RACING - DRIVING
From: Farzaan Kassam
Subject: Launching from a stop
2. Launching:
Personally, I don't like losing in autox because my car has no low end torque, so I've spent the whole year mastering a launch and I think I've got it down pack. This launch is not an allornothing type, it's not going to give you that last 1/10th at the drag track, but what it will do is give you consistent launches and similar launches to other nonturbo cars.
I get up to the line and rev the engine to get a feel of what the car is feeling. I rev it up to around 4500rpm, once the revs drop to around 3500rpm, I start to let out the clutch while I get on the gas. This is kind of like slipping, but if done right, there is almost no slipping involved (except for a few rotations from the tires). The car should accelerate at a rate that prevents the clutch or tires from slipping.
This launch technique was so successful on Saturday that I launched so hard, when I shifted into 2nd, I had the car completely wound up and on the edge of traction and had to make a kink. This, of course, set into action the infamous 944 wag, or the new name I'm giving it, the Transaxle Toss, countersteer right, countersteer left, then right again and damn, lost it! You shouldn't have problems like this though since most of you use those tame computer chips:) not the torque rise that the turbo cup units have. Farzaan.
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From: gUmBy
Subject: Re: launching a 951
I've had best results launching my 951 at about 50005500 rpms. The problem with lower rpms is that they are much more likely to drop. Like people said earlier, you slip it out instead of dropping it. You don't want to spin your tires at all because then you lose acceleration. Get a Centerforce Dual friction clutch and you won't have any problems. As for the tranny wear and such, as long as you don't drop the clutch, they shouldn't wear excessively (dropping the clutch puts serious torque along everything while slipping lets the clutch and basically the clutch alone take the abuse). andrew, '87 951
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From: Farzaan Kassam
Subject: Little tricks.
Here are some tricks that allowed Paul and I to be more competitive in autocrossing this year:
1. When waiting in the starting line, keep the engine running, DO NOT SHUT IT OFF. Remember, it takes exhaust pressure AND heat to spin that turbine. The colder the exhaust, the less boost can be created. If the exhaust is only luke warm, the max I've been able to get in 1st is 12psi, and usually it's 10psi. By the time you shift into 2nd, the exhaust should be hot enough to get up to 14psi. If it's nice and hot and the coolant is hot, the car will be able to produce an easy 15psi in 1st gear.
2. Drag your brakes up to the start line, you'll need all the heat you can get.
3. Learn how to launch your 944T, it's worth 12 seconds on a run. If done properly, no undue stress should be placed on the car. Learn to spin the tires, not the clutch, and even then, the tire spinning should be only for a few rotations. Learn on something with a cheap clutch :)
4. Fill the gas tank full, unless you really like poweron oversteer. With the wonky boost chips I have, my car is almost uncontrollable with an empty tank on street tires.
5. Make sure your compressor bypass valve is operational. I disconnected mine to know what it feels like if and when it goes bad. The first time you apply throttle, there is no difference, but the second time when you get off it and on it quickly, the boost is not there and it has to build it again, think slalom, think on and off, think you are losing time if that cheap part is not working, not to mention the extra stress you've put on the turbo.
6. If you have stock suspension, huck the car around the course. You'll be surprised with the results. While being smooth is essential, getting the car over to the Apex as soon as possible is even more important. Because of the soft suspension, fast "jerky like" actions feel like you are being jerky and therefore slow. Wrong. You need to get the car to take a set as quickly as possible, throw the car through the course and videotape your run. From the outside, it looks like you are smooth as glass, but inside, you feel like a hack. The only difference is your time will be much faster when you throw the car around a little. If you have modified your suspension to make it stiffer, the car will take a set faster and you do not have to manhandle the car as you will automatically become more aggressive as you get more comfortable. I watched a video clip of a 924 being driven by Hans Stuck and couldn't believe what he could make that car do. I tried the hucking method the next autox and we haven't looked back since. Remember, smoothness with aggression is the ultimate fast way through a course.
7. Plough is your enemy, set the car up twitchy in autox, it's faster than neutral. I like a twitchy car on the track too if I have sticky tires. If you are ploughing in an autox, next time around, make a special effort to slow down there. Even though it feels like you could run faster around the cone, you'll likely drop 0.31.0 second off your run.
8. Steer with the rear. Use the throttle at mediumhigh speed corners to get the car through the corner faster. It also allows you to develop boost for the exit, which is very important.
9. With turbo cars, slowin fastout works. Come in hard, but make sure you are on the throttle as soon as you are turning in. You only really need to use trailbraking in some circumstances. I know a lot of people use it for turning the car in, but that's what alignment is for. All of the National calibre drivers I've been with have not used it except in very tight situations, it's much more important to get out of the corner with acceleration than to come into the corner harder.
10. Position yourself correctly in the seat, and sing a stupid song to yourself before going for a run, it calms your nerves. At the start line, before running, hit your chest twice, this gets the adreneline flowing, but be careful the first time you do it, both Paul and I spun when we tried it for the first time.
I've taken a risk by giving this info out; there will definitely be people who think I'm an idiot and that all I've written is wrong. Take it for what it's worth. Paul and Darren both use advice like the above, and I feel that Paul is turning into a national calibre driver and Darren has also shown some serious promise.
When you take all these little things and add them up, it makes quite a difference. Happy autocrossing! Farzaan.
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From: "Menelaos N. Karamichalis"
To: Da 924/944/968 List
Subject: re: downshifting
As far as preventing the overrevving of an engine on a downshift, I found it easier to simply learn the speed each gear generates at 3krpm. Ie 2nd @ 3kprm is 30mph and 3rd @3krpm is 45mph. If I am going 48 and downshifting from 5th or 6th (I wish) before a turn, 4th gear will bog the engine, 2nd is probably too much and the tail may get kicked out(this is reserved for Mr. WOT), 3rd will do fine (no this is not the Goldilocks fairy tale). Smoothness counts most, IMHO. Picking an engine speed that puts one close to the beginning of the torque curve seems appropriate. This way I do not have to sequentially downshift and yes, I do double clutch, good transmission oil that has warmed up helps a lot.
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From: "Henry A. Watts"
Subject: Re: "line" critiques
While much of what Ross said is certainly true, the more general truth is that lines don't differ too very much among most of the cars you'll see at a club race. Get some motorcycles, NASCAR cars or F1 cars on the track and the story begins to change.
The line can be thought of as both the path the car takes and what the driver is doing with throttle, brakes and steering along that line. The biggest differences will be in the use of throttle, brakes and steering. For those cases where you're not hiding the right path from a competitor, practicing alternate lines, avoiding surface problems or trying to keep someone from passing you, the PATH is pretty much dependent on a few factors: the extent to which the car will increase speed from the beginning of the corner to the exit point, the extent to which the driver is willing to accept increased risk by using an earlier apex whether the car has the ability to generate powerbased oversteer on this surface at this speed in this corner.
Cars that won't accelerate much in a corner (most 914 fours) should normally be on a line that is pretty much a constant radius curve, which ends up being moreorless a neutral apex point. The greater the ability of the car to accelerate in the corner, the later the apex will need to be, but, again, the differences in apex point are usually a very few feet at most. The turnin point may be different by 1015 feed in the most extreme comparisons.
The safe line at the beginning (of a day, a career or learning a new track) involves somewhat later turnins and later apexes. The search for optimal lap times pushes the turnin and apex points back to a more neutral position.
With a car that understeers mightily, the driver might be on the brakes (somewhat lightly) to the apex and beyond, while a 911 set to "twitchy" might have to put the loud pedal all the way down before even initiating the turn. But the paths they are on will still be pretty similar.
A key exception to this is for certain turns where the optimal path isn't at all clear. There are some turns that involve intricate tradeoffs between finishing one turn and beginning the next. At issue may be where to be where you turn in to the second turn, with tradeoffs involving extra ground covered (to get wide enough for the second turn entry, for example) versus the higher speed through the corner if you do get wide enough. The real truth of the matter will somewhat depend on the length of the straight after the second of these turns. Turn 9 at Laguna Seca is like this, and there were also some issues at ThunderHill (original configuration) between three and four and 8 and 8A. At Seca you can see the professional drivers taking a number of lines into 9. The bikes (which are very much pointandshoot vehicles, sort of the ultimate 930) usually don't even bother to set a proper entry for 9, heading from the exit of 8A to moreorless the apex of 9, effectively creating the earliest apex conceivable.
Forgetting about formula, NASCAR and bikes, even within competent club racing you'll see a lot of variety in such corners. Ask 5 good club racers/timetrialers about their line in 9 at Seca and you'll get five different answers (six, if one of them went to Stanford!) hank
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Subject: proper line
I highly recommend Alan Johnson's book "Competition Driving." It is (in my opinion) the best primer for competition driving I've seen. There are many books out there, some of them VERY good. Henry Watt's book is also spoken highly of.
skip carter, trackside products,
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From:
Subject: Trail Braking
On Thu, 8 Jan 1998, Doug Donsbach wrote:
That is bangon. The purpose of trail braking is to induce oversteer. Application of the brake while turning will cause the rear tires to be overstressed to the point where they are losing some adhesion, which is what you want. Anything abrupt at this stage will cause the rears to slide even more causing more oversteer. It is the opposite case of the 911 plague trailing throttle oversteer. Paul Foster
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From: Farzaan Kassam
Subject: Accident.
>stoplight in the outside lane of a two lane left turn. Very wet roads but only >light rain at the time. I have an 88 951 with 3 month old SP8000s in the rear >and old SP8's with about half the tread left on the front
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You've asked for comments, so I will give them, but please realize that I was not there, so it's difficult to figure out what happened. I am very sorry to hear about your accident, and I feel that you did all that you really could to save the day. The most important thing is that you are ok. So, what would I have done different? I would have given in earlier. I don't know about others on this list, but I find that once the tail starts to slide in a 944TS, you get one chance to catch it, after that, it's best to ease off the throttle or if you are already spinning, put two feet in. Basically, if the rear steps to the right, you countersteer, if it comes back and swings to the left (I call this the transaxle toss), at that point, if you countersteer again, there is a good chance you are just increasing the velocity of the rear when it comes back to slide again to the right, so instead, I don't countersteer and keep light pressure on the throttle and keep the steering straight. That seems to bring the back into a straight line again without the second round of "ttossing". When it does straighten though, I find it comes into line really hard with a very sudden jerk, but it does straighten.
>straightened the wheel but ran out of road. By this point, I was doing under >10mph when I caught the curb with the right front at a slight angle (<15 >degrees). My control arm snapped right in half while my wheel suffered only a >1/4 inch gouge at the rim. From there, things only got
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Depending on how you hit the curb, damage can be super variable. I've seen some cars tap curbs where wheels and control arms are broken or even worse, the strut goes through the hood! I've also driven a car over a curb where the damage was a wheel with a 90 degree piechunk taken out of it with control arms and alignment still perfect (previous car).
>brain is working under those circumstances :( I also know I let the car try >to ride it out for 2 "wiggles" as it tried to grab. I did not come off the gas. >Should I have? I'm sure the rpms went up as the rears spun but I don't >remember.