said it felt like both wheels, i said no way, i turned around to check it out and couldnt believe my eyes. I have only done it one or two other times.

craigm1841

for your viewing pleasure:

straight line 2 wheel peel:

donut 1 wheel peel

watch the 530 on the left. as soon as it gets a little sideways, the driverside wheel stops spinning:

Alfonze

You cant see if there is a 2 wheel burn in the first vid, there is a lot of smoke, and maybe the car has a lsd/atb... The other 2 are a joke:-P

I dont justify burnouts other than to warm up the tires before a drag race on legal event, but if i spin a wheel every time out of the corner, or get stuck in the snow etc, i really hate it, so diff is the must have mod, the same goes for the soft and good gripping tires (yes they wear, but traction is really important), other bling can ofcourse follow, but first of all the car must be drivable and not some kind of a cripple:-P

craigm1841

i agree that these cars rear setup sucks. my 93 mustang had an auburn posi unit, 3.73 gears, mooser 31 spline axles, c clip elminators... needless to say i was spoiled. no rear setup will compare unfortunately

Phantom Mark

My car has no LSD but will spin up both rears at the same time if im straight, no problem at all.

BTW OP:

Do you have any experience with the Gtech Pro RR's ??? or in fact anybody else.

I ran my car on cold winter roads and run flats with a tuning box fitted and was very pleased with 14.7

The Gtech kit claims to be super accurate and acredited by drag racing assosiation in the USA or something.

Alfonze

G tech result for me was 14.04@104Mph but i think its a bit optimistic. The best 0-60 mph was 5.47sec.

Phantom Mark

It really depends a lot on how accurate you setup your weight, thankfully I have a local trade weight bridge nearby, my car is 1740kg with me in it and quarter of a tank of diesel.

What model is yours Alfonze ??

Sorry to the OP for going off topic here

Alfonze

545iA 2005.
Weight is around 1625kg when racing on event, the G-tech test was with full tank and all the junk in the trunk and rear seat in the car, so around 1700kg-s. The mods that are listed below are after a test with g-tech (only diff was installed).

Mods that affect performance:
Quaife ATB differential
285 wide Pilot Sport PS2 (the tires are M5 profile, to get to 60mph with one less gearchange, on the road i have less rpm and on the start i have a bit less Nm to the wheel, so i can get better traction, not to mention on a mile long stretch i should get bit faster)
modified exhaust (rear muffler is 3" straight through)

When starting off i use the brake to hold the car until around 1500-1700rpm, and try to get off with minimal spin (wich isnt hard with a good diff and tires:-))

The g-tech quarter mile time was a dissapointment, but the top speed was really good, on an event i could only get about 100mph, so room for improvement. And maybe the mods help a bit:-)

I am doing dyno tomorrow, to see the changes with couple of engine tweaks and rear muffler, and plan to go to atleast one mile challenge and couple of quarter mile events. (I hope to achieve 235kmh on one mile and under 14sec quarter mile)

Sorry for offtopic.



And to the topic a bit also, how did it go? :-)