911T 2.0L Gr. 3 Sport Kit Jetting

[TargaFlorio]

Hi Guys,

in case anyone is re-jetting their carbs to Sport Kit settings here are the specs:

Hardware Up-date:
Free-flow muffler, Free-flow air intake, 34mm Venturis, Weber Jets

Jetting sizes:
Main: 145
Air Correction: 160
Idle: 50


Note: The Sports Purposes Manual for 1968 states the following jet sizes:
Main Jet: 145
Air Correction: 140
Idling Jet: 60

However due to the change in gasoline over the last 40 years we've had to compensate. This set-up will give you 30hp (according to Porsche + Bruce Anderson told me he saw the same 30hp improvement on the dyno). The one draw-back is that below 2000RPM the engine runs a bit rich when it's cold. Above 2000RPM to the redline it's a rocket ship. Also your fuel consumption will be higher. Cold starts are a bit rough. Once the engine is warm it will pull with no hesitation to the redline. I don't know if you want to adapt this to a street car, these specs were for FIA Gr. 3 motor sport applications.

Ciao,
n.

[superelfje]

Hello Nicholas,

in your setup you specify a free-flow exhaust. Do you mean totally open like megaphones or do you consider a Dansk 2-in and 2-out also a free flow exhaust.
Thanks

Chris

[TargaFlorio]

Hi Chris,

according to the literature that I've read, a 2-in 2-out exhaust was considered an upgrade to the standard muffler and considered free-flow. Note that this Kit also came with air cleaners (basically a K&N filter). So compared to the standard intake and exhaust it is free-er flowing.
I've attached a picture of the image of the muffler, sorry I don't have a better one.

A Racing set-up would consists of no air-cleaners and a completely open exhaust.

Porsche also mentions that:

"This competition kit can also be fitted for normal use with the standard exhaust system, i.e. the engine is driven normally with the standard exhaust and will be fitted with the racing exhaust included in the kit only for use on closed circuits."

I have a rally exhaust with 3 outlets, the two center ones can be capped. The muffler is open so it's quite loud (I wear ear plugs) you'll also get some sparks/flames on downshifts etc.

Ciao,
n.

[superelfje]

Hello Nicholas,

thanks for your answer.
I have both the 34 mm and the 32 mm venturies and I am considering the 32 mm because of the better torque. What are your thoughts about that. The 67S that is going to get this treatment will be used on the road and maybe for some very light rallying. Did you try the 32 mm's and if yes with what jet sizes?

Thanks,
Chris