RS 2.7 and RS 3.0 street exhaust

[Chris Pomares]

I've been reading up on the RS 3.0 engine. Unlike the 3.0 RSR the RS 3.0 had a street exhaust. Does anyone know if the 3.0 used the same exhaust as the 2.7? Or where the tubes and muffler upsized.
The 2.7 made 210 DIN hp and the 3.0 230 DIN hp.
On another note I keep reading about people talking about 225 hp from their 2.7's. I'm quessing that's SAE hp not DIN. The 2.7's were 8.5 CR stock and the 3.0 9.8 CR. If DIN where is the extra 15 hp comming from?

[gled49]

A cookbook MFI RS spec 2.7 will make 225 to 235 SAE HP.

[Richy]

The 3.0 RS exhaust was not like the 2.7 RS , it was more like the 911R exhaust , but with bigger tubing .

[Chris Pomares]

I spent an hour looking at a 74 RS 3.0 engine on a engine stand with heat exchangers and muffler off the engine, yesterday. The car is getting painted. What I was told is this car is totally orginal. Here is the muffler number. I measured the heat exchanger. Exhaust port 36 mm. 3 header tubes 1.5 inches OD. Collector tube 2.0 inches OD.

[911MRP]

Interesting Chris. Isn’t that the same bischoff exhaust muffler discussed in this thread ?

https://www.early911sregistry.org/fo...vs-Dansk-sport

I assume one you pictured has model year 74 date stamp along with impact bumper shaped outlet — hence the suffix .01?


See my post #10 and 12 on that thread for 73 part number and the link to another thread about Bischoff with a stainless outer wrap. Similar 72 dated with suffix .00 as in my post for the model 73 RS (and TES) with suffix .00 before outlet shape changed for impact bumper rear.



This photo above is mine for my late calendar 72 built model 73 RS it has the correct earlier outlet shape still with original square lip chromed tip. Also got same minus stainless wrap that’s four months older.

So it seems the 74 RS exhaust silencer (muffler) box is same for model 73 TES & RS other than tweaks for outlet shape and suffix stamp or sometimes overstamp that probably denotes this?


Steve

[Chris Pomares]

I found the date. The car got it's first coat of paint today.

[Chris Pomares]

Steve,
I wonder if there are any internal differences between your 4/73 and the 1/73 Bischoff mufflers?

[911MRP]

Mine are 672 and 1072. The over-stamping of Roberts example suggest same other than the reshaped outlet.

[Chris Pomares]

I have this muffler hanging in my shop. It doesn't say who made it. Aftermarket? It appears to have been built in 34/98.