Just dropped a deposit on some M Power - Trackday Project Car

Hi there

Both you and Housey are right, I'd love to rid the front-end of another 30kg, less 10kg from rear exhaust and some strategic trimming on the interior carpet/foam would be a further 10kg. That's 50kg more off the weight, then add back in 20-25kg for the cage. The result would be bang on 50/50 distribution and in the 1300-1350kg range with fuel.

So yes it is tempting to get the ultimate handling balance and further improved acceleration and Housey knows how quick my M3 feels, it is far quicker than a stock M3, very noticeable so even from a 2nd gear roll, to the point now it can easily match my Carrera or a 996 GT3 in a straight line which is some accomplishment because the 911's normally destroy the M3 in a straight line.

But at the same time Housey makes good point, the AC does come in handy on a summers day when I go for a weekend blast or for hot track days or even wet ones to keep visibility good.

I think for now I leave as is as changing the final ratio could be more than enough, as the thing I dislike about the M3 is the long gearing, 3rd and 4th gear pulls go on for so long, not because the car is slow but because the top of 4th is around 135mph, so bringing this down to around 120mph would be nice and make for much more zippy acceleration. So I shall wait until the new diff is in place before I contemplate removing AC. :)
 
Firestar_3x said:
I wouldn't be too keen on ditching the AC, i'd rather save the weight by changing the rear glass to plastic.
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True, why I've got this Milltek, its over 10kg ligher and if I trim the deadening out the carpet that's another 10kg, which should more than compensate for the weight of the cage. :)
 
Think I will go with 4.10 gears for sure acceleration looks vastly improved.


That car is doing 0-100mph in circa 10s and 60-100mph in sub 5.5s which is impressive as with the 4.10 gears 4th is needed to hit 100mph whereas before 100 was possible in 3rd, so makes it more impressive.

My car does 60-100 in 5.5s now due to reduced weight and more power so looking forward to this modification as will accelerate through the gears much quicker and with SMG the shift time is 80ms so no worries about additional gear change. :)

80mph stock is about 3000rpm with the 4.10 gears it becomes 3500rpm so still fine for everyday use, top speed is reduced to around 175mph. :)
 
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Hi there

Not really updated in a while but I recently added silenced de-cats, a noticeable improvement at the top-end and no apparent torque loss. Maybe another 3-5BHP, feels good anyway and more weight savings of about 5kg.

Also got these items:

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For those wondering what on earth, what you are seeing is a M3 CSL ECU, new differential and new BMW motorsport polished 3.91 gear set. They shall be installed into the new differential which shall get a full bearing/seal refresh so be like brand new. I went with 3.91 as I got a good deal (£450) and 4.10's are not in stock at BMW and would have cost over £1000 after polishing procedure. These will give a nice improvement in acceleration and are perfect ratio for both road and track. Hope to have installed by March.

The CSL ECU, Map sensor and tune to match will improve drivability, power/torque improvements unknown but the car will be less likely to rob itself of power, so a worthwhile mod and I got the ECU for £300 which was an absolute bargain for a genuine CSL ECU.

I will also be sending my wheel off to get it finished as per example below:

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Can't wait, car will be an absolute monster and fingers crossed my rear cage/harness bar will be finished by March/April time by Nick at Track-Tec.
 
So this is what you've been up to :p

As the car will be used a lot on the track, do you not think the Alcantara re-trim will go off after a bit of use from the heavy use and sweaty palms etc? I was under the impression the finish isn't as long lasting as a leather one!
 
mrk said:
So this is what you've been up to :p

As the car will be used a lot on the track, do you not think the Alcantara re-trim will go off after a bit of use from the heavy use and sweaty palms etc? I was under the impression the finish isn't as long lasting as a leather one!
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Never had an issue with my CSL or 911, but I generally don't have damp sweaty hands, so not an issue for me. :)
 
Who is doing your wheel and how much??

Getting mined wrapped in alcantara with m stiching but without the 12 o'clock marker and then I've got a load of interior trim bits delivered I'm going to wrap for a lovely leather / alcantara interior/
 
Tom|Nbk said:
Who is doing your wheel and how much??

Getting mined wrapped in alcantara with m stiching but without the 12 o'clock marker and then I've got a load of interior trim bits delivered I'm going to wrap for a lovely leather / alcantara interior/
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Some guy on cutters.
 
HummuH1 said:
Nice, good mods there.

Take that means you'll be running Alpha N?
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Its running Alpha-N at the moment which is excellent but not perfect.

So I shall be running OEM CSL software with a map sensor, better drivability and the CSL ECU will not retard timing as much as the stock maps. So good gains in mid-range power too, especially in warmer weather.

Am most excited about the diff though, I know it will be a huge seat of the pants transformation in acceleration, 8% more torque everywhere for a start. :)
 
Simon said:
Who told you 8% more torque everywhere? You do know what a gearbox does so this surprises me
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Common sense. Torque at the wheels improves:
Changing the gear ratio in the final drive does two things. It changes engine speed relative to ground speed, and it changes the available torque at the drive wheels relative to engine torque. For achieving maximum accelleration you need the highest torque a the drive wheels, to which end you would want to increase the final drive ratio. But the magic red line on the tachometer (wherever you chose to paint it) dictates the highest speed allowable for the engine. The trick then is to use the highest gear ratio possible while not allowing the engine to run past red line at the fastest point on the race track. So on a short track where the car will not be moving so fast, it is advantageous to use a higher ratio final drive for improved accelleration. But for a longer track, especially with longer straightaways, the final drive ratio must be lowered enough to prevent over reving of the engine. To wit, it is common to swap out the final drive gearing between race dates.

http://www.rubydist.com/Family/Power.html


How I miss understood, I've being in M3's with higher final ratio like I'm going for and acceleration is improved as explained above. :)
 
You will like the shorter final gear. My Silvia has a 4.1 gear which is standard for 5sp JDM models. I've since spent some time in UK spec 200sx with 3.7 gear and the acceleration is notably duller. Most people swap to the 3.9 auto diffs but I don't know why when the 4.1 isn't stupid at all.
 
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