71 E -> Gentleman's RSH thread

Thank you Steve for your insights.

I had a feeling at some point my delving into the details of RS production would draw you into providing your expertise. I had no idea the RSH/Homologation cars were called the "basic" car by Porsche - in either case, replicating the car as delivered to the scale would seem an impossible task, and one not particularly suited to road use given their limitations (the tire size in particular would make a homage to the "basic" iteration a questionable pursuit). I'd also tend to agree that enthusiasts/"the market" seems not to fully appreciate the differences in the construction as Porsche got past the first 500 (or even the first 50 as you point out), all of which gets into the questions of how far to pursue replication in trying to capture the essence of the 2.7 RS. To my mind (and sharing my views are not intended to court controversy, but rather to elicit the views of others, particularly as those on this board have far more knowledge than me), there are two key elements to creating some vague sense of a tribute: as you focus upon, lightweight; and the engine and drivetrain. To be clear, the point of my creating Karen as a M471 replica is to essentially replicate the process I would have undertaken had I been someone of some means in late 1972 who wanted a sportscar that they could drive to the track, track, and drive home with reasonable confidence. Whatever my financial means, I don't think I'd have the cajones or desire to take a true M471 car from the first series of production and do something like drive it to Watkins Glen (on rt 17, which is one of the best driving highways in the world, particularly if you fly fish) and track it anywhere near the limit - hence the motivation for the car is essentially to have the car I'd like and in no regrets fashion so that I can use it freely. Lightweight is the essence of Porsche broadly (at least before they began producing SUVs and other passenger cars) and specifically of the RS line as it continues today (even though one can't, at least in the United States, specify the removal of an infotainment system and the addition of a factory roll cage, but I digress).

A lightweight car is to my mind a critical ingredient of what makes the early cars so attractive to drive. As you implicitly point out, a true clone of an early production RS is near impossible with a regular long wheelbase shell. Porsche currently manufactures some of the lightweight panels, which I am employing in the construction of this car, but not all of them. When I started this journey, the ideal "donor" would have been a '69 912 given its relative lightweight, with weight increasing as the years progressed due to the addition of safety features (e.g. 72/73 doors weigh more than earlier doors due to additional safety steel). Byutilizing the lightweight Porsche panels, an aluminum hood, and a few other tricks, my car should come in slightly below what would have been expected from a M471 built from the factory in '73, though in slightly different places. Also as you note, lightweight can be sacrificed for driving dynamics to the extent added weight materially improves performance, as do some RS "innovations" - the reasonably well-known transmission reinforcement as well as the RSR reinforcement of chassis/suspension contact points and the ability to put coil overs in the rear. For all of these reasons, I don't know that I'd call a backdated car that began life as a later impact bumper or even 964 as reflective of the driving dynamics of a RS compared to starting with a longhood. For those that are comfortable making a homage to a late series car, there is relatively less of a distinction to regular series production though I suspect you'd agree that an M471 from a car say in the 1300's or 1400's isn't the same as a M471 from the first 50, which makes it surprising that the market doesn't seem to delineate much for the order of production for these specialized cars (whereas the experience of a M472 RS, laden with things like sport seats and, gasp, power windows and a sunroof, is reasonably close enough across the production range even if the ducktail has a steel rather than aluminum frame that a '73 T base for a homage is entirely appropriate).

The other quite critical ingredient, at least from my perspective, is the high-strung motor and drivetrain (most specifically the gearing of the transmission, but also including a LSD). While I have no problem with owners plopping in a later motor into an early car for improved driving characteristics for the experience they enjoy , to my mind the most important (and appealing) characteristic of the early cars - particularly the more powerful engines - is that the power bands are narrow and at the high end of the rev range. The appeal of driving the cars, which admittedly is a function of my driving on rural roads, is that all of the fun happens between 4500 and 7000. The later engines with smoother torque curves deliver a different driving experience. To be fair, the 911/83 engine has a much flatter torque curve than most of the high strung early engines and is thus the "laziest" engine of the early cars (though it also delivers that magical feeling of getting on-cam higher in the rev range). Similarly, while Porsche has shown to great effect the value of turbo engines, I have no interest in them and think naturally aspirated is a critical ingredient of any homage to an RS (particularly as that remains true to current production). Needless to say, gearing and its relation to the torque/power curve of the engine is also essential (in my mind) to recreating the RS experience, and for a M471 recreation, so too is the presence of a LSD (and quite frankly, I have no appetite for driving a non-LSD car on the track given the way they behave under heavy breaking in addition to cornering).

Thus, I'm largely agreeing with your point on the specialness of the early RS production cars due to the lightweight philosophy which ran through these cars (and is more than just replacing the door cars and carpet), though I do think most anything that is a "homage" needs a similar engine and drivetrain (and MFI system). That is not to disparage cars with later systems, but to suggest that they become more of an RS-look car than a proper replica built either to the exact standards of the original (which is near impossible) or to attempt to capture the essence of driving one. I am very sympathetic to the aesthetic appeal of an RS given the body is to my eye the perfection of the 911 design. Though I love my S/T replica, I find the flares awkwardly large and exclusively appealing insofar as they allow wider tires and more traction (and at the risk of alienating another large share of our community, also view RSR and turbo flares as excessively large and "weighty").

Apologies for all of the text, my next update will have more pictures!

One additional point I'd make is that it is near-alarming to feel the difference between a conventional fender and a lightweight one. The thinner steel makes a difference. The difference between an aluminum and steel hood is more extreme - just as a heuristic, it is easy to pick up an carry an aluminum hood, whereas a steel one feels heavy to pick up and is noticeably harder to maneuver around.

A few years ago at the PCA race I took advantage of the scales and had Karen weighed - she came in at 2395 with me (215 lbs) and a 1/3 tank of fuel (est. 75 lbs) as well as the roll bar. Her weight bias was 35% front, 65% rear (she handled much better with ~3/4 tank of fuel). The car already benefitted from being built to race in solos/autocross, though my hope is it will come in a bit lighter. The M471 spec is rumored to weigh ~2150, so I am starting with a lighter car and with the addition of the lighter Porsche body panels and glaverbel glass, I should be reasonably close if not lower...

Don't apologise for the text. It’s interesting to see your thoughts set out in some detail. Enjoy it

Steve

a long time ago i bought some front fenders that were in a fire
I took them to my chrome guy and had them acid dipped
they were incredibly lighter

It’s not just thinner .8 metal it’s the absence of nearly all dimpled shutz on genuine early RS. Bonnet underside being just one case in point. Basic form (before they stopped bothering making them to proper spec after the first week of April) had to comply with nominal 900kg (~1984 lb) homologation weight target as shown in the model’s homologation papers. Weight of each early chassis was verified and recorded against the vin number after being driven to the independent Stuttgart town scales the paperwork being available to FiA as part of the evidence of 500 (plus 500 more) instances being made in compliance to the spec .

I think it was the acquisition of the 911/83 engine that sent me off into the deep-end in terms of building a "clone" rather than a "tribute."

For the most part, my contribution to the car has been finding parts and paying for them. Unlike many of you who actually do the hard work and do body work, paint, or even engine builds, I just exercise my hand in writing checks.

I have been much more involved in actually fixing things in my targa, and one of my forever projects has been re-webbing the autoflug friction belts that are correct (but not original) for the car. Like many of you, I was able to buy the webbing from Stretch on this board, who was extremely helpful and also provides the silk labels with your order of the webbing. Somehow I managed to convince him to send me both 1970 silks and 1972 silks, the latter destined for the RS. I was also able to source some NOS(ish) 72+ friction belts with the orange ROW tracer from Dirk, but then they had '75 and '76 silks on them. It has been a long-standing project to tackle all of this seatbelt work and I had hoped to contract out the work because I neither know how to sew nor had a heavy duty sewing machined needed for sewing seatbelts. After years of the occasional inquiry and search, I still couldn't find someone to sew the belts for my targa and the silks for the RS clone. Capitulating, I researched the right sewing machine and UV-resistant thread, procured my supplies, and let the whole mess sit on my dining room table for a few months. With the car starting re-assembly, procrastination no-more, so I sat down last weekend and taught myself how to load a bobbin and control stitch size, and behold...I will have the correct tension belts with the correct silks on them. Chances are no one will ever notice other than me, but my experience with my targa is that restoration is about an audience of one.

Attachment 623140

Note that I didn't stich the seatbelts beyond the silks - that sort of sloppy stitching is as it was from the factory. The autoflug belts/stitching is even worse. Many details we get wrong because we assume a level of perfection/competence that wasn't practiced at the time, though from my understanding, I'm happy not to have a factory paint job!

With the car emerging from paint, one of the more interesting details, hopefully of value for the community, is the entenbürzel or what we colloquially know as the ducktail. For many, it is enough to slap a reproduction of one onto the back of a longhood, call it a RS tribute and be done with it. To be perfectly clear, there is nothing wrong with that - particularly if engenders pride and results in more use of the car! My scratching and sharing neurotic attention to detail is mostly about sharing what I believe are fascinating nuances about these cars than it is encouraging (or demanding) a similar journey down the rabbit hole (though it is fun).

I had the good fortune of being alerted to a genuine ducktail for sale by Dirk and had the good sense to write a check at a reasonable, if still exorbitant, price. Again, I am no expert, but have the good sense to employ genuine experts and a few observations about real-deal ducktails. First is the shape, as discussed in a few threads on this forum. There is the shape of the tail, its size, and then the angle at which it emerges from the engine bay. To my eye, most of the reproductions get the angles wrong, but that's not the point of this post. There is also the frame, with the fiberglass mated to aluminum early in the RS run, and then later steel (presumably through the MFI cars and when factory ducktails were sold through dealer parts departments, though honestly I have no clue on the aluminum/steel timelines, etc). I was fortunate enough to get one with an aluminum frame, with only a modicum of damage to the fiberglass-frame joints. The main benefit of the frame is that the tail sits correctly on the car and as a result there isn't any twisting of the fiberglass or large panel gaps provided everything is assembled well.

Finally there is the fiberglass layup and the actual fibers visible on the bottom. This is what the below photo illustrates - for lack of a better description, the fiber is long-grained and quite visible in the factory-bürzel. Now, this ducktail arrived to me in white (as in earlier photos) and it would have been simple enough to just spray over it and call it a day. However, that would have hidden the fiberglass! Instead, the extremely skilled folks at Automobile Associates figured out a mild paint stripper that would, with repetition, strip the paint in the most gentle of manners while preserving the underlying structure. The result is an identifiably factory ducktail. Like the silks, it is a detail that will never be seen and it is doubtful anyone other than me will even notice it. That said, it speaks to the skill and care of those completing the restoration (as well as the business acumen of AA to encourage the deep neurosis of their clients).

Attachment 623141

Final one...just the rear brake light opening and the crisp factory stamp on the lightweight steel (which really is different, but more on that later).

Attachment 623142

Given this is a build thread and theoretically should provide some insight on tuning and tweaking early cars, I figured a beneficial detour may be going through the build of my targa - Rick. She is a 1971 911 T Targa (9111112883) that was a little "rough" when I bought it, but it had solid bones (floor is original, it required replacement of the front clip for the normal battery acid issues, some rocker and kidney rust repair, but otherwise had quite a bit of original paint and the tub was solid). Through the years I've owned it I've spent quite a bit of time making it into a "sleeper" hot rod for the rural backroads that I predominantly drive - no flares, not even rolled fenders, but fast as F. Too fast to be honest, but if drugs were as good as shifting from the redline in 3rd into 4th, I'd be a crackhead living under a bridge.

With that as a preface, my judgement on the order of importance:

Seats. Fairly quickly I swapped out the original comfort "buckets" for the Deser replica sport seats and finally in the last year I've installed original sport seats just to compliment the car (the interior is all original parts/vinyl so the new Deser seats were too nice relative to the patina of the rest of the interior).

• I am tall - 6' 4" - so the driver seat is mounted as low as possible. No tilt bracket, I used the Zuffenhaus bucket lowering brackets in combination with SC sliders which are the lowest profile sliders that you can use with the (I think) '69-73 sport seats that have the mounting brackets mounted to the seat base, rather than the earlier seats that have the sliders between the seat and bracket. In theory the early sport seats would be better to lower with the Zuffenhaus brackets. The passenger seat is mounted on a single locker tilt bracket to allow access to the back seats (which my girls readily use, though the dog rides on the shelf more).
• Though I prefer the fixed seat belts due to the fact that you can tighten them and slide your seat up into the preferred driving position and be anchored somewhat similarly to a harness, I use the autoflug friction seat belts which are very cool because they retain the original repa tongue and receiver, which is a foundational memory of mine from the old 912. Unfortunately I had to cut the rear 1/4 panels and install the targa seat belt guides which are NLA and hard to find!
• If you have sport seats, have them add extra padding to the lower bolsters - it is more comfortable to sit slightly on top of the bolsters than to have your rear end squeezed between the two.

Suspension: I added Stock S sway bars (15mm) fairly quickly in ownership, along with replacing the shocks with Bilstein sports, and all new rubber. I have plenty of experience with polybronze and delrin bushings in my two other longhoods and for the street, you don't need/want more than rubber.

• I also have the bump steer and turbo tie rods and switched the torsion bars to 930 (19 and 26MM). Lowered to European ride height. The suspension is perfect - it feels much more modern than stock, but not track stiff where you are bouncing around on anything but the smoothest roads.
• The steering wheel is a 380mm 914 wheel (aka the RS wheel). I include this in suspension because I strongly believe feel is improved by having the thinner wheel where you can use the tips of your fingers to steer and feel the road. The front-end feel is one of the more amazing traits of these cars and thicker wheels (i.e. the prototipo) reduce some of that feedback, in my experience. Maybe I am delusional, but I think the thin-grip 380mm wheel and the 6j wheels in front allow the car to dance much more than either my RS "tribute" or S/T clone do given they have much stiffer suspensions and bigger tires in the front. The thick wheels reduce feel which is fine on the track when feedback is more extreme and you are muscling the car a bit more (and smaller diameter is more appropriate- I prefer 360 for turn-in, I get too jerky with a 350mm wheel, and worse smaller).

Wheels: deep 6s in front, 7r's in back.

• The car originally had 5.5jx14 fuchs, which are interesting insofar as the tall sidewalls act as their own very nice shock absorber, but ultimately the choice of tires is limited and the gains from a wider patch are substantial.
• Tires: Pirelli CN36. These are phenomenal tires. They are almost as sticky as RA1s, but look period correct and thus far I have at least 7-8k of miles on them with the tread only now getting to the wear marks (and I've done some autocross on them). Because I drive the car in the rain on occasion, I can't really use the Avons.

Brakes: The car came with the normal T brakes, which were replaced in the front with the Alpha brembos.

• I am told I need to switch to a track pad to handle the speeds the car is now capable of, but currently without more aggressive pads, the car doesn't have enough brakes.

Transmission: When I bought the coupe to make into a RS clone, it came with a non-matching engine and transmission that were from a former SCCA solo national competitor/champion.

• The 901 transmission had shorter 2-4th gears which helped with acceleration (though are a bit of a pain - too quick -when the car isn't warmed up and you have to short shift below 4k). I haven't formally measured the 0-60 time, but it is definitely sub 5 seconds, and I don't know the precise gear ratios.
• The transmission has a wevo limited slip, which is something I can't drive without (once you get used to no tail wag under heavy braking with a LSD, you can't drive without one).

Lights: - the one clear aesthetic modification from original on the car is the lights. For the primary lights I have clear Cibie Bi-Iodes with the Tungsram megalight ultra +120 bulbs that John Audette recommends.

• They are mounted in SWB buckets. Relative to the H4's they replaced, which provide inadequate lighting at night, the Bi-Iodes function as well as they look. That said, the same can be said of the Ampliluxes and H1's, provided you use the megalight bulbs.
• Recently I added a set of Eric Linden's Hella TTG 118 replica driving lights and the amount of light and visible roadway is laughable. The car didn't come with driving lights from the factory and I don't love the look, but given how often I drive some rural roads at night (where bears can be an issue) the driving lights are indispensable.
• I have kroon relays and wiring harnesses for both lights, the driving lights are wired to go on with brights (i.e. no dash switch).

Engine:

• The original 2.2 was quickly bumped for a 2.7 RS build that was lying around my shop. The 2.7 RS engine is a fantastic early engine because it provides much more torque than the other engine profiles while retaining the peakiness of the early cams.
• With the larger engine an external oil cooler was required, necessitating the external lines, which for a '71 are a pretty clear giveaway of a hot rod and the other giveaway that something is up with this car in addition to the cibies (both of which I highly recommend). The oil cooler works well - in normal driving I try to get the temp up to 180 by driving around 4k and then really open the car up once it is pushing oil to the front cooler at 180 (though I will go to 7k once there is some temp in the engine - I've been told lugging the engine is far worse than opening it up at lower temps). When driving across the country at 4-4.5k in 90+ degree heat, the temps never really got above 210, though there was a stretch in South Dakota where the temps were ~98 and I was driving between 4.5 and 5k and the temps got to 230 which is at the higher end of acceptable. I use the Valvoline VR1 20W-50 with zinc.
• However, the aforementioned autocross 2.8 engine (E cams) spit out some metal and needed to be rebuilt, so as a crackhead does, I asked for a more powerful engine with the criteria that it would be indistinguishable from stock if you looked at the engine bay (e.g. it runs on a single plug distributor with pump gas (so 9.5 to 1 compression), using Weber 40s) and double-down on the peakiness of an early engine (the type of roads I travel allow me to drive between 4 and 7k - I totally get the appeal of the 3.0 and later engines for their relative ease of use in traffic).
• I've asked Scott at Auto Associates to explain this magical engine he has built me, many times, and I still have no clue as to how he is able to extract so much from so little (2.8L) except to say it has to do with spending a lot of time on the intake ports and a custom cam grind they've developed over the decades of caring for these cars. I can only suggest, if you have the means and inclination, of calling him up and asking to have one built. My race engine in the S/T has more peak HP (twin plug 2.5 ltr), but this engine is too fast for a long hood, hence the need for a bit more brakes.
• Interestingly, because airflow matters a lot to these cars, the engine prefers an early metal airbox for carbs as opposed to the '71 plastic airbox as the early airboxes have a bit more volume. It also much prefers a Dansk sport exhaust to a stock exhaust (and yes, I had them chop off the Dansk tailpipe and replace it with the square tip). I also find the air cleaner makes the intake sound a bit vacuum-y at lower RPMs compared to the hat-type air filters that have a much better induction sound, but again, the idea is a sleeper and no one knows what this lowly T is capable of.
• I recently changed the distributor to the 123 distributor from the stock which ran on points - it definitely improved start-up and fuel efficiency (driving across country at a steady 90 which is a little over 4k in 5th gear I got ~18 mpg). Otherwise, stock CDI unit and other electronics.

I love driving the car and have put on ~30k miles in the past four years, including track/autocross and more recently across the country without requiring a drop of oil or presenting any problem whatsoever. Much to my neighbor's dismay, it is my daily driver to the extent feasible from late March to late November. I also prefer the targa relative to a coupe, which feels unusual for longhood enthusiast. Yes, the chassis will shimmy over a decent bump but it is otherwise good enough and I'm never driving 9/10s or more on public roads anyway. I love the open air feel of the targa, the sound which is so much of the appeal of these cars, and the top is reasonably weatherproof so that I can use the car in the rain without issue (though at speeds above 80 mph, the whine of the top makes you want to slow down).

Hopefully this is a helpful reference and by all means if you have a differing perspective or more insight to share please do! Most of you guys have far more experience with these cars than I do (admittedly almost 100% of the changes are based on the suggestions of others rather than my own thoughts!

I've really enjoyed this build/thread! qq about an item in your last post: you mention the coupe having a shorter 2nd-4th when you got it..is that what you swapped into the targa and paired with the 2.7? if so, I'm curious whether you think it's a good combination for a street/backroads car. I have a 2.7 in my coupe and have thought about doing something similar when I rebuild the trans. thanks!