Track & Drag tips for newbies

prmateus

New member
For the x35 guys here is my limited experience

On my RFTs ive played with pressure all over the place with limited results, if anyone has anyother experiene please let me know.

I brake boost at 2000 revs any more and i brake traction on the line let alone once the race starts.

My boost is stock for 1st and second gear else i just spin so i shift at 5500 to get quickly to where my power is then shift at 6000 all the way down, doing this instead of revving to the limit gained me 9km/h on the 1km.

Also becareful on the tyres you choose, Most semis are designed for track use and have a side wall that is too hard for the give you need to really sling shot look at getting some proper tyres designed for drag use.
 

///Shaun

Banned
Section 2....Lets go.

Lots of information and methodologies have being discussed at length but for the purpose of this thread lets discuss further findings , formula derived from Tuner University.

How to Compare Weight Savings to Horsepower Gains

Have you ever wondered what 10 or 20 extra horsepower might “feel” like in your car?

Maybe you’ve wondered how removing 100kgs will affect your car in terms of how much horsepower you’d have to gain to accomplish the same thing.

These questions are wise to ask because they can be used to make significantly better modification choices and frankly it can be fun to “simulate” different modification scenarios.

For example, if I could buy a carbon fiber hood that weighs 20lbs less than factory, it’d be nice to be able to view that weight loss in terms of horsepower. In other words, how many horsepower would I need to gain in order to accomplish the same thing as losing 20lbs? (Hint: it’s pathetically little)

What if I wanted to determine if a dual exhaust system is worth while? How much more power would I have to make to offset the extra 9kg? (in a 1587kg car with 215 hp, not even 1.25hp, so probably do-able)

Can someone on the forum claiming to feel a 1-2hp gain on their butt dyno really do so? Well, using this formula you’d see that they’d have to be able to feel the difference between having groceries in the car vs not having groceries in the car to “feel” that supposed gain.

What about if I wanted to see how much weight I’d have to lose to compete with the same car with 50 extra horsepower?

All of these kinds of questions can be answered with the simple math in today’s article.

Section 3 - Weight to Power

You’ve probably heard power-to-weight more than weight to power, they’re the same thing but one has nicer numbers and a better visual representation so I’ll be using weight to power for this discussion.

Weight to power is one way to get a general idea of acceleration performance. For example, if I have a 1587kg car with 215 horsepower, I simply divide 3500 by 215 to get a weight to power ratio of 7.3kg per horsepower. The same car with 250 hp would have a weight to power ratio of 6.3kg per horsepower.

Now Tuner University explains this like so :

To give you a really over simplified visual, imagine that each “horsepower” is a horse. The fewer pounds the horse has to drag with it, the easier it is for it to run.

The Bugatti Veyron with 987 bhp and a curb weight of 4,162 lb has only 4.12 lbs/hp and thus is significantly faster than our example car.

Great, that’s all very simple. So how is this useful beyond comparing vehicles to one another?

Well, let’s go back to the 3500 lb car with 215 horsepower example. Let’s say I want to know how losing 100lbs would translate into horsepower gained, because let’s face it, most of us think in terms of horsepower gains.

So we take 3500 lbs (the original weight) and divide by 215 to get 16.28 again (rounding for simplicity, you’ll want to use the full number to get accurate results).

We take 3400 lbs (the new weight) and divide by 215 to get 15.81 lbs/hp. That is better of course, but what would that mean in terms of horsepower? Well, we do some simple Algebra to see what horsepower we’d have to have with the original weight to get the same weight-to-power. Stick with me as this is really cool/useful:

3500 / x = 15.81 (Non-geek translation: original weight divided by some unknown horsepower would give us the same power-to-weight ratio as 3400 / 215). Solve for X (which I have done for you below)

Section 4 - “Weight loss” to “Horsepower” Formula

Old weight (3500) / New Power-to-Weight Ratio (15.81) = 221.38 hp

So that means that by taking 100lbs out of the 3500lb car, we would have had to gain ~ 6.38 hp (221.38-215, (the new-original horsepower) to accomplish the same thing WITHOUT taking out the 100lbs. Thus in this situation, 100lbs is roughly the same as if we had done something to gain 6.38hp. So to some extent, this means that something like an intake that adds +6hp would FEEL kind of like losing 100lbs (or a very skinny passenger) in this particular vehicle. In another car with different weight and power numbers, this figure would be different but calculated in the same way.

Section 5 - “Weight Gain” to “Power Loss” Formula

You can also use this same method to determine how adding weight is hurting you in terms of theoretical power loss. So if I add 50lbs of stereo equipment to the same car, it’s

Old Weight (3500) / New Weight-to-Power Ratio (16.74) = 209.08 hp

So that 50lbs of equipment is LIKE losing a little under 6 hp as those horses will now be dedicated to hauling that 50lbs.

This will give you a new way to think about weight and power. You can also go the other way and see how power gained changes the car in theoretical terms of weight, though I find this less useful. To do that, you say a 3500 lb car with 215 horsepower has a 16.28 lb/hp power-to-weight, and let’s say we gained 50hp to get up to 265 hp. That’s a power-to-weight of 13.2 lbs/hp. Now it’s simple Algebra again to figure out how much weight I’d have to lose off the car to make up the same amount of power:

In formula form:

New Power to Weight (13.2) * 215 (old horsepower) = Theoretical Weight (2838).

So 50 horsepower in this particular vehicle would be roughly the same as shaving off 662 lbs. As you can see from this math, this is why losing weight is rarely as useful as gaining horsepower, or at least, horsepower gain is significantly more practical and cost effective than weight loss in a production car.

Of course, this is also if we only take into consideration the acceleration effects of weight and power. In road racing or in a daily driver, weight loss is more useful than in drag racing. Of course, regardless of our goals, the least amount of weight necessary is best.



Hope this makes sense , we can break down further if needed before we move along to the next section.


Waiting on you guys ???
 

Ga-3M

Well-known member
dvst8 said:
Ga-3M said:
:thumbs: Picturing Shaun giving us lectures in front of a lecture hall!!:rollsmile::

He must be sitting on a High Chair.

:biglol:

:roflol:...Okay enough of that, don't want our lecturer to get upset and walk out on us!!
 

///Shaun

Banned
:roflol:

Right moving along to getting that perfect launch with a MANUAL CAR.

Will do the explanations along with some video footage.

Making time in between to type so bear with me please.

What I do suggest in the mean time is to play around with these different calculators that will help us all understand our own cars and we will be able to guide each other of what a car is capable of and not.

If anyone is unsure how these calculators work , add in comments I will try and aid where I can . Please guys this is a thread for all to learn from so please jump in where possible be it a problem or solution.


So here is the list of calculators available to us that caters for 400m , 1km estimates etc

Power Conversion Calc:
http://khetan.gajjar.co.za/cars/calcs/PowerConversionCalculator.htm

Power Converter:
http://khetan.gajjar.co.za/cars/calcs/PowerConverter.htm

400m Estimated Calculator
http://khetan.gajjar.co.za/cars/calcs/QuarterMileETCalculator.htm\

1km Estimated Calculator
http://khetan.gajjar.co.za/cars/calcs/QuarterMilePowerCalculator.htm


.
 

///Shaun

Banned
Having received quiet a few requests to share my view as per title , I put together a little thread that Im hoping will aid us all. Please feel free to comment / add / subtract to the thread.

Before I start to share my personal experiences I would like to state I by no means confess to be a professional racer but more a enthusiast in drag racing.

I will be illustrating my view of the perfect launch at the drag strip for the following :

Categories
Manual – NA and Turbo Vehicles.
Steptronic Gearbox - NA and Turbo Vehicles.

BMW Platform:
E90 330d / 335i / 320d
E90 / E92 M3
E46 M3 / 330i
E36 M3 /328i / 325i

These are my personal experiences over the years with the different BMWs I have peddled down the strip with most cases proving to do decent 400m times and 1km exits.

Achieving that perfect launch with a Steptronic Gearbox
Category : Turbo
BMW Platform : E90 320d / 330d/ 355i


Add in NF boost additive – allow enough driving time for adaptation

On race day seeing that I used 265/30/19 street tyres. I drop the pressure down to 1.8bar. This will help with the hard launch Im about to explain

Now in any drag race the most important time is the 60ft time the car has to do. If a car can do a get a very good 60ft time , the 400m time will be lower.

Now you may be asking how do I get the best possible 60ft time?

Quiet simple :

Heading up towards the track I would suggest spraying the intercooler with lots of water to keep temps low as possible.

Line up the car at the Christmas lights.

Disable all driving aids, DSC etc

Engage 2nd gear in manual mode (steptronic box)

Hold 2000rpm with foot on brake

Handbrake down

Now this is key : Timing usually starts from the moment one has to leave the line , its does not start to count on green. So take your time and focus even if your opponent pulls ahead. It’s the 400m time that determines the winner and not the person that crosses the line first.

Lights goes green

Rule on the steptronic box with loads of torque available is not to hit the kick down mode , full depressed accelerator. If one does this it will engage the car back into 1st gear which will defeat the purpose of achieving a good 60ft time.

So lets try again : Lights go green , foot on accelerator holding a steady 1800-2000rpm, handbrake down , left foot on brake pedal. Do not feather the throttle.

GO

Driver has to gently press accelerator to get momentum (not granny pressing), once car revs past 3000pms its safe to engage kickdown mode as car will not revert to 1st gear.

Keeping in mind we are now in manual mode 2nd gear moving forward , driver has to catch each gear at 3800rpm. Rev counter will go up till 4300rpm and do the next gear change. The steptronic box has a delay in it (torque converter) which will mean this in order to do perfect shifts one has to cater for that delay hence trying to catch each gear change at 3800rpm

As with any Diesel , high RPMS does not make power. One has to know their power band , meaning keeping the car in that power band all the time. General conesus is 3500rpm to 4200rpm for a Diesel powerband.

And that sums up how to achieve a good 60ft time and 400m time.

In order to do 1km runs , lots of persons say leave the line with lots of wheelspin it will give one a higher topend speed. I disagree as when I tested with Vbox the results where the same for topend speeds. What I would rather suggest is to the 1km run the way one would run a 400m meaning leaving the line hard and keeping the car in its powerband the entire way.

This video will illustrate the launch technique . One will be able to see a E90 330d outlaunch a E46 M3.
I do not condone street racing. This video is just for viewing purposes.


Achieving that perfect launch with a Manual Gearbox
Category : Normally Aspirated / Turbo
BMW Platform : E36-E92 325i /328i / 355i / M3


Add in NF boost additive – allow enough driving time for adaptation

On race day seeing that I used 265/30/19 street tyres. I drop the pressure down to 1.8bar. This will help with the hard launch Im about to explain which works completely different to the steptronic gearbox launch explained above.

A manual car is all driver and to do consistent 400m /1km times , launch technique will need to be seamless.

Roll up to the Christmas tree lights

Pull up handbrake. Not all the way up, Just enough to prevent the car from moving forward.

Hold a steady 2200-2500rpm.

Clutch depressed.

Foot removed from the foot brake

At this point driver should have this in place : left hand on handbrake preventing the car from moving forward , left foot holding clutch in, right foot pressing accelerator holding a steady 2200rpm or 2500rpm

Added to the above statement driver needs to let go off the clutch slightly till it bites. This will make the rear end of the car sit to the ground with the front slighted elevated. Be sure not to do this to long as it will burn out the clutch.

Lights go GREEN

Driver immediately leaves the clutch and presses accelerator abruptly , the vehicle will start to spin and try to leave the line , driver needs to control this wheel spin using the handbrake ever so slightly. A combination of clutch and handbrake can also be used to eliminate wheelspin.

If perfected car will launch out the line very hard. The weight of the vehicle thrown onto the rear tyres will thrust the car like a rocket ready to take off.

This video will illustrate the launch technique . One will be able to see a Z3 outlaunch a E92 V8 M3
I do not condone street racing. This video is just for viewing purposes.


Achieving that perfect launch with a DCT 335i - Launch Control

One of my all time favourite gearboxes , pretty simplistic and the car does all the work so to say:

Put the car into Drive

Press the SPORT button

Press the DTC and then press and hold it till the flag displays

Press the brake and accelerator pedal together at the same time

Release the brake pedal


Courtesy of "HardM3" :
1- Car needs to be sufficiently warmed
2- DTC one push
3- Sport Mode (shift gear lever to left)
4- Sport + Button
5- Left foot on Break
6- Right foot flat down on accelerator
7- Flag appears
8- let go of the break
9- Launch


General Comments

With the rear wheel drive cars I did notice a negative either a (– 1.28) or (–1.38) camber offset seems to help with traction on street tyres. For daily driving this is not recommended.



Online Calculators courtesy of Khetan Gajjar

So here is the list of calculators available to us that caters for 400m , 1km estimates etc

Power Conversion Calc:
http://khetan.gajjar.co.za/cars/calcs/Po...ulator.htm

Power Converter:
http://khetan.gajjar.co.za/cars/calcs/Po...verter.htm

400m Estimated Calculator
http://khetan.gajjar.co.za/cars/calcs/Qu...lator.htm\

1km Estimated Calculator
http://khetan.gajjar.co.za/cars/calcs/Qu...ulator.htm




Hope this helps.


:thumbsup:
 
J

Jandre

Guest
Thank you for the info Shaun.

Now, while this thread is still fresh, let me please request the following:

1) No personal attacks on members. From anyone.

2) Tuners (if and when you comment), stay 100% objective.

3) Treat each other with respect. If you cant say anything constructive, rather shut up.

4) Give credit where credit is due.

Thank you. Regular viewing will now resume.

:=):
 

andrewbuch

///Member
I think the tips for launching a manual that isnt a 6cyl would be different. If I launch my 318i at 2500rpm I bog down like crazy :)
 
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