Heat Exchangers?

[95mpower]

Hey Guys! this may be a newbie question, but I have a 1976 911S Targa with a 2.7. If I was to take the stock heat exchangers out and replace them with Just headers, will I lose my cabin heat? if so.. Is there a way to still have heat?

[darrin]

yes, the heat exchangers are the source of cabin heat -- have you looked into SSIs? These are stainless copies of the headers the 911 engines used before emission regulations necessitated the single-out headers used by your '76 (and later 911s)- these do have heat exchangers, provide a near-ideal exhaust setup and should provide objective changes to your 911

[Trackrash]

Originally Posted by darrin

yes, the heat exchangers are the source of cabin heat -- have you looked into SSIs? These are stainless copies of the headers the 911 engines used before emission regulations necessitated the single-out headers used by your '76 (and later 911s)- these do have heat exchangers, provide a near-ideal exhaust setup and should provide objective changes to your 911

+1 on SSIs or just stock 69-73 heat exchangers and muffler.
Only problem might be smog certification, depending on your location.

[Pstallo]

Do the stainless SSI's alter the sound any? Or, increase HP a couple of points?

[darrin]

Originally Posted by Pstallo

Do the stainless SSI's alter the sound any? Or, increase HP a couple of points?

yes and yes -- Unlike the 74+ heat exchangers, the SSIs don't merge the two cylinder banks together into a single outlet -- each cylinder bank exits into the muffler from its own outlet and requires a dual inlet muffler to work. These dual inlet mufflers generally provide a bit more "engaging" of a sound than their single inlet counterparts.

Further, since SSIs are freer flowing than the 74+ heat exchangers, they provide a minor boost (few HP) over the stock 74+ heat exchangers on 3.0 liter and smaller engines. On 3.2 and larger, they are a bit undersized and compromise top end power (but do provide a bit of a midrange bump)

[95mpower]

Thanks for the great info. Guys!! I'll definitely be looking into the SSI's.

[Matt Monson]

Just a point of record 74 still used the early style HE's. One of many one year only transition features of 74.