CIS air boxes - definitive small/large runner sizes

[911AtLast]

Hi all, as I am currently looking for an air box for my 3.0 euro carrera 3.0, I would like to know what the definitive runner sizes are - Is it 34mm for small runners and 39mm for large?

Also, should I assume that these are outside diameters?

Thanks!

Warren McAllister

[kstylianos]

Is it 34mm for small runners and 39mm for large?

Correct. 39mm up to 1979 models, 34mm from there after (3.0 liter models). These dimensions are inside diameters of the intake runners and head ports (should be matched).

[911AtLast]

"39mm up to 1979 models, 34mm from there after (3.0 liter models)"

Hmmm - I thought the larger dimension (39mm) was for 3.0 litre engines?

I have a euro Carrera 3.0....

Warren

[kstylianos]

The Carrera 3.0's were the predecessors to the early SC's...very rare indeed. Intake ports were 39mm, exhaust 35mm.

[Randy Blaylock]

76 and 77 3.0 Carrera CIS RoW (rest of world, non-usa) cars had 39mm runners/ports, 8.5:1 CR and were rated at 200hp @ 6000/188tq @ 4200

78 and 79 3.0 SC RoW had the larger runners and ports, in conjunction with a CR at 8.5:1. Rated at 180hp @ 5500/165tq @ 4200

78 and 79 3.0 SC USA/Japan/California cars same except 175tq @ 4200

80 SC 3.0 RoW had the smaller runners and ports w/8.6:1, 188hp @5500/175tq @4200

80 SC 3.0 USA/Japan small runners/ports, 9.3:1, 180 hp @5500/175tq @ 4200

81-83 SC 3.0 RoW small runners/ports, 9.8:1, 204hp @5900/189tq @ 4200

81-83 SC 3.0 USA/Japan small runner/ports, 9.3:1, 180hp @ 5500/175tq @ 4200

here's the cool one,

83 3.0 SC/RS mechanical injection, 43mm ports, 10.3:1, 255hp @ 7000/184tq @ 6500

Euro models, except mech inj had a different fuel distributor (head) and no lambda.

[911AtLast]

Thanks guys - starting to understand this!

Next question:

Anybody got a large runner box for sale? :-)

Warren

[Randy Blaylock]

Possibly, I'll check.