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964 / 993 RS body modifications are described in the 964 body manual, here are the relevant pages -> 964 RS BIW modifications
Thank you very much Tosi, for this very precious material!
I found out that some versions had a genuine porsche reinforcement on the outer side of the body, where the suspension strut mount is connected to the chassis
Good to know, so I must add the lowerside reinforcements on the front.
What do you think Tosi, I am reading a lot about 3,8 RS engine and I was asking myself if the differences between the CUP and the RS engine were substantially just the mechanic valve lifters (were they reinforced or just like the 964 ones?) and different camshafts (together with different engine map) or if there are consistent bigger (and very important) difference than just changing the upper part of the RS engine.
Here in the forum I read that removing the steering pump saves 5 to 10 Nm along the bandwidth and that a similar effect comes from using mechanical valve lifters.
if what the rumors say is true, i.e. the RS engine has more likely 315/320 than the declared 300, the 2 mods above, together with a LWF should bring even more vitality to the package.
but maybe this is just a fantasy: usually in physics and engineering one can apply the principle of overlapping (I don't know if this way it is translated well from italian) effects, if this were the case, one could expect something around 330/335 hp with a rev limiter similar to the cup one, close to 7000 rpm.
P.S. & Errata Corrige
No, I checked and the correct name of that principle is "superposition principle" ( in italian " principio di sovrapposizione degli effetti")
The 993 rs intake plenum is completely different regarding the cup plenum which is the plastic one 272 hp.....
all the internal engine parts are the same . Mechanical valves lifters were not adjustable as 964 , you need some calibrated parts to adjust the valves clearance.
but we use Rsr adjustable parts to replace them . I’m not sure that camshafts are the same ....
The 993 rs intake plenum is completely different regarding the cup plenum which is the plastic one 272 hp.....
all the internal engine parts are the same . Mechanical valves lifters were not adjustable as 964 , you need some calibrated parts to adjust the valves clearance.
but we use Rsr adjustable parts to replace them . I’m not sure that camshafts are the same ....
So basically if I find an RS engine, changing the valve lifters to the mechanical standard 964 (adjustable) and using some more aggressive camshafts(maybe not too much) in comparison to the standard RS, maintaining che RS intake with varioram, the car should gain a bit more hp in the higher rpm, without scarifying torque in the mid range?
Is it worth investing in such a mod on a genuine 3,8 RS engine, performance related?
Little update and questions, related to full original rebuild or introducing some mods performance oriented
1) In the engine rebuild process, I finally found an experienced shop where to make the cleaning, check, and eventually the overhaul of each component of the engine, together with crankshaft balancing (I don't know if this is the right way to say it).
During the last months, searching for other parts, I also found and bought used mechanical rocker arms from the 964 and here comes the question: would you upgrade (or backdate) the hydraulic lifters (I already bought the INA oem replacement) or would you sacrifice a bit of originality to get some more performance?
2) the second question is somehow connected to the first one: if I go for ful restoring, this question doesn't make sense. But in case I go for mechanical rocker arms, I think I would also change the camshafts with some more aggressive one, but still compatible to perfectly work with its original 3.6 pistons and cylinders and valves, springs etc. in the heads ----_> Would it make sense the power stearing pump? Somewhere here on RL I saw that such a removal asks for other change, maybe if this envolve the cammes, it could be something to be done.
I also got this, together with 996 GT3 Crankshaft, 996 GT3 Oil Pump, but I would like to use these parts for the build of the Step 2. For what kind of application are indicated the mechanical rocker arms? Until how many rpm? I saw the peuteur rods and rocker, no idea how much they would cost, plus valve springs and valves, no idea, it is strange only prices of used parts and bran new mahle parts are available...
I mean, either I go for a full restore, preserving 100% of its originality, or if I change, I would also change the cammes, not just the rocker arms, and would also remove the steering pump: If the 964 rocker arms are good for application up to 7500 rpm, I would take them on the shelf to use them later.
Basically for the step 2 I will need to find a good used engine block and the cylinder heads (with all the hardwere), cammes, 3,8 cylinder and pistons.
So far I found a 964 92 engine block, plus 964 used heads for a very good price, but I don't know if this parts would mate the mahle 3,8 cylinder and pistons: somewhere I read that one can use the 964 heads with some modification, but I don't know what was the case they where talking about, because in my case block and heads would be from the same engine type, are the cylinder of the 993 different shaped?
In regards to piston roundness and piston walls Ra (in micrometer) what are the tolerances and what is the expected result for a very good job?
Last edited by nothingbutgt3; 05-22-2020 at 09:46 AM.
Finally in grinding shop they dismantled the heads and the verdict is as follows: perfect valve guides, the seats and the valve edge must be very slightly rectified, to ensure perfect closure between valve and seat.
Can anyone tell me if the valves were originally subjected to some heat treatment?
Regarding the crankshaft it will need to be carefully cleaned and polished, the connecting rods disassembled and cleaned as well.
About the cylinder, it will be measured the ovalization and the clearance between each piston and its cylinder: after this, the crankshaft will be balanced.
What is the best way to do it? Crankshaft by itself or cranckshaft + flywheel ?
I took advantage of the parts that I had to buy to put the coachbuilder in a position to work at his best, for buying the parts necessary to reinforce the body like the RS was.
I imagine the front reinforcement is used to add the track towing hook: could someone tell me where I can find the original part/code?
The last two are the steering arms which will be installed on the 993 silver at the beginning of June: I can't wait to get the final driving result.
Meanwhile these wheels pop-up, it would be really nice to make a sort of Cup Tribute, but an experienced friend of mine is telling me that magnesium is fragile since brand new, even though the x-ray would say they are free from invisible cracks, he wouldn't buy them, because after 25 years they are for sure not become stronger and if they break, they do it all in a sudden
This is the only pastel yellow RS/CUP/RSR I've been able to find so far, the closest color to mine
I already took a set of BBS E29 (same shape of magnesium E28, but in aluminum), I think it is more advisable, for safety reasons, to go for them, changing the outer channel.
Completely overhauled and painted in BBS gold, with stickers, same as this one
It is a long long road, basically you are alone, the one entitled to carry on the heaviness of such a challenging project, for someone like me that is totally outside from his environment, it is like a solo navigation.
the help of friends and people, porsche enthusiast or not, persons who have already tried the same or similar experience, I must confess are of great help, if not materially, definitely psychologically
Paolo I have a set of the Centerlock Mag wheels NOS on my '95 Cup tribute and have no doubt they are sound despite age , I think many
'95 993 had mechanical rockers stock but possibly I'm mistaken .
my engine is a '95 Cup M64/20 so it has the RS cams , mech rockers and 3.8 P's and C's a very lucky find if I can transfer a few shots from my phone I'll do so , your not alone many are attempting similar endeavors haha ! Bert
Paolo I have a set of the Centerlock Mag wheels NOS on my '95 Cup tribute and have no doubt they are sound despite age , I think many '95 993 had mechanical rockers stock but possibly I'm mistaken .
All 993s have hydraulic recovery of the clearance: this systemi recently read it was introduced in many cars because of two factors: maintenance intervals and noise reduction, scarifying some performance.
this because of many reasons, mainly because the principles is base on incompressibility of fluids, but some pressure goes lost because some oil passes between each small cylinder and the walls, in the phase when the arm goes forcing on valve's hat.
The viscosity of the oil probably plays a big role when the engine is running at high temperature as well.
but mechanical rockers I am quite sure were installed in all the 993 race engines.
finally I found the way to go with the original engine rebuild, using its original layout in the lower part, changing the hydraulic with the mechanical rocker arms, and introducing the varioram intake plus varioram dme.
These mods, together with crankshaft balancing should give some pepper to the stock layout.
I still don't know if it is the case to go for power steering pump removal, together with different camshafts, but pistons and rods are going to remain its stock 3,6, so I don't kmow how much performance there woild be with different shaped camshafts.
At first I was considering also the center locks, very exotic and sexy system, I must say, but I must be realistic and consider the budget and the fact that performance related the center locking system doesn't play any role.
I must direct my attention more towards the unsprung masses reduction adding floating braking discs of 302 mm front, if they are available, and an efficient cooling system for the front rotors.
I must stay focused first of all to get the car on the road, and then maybe start thinking how to build a step 2 engine, after some time.
The next step now is building the G50.21 2 or the G50.32 2 gearbox: is the gearbox case of the RS CS version somehow different to the first one, i.e. can I install G50.32 hardware inside a gearbox case that originally was meant to have G50.21 hardware?
I am still searching for a supplier for the roller bearings, that I suppose must be available somehow for considerable lower price, especially if I consider the asking price for a gearbox overhaul (which shoule provide new bearings) because I already found a supplier/manufacturer that can replicate the original helical gears for a decent price (and high quality, but ordering at least five gearsets), together with cementing and grinding process, and giving me the gearbox back closed and calibrated, ready to be installed.
For a track and very light car I think a longer 1st gear must be very useful: in which parts the G50.32 is different to the G50.21, apart from gear ratios?
For my 993 track engine I modified the 993 hydraulic lifters to mechanical. It was a bit of work but I am hoping we did our homework and got it right. I also removed the power steering pump and installed a cup style electric pump in the frunk. You will need to cap off the back of the cam where the pump assembly attached. Patrick motorsports sells one for this purpose. IIRC the cams of the 993 don't allow the freeze plugs used on the 964 engine. The 964 engine will be different port sizes and uses 9mm vs 8mm valves and guides. I believe they use a different alloy as well. The cam towers of the 964 are different and they don't have the oiling for the 993 lifters but run tubes for splash oiling for the rockers. Although my rockers are now mechanical I will be using the oil formerly used to feed the lifters to lubricate the rockers but pluged the holes to where the lifters were amongst some other small mods.
These are my modified mechanical 993 forged rockers left vs stock mechanical cast 911 rockers right.
Paolo,
The next Rennsport Reunion, a world-renowned Porsche event in the U.S., recently held at Mazda Laguna Seca Race Track in California, probably will next occur in September, 2021. Might be your goal to finish? Consider shipping it over, showing the car, telling its story, then doing another drive here. Some of us can help you with logistics.
Take lots of pictures as you restore.
Have you made contact with the Porsche factory and Porsche Classic in Zuffenhausen? Perhaps they would be of assistance, or offer advice in your amazing project?
Fred
Deadline is middle May 2021, maybe I will encount some issues, but I definetely hope having 1no more than 1 or 2 months maximum time delay, so maybe September 2021 could be possible doing what you are suggesting: what kind of reunion is it?
In the past almost 18 months I contacted Porsche, Porsche Classic, Porsche Museum, but nothing came back, nothing: what I got as source, help, nearness, I got from you guys here on RL and from few close friends Porsche very much enthusiast like many of us here are.
I don't do it every time, but I must really thank you.
In the past days I created an instagram profile specifically for this project and I must say that while I was talking to the person who advised me to open it, all your comments flowed in front of me, which have kept me company over these long months and still are, and I told him that it is not my intention to appear explicitly as a person on the instagram account.
Everything was somehow revealing itself for what I unconsciously from the first moments in which I created this post in my heart I already knew all of this could represent: infact I called it Projekt Limoncella, nothing more, nothing less.
It's not about me, I realised I'm just a vehicle, a link, a carrier: this is a project and the protagonist is the car itself together with the processes, suggestions and sharing with the people with whom I've shared doubts so far, indecision on what to do, evaluations, or even simply the madness of even thinking of putting this beautiful 993 back on the road, in shape more than before (and they are all beautiful, but the ones you rebuild, or on which you put your hand, I'm starting to understand it, or to become aware of it , they are even more than the others).
Of mine what makes me look forward with confidence and does not make me break down in the face of difficulties in giving continuity and support to this project, which I already understood will leave me much more than saving a beautiful creature, there is an energy that does not end.
I recently received this photo from the cleaning shop, I must go there this saturday and ask what type of cleaning system they used onto expendable parts that I gave them for a test, but the result looks amazing, since they were much worse than in bad condition!
In the shop they have the ice dry blasting system, but I am not sure they used that system to clean these parts, that were really in bad bad shape.
Fascinating project and a compelling read. What a quest! I can’t wait to live vicariously through your first drive on a beautiful winding road, enjoying the result of your dedication and passion.
Fascinating project and a compelling read. What a quest! I can’t wait to live vicariously through your first drive on a beautiful winding road, enjoying the result of your dedication and passion.
Thank you Tlaloc75!
I was looking for parts to buy for the engine heads overhaul, valve guides are perfects, as valve seats and valve themselves.
the inly thing the grinder shop asked me to buy are the sealings for the valve stem, so i was considering to buy also the piston rings.
I sked rosepassion, as I usually do to every shop other than Porsche local dealer, if the parts enclosed in the basket are all genuine porsche parts, just to be aware what I am buying and they answered that they are, except for piston rings that are from Goetze.
Now I am asking myself what to do, what is best for the engine rebuild, Goetze or Genuine Porsche rings?
Yesterday I've been to the rectifying shop, and the result is amazing: the craftsman couldn't believe the car has been submerged for almost five years.
he really still thinks I am kidding.
Cylinder heads are now perfectly clean, valve seats have been just mildly rectified, so the valves, the inlet valve guides are perfect, the exhaust guides have a very small play, so they will be all changed with brand new ones.
The camshafts after being worked look as brand new, and so will the crankshaft.
cylinder heads on the exterior part look great, only two of them have some corrosion on the boarders of cooling fins, that compromise just the esthetics.
I like the original engine to maintain sort of a scar on its skin, it tells the story of the car, of course this only because it doesn't compromise in anyway its efficiency.
Pistons now look as brand new after a microwave bath.
This week the shop will measure the cylinders ovalization, the geometry of the crankshaft, together with the rest of what is necessary. I really hope the result will be positive.
body work is going to start really soon.
05-15-2020, 12:31 PM
