This might sound silly, but is there a technique to getting the best possible launch with a 4-speed auto C36 other than mashing the gas pedal? The reason I'm asking is because sometimes the car runs very smoothly from stop, but can also be sluggish. I normally don't floor the gas pedal unless I'm trying to pass someone on the freeway. I've been driving a stick for the last 10 years and I thought that there might be a trick to this in an automatic.

Well it hink for an automatic the only way to get a real good launch is by doing a brake stand.

The brake stand might end up making your tires break loose until you hit the revs that you want to launch from.

There has been a bit of discussion on this, try searching for brake stand, burnout, heel toe, or something along those lines. you should come up with a few posts about it.

Alon

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Send Lee Scheeler an email...he'll know.

BTW, a brake stand is not always the quickest...for example, in my 500E the quickest way to leave the line is to simply punch it in Drive; that way the first few feet are in second gear, so the tires don't necessarily break loose (and invoke ASR, which KILLS times) and it's already rolling when 1st is engaged. Using this technique (and a GTech) I was able to attain a 0-60 of 5.08 seconds. Not bad for a relatively stock 4,000 lb. 4-door, eh? And 0-60 is not even what it's good at

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

Launching a 4-speed C36...hmmm

After a bunch of G-tech + dragstrip testing and a new set of rear tires (only sort of kidding) I've noticed some things. The "brake stand" is more commonly called "brake torque-ing". This is when you put your left foot on the brake to some extent (at a stop with tranny in gear) and apply the gas in some amount.

Don't bother shifting tranny in that car, just stick her in "D".

If your car has ASR/ETS hit the "disable" switch (doesn't really turn it off but snoozes it some)

If you are at the track pull forward about 5 feet further than you have to, then backup absolutely straight. This causes both rear tires to hook up and prevents the single tire/sided burnout.

The "perfect" launch is with a hint of wheelspin or tire "bark" but not lighting it up smoking tires ala motortrend... No more than 15% wheelspin. As Michael said, you are best to stay out of hardcore ASR on this car. A little blink is okay, no any more than that and your run is toast. (as opposed to M119 W124's where you don't want to see the triangle EVER)

Put your left foot on the brake and hold it down most of the way. (don't let car move) Then move your right foot onto the gas and bring the revs up to about 1500rpm.

Here is the tricky part...you will want to feel/observe/etc how many revs it takes on the tach to break the rear tires. You want just under that point. 1500rpm works when the motor/driveline/ambient temps are normal. If car and atmosphere are hot then it may take 2000rpm. If it is a cold night or the car is running particularly strong (or rear tires are not as grippy) you can drop it to 1200-1300rpm. With a little practice and observation you should get a feel for the optimum revs pretty quickly.

So, you have backed up....snoozed ASR, have tranny in "D", and have the A/C off. You know about what revs are right for the situation.

Now...here comes the fun part: as quickly as possible let up on the brake and simultaneously PUT YOUR FOOT/GAS PEDAL THROUGH THE FLOORBOARD and hold it there till your "run" is over.

I've used this basic technique at the track on several occasions. (and on the street to greater effect) You will notice a HUGE improvement versus just hitting the gas off the line.

My times: hot day/hot car (engine at or +100 C) 0-60 6.1-6.4, 1/4 mile 14.4-14.6 at upper 90's (mph)

cool day/normal car (engine temp 80-90 C) 0-60 5.5-5.8, 1/4 mile 14.0-14.3 at VERY high 90's or low 100's (mph)

That is with just me in the car, nothing significant in cargo, no mods/tricks/etc. I'm currently running Bridgestone RE730's F/R in stock sizes. Great tire for the money, but not quite up there with S-02's or the Mich. Pilots. The driver is so important in getting the most from a car that perhaps the best "bang for the buck" performance enhancement you can do is buy a G-tech and test things for yourself. Providing you can find a 1/3-1/2 mile stretch of road that is free from DOT patrol you really can't get more performance for the dollar. (if you don't know of any such stretch of road or don't want to push it on public roads, just do 0-60 runs)

Give the above a try and let me know how it goes. If you have any questions or whatnot just drop me a line and I'll be happy to offer what advice I can.

Hope this helps...Lee

(95 C36, B-silver/black)

Lee,
Thanks for the advice. Those are pretty good 1/4 mile times.
I'll see if I can get a G-Tech pro to try out.

But how reliable is G-Tech. I heard it's just a toy that's not accurate from some people, and I have also heard that it is pretty accurate from some other people. What are your impressions Lee?

In my opinion a G-tech is accurate provided you know how to use the thing. That means that you have it stuck to your window and set accurately to what "level ground" is. This also means that you take times from runs on the most straight/level ground possible.

Where G-Tech varies from traditional dragstrip measurements is that it measures your trap speed (by calculation) exactly at the end of the 1/4 mile. This is opposed to reading it in the last 60 ft.

Also, times will vary because the G-Tech ignores reaction times (r/t) altogether and tells you just what the car is running.

Last, even if its results are not 100% accurate, they do give you a baseline to work with. So if a g-tech 14.2 is a dragstrip 14.3 it doesn't matter as you can compare back to back g-tech numbers to g-tech numbers. The only time there might be discrepancies is when you go (apples/oranges) g-tech to dragstrip numbers. Learn what produces the fastest numbers with the g-tech...use the data to lean from, as opposed to brag on. (though it never hurts to finally see your target time/speed flash accross after learning how to drive it that quick)

That said, dragstrip numbers can vary a TON from strip to strip track maintenance, launch conditions, even line speed/length can make a huge difference in the numbers you run at the track.

Hope this helps...Lee

PS a tip to those who do a good bit of drive and tune...the car will heat up (engine, tranny, drivetrain, etc) and cause you to lose time the more runs you make back to back. Some performance loss is normal. Still the first 2-3 runs should be free from too much "heat soak".

Michael said he got 5 seconds in his E500 with the G-Tech. It seems to me like the G-Tech got a little optimistic there. But you're right Lee, the important thing is to get the form down and get consistent numbers's with G-Tech.

I've got a 13.8 dragstrip slip to authenticate the 1/4 mile thing (as well as an E55 owner/witness who will stand by the time). That time is completely consistent with a 0-60 of around 5.0 seconds, so I'm inclined to think a G-tech is accurate.

I've bored with the 1/4, largely. Let's compare lap times!!

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo

Check a service manual, you will find the variation of immediate performance has to do with what the computer is attempting to do at the particular time. I have found the peddle to be as or more responsive at 80-90 rather than "mashed"...just a thought