Headers for 85 Carrera

[ncseahawk]

Will the following work with stock 85 carerra?

911 headers with 43 mm exhaust ports

This is the inside diameter would convert to 1.7 inches or almost 1-3/4".

Any advice on this would be great.

[trak ratt]

From Rennsport site –excelent reference for all things 911, except car wax.
"Here are some guidelines for 911 engines equipped with "S" cams or larger. Using RSR, Schrick or GE-80 camshaft profiles can allow the use of larger headers. You should consult your engine builder for advice.
Engine Header
2.0 to 2.4 1 ½" or 1 5/8"
2.5 to 2.8 1 5/8"
3.0 1 5/8" or 1 ¾"
3.2 1 5/8" or 1 ¾"
3.4 to 3.5 1 5/8" or 1¾"
3.6 to 3.8 1 5/8" or 1¾" or 1 7/8"
These sizes are based upon street and racing applications. In the case of 911’s driven on the street as well as track events, use the next smaller size if in doubt. SSI Heat Exchangers are only available in 1 1/2" so they have limited applications on engines larger than 3.2 litres".

[ncseahawk]

bump,

I know some of you senior smart guys can help me with this

[Bill Verburg]

That's big for a street driven Motronic 3.2, now if it was constantly driven between 6 and 9000 it might be good.

1.5" ID(1 .625" OD) is about right for that engine

again tuned headers w/o cams to feed them are mostly about flow volume while keeping the gas velocity up. Too samm and there isn't enough volume, too big and there isn't enough gas velocity.

[my85911]

Anyone have a comment on B&B's stuff?

[Bill Verburg]

B&B makes a solid header in 2 sizes 1 5/8" OD and 1 3/4" OD. They work ok on the 3.2 and 3.6+ engines. They are not perfect but do the job and allow heat. For the bigger engines they are almost the only option that does so.


They have had reliability issues w/ their mufflers for years. These issues may or may not have been fixed.

[Steve@Rennsport]

Originally posted by ncseahawk
bump,

I know some of you senior smart guys can help me with this

I'm not sure that I fit that category but I would use 1.5" on a stock 3.2 and 1 5/8" for an extensively modified one.