1.8L VS 2.0L T4 exhaust systems Options

[technicalninja]

I've wondered why Porsche built different exhaust systems for the T4.

It appears that any year complete exhaust system can be installed on any year T4.

And yet the systems are so different that even the mount at the transmission needs to match the exhaust.

Why?

It seems the systems have the same size pipes.

The 1.8/1.7 have a short "S" kick up at the back that doesn't look like it will affect flow very much.

What am I missing?

Are the 2.0L mufflers higher flow?

Was it just a sound difference?

I didn't "see" an obvious flow difference when I bought a pair of used 1.8L SSI exchangers and the Bursh muffler that fit them.

Was I wrong?

[Jack Standz]

The 2 liter exhaust system heat exchangers have a very slightly larger inside diameter. This probably allows for greater flow, especially on modified motors. Not sure if it makes a meaningful difference to stock 914s.

Other than that, trying to get into the minds of what Porsche engineers were thinking 55 years ago is a difficult task. Why all the complicated stuff on 914s and other Porsches? Why do we have to buy all these special tools? Why did they run the full power of the starting system through the ignition switch? (clearly they knew about relays)

And why did they not provide a safer better way to jack up the car so you can work on it?

[Geezer914]

I believe the aftermarket SS exhaust use the the same diameter pipes. The intake runners on the FI 2.0 are slightly larger than the 1.7 and 1.8L.

[Jack Standz]

Am out of town and won't be back for a couple weeks, so can't measure things right now. But, someone has probably posted the dimensions here somewhere. At least have OEM 1.7 and 2.0 as well as 1.7/1.8 SSI aftermarket ones (which I think are the same size as the 2.0 SSIs).

Not sure, but one of the changes to the heat exchangers, exhaust hanger, and muffler may have something to do with the end of the 901 tailshifter in 1972 and the 2 liters production after then?

[bdstone914]

1974 1.8 stock heat exchangers have the same tube size as 2.0.
@mb911 might have flow info on stock mufflers

[914sgofast2]

Aren't the exhaust outlet ports on the heads all the same, regardless of engine displacement? They all use the same infernal copper exhaust washer between the pipe and the port on the head.

[mb911]

1974 1.8 stock heat exchangers have the same tube size as 2.0.
@mb911 might have flow info on stock mufflers

Sorry long gone information

[Superhawk996]

The differences between OEM versions are sort of moot.

If you are running near stock, the differences are negligible though even that minor s bend surely adds some incremental head pressure vs a straight pipe.

If you’re running a performance build you would be running headers and a free flow exhaust.

[Superhawk996]

1974 1.8 stock heat exchangers have the same tube size as 2.0.
@mb911 might have flow info on stock mufflers

Sorry long gone information

@bdstone914 now has a flow bench. (IMG:style_emoticons/default/smilie_pokal.gif) We’ll make it Bruce’s job to set up fixtures and measure flow for all the OEM mufflers as well as Triad, Bursch, Monza, Ben’s, etc. Probably has nothing better to do with his time.

(IMG:style_emoticons/default/av-943.gif)

[technicalninja]

1974 1.8 stock heat exchangers have the same tube size as 2.0.
@mb911 might have flow info on stock mufflers

Sorry long gone information

@bdstone914 now has a flow bench. (IMG:style_emoticons/default/smilie_pokal.gif) We’ll make it Bruce’s job to set up fixtures and measure flow for all the OEM mufflers as well as Triad, Bursch, Monza, etc. Probably has nothing better to do with his time.

(IMG:style_emoticons/default/av-943.gif)

NO, just flat freaking NO!
(IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif)

If Bruce has extra time on his flow bench, I can think of HUNDREDS of things I'd test before I jacked around with stock 914 exhaust...

BAD Superhawk!
BAD, BAD, BAD!
(IMG:style_emoticons/default/beerchug.gif)

[bdstone914]

@technicalninja

@Superhawk996

' @mb911 might have flow info on stock mufflers
[/quote]


Sorry long gone information
[/quote]
@bdstone914 now has a flow bench. (IMG:style_emoticons/default/smilie_pokal.gif) We’ll make it Bruce’s job to set up fixtures and measure flow for all the OEM mufflers as well as Triad, Bursch, Monza, etc. Probably has nothing better to do with his time.


Yeah I have been wondering what to do in my spare time.
In the plans is to develop an equal lenght header system with heater boxes for large displacement type 4 engines. Need to know flow of stock heat exchangers, mufflers, Triad ( which we have) 911 type mufflers to optimize our system.
Have a stock 2.0 banana mufflers. NO plan to test a Monza or any 4 tip muffler unless someones wants to pay to see how bad they are.
May offer flow testing of intake manifolds and other components. having correct adapters is the determining limiting and what it costs to make them.
Stay tuned

(IMG:style_emoticons/default/av-943.gif)
[/quote]

NO, just flat freaking NO!
(IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chair.gif)

If Bruce has extra time on his flow bench, I can think of HUNDREDS of things I'd test before I jacked around with stock 914 exhaust...

BAD Superhawk!
BAD, BAD, BAD!
(IMG:style_emoticons/default/beerchug.gif)
[/quote]