SSI's Vs. Early Heat Exchangers

[MarkT.Bevans+]

I have a nice set of early Heat Exchangers on my 2.7 high perfromance engine, and was wondering if I could get a substantial increase from SSI's and a sport muffler.
My engine has high performance cams/webers/heads/pistons/etc./etc.
Thanks

[al lkosmal]

Mark,
If your heat exchangers are 74 or earlier, they are pretty much the equivalent, performance wise, to the SSI's, as that is the design the SSI design emulates. The only advantage to the SSI's is they modified the tube length slightly for equal length headers and they are stainless steel. Nice upgrades, but not appreciable performance upgrades over the 74 and earlier design. If, however you have a 75 or later exhaust system, you will notice a power increase.

[MarkT.Bevans+]

Yes Al

Mine are pre-1974, in very nice shape. What kind of muffler would help? I have a stock stainless version, but I do NOT want a Bursch, as I have heard them, and for the street they are a bit loud.

[dd74]

If the induction of your 2.7 is MFI, then you should probably stick with the stock muffler. However, if not, then I recommend the Triad dual-in-dual-out muffler. Great workmanship, light and quite inexpensive. There was a bit of a performance increase, too.

[MarkT.Bevans+]

Thanks...........Yep, I have webers/cams/pistons/heads/etc. I'll look into a Triad

[al lkosmal]

I have a 2.7 w/CIS and SSI's. (I've had carbs on it , as well. I have installed, at one time or another, the following mufflers with SSI's: Stock 77S w/the emissions port plugged, Bursch, Dansk 2 in-1 out, Bischoff, and Triad 2 in- 2 out. The Bursch was too raspy thru the 2-3K range, The Triad was/is a work of art, I loved it, but it was too loud and gave my wife migraines, litterally. If you are concerned about being too loud, I would stick with a 2 in - 1 out, Dansk. Good sound, not too restrictive or too loud.

P.S. I have the Bischoff on my car, but I'm headed back to 2 in - 2 out. I may modify the Bischoff int othis config. That extra cutout in my valence is begging for it.

[Wayne 962]

Sport muff! Best sound ever!

-Wayne

[jhora]

Mark,

Go to the Early 911S Registry Message Board at this location:

http://d240157.u39.zeonhost.com/forum/showthread.php?t=4752&page=1&pp=15

There is an excellent discussion on this very topic and the testing is being done on a dyno...with the results charts posted.

John

[MarkT.Bevans+]

Thanks John

Very good information. Thanks again for the research.

Mark