Jump to content
SAU Community

Recommended Posts

Ok, basic question.

Car A: From the factory has a 2.0L engine making 123kw with a 2.25" exhaust, one muffler and one resonator. (And a cat)

Car B: From the factory has a 2.5L engine making 123kw with a 1.75" exhaust, one muffler and one resonator. (And a cat)

I own Car A, and the aftermarket muffler on it is too loud for my daily needs. I can get the muffler off Car B for $20. Being that they make the same power, will putting the muffler from Car B onto Car A cause a restriction due to the drop in pipe size?

Cheers

p.s. purpose of this is to save money. OEM replacement for my car is $400. Universal muffler is still alot more than $20 and may be louder than a stock option off another car.

Edited by Bennis

What if car A needs no more than 2.25" to flow freely and reach it's calculated power output.

And car B, given that it has a bigger motor has the potential to make more power, but the manufacturer uses a 1.75" for nvh purposes which also has the effect of restricting power to 123kw.

Disclaimer: I know absolutely nothing about exhaust design haha

Edit: My point is it may be a restriction

Edited by r31slpr

You're going from 2.25" to 1.75", of course it will there will be restriction. If the goal is to quieten your exhaust and you're too poor to buy anything other than that muffler mentioned, then you don't have much of a choice do you?

If you have a crappy hotdog resonator, replace it with an oval type (bigger/heavier the better, more baffling). Same goes for a cannon rear muffler.

I doubt very much that a drop in size of 0.5" at the muffler will make enough difference to be discernable.

Do a bit of reading on Charles Law, and you will see why. The gas temp at the muffler is about 25% of the temp at the manifold, ergo you can quite drastically reduce the diameter of the exhaust a fair whack (and a lot of manufacturers do) without causing a restriction. There are also more than a few proponents out there that support the idea that reducing the back end of the exhaust diameter will actually help pulse scavenging (in an NA car, obviously not in a turbo application) which will contribute to low end pulling power.

Its also for this reason why hi-flow cats make a difference to performance, and cannons do not.

Personally, I would not let the back end diameter get below the std exhaust size from the manufacturer though.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • I removed the IACV, cleaned it and reinstalled.  I found a video on youtube that helped with the whole process, the guy then said the idle needed to be set, so the process was to get the vehicle up to operating temperature, unplug the TPS, set the idle screw in the IACV so the RPMs were around 600, then plug the TPS back in.  After I reinstalled the IACV, the car started (because, it was a cold start), once it warmed up, the car died, I adjusted the idle screw to see if that helped anything, it did not, I had to wait about 3-5 minutes, then the car would start back up. Only to shortly cut out, and only crank.  I loosened the TPS to see if adjusting that would do anything, and when I would rotate the sensor clockwise, there was a humming noise, but it would go away when I got the sensor in the horizontal position.  It only made the hum noise with the key on.  What do you guys think? 20250414_172604.mp4
    • Quick update.  The engine grounding strap was replaced, the engine is now happily running.  Tested the voltage drop before replacing the strap, was about 1.2ish volts down between engine to battery, chassis to battery. With the new grounding strap, pretty much no voltage drop at all. 
    • I was chatting with an ex SAU person who is involved in chooning euros now. He was saying the factory cars like Audi VW etc have something like 2000 tables that the ECU uses for getting everything "just right". Compare that back to any aftermarket ECU, and you'd be hard pressed to surpass 50 lookup tables. Even the Ford Barra engine has a few hundred lookup tables to run it (and they're still working some tables out too!)
    • Grab a temp probe, and probe each exhaust inlet runner with it sitting idling. Each one should be pretty darn close to the same temp. If you've got some reading higher or lower than the others, it's likely either air flow isn't equal, or your injectors aren't equal to each other.   The other things to check, is from the wiring changes that were made, were any earth's or grounds moved/changed.   Lastly, for the strut brace issue. It's not perfect, but can you get away with slipping a washer or two under the strut brace to raise it, and it still clean the bonnet? If you can, work out the height you need, that the motor can't torque up into, and get a spacer made for each side.
×
×
  • Create New...