Hello all! I'm looking at building a Street Touring car for next year's autocross season, and since Porsche just became un-excluded from the STS2 class I thought I'd see if a 914 can get it done. I know a member here built one and did well on a local level, but I'm looking for a championship car.

I was excited to see Porsches become legal because they always do so much better than the numbers would imply. Still, I need to make sure the numbers make sense before diving in. There's another car I think might have a better chance, but it's not a car I want to own for any reason other than being classed well. A 914, on the other hand, would just be a great car to have.

I'm hoping the Porschephiles here can help me out with my research. I want the lightest, most powerful 914 that can fit the biggest tires and take to the STS2 legal mods the best. For those unfamiliar with SCCA Solo STS2 rules, the car must come exactly in factory configuration except for the allowed mods. This means no using '74 engines in a '70 chassis, etc.

Rules allow cars with 1900cc motors or smaller.

Here are the allowances I'd want to exploit:

Dampers are open as long as they mount to stock points.
Anti-roll bars are open.
Wheels are open, tires are limited to 140 treadwear. More about tires later.
Springs must be stock type (torsion all around, right?), and must mount to stock points, but are open in rate.
Non-metallic bushings are allowed.
Camber kits of any type are essentially open.
Lightweight batteries are allowed.
"The air intake system up to, but not including, the engine inlet
may be modified or replaced. The engine inlet is the throttle body,
carburetor, compressor inlet, or intake manifold, whichever
comes first."
Chipping is allowed. On EFI cars a Mega-Squirt system may be installed in the factory housing, using only factory sensors.
Engine pulleys are open.
Seats may be replaced with seats weighing at least 25lb with mounting hardware - probably not an advantage with a 914.
Exhaust is free, but cats must remain in the stock location.

Suspension I can handle. I'll dig around for info on my own.

I really don't see much weight loss coming from that list How light can I get from headers/exhaust, battery (assume 10lb replacement), seats (are stock under 25lb with hardware?), and anything else on that list that can replace a heavy component? Note that I can replace control arms as part of the camber allowance.

Please say well under 2000lb!

Tires and wheels. I am going to assume a 225/45R17 is out of the question. With that out of the way, all my options are about the same size and should fit great: how about a 205/40R16, or 205/50R15? Or, could I squeeze a 215/45R16?

How about power? Is the 1.7L the way to go with those mods? Can I change engine management without adding sensors? I'm still checking out some threads, but so far I haven't had luck finding details. Not many people force themselves to work within these constraints, so it doesn't look like much of it has been done on the engine side of things. What does a decent condition bone-stock 1.7L put down with headers and exhaust? Custom headers are not out of the question.

Any help you can provide is much appreciated. I hear y'all are very good with knowing exactly what models came with what options and how much they weighed, which is a huge help in picking a car to start with.

Thanks,
-Phil

So no 2.0 914s; those are 1971cc. I assume that only the US-spec stuff is viable, in which case your options are:
70-71 1.7 == lightest, most primitive, most power
72 1.7 == almost as light, less primitive, most power
73 1.7 == heavier, less primitive, most power (or least power if you find the EB-code CA-spec 1.7!), better transmission linkage
74 1.8 == heavier, least power but for the CA-only 73 1.7, better linkage
75 1.8 == heaviest, least power, better linkage

(Note that "most power" == 80 DIN HP, and "least power" == 76 hp, except for those 72 HP CA-only 1.7s! Not a huge amount of difference.)

Since the suspension is relatively free, the fact that the early cars didn't have anti-roll bars is a non-issue. So I recommend going with the 1970 or 1971 1.7; the high-compression 1.7 made more power than the low-compression 1.8, and once you pull the spare tire out of it you have a car that weighs in at just under 2000 lbs.

Stock suspension is coil-springs in the back, torsion bars (different # of splines than the 911) up in front.




You'll want the hard plastic bushings, which are a pain to install reasonably correctly. Done wrong, they will bind up and give very uneven handling characteristics. There's an article in the most recent "Excellence" magazine about how to do them well.

You may gain a little power, and certainly some noise, by changing the air cleaner assembly for a lightweight cone-type one. A rain shield on it is likely a Very Good Idea...




Then you cannot use MS. Or chip anything. Because the primary stock sensor (the Manifold Pressure Sensor) is a weirdo electromechanical gizmo that alters the inductance between two coils of wire when it detects a difference in air pressure. And there's nothing I know of that can make use of that except the stock EFI system. You could make it work with 1.8 sensors and such, but the weight penalty of using the 74 chassis instead of the 70 chassis is probably going to wipe out the relatively-small gains you might pick up.




Non-issues; the pulley in the 914 is the fan. The only gain would be to remove the "fan belt" so you don't spend any power turning the alternator.

The stock 914 seats are much lighter than 25 lbs, IIRC. They're just a fiberglass shell with a little bit of padding and some vinyl covering. And the mounting hardware is pretty minimal, too.




No cats on a pre-75 914, so no worries there. The Tangerine Racing header is over $1K, but that's the one you want.




"Well under"? Nope. There isn't that much fat to lose on an early car. The good news is that it starts out under 2K lbs. You'll lose a few lbs going to the tuned header exhaust, but the rest of it is onesie-twosie type of stuff. A pound here, a few ounces there...

You can fab up some lighter control arms for the rear--there are a few really super trick ones out there that have the camber/caster adjustment out at the wheel end, so you don't have to mess with the stock alignment hassles. I don't think you'll be able to lose all that much weight, but a pound or two here and there doesn't hurt...




Are you allowed to modify the fenders in any way whatsoever? If not, you are stuck with 205 width at the most! And you might not be able to fit those either. The stock wheels were all 5.5" wide, and the 4x130mm bolt pattern is hard to find in aftermarket wheels. Particularly ones with the ~5" backspacing the 914 needs (Bugs share the bolt pattern but want about 3" of backspacing). Stock four-bolt Fuchs are about 13 lbs, so unless you can find some wider rims that weigh less than that with the right bolt pattern and backspacing, don't bother changing.




I would guess that you'd be putting out on the order of 85 HP, maybe as much as 90 if you're really lucky. If you were allowed to go into the engine, you could bump that up--but you're not, it appears.

With the rules you have mentioned, I think the 914 might be a real tough car to do well in. And that assumes that you are an absolutely amazing driver (if you're not, you won't be nationally competitive in any car!). I know you could put me in the total overdog car and put me up against the top ten national finishers in junker cars, and they'd still kick my butt...

--DD

Philip,

You may find some ideas in The Paddock . At least one other 914er has run STS2 and he may have some input.

good stuff from dave ...

a few things to add:

- engine: *if* you can dig into the internals of the engine, you can get around 180HP out of a 1.8L T4 motor. not going to be cheap or long lasting, but ...

- weight: dry weight if stripped of all unneeded things like carpets, sound insulation tar and various other elements will be under 2000 lbs.
my car is down to ~1900 now and i have a full rollcage and steel hoods and flared fenders and lots of bondo and seam sealer.
you *WANT* to start out with a '70 or '71 as those were the lightest chassis from the get-go! especially the early doors are much lighter ...

- tires: 205 will fit under stock fenders. 225 if you roll 'em.
how about flares? they were available from the factory, so you *might* me good putting on flares.
those will get you into the 245 (front) and 285 (rear) range ...

- exhaust: no cat on early cars. there are very good header systems out there.

Andy

PS:

PPS: early euro spec cars came with carbs, so you may get away with that as well.

I think its going to be tough to build a STS2 car from a 914 that would be a nationals winner if youre honest with yourself. The top cars Miatas and Honda Si's currently competing in STS would have a signficant power advantage over a 1.7 liter 914.

From my understanding you cant touch engine internals. Intake and chip mods are not really option for the motor. If you can add a header I guess you'd bump HP by about 10% Youre not going to get the car above 90 to 95 hp in STS trim. HP gains in T4 are from compression improvements and better flowing heads both illegal in STS.

Weight reduction. Can you lighten flywheel in STS? With 914 in AX its all about reducing rotational wieght - you can pull weight out of wheels by going with custom 9 lb wheels from somone like Keizer Wheels.

Can you use adjustable spring perches for rear springs in STS?

Tires - stick with 205/50/15. You wont have enough power to turn anything bigger with a 1.7.

Hope you stick with this however as it would be cool to see a 914 compete in STS - A good driver could probably get one in top 10 in STS.

I do not think the 914 or any Porsche is legal for STS2. You may want to check the rule book.

The 2007 rulebook lists them as excluded, but a FasTrack a couple months ago over-rode that. They're legal.



Of course, I see why they're legal. Even with a big CG height advantage and some of the other "Porsche stuff" I just don't see it even being close. An STS2 Miata is just as light, and has nearly 120rwhp in STS2 trim. Even not fully built it's over 100rwhp.

Bloody shame. I have to say - I've looked at a few cars and you guys gave me more awesome info in a few posts than all the people at all the other car's forums combined. If I can convince myself to buy a car that's not for competitive autocross use, I might just be back... In any case I'll be lurking, learning.

Thanks again,
-Phil

I think a 1.7 914 can be a fun choice for STS2, but there is little chance of it being a championship, much less a podium placing car at the big show. Locally, you can do really well. But Nationally it'll be a really tough haul.

The 914 just doesn't match up with the newer japanese cars that dominiate the class.

The 914 will weigh in around the same as an early miata. But the miata will have something like a 30 hp advantage, can fit 225's under the fenders, has a limited slip (viscous), and a much better suspension design.

-Josh2

Local fun, yes, national dominance, no. Here are some results from our club last season.


FTD, winning sts2, 914sts2,
32.7, 35.1, 37.3
71.3, 75.9, 79.5
79.1, 91.9, 95.5, (ftd was an Fmod formula 500)


The owner of the 914 will be helping us with our novice school this season, so he knows how to drive. And, he's co-driving a BMW M3 this season. That should tell you a little more. He still ownes the 914, but races the M3. I'd be nice if they (scca) would let the 2.0's in. I'd do that class in a heartbeat.

Only if they let in the 914 2.0L's and no other 2.0L cars...

-Josh2

Exactally. That would give us a power/wt that would keep 914's near the top of the class.

-70 car with window sticker 1980 lbs
-70 motor 80 HP stock.
-Tangerine 1 5/8" header cuts 30 pounds and adds some HP (10 maybe)
-Strip out all the undercoating andsound deadening. (up toyou to prove it came rom the factory under protest.
-Mallory Dizzy Pro E coil and Hyfire CD box
-Brakes Portefield R4S pads on stock stuff. end of story good brakes.
-Yokohama Advan tires 140 tread wear but grip like an R comp (expensive) but you got to pay to play
Koni 8610-1437 race front inserts and Fox rear shocks
21mm front T bars
Rear coil over springs to balance car
Limited slip
22 front sway no rear sway
CF race seats and sliders will put you lower in the car and provide better support.
CAmber plates up front
I would like to do it. Somebody get me a complete W motor and clean 70 tub

Hey Guys,
I own a nationally competitive STS2 Miata and 1.8L Porsche. You will be able to get the 914 to handle as good or even better then a miata. However, you will always be at a drivetrain disadvantage. STS2 only allows stock drivetrains and viscous type LSDs. So a fully prepped sts2 miata has 120 wheel hp, does not run out of gear(hits 60 in the top of second) and has viscous lsd. In the 914 you are going to make 80-95hp at the wheels, top of second is low 50s and you cannot use any of lsd that are offered for the 914.

I love my 914 but I would make a DSP car first.

Kyle