Factory T/R cars

[StephenAcworth]

Can anyone share definitive information on the mods made to the 'factory' T/R cars, and their engines?

For example:

Were the cases magnesium or aluminium?

Were the internals the same as in the 901/20 engines used in the 906?

Thanks in advance for your help ...

[dpetterson]

I'll let the experts chime in here but the following is from John Starkey's Porsche 911 R-RS-RSR book which may provide some insight. I believe the T/Rs also used a magnesium case, cast in the earlier aluminum sand cast molds, but will let others confirm.

[RennTyp]

Strictly speaking it depends on what the intended use of the car was. A T/R could be built to Group 3 or Group 5 spec. Your best reference is the Porsche document "Information Regarding Porsche Vehicles Used for Sports Purposes" published in March 1968. This lists all the engine options. Having said that I'm not aware of any T/R leaving the factory in anything other than Group 3 spec as most of the events you could run the car in competitively ran to this rule set.

In answer to your specific questions:

The T/R was homologated in Group 3 with titanium 906 conrods. This doesn't mean they all had them, just that they were legal if specified. Similarly, 906 pistons, camshafts and 46 Webers were also allowed. Twin ignition and large valve 906 heads were not.

I am aware of T/Rs being built new with both aluminium and magnesium crankcases. The magnesium crankcases were the 911 production type introduced mid way through the 1968 model year.

Hope that helps.

Philip

[dpetterson]

Great info from Philip ^^

Also came across this: https://www.early911sregistry.org/fo...ate-T-R-Thread

[68S_SK2]

Here the 1968 MY Sports Purpose car list:

https://www.early911sregistry.org/fo...11S-L-and-T-Rs

BG
Claudius