Turbo Motor fitment
- Thread starter TISPKJ
- Start date
Guest
New member
I'm not sure if the clutch is the same diameter.
But more importantly, either the turbo engine sits further back in the car and/or there may also be some modification to the engine bay. The oil tank has to be accommodated which sits on the front of the engine on the drivers side.
I suppose one could be made to fit, but I would guess it is not just a drop in arrangement.
But more importantly, either the turbo engine sits further back in the car and/or there may also be some modification to the engine bay. The oil tank has to be accommodated which sits on the front of the engine on the drivers side.
I suppose one could be made to fit, but I would guess it is not just a drop in arrangement.
Guest
New member
Are you sure the C2 gearbox is strong enough?
If I remember rightly, the turbo gearbox is an evolution of an older design (coming from the 993, and 964 before that).
The C2 gearbox was a new design for the 996 and is lighter. But I do not think the torque rating is high enough.
It might all go bang when you hit 0.8 bar boost.
If I remember rightly, the turbo gearbox is an evolution of an older design (coming from the 993, and 964 before that).
The C2 gearbox was a new design for the 996 and is lighter. But I do not think the torque rating is high enough.
It might all go bang when you hit 0.8 bar boost.
Guest
New member
Who knows - give it a go.
The feature with turbo 996 cars (at least) is that the max torque is spread over quite a wide band from 3500-5500 (or something like it). You don't need to be at the top end of the rev range caning it, you can just be pootling about and press the throttle down, e.g. for overtaking.
The ECU regulates the boost, and on cooler days, I reckon you can get a goodly dose of torque without even using full throttle.
Therefore, I reckon you would be running something of a risk.
Porsche are conservative with their engineering judgements, but I would still be nervous.
http://www.porsche.com/uk/models/911/911-turbo/indetail/drive/
Have a look at the picture on the link above to see the front of the engine. Not sure if that looks like it will match a C2 gearbox or not.
The feature with turbo 996 cars (at least) is that the max torque is spread over quite a wide band from 3500-5500 (or something like it). You don't need to be at the top end of the rev range caning it, you can just be pootling about and press the throttle down, e.g. for overtaking.
The ECU regulates the boost, and on cooler days, I reckon you can get a goodly dose of torque without even using full throttle.
Therefore, I reckon you would be running something of a risk.
Porsche are conservative with their engineering judgements, but I would still be nervous.
http://www.porsche.com/uk/models/911/911-turbo/indetail/drive/
Have a look at the picture on the link above to see the front of the engine. Not sure if that looks like it will match a C2 gearbox or not.
I would think the electrics would need to be considered as well?
Got to be a fair bit invilved there....
Got to be a fair bit invilved there....
lee fulford
New member
Stuart....I've tried telling Steptoe, sorry tispkj, that the gearbox is not man enough as probably the diff. He won't listen to me.....never has...think it's his age.
May as well go buy a TT and be done with it.,.....far cheaper.
May as well go buy a TT and be done with it.,.....far cheaper.
Guest
New member
I have had a look for some information.
I haven't seen the torque ratings for the gearboxes though.
However, consider the C2 has 350Nm @4600rpm (3.4l), 370Nm @4250rpm (3.6l).
Turbo has 560Nm @2700-4600rpm (620Nm for the X50 cars).
GT2 was 620Nm rising to over 640 after revision (can't find the exact figure).
GT3 Mk1 370Nm @ 5000 rpm (Mk2 I can't be bothered to look up).
All manual transmission cars use the same diameter clutch, 240mm,
Aside from the GT3 Clubsport, all use the dual mass Freudenberg flywheel, as in the
G50 transmission of the 993 cars.
All cars have hydraulic clutches (no cable), but the turbo has a hydraulic servo fed from the
power steering to reduce the pedal pressure.
Although the clutches are the same diameter, the spring force must be higher on the
more powerful cars.
Gear shifting is actuated by Bowden cables in compression and traction, to reduce
"telephoning" gear noise into the cockpit. The 993 used rods.
The 996 C2 had an all new gearbox develeped, manufactured by ZF by the way.
The aim was to reduce the length (compared to the G50 boxes), reduce the weight, lower
the shifting force, improve the efficiency, and have 100k miles oil changes.
The new gearbox was a one piece housing (unlike G50 2 piece). The flywheel, clutch and
differential are in one housing, the gearbox in another.
The unit is 43mm shorter than the G50 box, by having the input and output shafts running
in 2 bearings instead of 3, and the same primary shaft pinion is used for first and reverse.
All gears have synchromesh inc. reverse, and there is double-cone syncromesh on 1st and
2nd for easier engagement. The synchronising system is the same as on the G50 box.
Despite its higher torque rating (than the 993 C2) the box was 2.5kg lighter.
An asymemetric limited slip diff was available as an option on 1998 models only, since
it is not compatible with PSM. It had 25% locking on drive, and 65% on overrun.
C2 uses G96/00 box on 3.4l cars, and G96/01 on 3.6l cars.
C4 uses G96/30 box on 3.4l cars, and G96/31 on 3.6l cars.
Since the torque rose by 10Nm (or 2.78%), the torque rating for the 3.6 cars
gearboxes was increased by using higher resistance steel for the components and
moving to a 4 satellite differential from 2 satellite.
A third bearing was also added just behind the clutch, to control vibrations in
the gearbox input shaft. (I don't think this caused it to be lengthed, since this was
one of the ways they made the box shorter - but this may affect the RMS on early cars?).
Speed at 1000rpm (in 6th) 26.8mph.
The GT3, Turbo and GT2 have heavy-duty gearboxes developed from the G50/53 gearbox used in
the 993 GT2. The three piece housing for clutch, final drive and gearbox, has been redesigned
to suit the different mounting arrangements in the 996, but the shafts and gear
arrangements are similar.
A four satellite diff is used.
The turbo has no LSD, and uses the PSM for that (which brakes the wheels).
A 40/60 mechanical LSD is used in the GT2 (I presume the same for GT3).
The biggest design change is for the cable operated shifting.
GT3 uses G96/50, turbo uses G96/51, and GT2 uses G96/88.
The G96/51 has a longer front output shaft with a flange to connect to the viscous
coupling to go to the front wheels.
On the G96/88 gets an oil pump which circulates the gearbox oil through a water/oil
heat exchanger and sprays oil directly onto the gears.
Ratios are different, GT2 and turbo the same, GT3 different.
Speed at 1000rpm (in 6th) 28.1mph turbo. 29.1 GT2, 25.4 GT3 (since it revs higher).
Mk2 GT3 (and all Japanese spec GT3s) have heavy duty steel synchronising rings on 3rd,
4th and 5th.
BTW - the C4S had the turbo gearbox.
If you take the X50 option, some modification is made to the gearbox, but I don't know
what exactly.
In summary, the C2 gearbox is 43mm shorter than a turbos, it is designed to handle
the torque of the car with not too much margin, so I expect putting 60% more torque
through it will either cause it to fail, or will significantly shorten its life
expectancy.
The clutch diamter is the same, but the thrust bearings and release mechanism are not.
I think you need to take the turbo gearbox (or GT3 might be better as you only need
2wd) as well as the engine.
I have not looked to see if the drive shafts are the same.
I haven't seen the torque ratings for the gearboxes though.
However, consider the C2 has 350Nm @4600rpm (3.4l), 370Nm @4250rpm (3.6l).
Turbo has 560Nm @2700-4600rpm (620Nm for the X50 cars).
GT2 was 620Nm rising to over 640 after revision (can't find the exact figure).
GT3 Mk1 370Nm @ 5000 rpm (Mk2 I can't be bothered to look up).
All manual transmission cars use the same diameter clutch, 240mm,
Aside from the GT3 Clubsport, all use the dual mass Freudenberg flywheel, as in the
G50 transmission of the 993 cars.
All cars have hydraulic clutches (no cable), but the turbo has a hydraulic servo fed from the
power steering to reduce the pedal pressure.
Although the clutches are the same diameter, the spring force must be higher on the
more powerful cars.
Gear shifting is actuated by Bowden cables in compression and traction, to reduce
"telephoning" gear noise into the cockpit. The 993 used rods.
The 996 C2 had an all new gearbox develeped, manufactured by ZF by the way.
The aim was to reduce the length (compared to the G50 boxes), reduce the weight, lower
the shifting force, improve the efficiency, and have 100k miles oil changes.
The new gearbox was a one piece housing (unlike G50 2 piece). The flywheel, clutch and
differential are in one housing, the gearbox in another.
The unit is 43mm shorter than the G50 box, by having the input and output shafts running
in 2 bearings instead of 3, and the same primary shaft pinion is used for first and reverse.
All gears have synchromesh inc. reverse, and there is double-cone syncromesh on 1st and
2nd for easier engagement. The synchronising system is the same as on the G50 box.
Despite its higher torque rating (than the 993 C2) the box was 2.5kg lighter.
An asymemetric limited slip diff was available as an option on 1998 models only, since
it is not compatible with PSM. It had 25% locking on drive, and 65% on overrun.
C2 uses G96/00 box on 3.4l cars, and G96/01 on 3.6l cars.
C4 uses G96/30 box on 3.4l cars, and G96/31 on 3.6l cars.
Since the torque rose by 10Nm (or 2.78%), the torque rating for the 3.6 cars
gearboxes was increased by using higher resistance steel for the components and
moving to a 4 satellite differential from 2 satellite.
A third bearing was also added just behind the clutch, to control vibrations in
the gearbox input shaft. (I don't think this caused it to be lengthed, since this was
one of the ways they made the box shorter - but this may affect the RMS on early cars?).
Speed at 1000rpm (in 6th) 26.8mph.
The GT3, Turbo and GT2 have heavy-duty gearboxes developed from the G50/53 gearbox used in
the 993 GT2. The three piece housing for clutch, final drive and gearbox, has been redesigned
to suit the different mounting arrangements in the 996, but the shafts and gear
arrangements are similar.
A four satellite diff is used.
The turbo has no LSD, and uses the PSM for that (which brakes the wheels).
A 40/60 mechanical LSD is used in the GT2 (I presume the same for GT3).
The biggest design change is for the cable operated shifting.
GT3 uses G96/50, turbo uses G96/51, and GT2 uses G96/88.
The G96/51 has a longer front output shaft with a flange to connect to the viscous
coupling to go to the front wheels.
On the G96/88 gets an oil pump which circulates the gearbox oil through a water/oil
heat exchanger and sprays oil directly onto the gears.
Ratios are different, GT2 and turbo the same, GT3 different.
Speed at 1000rpm (in 6th) 28.1mph turbo. 29.1 GT2, 25.4 GT3 (since it revs higher).
Mk2 GT3 (and all Japanese spec GT3s) have heavy duty steel synchronising rings on 3rd,
4th and 5th.
BTW - the C4S had the turbo gearbox.
If you take the X50 option, some modification is made to the gearbox, but I don't know
what exactly.
In summary, the C2 gearbox is 43mm shorter than a turbos, it is designed to handle
the torque of the car with not too much margin, so I expect putting 60% more torque
through it will either cause it to fail, or will significantly shorten its life
expectancy.
The clutch diamter is the same, but the thrust bearings and release mechanism are not.
I think you need to take the turbo gearbox (or GT3 might be better as you only need
2wd) as well as the engine.
I have not looked to see if the drive shafts are the same.
Guest
New member
As for the intercoolers, I saw some conversion that used an air to water intercooler.
This was to turbocharge a C2 or C4, and it meant that externally there was nothing to see.
(I quite liked that idea). They used a separate radiator to dump the heat.
The alternative is to use the air-to-air intercooler used in the 993, with a suitable fan, then modify the engine lid to fit it in, then you don't need the wider rear.
Ruf do not use the wider car, so there is a way to get the intercoolers in.
I believe, the width is more to get the wider track for the rear tyres than for the plumbing arrangements.
Without the large silencers, there is a reasonable amount of room.
Overall, I think buying a turbo is cheaper - only 50K now.
This was to turbocharge a C2 or C4, and it meant that externally there was nothing to see.
(I quite liked that idea). They used a separate radiator to dump the heat.
The alternative is to use the air-to-air intercooler used in the 993, with a suitable fan, then modify the engine lid to fit it in, then you don't need the wider rear.
Ruf do not use the wider car, so there is a way to get the intercoolers in.
I believe, the width is more to get the wider track for the rear tyres than for the plumbing arrangements.
Without the large silencers, there is a reasonable amount of room.
Overall, I think buying a turbo is cheaper - only 50K now.
lee fulford
New member
Stuart....I trust you did't sit there all day typing that lot surely?
Ninemeister
New member
No.
The GT3, GT2 & Turbo have a different bolt pattern.
Guest
New member
No, I have no friends.
I'm not keen on January anyway - there's not enough light, it's too cold and it's too early to start the gardening. I've got nothing left to buy and since I drive everyday, am not really looking for an excuse to drive anywhere. So, read some books and watched the footy on TV.
And of course - I'm a workaholic; didn't get where I am today by having a life.
High point of today was cooking (and eating) some parsnips from the garden - very tasty.
(I need a bigger garden.)
I lead such a high flying lifestyle.
It only took about 30 mins to type. You can type it in using wordpad or notepad (quicker and easier than Word) and then cut and paste it into a posting a leisure.
I have written something similar before, so I knew where to look.
Unfortunately, I spend far too much time reading about cars. Besides growing things, my main hobby.
Stuart, thanks for the great technical data, it made a great, interesting read.
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