Absurd exhaust system proposal for e53 X5 3.0i M54 // headers back for under $1,250?

[bcredliner]

Originally Posted by IkirisTheX5

I wouldn't add headers unless they were a name brand that lists gains. It doesn't mean the claims will be accurate but that is why they build headers. The gain with the right exhaust isn't much. As an example the Dinan free flow muffler for a 3.0, when it was available, increased the HP by 5 at 6500 RPMs and TQ 4 also at 6500 RPMs.

Also bcredliner: the headers I was interested in are definitely not manufactured by a name brand, but from what they claim and I’ve read they are pretty good knock offs of the Supersorint E46 M54 headers which are equal length and claim to increase power by 20hp on a 330i. Yes, there are fitment issues regarding the O2 sensors and bolting up to stock exhaust, but those are the same complaints I hear about the $1,200 authentic ones as well and can be worked around fairly easily. Everyone says they bolt up to to the head just fine, which if they didn’t would obviously be a deal breaker. In summary, they sound kind of annoying, but effective and at 1/10th the price of the genuine ones still very tempting to try.

The gains on a 330i are not transferable to the M54 engine.

[nick325xit 5spd]

Originally Posted by bcredliner

The gains on a 330i are not transferable to the M54 engine.

I'm trying to understand what you mean by this? It's the same engine.

[bcredliner]

Originally Posted by nick325xit 5spd

I'm trying to understand what you mean by this? It's the same engine.

Sorry, I read it wrong, I was thinking of 335 turbo engine. Gains usually have a direct correlation to beginning TQ/HP. However that depends on how restrictive the stock components were.

[nick325xit 5spd]

Originally Posted by bcredliner

Sorry, I read it wrong, I was thinking of 335 turbo engine. Gains usually have a direct correlation to beginning TQ/HP. However that depends on how restrictive the stock components were.

Stock manifolds and cats are pretty restrictive. There's a bunch of power on the table.

Now, whether it's worth the effort is another question.

[nick325xit 5spd]

I would strongly suggest buying headers that fit vs. hoping that you’ll save money getting an exhaust shop to make them fit. There’s a hood chance you’ll end up breaking even cost-wise, and you’ll definitely have a worse final product.

[workingonit]

It seems that the M54B30 engine was made for a balance of torque and horsepower, using higher compression to offset the undersquare design (stroke greater than the bore). I've seldom had a "stroker" engine before, and my favored engine type is "oversquare" (piston diameter greater than the length of stroke), so I'm just saying that just adding headers is an expensive exercise on a semi-stock engine with tight exhaust parameters.

My Chevy race engines were high compression, large bore, short stroke (except for using longer rods on some), and high-lift cammed. My penultimate 427 engine, barely streetable, used 2" headers (3/4 length tubes), and a collector with swing-away exhaust pipes, where I could easily substitute collector extensions in a few minutes (even better if I had a place to detach and leave my pipes and mufflers behind). That engine was good for sub-12 second 1/4 miles, and lasted for quite awhile. Then it blew when the #4 con rod vaporized.

When I replaced it with another 427, it became too race-specific for the street, and it was a real challenge to work on...especially due to the 2.5" header primary tubes. I had to index my plugs, so I had to struggle to get past the large tubes (finally resorting to partially removing them), rerouting oil cooler lines and filter for clearance, and using fire-proof matting under my seat (and over the flexplate blanket) to be able to survive the high heat given off by the large full-length headers/collectors/extensions just under me. Sure, the massive exhaust was warranted, and it made more power than the earlier exhaust system, but it was a pure race motor, after all. I'd never had changed it, if it was just for a small % gain.

I plugged some numbers I found into an exhaust sizing calculator, and found out exactly how restrictive the M54B30 exhaust is...designed for balanced torque/power. Looks to me like it's comparable to using "peanut port" cylinder heads on my race engine (I used massive "square port" Brodix heads, opened even more by Reher-Morrison CNC-machining); I would've retained most of the torque, but lost most of the top-end horsepower that wins races.

If it's power you want, get bigger cam(s), valves, ports enlarged on the head, or if you just want the sound of power, then use by-passes, remove the central muffler (replace with an X-pipe, too), and forget the expensive header. Too much money spent & too many problems often accompany such a change, IMHO.

[bcredliner]

Originally Posted by workingonit

It seems that the M54B30 engine was made for a balance of torque and horsepower, using higher compression to offset the undersquare design (stroke greater than the bore). I've seldom had a "stroker" engine before, and my favored engine type is "oversquare" (piston diameter greater than the length of stroke), so I'm just saying that just adding headers is an expensive exercise on a semi-stock engine with tight exhaust parameters.

My Chevy race engines were high compression, large bore, short stroke (except for using longer rods on some), and high-lift cammed. My penultimate 427 engine, barely streetable, used 2" headers (3/4 length tubes), and a collector with swing-away exhaust pipes, where I could easily substitute collector extensions in a few minutes (even better if I had a place to detach and leave my pipes and mufflers behind). That engine was good for sub-12 second 1/4 miles, and lasted for quite awhile. Then it blew when the #4 con rod vaporized.

When I replaced it with another 427, it became too race-specific for the street, and it was a real challenge to work on...especially due to the 2.5" header primary tubes. I had to index my plugs, so I had to struggle to get past the large tubes (finally resorting to partially removing them), rerouting oil cooler lines and filter for clearance, and using fire-proof matting under my seat (and over the flexplate blanket) to be able to survive the high heat given off by the large full-length headers/collectors/extensions just under me. Sure, the massive exhaust was warranted, and it made more power than the earlier exhaust system, but it was a pure race motor, after all. I'd never had changed it, if it was just for a small % gain.

I plugged some numbers I found into an exhaust sizing calculator, and found out exactly how restrictive the M54B30 exhaust is...designed for balanced torque/power. Looks to me like it's comparable to using "peanut port" cylinder heads on my race engine (I used massive "square port" Brodix heads, opened even more by Reher-Morrison CNC-machining); I would've retained most of the torque, but lost most of the top-end horsepower that wins races.

If it's power you want, get bigger cam(s), valves, ports enlarged on the head, or if you just want the sound of power, then use by-passes, remove the central muffler (replace with an X-pipe, too), and forget the expensive header. Too much money spent & too many problems often accompany such a change, IMHO.

I used to race corvettes. We started with small blocks and then went to an L88 big block largely because of the huge torque. It was beneficial both for road and drag racing.

My point about making sure you don't negatively impact torque, moreover choose what increases torque the most and will certainly also increase HP is because of the weight of an X5. if one is only concerned with performance on the street the first 60 feet will most likely determine a win or a loss.

[IkirisTheX5]

Well, you guys convinced me… …and truth be told I was never really setting out to build a sleeper AMG E63 killer (it seems the only way to truly make a m54 competition worthy is forced induction and that’s an expense and headache 🤕 I’m not willing to invest in), but the sound is very important to me so I decided to forego the headers for the moment and (after some pretty exhaustive research) decided to go in on a pair of BadlanzHPE SS electric exhaust cutouts - they have excellent reviews, strong materials, manufactured in the US, reasonably priced and a 5 year warranty. Along with those I ordered a pair of Cherry Bomb M-80’s, a stainless stamped x-pipe to replace the resonator, and finally - the cherry on top - my faux M3 quad 3.5” tips. I’m pretty sure I’ll get all the sound I was hoping for with this setup, and it’s plenty absurd to keep me entertained for awhile, although I’m already bracing myself to be underwhelmed in terms of any performance gains.

Thanks again for your input guys; it definitely pointed me in the right direction. I’m hoping for install to happen mid-next week. I’ll throw up a link with a before/after video of the sound and you guys can judge whether it was worth all the goofy trouble!

[Happy]

Originally Posted by IkirisTheX5

it seems the only way to truly make a m54 completion worthy is forced induction and that’s an expense and headache

Very true! It is the only way to gain more power.

Expense, yes. Headache, no! The sweet sound of an M54 purring, is music to my ears.

[crystalworks]

Originally Posted by IkirisTheX5

Well, you guys convinced me… I decided to forego the headers for the moment and (after some pretty exhaustive research) decided to go in on a pair of BadlanzHPE SS electric exhaust cutouts - they have excellent reviews, strong materials, manufactured in the US, reasonably priced and a 5 year warranty.

I've run a set of those cutouts on my 4.8 for years. No issues with them. Hope yours serve you as well as mine have.

Originally Posted by IkirisTheX5

Happy: Holy $&!t, is that yours?! That sounds incredible.

Thing is crazy right? Forced induction AND a manual. Still disappointed I haven't had a chance to see it in person yet. Thought the CnC at TMJ Bimmers might be my opportunity... but alas was not to be.