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Updated: May 22, 2024     CONTACT    
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240 Exhaust Basics
240 Custom Exhaust
Larger Exhaust
Mandrel vs Crushed Bends?
Eliminating Drone



 
240 EXHAUST BASICS
 
240 NON-TURBO EXHAUST
The 240 exhaust pipe for your non-turbo has changed very little over the years. The B21 engine began in the 240 in 1976 and the similar B230 continued from 1985 to 1993. This factory exhaust was about 2 inches (51 mm) in diameter and began at the 3-bolt flat flange attachment at the bottom of the exhaust manifold. All of the exhaust variants looked nearly identical and most parts are interchangeable.

The catalytic converter was used for all U.S. versions. Canadian versions didn't seem to have catalytic converters on early 240s. Some versions in non-U.S. markets had a middle pipe without the catalytic converter.
In May 2024
I received info from a Canadian Volvo owner. He said he had been picking parts for Volvos from junkyards for years in Western Canada. 240's there did not have converters until 1985 or later. He had seen pre-'85 cars with a resonator looking device instead of a converter, which had a bolt in it where it appeared an the O2 sensor could go. T
he junkyard crews would chop up the exhaust, thinking it was a real cat, ruining a perfectly good exhaust.


240 TURBO EXHAUST
The 240 exhaust pipe for the TURBO has also changed very little over the years (1981-85) for the B21FT (or B21ET outside the U.S. and Canada). This exhaust was about 2.3 inches (60 mm) in diameter and began at the 3-bolt cone shaped flange attachment at the back of the turbocharger. All of the exhaust variants looked nearly identical and most parts are interchangeable. The catalytic converter was placed in the front down-pipe and was used for all U.S. and Canadian versions.  Some versions in other markets outside North America had a front down-pipe without the catalytic converter.




240 CUSTOM EXHAUSTS

For those of you interested in building a custom exhaust for your car, here are some topics you may be interested in.

LARGER EXHAUST
I have been a hot-rodder for many years and I'll be the fist one to tell you a bigger exhaust will usually help with engine power and fuel economy. There are a number of articles and videos available which will demonstrate the difference.  My personal belief is that a larger exhaust is worth the price for a TURBO or NON-TURBO car, however a non-turbo will pretty much always see LESS return for the money spent. Plus in most cases a larger exhaust is going to be louder inside and outside the car, depending of course on the muffler combination you select.

In the early 1990s my first 240 was a 1983 244 DL. I improved the exhaust on that car by installing a larger 240 Turbo 2.3 inch exhaust "back-half," which was inserted beginning at the back of the original catalytic converter (a cat-back exhaust). I installed a used factory 240 turbo exhaust from a salvage yard. It did noticeably improve performance. These days you can find just such a "cat-back" system for a non-turbo car from places like iPd.

Here's a video of this type of exhaust being installed
.
https://www.youtube.com/watch?v=tHzaRl3QSkw



EVEN BIGGER EXHAUST
Years ago I had the below 3 inch exhaust built for my 240 Turbo. The down-pipe was custom made using mandrel bent tubing. The rest of the exhaust was made by a local exhaust shop using standard 3 inch aluminized tubing, using an economical crush-bending method. A 3 inch catalytic converter was used and one large 3 inch muffler was put in back.
If you're curious about a performance comparison between mandrel bent and crush-bent: CLICK HERE.

The 3 inch catalytic converter above was placed in a non-original location for a 240 turbo, although that location is the normal location for a non-turbo car. In some places where more strict emission rules apply, this location may not be acceptable, although this worked fine for all the years I lived in California and had to smog test the car every two years.


Reportedly a larger exhaust will help a turbo spool up faster. That's a hard thing to quantify, but what about the horsepower gain with a bigger pipe?
Here's an episode of Engine Masters where they dyno tested a 2.5 versus 3 inch exhaust. Definitely good info to know.
The Power of 2.5 versus 3 Inch Exhaust - Engine Masters Ep. 9
https://www.youtube.com/watch?v=_PVXvHkr-Vs


BUILDING A CUSTOM TURBO EXHAUST
The first thing you'll need when you decide on a custom TURBO exhaust will be the downpipe. The most common or original turbo found in a 240 Turbo will have a 3-bolt "cone" shaped flange on the exhaust side as shown below, which is made for a 2.5 inch flange.

 

If you're going for a larger 3 inch pipe, there are transition flanges available to create a 3 inch downpipe for the above turbo.  Usually searching for a "Saab turbo downpipe flange" will find something useful.  Sometimes these can only be found in Europe. The first photo below is a 2.5 to 3 inch flange, which was offered by GenuineSaab.com
off and on in the USA (2023 link here: https://genuinesaab.com/catalog/product_info.php?products_id=621). This is one I have used before, but it has been discontinued off and on, so ask them if the link vanishes again.
The second photo below is a 2.5 to 3 inch flange that used to be offered on eBay by Zaustworx in the UK.  Also a similar one is offered by KSR in Norway. Most performance parts places like this in Europe speak pretty good English and will usually be happy to help with questions.


It's possible to find ready made 3 inch down-pipes also, but often the sources will be outside the USA. The first image below is from Martelius Exaust Systems in Finland.

It's also a good practice to use a FLEX UNION somewhere near the engine to help with vibration, such as the second photo above. Reducing vibration in the pipes will reduce the chances of cracked welds later. It will reduce stress on the  pipes as they expand with heat and then contract as they cool.




MANDREL BENT versus CRUSH-BENT PIPE
Nearly everyone will tell you for the BEST performance you MUST build a mandrel bent exhaust.  Anyone with eyes will agree that smooth consistent bends without any bottlenecks will flow better, but you might be surprised about the real world difference.

I saw an episode of Engine Masters on Motortrend TV that offered some of the best evidence toward an answer. In Season 6, Episode 83: Mandrel- v. Crunch-Bent Exhaust
, (subscription may needed to watch) a 530 HP naturally aspirated V8 was dyno tested with both exhaust types. The difference between MANDREL BENT 2.5 inch and CRUSH-BENT 2.5 inch exhaust was less than 10 hp at a 530 hp level. 
So you may consider this if the cost increase for a mandrel bent system is significantly more money.



EXHAUST DRONE

Looking at the photo of this exhaust above, there is no intermediate muffler between the catalytic converter and rear muffler.  I was getting an annoying drone a during a narrow RPM window at highway speeds. A few years after this photo was taken I added a small 12 inch glass-pack style resonator after the cat in an effort to reduce drone. It helped a lot.  Now there may be a more modern approach.  Have a look at the below videos.

Eliminating Exhaust Drone with a J-Pipe (Helmholtz) Resonator

https://www.youtube.com/watch?v=ds72D4rr4hg


https://www.youtube.com/watch?v=cwWK-xz7jho


https://www.youtube.com/watch?v=l9CrmkIxDQU


If you have any comments or any experiences with the above J-Pipe methods, please email:
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