Learn me the Porsche 924S for track work

Weirdly enough, about six years ago I posted a thread asking about 924s. That thread has lots of good info but it's very early 924-centric. Today I am here to ask specifically about the 924S, singular "big S" that is, and see if one might be a good choice as a track car for me.

I know that they are more slippery and lightweight than the 944, which are Good Things. But how can you make one better? 150 crank horsepower seems kind of paltry from a 2.5L engine, though I know the torque curve is fat. What's the best way to take advantage of all that displacement and get that number higher? It seems like the AFM is a big bottleneck and weirdly a lot of chiptunes delete the O2 sensor, what the heck is the deal with this? What's the secret to more naturally-aspirated power from the 2.5?

Also, how do you make one handle and stop well? Are there 944 bits you can swipe to improve them, or is there a better solution? If I could go pretty far with 944 take-offs that could potentially make one a really fun and easy project.

I think I read that the last 2 years of the 924 used 944 suspension & brakes as well as the motor.

They also raised the car above optimum ride height to comply with bumper height requirements.

http://www.924.org/techsection/SuspensionPreparation.htm

There isn't anything more left in the 2.5L SOHC without spending cubic dollars. Sorry, but this is a fact of life. You can up the compression a bit, maybe play with different cam profiles, but they are pretty well maximized from the factory so you're just playing around in the noise range of most chassis dynos.

You can add displacement by swapping in a 2.7 or 3.0L block, but those are expensive and rare in comparison. Though I've seen two 924S with 16V swaps and one with a 951 swap, none of them are track cars though.

You can add a turbo or supercharger, but there's a lot of extra cooling and internal improvements needed to make that work for the track. Not too mention the changes needed in the engine management to provide the necessary fuel and ignition.

Ditching the AFM can help a little, but after you get the replacement EFI tuned as well as the factory solution, you'll have been better off swapping in another motor.

You can drop about 40lbs with a lexan rear window, maybe another 10-15 with the side windows, ditching the interior and using lightweight seats, gut the dash down to just the driver's side, swap in a 924 manual rack to drop all of the power steering weight, etc. Euro bumpers drop a few more pounds as well. You can probably get one down to 2100lbs if you work at it.

This might help for handling:

http://www.944spec.com/944SPEC/technical-articles

http://www.clarks-garage.com/shop-manual/susp-15.htm

Basically 30mm rear torsion bars with Ground Control's front and rear Koni struts, springs and upper strut mounts. Order the optional 944S sway bars from Porsche for about $100/ea, slap on some DOT 225/50 15 Ho-Ho's, freshen the bushings and other suspension bits and have some fun.

I'd freshen the motor up with new bearings, make sure it is built to the 160hp spec (more compression ratio via thinner headgasket), add a throttle cam and a cage in it and go Spec944/ITS racing. You'll get to play with the SpecMiata folks at many tracks.

If you really don't care about wheel to wheel racing, then look at an engine swap:

http://944hybrids.forumotion.com/

http://www.944-20v.nl

Do a sump baffle and the rod bearings. Lots of other longevity mods but start with those.

Just looked up the weight figures. 2765lbs for the 924S, 2790 for a 944? Well gee whiz, that isn't much of an advantage! Maybe a 944 really is the better starting point.

A 944 will always be 30lbs heavier. The latest models of the 944 were even heavier as they were moving them up market and trying to reduce the NVH. I know my 951S was a porker compared to my 924 and I could feel it.

Ditching the factory AC and power steering (pump, belt, hoses), Euro bumpers (or composite replacements), replace sunroof with composite panel riveted in place, remove the carpet, under coating, lexan windows, lighten the doors, etc.

In the end, you'll be faster than a 944 in a straight line, faster to accelerate AND decelerate. The 944 might have a slight advantage through a corner due to the wider track width, but on similar sized tires it's about even and more up to the driver skill.

There's really no advantage to using a 944 over a 924S. They are the same car inside and underneath as the early 944. If you like the wider body, there's composite flares available to make it look like a Carrera GT, GTS, GTR, GTP or a 951 all still below the weight of the 944 :)

924s trans is coveted by the 944spec guys.

Unless you are racing spec 944 the days of a 944 or a 924s being coompeditive are over.

Forget about upping the hp in these things. All the motor swap stuff you are talking about is great on paper but reality is it is not worth it. If power us what you want go get the car with the motor already installed.

Now what the 924s is a great sports car. Handling and brakes are its strong point. I raced mine for years and found that all you need is a pad upgrade. That is it. I ran cool carbon or porterfields. Never wad a want for more or better breaks.

Handling can be improved. One of the first things you need to decide is if you are going to go coil overs. I did not as I wanted the car to look stock to the casual inspection however the rear torsion bar spring set up is a pita to index if you want to upgrade the bars. But once done they work just as good and not having the coil over in the rear lets you run bigger tires. The basic handling package is eibach springs in the front lowering it about 1.5 inches. Hollow torsion bars for the rear. Weltmizer fully adjustable sway bars at both ends. Koni yellows and make sure you get the bump stops for the shocks and struts (sold separately). Add urethane bushings and you are done. Then corner weight it using the ride height adjustments in the rear suspension.

BUT THE MOST IMPORTANT thing to do first is deal with the oiling issues that the motor has. The laied over motor and the angled pan walks means sweeping left hand turns will starve the motor of oil and #2 rod bearing failure is guaranteed. Over filling tge oil helps but I still killed two motors. Adding an accusump solved the problem.

These are great cars that are lots of fun to drive. If you want to compete for wins in anything other than spec 944 go get a different car. I always joked that spec 944 was created because 944s just can not compete with other cars.

Tires. My car was faster with 225s but was also more on edge. 215s or even 205s were much nor fun. I recommend them until you learn the car as the breakaway is more predictable.

Enjoy the car for what it is. The money spent trying to modify or increase power with the stock motor is big and you don't get much return on your money spent.

Make it Handel and stop and address the oiling issue and go have fun with it as is. When you get board with it move on to a 951 or somthing.

I have had my 924s for 27 years and it still makes me smile every time I drive it. It is a car that by the numbers is really not that great by today's standards but the driving experience is fantastic. It really is more than the sum of its parts.

Think old sports car not modern sports car.

Am I correct in that the 1988 924S already has the 944-spec engine with more HP? So really that is the one you want to start with?

Also, would you experts say this is a good deal, or something to run away screaming from? (968/944 hybrid)

http://chicago.craigslist.org/chc/cto/5535471450.html

87 has pre 85.5 motor and a mix of pre and post 85.5 suspension. 88 is all post 85.5 944. Both are 100% 944.

For racing I like the 87 cars as the consumables in the front suspension are cheep and easy to source and easy to install. They have stamped steel a arms. 88 has cast alu a arms with an integrated ball joint. Much more of a pain to service.

Stop fixating on hp. Unless you are a professional driver you will never know the difference.

My formula is.

87 924s. 83 short block. 89 cam and head. Suspension and brakes as noted previously.

Ohya I am a hair under 6' tall and with a helmet the stock seats are to high. You will need an aftermarket seat mounted lower if track use is planned.

I was thinking.

A 924 or 944 is 160HP at 2700lbs = 16.88 lbs / hp Here are the Miata Specs I could find:

• 1990 NA 1.6L 2182 116 18.81034483 0.053162236

• 1991 NA 1.6L 2182 116 18.81034483 0.053162236

• 1992 NA 1.6L 2214 116 19.0862069 0.052393857

• 1993 NA 1.6L 2223 116 19.1637931 0.052181736

• 1994 NA 1.8L 2293 128 17.9140625 0.055822067

• 1995 NA 1.8L 2293 128 17.9140625 0.055822067

• 1996 NA 1.8L 2293 133 17.2406015 0.058002617

• 1997 NA 1.8L 2359 133 17.73684211 0.056379822

• 1999 NB 1.8L 2299 140 16.42142857 0.060896042

• 2000 NB 1.8L 2332 140 16.65714286 0.060034305

• 2001 NB 1.8L 2387 142 16.80985915 0.059488898

• 2002 NB 1.8L 2387 142 16.80985915 0.059488898

• 2003 NB 1.8L 2387 142 16.80985915 0.059488898

• 2004 NB 1.8L 2447 142 17.23239437 0.058030241

So it is basically the same as an 01 - 03 miata BUT it is heavier so in the end a Miata should be faster

924s and 944's are a porky Miata. They are not going to impress you with acceleration and HP increases are probably 4x as costly in a 924s/944 than in a Miata. (Trust me I know this)

It sounds like you need to go get a F body. Build a 350 stuff it in and go have fun if you are looking for something to scratch the HP itch.

pointofdeparture wrote: Am I correct in that the 1988 924S already has the 944-spec engine with more HP? So really that is the one you want to start with? Also, would you experts say this is a good deal, or something to run away screaming from? (968/944 hybrid) http://chicago.craigslist.org/chc/cto/5535471450.html

The 160hp is a matter of giving the 924S the full 944 motor, versus the previous one with the slightly lower redline and compression ratio. Thinner HG and a standard HP chip and you'll be there.

as I mentioned on FB, that 968 hybrid looks interesting, certainly better for track use than a turbo car (they will break you monetarily if you mod and track them a lot, they are just highly stressed and you're burning the candle at both ends). Verify the timing belt and cam chain guide are in good shape and it will reliable for hundreds of thousands of miles with normal maintenance.

Did I mention that I have a long term project that includes bolting on a MS2 and a M62 supercharger that is a hybrid that I combined the back housing from a c230 Kompressor and the front snout and impellers from an early Supercharged Riviera? For the $$$$$ I will have spent when I am done I could have gone and got a perfect 951 but what fun is that? I will be the owner of a 924ssc.

Here is a excell sheet I created to calculate a bunch of stuff as well as look at the bernoulli effect calculations looking at the disruption of the air flow in the piping at different diameters as well as rough PSI.

http://www.ehadesign.com/~dsmith/ENGINE_AIRFLOW.htm

F body's have pop up headlights as do the early Miata's..

dean1484 wrote: Stop fixating on hp. Unless you are a professional driver you will never know the difference.

You will certainly know the difference if you are the slowest guy at your track day a wide margin!

I've talked about this in other threads. My local track is Road America, which is a very long, very fast track. The reason I haven't just gone out and bought a Miata is because the number of guys running cars at that speed level has just about dried up. I was wondering if something like a modified 924S might bridge the gap between a Miata and something like an E46 330i speed-wise. Unfortunately it is sounding like a modified Miata might actually be the better deal, though I am still surprised that it's easier to get 150HP out of a Mazda 1.8 than it is to get 180 out of a Porsche 2.5. That said my fixation on the 1987/1988 difference is that if I'm starting fresh, might as well begin with the engine that's already 160HP.

The 968-swapped 944 may be just right if it's put together well, going to call and have a look once I'm done moving next week, otherwise I will probably end up with a MR2 turbo or similar like I was originally planning on.

In reply to pointofdeparture:

Yeah and? Watch your mirrors and let the fast guys pass, pull off into the pits if you need to.

Its not a race, its a track day and you're supposed to learn and have a little fun.

There will always be someone with more speed and I guarantee you that folks driving Chump/LeMons cars among others will take advantage of track days and they aren't exactly fast either.

I have way more fun driving a slow car fast than the other way round. Who cares what the other people are doing. Are you on track for them or for you?

If a fast car is more fun than go for it. It really sounds like a c5 zo6 is where you should look. Dollar per fastness (not sure that I a measurable thing) it I one of the best deals out there.

What about a 350z? GRM did an article on those a while back. Those seemed like a good step up from a Miata.

Probibly a dumb question but how much track experience do you have? Decades, years, couple of track days? This would help. Not being a wise guy we need to know. A zo6 at your home track is probibly not a car that I would recommend to someone that only has a couple track day sessions.

I had a summer's worth of events (about 6) under my belt in a BMW 330ci (~230hp, ~3300lbs) and had moved into the intermediate run group when I sold the car. I don't think it's worth stepping down to a significantly slower car unless I'm going to learn something from it, which is why I'm looking at MR2s, as it's an excuse to learn mid-engined driving dynamics. And good luck finding a C5 Z06 for $5k, as much as the idea sounds great

Regardless, I already had my list whittled down pretty narrowly to suit my budget and desires (MR2 turbo, 6-speed C4 'Vette, Z3 2.8, RSX Type-S) when I came across the 924S and the 3.0-powered 944. Figured I'd ask to see what the consensus is. Unless that 3.0 944 is real nice, I'm just going to continue searching for my original picks.

When I get another it I going to be a S2. To me it is the best balance of motor to car and I like the looks much better than the 968. However they are closer to 9k and up for a decent one.

I'm with dean1484 much more fun to go fast in a slow car. At track days I instruct as well as run the 100 whp wonder in the intermediate group. When you pass people in faster cars with a gutless wonder they tend to take advice.

@pointofdeparute moving up in six events is pretty good. I am curious were you going faster than the Spec Miata lap record? I think it's 2:40 to 2:41 at RA. I seem to recall seeing posts on one of the forums that intermediate guys in Vettes were doing between 2:40 and 2:45. When I instructed at an NSX event several years ago, someone mentioned laughingly about turning 2:45s in a stock NSX at RA and how they were getting their butt kicked by racers in Miatas.

Since you are not bound by a rule book I'd build a 924S and learn to go fast in it. You could do the same with a Miata by converting it to super Miata spec. Here is the thing with slower lighter cars; I see video of people in higher horsepower cars getting up to 115 before turn 1 on my local track. (Spring Mountain Motorsports) I'm hitting 106 but I'm also entering the front straight at 80mph where they are only doing 75mph. Why this matters at track days is very often faster cars I've passed just start to catch me but run out of room before the passing zone ends. With each section of turns I pull out several car lengths and steadily pull away. The approach in a momentum car is a mindset of stringing together a series of good laps, this takes a lot of focus and experience to get the most out of.

I make this comment about driving a momentum car; once you turn the steering wheel you should be a passenger from that point until you exit the corner, if not you're not trying hard enough (please don't do this at RA or track days). At track days I might drive about 95% of this level and if I do drive 100% I won't do it for more than a lap or so. I see very few people, especially in the lower groups driving a car on a trajectory, they might get 100% out of the front tires or 100% out of the rear tires but seldom get 100% of the front and the rear tires at the same time. This is understandable as many of the cars need to be driven home. I have a full cage, fire system, fuel cell and HANS device so I'm not taking the risk they are.

You will be a much better driver after a year in a momentum car.

Now with all that said there is nothing wrong with buying a fast car they are lots of fun, they just go through tires faster.

Tom

I think at the end of the day, it will come down to whatever I can get the best value from. I watch Craigslist like a hawk, if a really well-kept example of something comes around for a great price I very well could end up with something unexpected!

In reply to Tom1200:

I agree compleetly. Also just because you have a fast car you may not be going fast.

Everything you said about driving a slow car fast and piecing a set of corners together is something that most people don't get.

The other thing that I find irritating is when I get behind some high hp car that blasts down the straits and then tiptoes through the corner. That is not a fast driver that is a fast car being driven by a slow driver.

@ the OP. Sorry but 6 track day events does not make a race car driver. I have been doing this for 30 plus years and I am still a student. You now have conference and the need for speed. This is excellent but needs to be tempered so as not to learn bad habits and get to confident ad develop a dependency on HP.

In a fast car everything happens faster and the opportunity to learn is that much smaller. Your ability to process all the information in a fast car is harder if not impossible and for that matter you will probably miss things. Slower cars let you process all the incoming information and you can then use it to work on things that in a faster car you would never know need improvement. Faster cars don't make for better drivers. Also don't confuse faster and capable. Your 330 was one of the most capable cars you could get. BMWs also have the ability to cover up many a drivers shortcomings. It is why people like them so much. They are easy cars to drive.

What Tom1200 said about using 100% of all four tires is something that separates the average track driver from the truly talented driver. Once you learn how to do that in one corner then you can work on stringing together two and then three corners and after years of trying you may get that one perfect lap. This is the ultimate pursuit of track driving. I call it drivers OCD-ADD

Obviously at the end of the day we all do this to have fun. That is the end game here. If not having STOD is at the top of your list to having fun purchase accordingly.

My having fun wants after doing this for a while is to try and drive the perfect lap (or as close as I can get). But also important to me is consumables and there cost as well as ease of obtaining consumables. Ease of working on the car and the overall simplicity of a car are important to me. My 924s does not meet these. Parts are expensive and rarely on the shelf anywhere. Working on it is a pita compared to a Miata or a fox body. On the flip side when it is in good running order it is one of the best balanced cars that let you feel what is going on at every corner of the car. This is a very rare thing and why I put up with many of its short comings for all its years on track.

Great info and insight in this thread guys, thanks for sharing

So, I do understand all the 'drive a slow car fast' comments here, but I have also driven road america with BMWCCA.

Now BMWCCA probably attracts faster cars than other sanctioning bodies, but I also think RA does. Fees are higher than most tracks for track days, and that means more expensive machinery shows up. Long straights mean the turns don't equalize cars as much.

I was in the instructor group (even though I am a much better instructor than I am driver) with a 302 swapped e36. The sheer difference is speed between me an the e92 M3s, c6 zo6s, and 911 GT3s was more than a little unnerving. It was like riding a bicycle on i70 through Kansas. I actually stopped driving after a few sessions because I was uncomfortable and I felt like I was a moving road hazard in that group - worked out ok though because I got to spend more energy focusing on my student.

other than the various e92 M3s, c6 zo6s, and 911 GT3s there was a 135tii (the one year 1 series M car), a few ferraris, vipers, a few e46 m3s, some lotuses, etc. The beginner group wasn't quite as bad, but still the e36 m3 was a lowly piece of equipment in that group.

I am a firm believer that RA is one track where people should be separated by both skill level and HP/bracket lap times/etc.