Hi,
I am going to fit a 6 speed G50 trans (inverted) from a 993, with a 3.6L varioram engine.
I will have to use a cable shifter (from Patrick Motorsports or CableShift. California Motorsports modifies the trans for a cableshift running from the side but that is excluded for me as I am based in Europe and would have to send the trans to the US to be modified, and back to Europe).

My question is if there is enough length for the long nose of the trans . I know I have to cut the trunk for the inverted trans.
I have seen at the Renn... forum a car which had the bellhousing and shaft shortened at Patrick Motorsports in 2005 but they did not explain if that was necessary, or if as an alternative, the opposite side could have been shortened.
CMS states that shortening the bellhousing is not recommended for G50's later than '89 due to starter compatibility issues. I guess the issue is the elimination of the guide bushing for the starter when the bellhousing is shortened, and that is not an issue for '89 and earlier cars, because High Torque Starters which do not use that bushing are available.
For '90 and later cars I have not been able to find those starters.

Can someone help with information on the application of the 6 speed trans from a 993 ?

I am building a 914-6 GT replica and already started applying the fender flares, and modifying the engine cover with a second grille.

I don’t know the exact length but the G50 trans at our shop look a lot longer than a 915 trans, not to mention they are pretty heavy. You will need two separate mufflers, one for each side of the trans. Not a big issue but won’t look like a GT. The varioram also is too tall for the 914 engine bay. The induction won’t fit under the engine grill. The combo of engine, trans and associated parts will add a lot of weight over the stock 914-6.
Might want to rethink some of your choices before you buy the parts.

You can probably get the starter you need from a Porsche dealer or online parts store.

I would post this in the garage instead of the paddock.
@SirAndy

I would also be worried about weight...

but hey... my -6 is 1825lbs.

Online it says length for a 915 is 26" and 6 speed G50 is 32"

A 914 trans weighs 72 lbs.
According to this thread Transmission weight?, mid-80's 915 weighs 128 lbs with oil and starter, similarly configured N/A G50 158 lbs.

However, a spring-centered 915 clutch weighs 18 lbs, and rubber-centered G50 clutch 29 lbs, so that could be another 10 lbs difference installed in the car (as many/most folks with a 915 choose to replace the rubber-centered clutch with spring-centered) - so either 30 or 40 lbs.

Clay has a 4 liter 964 engine with a boxster trans. He could probably comment on how the extra weight feels in the car.

I researched using a G-50 6 speed, and decided to go with a Cayman 6 speed instead.

Reasons for this:

1. The G-50 will not bolt directly to an air cooled 911 engine upside down. The four bolt pattern for the transmission is asymetrical. You have to weld up the bolt holes and redrill them. And there is not a lot of meat where you have to drill the new holes, so I worry about the structural integrity of the trans case.

2. The G-50 is longer. You can't get a 6 speed between the engine and the rear of the 914. The Boxster/Cayman G-86/21will fit. It doesn't leave much room behind the trans, but it will fit.

3. The cable shift setup on a G-50 is an add on aftermarket item. The Cayman 6 speed was designed for the cable shift.

4. I would have to cut the rear trunk floor to fit the G-50. With the G-86/21 it fits under the unmodified floor.

5. This is the big one.... Cost. A clapped out G-50 fit only for a core to rebuild is going for over 10K right now. A ready to run, low mileage Boxster/Cayman G-86/21 is going for about 4K.

I would recommend you look at a Boxster/Cayman trans for your engine setup.
And the Varioram height issue can be overcome by putting a big dimple in the engine lid.



Coming in January, I will be pulling my engine/trans out to put in the mark II clutch assembly. We are also making adapter plates, starter mounts, and flywheel spacers for the coming kits. Yea, I know.. its taking a long time. Give me a break. I am enjoying driving it.

As for the extra weight in the back, yea...it's an issue.

I am increasing the spring rate and installing a bigger sway bar in the rear to correct the severe understeer issue I have with the extra weight.

I still LOVE driving it!

I see 175 lbs listed for a boxer trans.

Thank you guys for your comments and help :

1 - I am aware of the extra weight, but I will have to live with it. I am getting reinforcing plates from Patrick MotorSports for the body, and will build a structure to support the trans, connected to the rollcage. At least I got a flywheel and clutch from Kennedy Engineering to replace the heavy parts from the 993.

2 - Eight years ago I bought the trans and engine from a 993 which had crashed, and the insurance company considered totaled. It only had 12 thousand miles and it was a bargain (just 6000USD for the engine, and 3500USD for the trans).
Being in Europe it is not so easy to find a Cayman/Boxster trans (I would have to search with the words in German, in French, in Italian, etc. ...), so I am planning to stick with what I have.
I have found some interesting photos at https://rennlist.com/forums/914-914-6-forum...d-in-914-a.html

3 - The G50 upside down will not bolt directly to the engine ... I was not aware of that !
I will have to think of some welding ... I have tried to contact the guy who placed the photos of his car in the above mentioned site, but so far I got no reply.

3 - Varioram too tall for the engine bay ... I will have to check that, and if necessary will have to replace the Varioram by the inlet manifolds of a 964.


4 - GARAGE or PADDOCK for this suject : I hesitated a lot between the two, but in the end I concluded that the Racers are more likely to modify their cars, and I assumed that it was the best choice to get some advice.
I may consider placing this at "GARAGE"
Is there a way to transfer it from PADDOCK to GARAGE, or do I have to enter the subject in GARAGE ?

It's not just the intake you need to replace. You have to replace the DME and the harness too.

SirAndy moved you to the garage.
I would sell the G50 and buy an aluminum 915.
Sell the Variram and buy the standard induction.
You will be ahead with money and time.

Welding on a G50 actually doesn't seem too terrible to me. It's just an aluminum casting, right? Seems like an expensive tranny to modify vs. sell and buy something else though.

You can also use a FWD Audi or VW Passat tranny (if I'm remembering right) which is basically the same thing as a Boxster and should be relatively common. I know some people here have shipped them from Europe. I'm sure someone will chime in with the numbering.

Thanks for the ideas.

I am new in the Forum and have not yet learned how to add photos, but anyway, I just got a photo of a modified engine lid (for the Varioram) at
https://rennlist.com/forums/914-914-6-forum...d-in-914-a.html

sounds like CMS is the place
http://forums.pelicanparts.com/porsche-aut...conversion.html

more fitting Lid Gamroth Built ..Portland Ore.

Check it out here;
http://www.914world.com/bbs2/index.php?sho...16306&st=20

Looking at cars with the engine lid and grille raised to allow space for the varioram inlet, I decided to buy the inlet system and the fuel rails from a 964.
I will have to enlarge the exit of the 964 manifolds from 41 to 43mm to match the inlet of the 993 engine.
I will use the injectors of the 993, and I will have to program the Engine Management System (it's not a Motec, but a Sybele, made in Belgium by Skynam : http://www.skynam.com/index.php?id_lang=1 )

I am now convinced to forget my 6 speed G50, and buy a 6 speed Boxster or Cayman trans.
I still have to figure how to connect it to the engine, and how to install the starter.

Good move. The "hump" might be ok for a track car but on a GT replica, it would never look right.

Clay has the Boxster trans worked out but needs to get parts made for the conversion. At the shop I worked, we did many 964/993 swaps into earlier cars. The 915 trans works well and you could purchase a WEVO kit to make it shift. Then you can fit a regular exhaust to the car to keep the GT look.

Hi Clay,
Thanks a lot for your help.
I am now convinced to forget my 6 speed G50 (and sell it), and buy a 6 speed Boxster/Cayman trans.
I searched a bit about this and people were mentioning that an adaptor plate was not available, and a there was an issue for fixing the starter.
Were you able to buy an adapter kit, or did you have to design your own, and do you have drawings ?

Thanks in advance for your help

Miguel

Miguel,

I had some help, but we ( @partsguy22 ) and I were able to make the adapter parts. It took months, and we are planning on selling a kit after we make and install the mark II clutch assembly. You can see the whole thing in my build thread. http://www.914world.com/bbs2/index.php?showtopic=279084

It's not easy, but it can be done. And the kit won't be cheap either.

Clay

That's within a few lbs of the 996gt2/ inverted that we are using; what trunk floor ¿

I have the Cayman S trans, and I have an intact trunk floor.



Neener neener neener!