4.8i Exhaust on a 3.0si?

[divinchi]

Hello to all, forgive me if this question has been asked before, I've done searches and have had no luck on finding info.

A friend of mine upgraded his exhaust on his 4.8i and gave me his exhaust system. My question is, can I add it to my 3.0si? I remember having my 2002 3.0 and added a 4.6 exhaust without issue, is it the same for the E70?

Thanks for the help guys

[Tchleung]

It'll fit physically, but the V8 muffler has dual inlets. Where yours has single inlet. You'd have to weld in a Y pipe transition. Or just cut the tips off and weld them to yours.

[divinchi]

Originally Posted by Tchleung

It'll fit physically, but the V8 muffler has dual inlets. Where yours has single inlet. You'd have to weld in a Y pipe transition. Or just cut the tips off and weld them to yours.

Thank you so much for answering my question, my next question is, will I notice a difference if I install this exhaust? I noticed a difference when I added the 4.6 exhaust to my 2002 3.0, will it be the same for the 2002?

Thanks again for helping me out

[Entropy]

I would imagine it will be quieter with the 4.8 exhaust.

[ard]

lol

you ask about the 'exhaust' and some guy w 2 posts on this forum says 'the muffler will fit'.

By 'difference' do you mean 'better performance" or 'better sound' or 'check engine lights from the wrong backpressure'???

[blndweasel]

Originally Posted by ard

wrong backpressure

^^ +1

There is considerable engineering that goes into designing an exhaust system for any vehicle. Achieving proper backpressure has an important effect on exhaust scavenging, and changes to backpressure could affect performance (negatively), emissions, and resonance. Yes, the sound will probably change. It's a subjective matter as to whether that's good or bad, but in measurable terms unless you have made flow improvements to the powerplant, you're only likely to experience negative effects on performance.

I once had a cafe racer for which I thought "I'll run open pipes, it will be cool" except it couldn't maintain idle due to lack of backpressure. I ended up having to re-engineer the pipes to add enough resistance for the engine to even behave modestly well. Compared to a stock configuration, the performance was terrible. BUT IT SOUNDED COOL. #blunderyears

[divinchi]

Originally Posted by blndweasel

^^ +1

There is considerable engineering that goes into designing an exhaust system for any vehicle. Achieving proper backpressure has an important effect on exhaust scavenging, and changes to backpressure could affect performance (negatively), emissions, and resonance. Yes, the sound will probably change. It's a subjective matter as to whether that's good or bad, but in measurable terms unless you have made flow improvements to the powerplant, you're only likely to experience negative effects on performance.

I once had a cafe racer for which I thought "I'll run open pipes, it will be cool" except it couldn't maintain idle due to lack of backpressure. I ended up having to re-engineer the pipes to add enough resistance for the engine to even behave modestly well. Compared to a stock configuration, the performance was terrible. BUT IT SOUNDED COOL. #blunderyears

Thank you so much for this response, it was a thoughtful write and I appreciate your help. I see how sensitive our cars are compared to the E53. I changed my 3.0 exhaust to the 4.6 and there was an improvement, but now I understand why there really hasn't been much information on this. So, what would I need to install the 4.8 exhaust? I was just going to keep it all original as far as adding the 4.8 exhaust and not delete anything. But the last thing I need is to have the check engine light on all the time with no benefits at all from the exhaust change.

[blndweasel]

It's probably not a common swap, so you'd want to check where you plan to connect things back of the cat, and see if the flanges will match up. If I had to guess, I would assume the I-6 exhaust collects into a single cat? Or does it merge post-cat?

If it's truly bolt-on, then you'll need an extra set of hangers and matching fasteners - realoem.com will point you in the right direction, just look at your same year vehicle with the 4.8 powerplant option.

Be sure to put in new bolts and copper washers if it is a true bolt-on process. Those copper washers are one-time use only.

Probably also worth checking TIS for an exhaust replacement, you'll get good pictures of the process and understand if other systems or components may interfere.

Lastly, you may need different underbody paneling - although I doubt this is the case.

[blndweasel]

Just looked at the diagrams, it appears the I-6 exhaust exits the dual cats/resonators with different spacing from the V8, and the pipes I'm sure are different diameters. You'll need a welder to match up the pipes.

[95wildtt]

It can be done, no issues if you have right tools and skill set.

Buddy of mine used my old '08 4.8 exhaust on his '08 3.0si, when his exhaust rusted out and got a hole in it...

As stated above he had to weld in a Y pipe.

It's working fine.