[AWSAWS]

I'm going to have to try Santa Pod again to see how my car performs now I have my meth injection better setup than before. Logs are looking good with the JB4.

Anyway with my car, as with all 335i's I'm sure, power isn't the major issue, traction is. Getting the power down and the car moving.

So with the quick and high torque of the twin turbo engine (you diesel guys will have this even worse than us petrol guys), what is the best strategy to cover the first 60 feet in the quickest time?

Anything more than a little wheel spin seems to really hit times hard. What I'm wondering is what's the best strategy? I once heard a spinning wheel retains about 70% of it's traction but then 70% of 100HP is better than 100% of 50HP so there is some compromise.

Strategies like limiting boost on 1st and 2nd gear? Even a NA 3 litre engine can really spin up the wheels though if the throttle isn't feathered. Does boost reduction early on hurt boost later on? Is it better to not limit boost and just restrain yourself so that you may not have full boost most of the time but you do at some time.

Short shifting? Literally get moving in 1st and then up into 2nd and 3rd to keep the power controllable.

Go to 6200 on each gear but be gentle about it?

I'm interested in how the flat torque curve of the 335i means the car should be driven, if you know what I mean.





So what do you find to work best?

That's before we even get onto manual vs automatic vs DCT etc...

[windymissile]

Start in second aparently.

WM

[mob17]

There's a guy in the States who does the 1/4 mile a lot in his modified D. He also reckons to start in second with a little brake boost of 400rpm

[AWSAWS]

I have seen the same on AT but not so sure how well this will work out with a DCT. I tried lining up in 2nd without brake boosting and the launch is incredibly slow (clutch wise). I will have to try 2nd and the brake to see what the result is.

[djgandy]

I don't think starting in second is a good strategy on the DCT. This works on AT as the torque converter manages transmission of power it means the engine can run at full boost and you don't have shift time from 1st to 2nd.

I think the solution you'll find is probably slightly wider tyres and LSD. Perhaps M3 rear subframe parts too. The rear on the 335i is not designed for 400hp, it doesn't take much to cause power to not be transmitted to the wheels.

If you look at cars that pull away well with similar power, say Porsche, they have 285+ tyres on the rear and an LSD and a far superior suspension setup.

[mob17]

Pretty much what djgandy said, i'll be trying to do wider rears (285/295), and defo solid aluminium subframe bushes.

Even though a firmer rear generally means less traction, i think it will still greatly help you in your drags as you will feel the rear better, i.e more predictability.

[djgandy]

The e92 M3 runs 265, and the new M3/4 runs 275.

Both also have a thicker profile (35), which I think helps too.

I would guess that there sweet spot for profile, and I would also guess that 30 on the rear is beyond it for drag racing. I imagine that you want the tyre to flex providing grip, rather than just being stubbornly stiff and ending up slipping.

If you are really serious about the drag strip get yourself some semi-slicks!
http://www.tyreleader.co.uk/car-tyre...-zr19-89y-9170

[AWSAWS]

Well tried some 2nd gear launches with DCT. It doesn't like it at all.

The boost just wont kick in, even with my foot to the floor. It would be quicker to be in 1st gear at 20% throttle, it's that slow.

The clutch is engaged so it'll be a software thing.

When I go to Santa Pod, it's more about finding how fast I can go with my daily driver.

I know that some drag radials could get my 60 foot time down to around 1.8 sec by looking at what other's are achieving.

Some wider road tyres and suspension mods would improve over stock for sure.

[AWSAWS]

Can I put 265 on my stock rims at the rear???

[windymissile]

Yes. I have that size. 265.30.19.

WM

[AWSAWS]

Originally Posted by windymissile

Yes. I have that size. 265.30.19.

WM

Thanks

The dang things arrived today. 255 feck!

Should I see if I can swap them. This is the problem with online sales.

[shadow191]

For the drag strip, wider tires won't help that much. The overall contact patch remains about the same, it's shorter, but wider. Taller tires will help more.

LSD won't help much either, in a straight line at the drag strip, you're rarely going to spin only one wheel. Even on public roads, launch hard and you'll see 2 strips of rubber. LSD is more for putting power down in turns.

Do UK DCT equipped cars have launch control? If so,

http://www.e90post.com/forums/showth...t=buraq+launch

Or just search on BuraQ, he has a DCT car and apparently goes to the track a lot.

[windymissile]

Originally Posted by AWSAWS

Thanks

The dang things arrived today. 255 feck!

Should I see if I can swap them. This is the problem with online sales.

usually the postage makes it not worth your while. As has been said, there's not much difference. I did it to offer a little more rim protection rather than gain contact patch.

WM

[AlanYoro35i]

am planning to go on summer, shall a few of us go together? Ive been talking about down the strip with my uncle and its finally showdown between his Golf r and my beast

[djgandy]

Originally Posted by AWSAWS

Well tried some 2nd gear launches with DCT. It doesn't like it at all.

The boost just wont kick in, even with my foot to the floor. It would be quicker to be in 1st gear at 20% throttle, it's that slow.

The clutch is engaged so it'll be a software thing.

When I go to Santa Pod, it's more about finding how fast I can go with my daily driver.

I know that some drag radials could get my 60 foot time down to around 1.8 sec by looking at what other's are achieving.

Some wider road tyres and suspension mods would improve over stock for sure.

Not surprised. DCT is an automated manual, so this is just like launching a MT in 2nd, which is no use at all.

Maybe you are expecting too much from your launches? Are you getting a lot of spin? You're always going to get some spin, you actually want a small amount.

I find even with the MT there is wheel spin. Generally from 5-7k rpm in first, there is just so much acceleration they spin a little, and then on the change to 2nd once the turbos spool the change in power gives a little DTC flash. I don't think you'll solve that without slicks or $$$$$

[dxb335d]

Run low rear tyre pressures. Soften the rear end up also.

[zltm089]

I would say not to floor it in 1st and be gentle with the throttle....

sometimes i get wheel spin in 3rd gear!

[AWSAWS]

Originally Posted by Yoro35i

am planning to go on summer, shall a few of us go together? Ive been talking about down the strip with my uncle and its finally showdown between his Golf r and my beast

If it's remapped you may be in trouble.

There was one there doing 12.4 fairly easily with a DSG box.

The 4WD meant it getting 1.8 sec 60ft times. I think I'd only get that on special tyres. The joy of all wheel drive.

335i is faster from a rolling start for sure. So on the real road in real conditions we know who's faster.

[AWSAWS]

Yes I have to feather the throttle or it'd spin the first 3 gears.
Once at full speed in 2nd I can usually keep my foot to the floor.

[AWSAWS]

Just how low would you let your tyres down to by the way?

I have XL's which I often run as high as 48 PSI (Max is 50 PSI) for a really firm ride but let down to 25PSI for the runs at Santa Pod.

[mob17]

Originally Posted by AWSAWS

Just how low would you let your tyres down to by the way?

I have XL's which I often run as high as 48 PSI (Max is 50 PSI) for a really firm ride but let down to 25PSI for the runs at Santa Pod.

Couldn't sleep tonight so did some late reading on tire contact patches and found a calculator: http://bndtechsource.ucoz.com/index/tire_data_calculator/0-20

Obviously i'm not sure how accurate it is as i'm not an engineer/physicist, but it's the best i've found so far. I'd assume it's a good guesstimate tool. It takes into account corner weights, air pressure, tire specs and rim sizes. Only thing missing is the tire material, but again i'm not sure if that makes a significant difference when comparing the contact patch.

[mob17]

Thinking of maybe trying 245/40 and 285/35 next. They seem pretty similar in terms of height, rolling radius and circumference. Currently on 245/35 and 275/30