Muffler swap on a MFI motor. What works?
03-05-2002, 12:14 AM
#1
Racer
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Muffler swap on a MFI motor. What works?
I have a 1973 911T with the 2.4L MFI motor. It presently has the stock muffler. I have a bursch muffler that is supposedly designed to work with the MFI motors. I'm not too sure it will fit. But, has any one else swapped the stock muffler for another?
Scott Harris
1973 911T targa
2.4L MFI
Scott Harris
1973 911T targa
2.4L MFI
03-05-2002, 10:21 AM
#2
Technical Specialist
Rennlist
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Rennlist
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Scott,
As I recall, one that doesn't work with the MFI-based motors, due to it's internal design, is the Monty muffler. I'd have to go dig up the reference (it's in Up-Fixin') for any more details.
As I recall, one that doesn't work with the MFI-based motors, due to it's internal design, is the Monty muffler. I'd have to go dig up the reference (it's in Up-Fixin') for any more details.
03-05-2002, 03:00 PM
#3
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Hi,
it is not the muffler itself that is problematic with MFI engines, but it is the hot air support that comes from the heat-exchanger and goes to the warm-up thermostat. It is important to have good air flow with little temperature drop here, otherwise the engine will run too rich.
As long as you change only the muffler itself and not the heat exchangers all double inlet muffler types (standard for the 65-73 cars) should work fine.
Andreas
it is not the muffler itself that is problematic with MFI engines, but it is the hot air support that comes from the heat-exchanger and goes to the warm-up thermostat. It is important to have good air flow with little temperature drop here, otherwise the engine will run too rich.
As long as you change only the muffler itself and not the heat exchangers all double inlet muffler types (standard for the 65-73 cars) should work fine.
Andreas
03-06-2002, 02:31 PM
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For a 2.4 "T" w/ MFI, I believe you need a muffler with adequite back-pressure. A "sport-muffler" will leave you with "flat spots" in the mid-range.
A 2.4 "S" with its more agressive cam and ports can use a sport muffler. For a stock "T", I would go with an OEM or stock, 2-in 1-out banana style muffler...
A 2.4 "S" with its more agressive cam and ports can use a sport muffler. For a stock "T", I would go with an OEM or stock, 2-in 1-out banana style muffler...
03-07-2002, 03:08 AM
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I found that my 70E ran like crap with the "triple glasspack" Bursch that is supposedly designed for MFI cars.
It ran extremely well with the AJ-USA 2-in/2-out factory-style sport muffler as well as what I currently have installed, the AJ-USA 2-in/1-out sport muffler. Both are based on the factory type 'sausage' with correct fit, appearance and flow characteristics, but have some of the internal baffling removed for increased power and sportier sound.
The 2-in/2-out style sport muffler has been well-documented to provide a 5-10HP gain on most cars. The downside is that it is LOOOOOOOUD.
It ran extremely well with the AJ-USA 2-in/2-out factory-style sport muffler as well as what I currently have installed, the AJ-USA 2-in/1-out sport muffler. Both are based on the factory type 'sausage' with correct fit, appearance and flow characteristics, but have some of the internal baffling removed for increased power and sportier sound.
The 2-in/2-out style sport muffler has been well-documented to provide a 5-10HP gain on most cars. The downside is that it is LOOOOOOOUD.
