Header size for a 2.7 1 1/2 or 1 5/8

[emnemn]

I cannot find my Bruce Anderson book and I'd like to know
what size headers I should get for my 2.7 engine.

Specs

2.7 RS p/c 's
S valves
Solex cams
Fresh 40's from 1quickS

What is best for my engine?....1 1/2 or 1 5/8...

Thanks.

[Frankr]

1 5/8 worked fine for mine. 2.7 RS clone with GE 60 cams. 220 HP at rear wheels. No flat spots. Very tractable.

[911pcars]

Knowledgeable engine folks recommend 1-1/2" OD (1-3/8" ID) tubes for 2.7 and smaller engines and 1-5/8 OD (1-1/2" ID) for 3 liter and larger engines.

Do you need heat in the cabin? If so, factory heat exchangers or SSI/Dansk heat exchangers are suggested, both use 1-1/2" tubes. If not, it's up to you, your engine and your operating conditions. What's the optimal size for your particular engine? Only an A/B dyno test can provide a definitive answer.

Actually, modified 993 heat exchangers (1-5/8") can be fitted to larger engines. These provide the needed gas flow as well as cabin heat. However, a proper muffler system will need to be fabricated or purchased separately. There's lots of internet info regarding this.

Sherwood

[emnemn]

Thanks Frank, thanks Sherwood your replies are appreciated.
Looks like I'll go for 1 1/2 primaries.
Now you've got me thinking about heat...