aualexa2

Hi guys,

My 991s had been a daily driver and weekend autocross toy, but I'm considering making it a more dedicated autcross/track car. What modifications would you make to optimize its potential while not breaking the bank? My initial thoughts were lighter seats and new exhaust (it does not have PSE currently). What else would you recommend, and if you know the cost of the modifications, could you post that as well?

TIA

Porscheforever

Take out the rear seats
Straight or X-pipe
Lower the car
Racing fuel

chuck911

You're asking the wrong people. There's an autocross forum. However since nobody reads that I'll help you out.

First up, if you do want to autocross other than just for fun and driving experience, then that means you want to compete, and THAT means nobody can answer your questions without knowing the rules. So determine which group you care most about auto crossing with. Get their rules and study them.

Generally, as in almost always, the fastest car in any category is the one with the most allowed modifications. So any dreams you have of finding some magic answer, forget about it. In racing, he who spends the most wins the most. Once you understand the rules and become familiar with the allowed mods you should be able to walk the grid and spot the cars and notice exactly what I'm saying, that the fast guys have done everything. The others spent a lot but got nothing to show for it, and you can practically rank them by what they spent. Plan and budget accordingly.

With a Porsche, almost always your best bet is to autocross PCA stock. Even PCA regions vary so you still have to DYODD but most of them have a stock class where you'll compete with half a dozen similar 911 variants. Even in stock there will be a list of "free" mods like seats, seat belts, and brake pads. In other words you just spent $5k and your car is still stock! Changing exhaust like you mentioned, usually will put you in a higher class where you can spend another $20k and still be just middle of the pack.

Another consideration, in setting a car up to win at anything beyond stock almost always results in a car that is just plain too stiff and uncomfortable to drive even just to and from events. Even if you can tolerate it, you'll be running Hoosiers and they won't. Look around and see how many winners drove there. They come on trailers. Plan and budget accordingly.

Here's a true story to illustrate. When I was doing this regularly there was a group of us with very similar cars. We all had 2-4 or more years track and autos experience. We all had done the usual things- stiffer bars, R-comps, exhaust, etc. We were all very close. One year one guy takes his car to Fordahl Motorsports
says do what it takes to win. Greg made every allowable mod. He shows up next season, instantly #1, and proceeds to win the championship three years running. Of course his formerly fun to drive car is now always on a trailer as its undriveable for anything else, and his bank account is $35k lighter. Not counting the trailer.

Oh, and that was an '85 Carrera. So pick your 991 multiplier, budget and plan accordingly.

chuckbdc

Assuming you have seasons of intense learning from the folks who are fast, and you know how to tune the handling with tire pressure, the most effective place to start is suspension alignment, dedicated optomized rubber and lowering and stiffening. The marginal gains from removing seats and making the car louder are tiny compared to lowering the center of gravity and making the tire contact patches work for you.

drcollie

Ho boy, this is a sticky wicket.....

First, how good are you? Can you routinely and regularly take one of the top two Auto-X spots in class at your local venues? Are you an A-Group driver on track days? if the answer is 'no', then what you need to is sharpen your skill set, not upgrade your car. A 991 has a VERY high set of limits stock - only a few people can get 10/10ths out of the car consistently, lap after lap, event after event.

Next Autocross you go to - set your best time of day, then go find the hottest guy there and ask him to drive your car across the course at the fun runs at end of the day, give him two runs. If your best time is within 1 second of his time, then perhaps you can look at upgrades (which in AutoX is not exhaust and seats, but tires and camber). If you're not within 1 second, then you need to keep improving your skill set.

Same with the track. If you are not an A Group driver or an Instructor - you need to improve YOU.

I have been an Instructor for 18 years now, and can routinely place in the top three in Auto-X at local events when I go. My 991S is stock - that's how good the car is.

bigkraig

tires

Rallyeporsche

+ 1 on the tires

chuck911

See, that's what I'm talking about. This is all good advice. Great advice even if you just want to have fun, drive better, etc. It just won't get you far if you want to win. Or even if you just want to move up the rankings.

For example, tires. Great idea. So you go buy the stickiest R-comps or Hoosiers you can find. Instantly you are 2 sec faster. Yippee! Only then you find the tires put you in a class where everyone is 3 sec faster. You spent all that money to LOSE WORSE!

chuck and drcollie are right, intense learning to improve YOU is the way to go. Even my friend, who basically bought himself a trophy, was only able to do this by having FIRST put in five years learning how to drive.

ADias

Best advice here. But… the mod bug is strong and it's tough to consider oneself the weak link.

chuck911

That's the problem. It is so totally the easy way out. For starters everyone is egging you on. Look how fast people are to recommend tires. Look at all the other threads where everyone is encouraging the guy who wants to mess up his car. "He's spending money! Yay! Go! How wide can you fit in there???" All the backslapping feels quite good. Until you find yourself creamed by some guy like Bill Beutow utterly embarrassing you in a stock 924. http://www.pnwr.org/Track/autocross/...odifordahl.htm

Thus the old drivers advice, the first part to upgrade is the nut behind the wheel.

aualexa2

Thanks, everyone. I appreciate the advice. I am far from being the best driver out there, but I'm working on it. While I put my time in and work on my driving skills, I don't see any reason not to upgrade my car at the same time. Why should the two be mutually exclusive? I also don't really care about winning my individual class at autocross. I'm much more interested in driving my car as fast as possible and having as much fun as possible!

Grunty

Gee, that sounds like fun...

I am assuming that not everyone who goes to PCA auto cross days is that competitive?

aggie57

Personally the most fun I've ever had on the track was sharing a cheap car with someone else. No ego's, no hardware advantage, someone to share the costs and share the learning.

Having said that, yeah it's a mix of skills and car. No reason to be exclusive one or the other. Have fun!

chuck911

Yeah, you're right. They are all just out to have fun. Which they define as winning….

drcollie

Well then, let's look at a few things! First of all, a car set up for Autocross is not the same configuration as one set-up for the Track. In Auto-X, you are doing sharp turns and sprinting with low speeds that require a tire that gets hot instantly. For the track, you will be doing sweepers, need different suspension settings and want to run tires that will last a little longer than the Auto-X ones. If you take a well-set up Auto-X car to the Track it will down right scare you as it will be extremely nervous and twitchy at speed due to the aggressive camber and toe settings. If you are setting up for the track, then you want clean body work - no spoilers as they cut your top speed down and you won't have the suspension settings or tires needed to take advantage of 'real' down force.

But let's assume you want to move in that direction. The first thing you need to do is install safety equipment in your car and this is going to eat up most of your money. At the very least, a Roll Bar or Cage, 6 point belts and then a proper racing seat that will be 1-piece and hard-bolted to the floor (non-adjustable). Now you will not only keep from sliding around inside the car, but stand a really good chance of surviving a crash at the track while you go "as fast as possible". Street cars are not designed to crash at high speed with any degree of survivability (over 40 mph). In a 400 HP car, you can get serious speed going and the roof will go flat as a pancake if you roll it.

Next is tires. R-Compounds. You'll need an extra set of wheels for these and ideally someway to haul either them or your whole car to the track since they are heat-cycle tires. That is, they lose stick every time they get hot and have almost no protection against road debris and nails, so you don't want to drive them to the track unless its a very short distance away. After that, brake pad upgrade to take advantage of the extra stopping power you are getting with R-Compounds. Pretty much that's it because you just spend $ 12K to 14K on all this (Safety Equipment plus Tires/Brakes).... but if you have more money left over, then its time to go to work on the suspension. Also budget or a truck and trailer since you will want to haul to the track and auto-x, not drive to it.

Notice that none of the emphasis above is on speed. Its on cornering and braking. Speed is for drag racers. You can spend a lot of money for 30 more HP (real, not the imagined crap from people trying to sell you exhausts) and that 30 HP will give you 3 car lengths on a lap, if that. However, tires and brakes will give you 20 car lengths. You can pickup more time driving harder and deeper into a corner then you can accelerating on the main straight.

Anyways, thats the way to go - or you can buy into what the aftermarket guys want to sell you to 'go faster' and spend money on their bling if it makes you feel better about it.