I'm in the process of changin out my 240 DL transmission due to no reverse(previous owner seriously neglected car), and since I have the downpipe and catalytic converter already disconnected, I wanted to change out the exhaust to something a little less restrictive as well as get a nice exhaust note in the process.

However, I know from reading this and other sites that these engines are tuned for a certain amount of backpressure, which is why they have 2 stages of mufflers.

How much trouble will I run into by going to a single stage, less restrictive muffler such as a Monza type exhaust or something similar?

Also, I'd love for you guys to make some reccomendations for an exhaust system if you've tried something with success.

Many thanks in advance!

 

This is an NA car right?
no car really wants backpressure....
One muffler will be fine, just louder than a turbo with one muffler.
the biggest diameter I would go is 2.5" for NA.

Not sure about muffler choice. never done it to a NA.
A friend done here has a 3" custom exhaust and headers on his. sounds pretty good for a 4 cylinder, just loud in the car. he can't hear anything.

 

Yes, it's normally aspirated.

I'm just wanting to give it a little more of a peppy sound.

I used to own a Triumph Spitfire with a Monza exhaust and loved the way it sounded. However, that was over 15 years ago and I kinda figured that technology had allowed more advanced systems to be designed.

I just wanted to ask here because I have read on other sites that the factory 2-stage Volvo system mainatained a certain amount of backpressure, and I didnt want to risk having to change ECU parameters by altering the design spec of the factory system. But if backpressure isnt a real concern, then I guess any aftermarket system would do?

 

Engines needing backpressure is the biggest perpetuated myth in the auto industry. You want more power, you need more flow, simple as that. People who perpetuate this myth have no understanding of gas flow theory, internal combustion engines or anything much to do with cars frankly.
If you change the intake or exhaust for more flow, you MUST put in more fuel to compensate for more air entering the engine. Most decent fuel injection systems will automatically compensate up to a point, and an exhaust will be well within the stock system's abilities to compensate on ANY car.
There is no way to make more power without burning more fuel.
The very best thing you can do is run a single 2.5" system with a large, high quality muffler in the front position only. A large muffler does not have to be an expensive, polished $300 one, light truck mufflers flow very well and have nice large inlet and exit tubes on them. You also don't need stainless steel tubing, mild steel will last 10 years or more with ease, how long will you own the car?
As an example, here is my turbo with a single truck muffler:



Regards, Andrew.

 

Well, I'm not talking about building a street racer or anything.

I understand the concept of what happens in a less restrictive exhaust system, and yes, more gas is needed to prevent a "leaning out" effect from occuring, and not to disagree with you, but I've read in plenty of places and have been told by quite a few mechanics that backpressure, along with the scavenging effect in a properly designed exhaust system can yield quite substantial power gains along targetted RPM ranges.

I'm looking for an aftermarket exhaust solution that will not exceed my ECU's ability to compensate. I see in another thread that IPD makes a single muffler system that was adapted from a turbo system with promises of 5-6HP gains at the rear wheel. I may give it a try and see how things go.

 

1. You say you took off the downpipe and CAT, that means it is a turbo model.

2. Someone mentioned this is an NA right and you replied yes this is an NA.

****My question truly is, what is this car? Is it turboed or NA? You say it is both in this thread.****

If your turboed do a full 3" mandrel bent turboback system (Downpipe/Catback) with a free flowing straight through design muffler like a BORLA or MAGNAFLOW.

If your NA then I would suggest a 2.5" mandrel bent or crush bent system with a baffled muffler such as a FLOWMASTER.

 

It does?

I was under the impression that the downpipe is the pipe that connects the exhaust header to the catalytic converter? I had a muffler shop inspect my exhaust system when I got the car running and even the mechanic referred to that pipe as a "downpipe"...??

My apologies for the terminology confusion. But I assure you it is a normally aspirated 240.

 

Re read my post. No exhaust wil exceed your stock ECU's abilities.
Most mechanics do not know more about engine theory than the bare minimum to pass a course. Most mechanics who claim to be mechanics are generlaly not mechanics. The internet is full of bull**** perpetuated by people who do not know a thing about a subject but want to be popular, so spread the same thing they heard around a thousand times.
Again, backpressure is bad in any engine of any size.
Why do you think top fuel engines, areo engines etc all run massive, open exhausts?
If you want peak torque, you must have an engine that has high volumetric efficiency, that means as litle restriction in teh intake and exhaust as possible.
All backpressure in an exhaust system does, at any rpm, is cause teh engine to work harder to push out waste gases and in doing so, hampering exhaust scavenging.
If you will not listen to advice after asking it, you will be doomed to fail in everything you do.
I've built up over 20 engines in widely different cars and boats, not a single one went worse or made less torque with a larger exhaust system on it.

Regards, Andrew.

 

So hypothetically if you could fit a 7" exhaust on this N/A Volvo that wouldn't be too big? You would still gain power?

I am not saying I understand or am a know it all, but I can see where things could be too big to benefit and could only hinder performance.

Also I think people have tried 4" systems and have seen that they produced less power then a 3" system on their Volvo's.

 

you need to match the pipe diameter with the hp/tq goals.

 

Mechanics have to take a course? Did not know that...

 

I dunno, I asked a simple question about putting a cat back system on my Volvo 240 that would give me a better exhaust note and I wind up in exhaust theory class.../shrug.

 

This is one answer.