Dual Exhaust?

[Zonian22]

I see that the pitures from the 128i and 135i in europe have a single exhaust. When the car hits the US market, will it be like the 3-series where the 328i has a single exhaust, while the 300hp turbo-charged 335i has dual exhaust? Anyone know?

[BForbes]

If I'm not mistaken the 135i does have dual exhausts. The 535i has a dual exhaust even though the pipes are on one side.

[SCA]

Originally Posted by Zonian22

I see that the pitures from the 128i and 135i in europe have a single exhaust. When the car hits the US market, will it be like the 3-series where the 328i has a single exhaust, while the 300hp turbo-charged 335i has dual exhaust? Anyone know?

Neither models (128/135) will have the exhaust outlets from the 335i (one on the left and one on the right). It will remain dual outlets on the left side. BMW AG will not change the exhaust outlets for just the NA market. It would have to be for worldwide sales.

[larryn]

Dual exhaust and dual muffler are two different things. These cars will have dual exhaust, but they won't have dual mufflers.

[TheoIam]

Originally Posted by larryn

Dual exhaust and dual muffler are two different things. These cars will have dual exhaust, but they won't have dual mufflers.

Was that ever actaully figured out? The other thread about this I posted in did not have an answer. Has someone actaully see under the car?

[BForbes]

Originally Posted by TheoIam

Was that ever actaully figured out? The other thread about this I posted in did not have an answer. Has someone actaully see under the car?

If this car dosent have dual exhausts, its going to have have some issues. I can tell you that much.

[adc]

Originally Posted by TheoIam

Was that ever actaully figured out? The other thread about this I posted in did not have an answer. Has someone actaully see under the car?

The 135 has 2 separate exhaust manifolds (2 turbos) - so I am pretty sure it has a dual exhaust. But as others have mentioned, not a dual muffler.

Which I for one am thankful for. I hope this decision will keep aftermarket exhaust prices reasonable (335 exhausts are from $1200 up) and who knows, maybe it also leaves room under the trunk floor for a spare wheel well.

[chemhalo]

Originally Posted by onehots2k

If this car dosent have dual exhausts, its going to have have some issues. I can tell you that much.

At what point does it not have "dual" exhausts? We know for a fact that the car has 2 exhaust manifolds and 1 muffler. I am almost certain that the car will have dual cats. If after the cats, the pipes merge and one pipe runs to the muffler, is that no longer dual exhaust to you?

If you estimate that half of the wheelbase (52.36 in/134cm) is the length between the cats and the mufflers, the difference between 2 2" pipes and 1 2.75" pipe is almost nothing in terms of volume but the dual pipes would weigh 10lbs more.

I for one hope there is only 1 pipe. :wink:

[eMINI]

Aesthetics aside, if the HP and torque numbers are the same as the 335, less exhaust plumbing is just less weight, right?

[Robert]

Originally Posted by eMINI

Aesthetics aside, if the HP and torque numbers are the same as the 335, less exhaust plumbing is just less weight, right?

More exhaust flow if you have dual muffler and exhaust?

[atr_hugo]

Well there's a pretty good technical reason why dual exhaust on a straight six (with the firing order that this engine uses) is good. It involves scavanging the 'three cylinder' groups exhaust (because of the pulse spread - based on firing order). A truly dual exhaust would be the best - a dual exhaust back to the muffler would be the next to best and a combined exhaust just aft of the turbos would be less than ideal. Keep me honest, but I believe that's what we're talking about.

[Zonian22]

335i (300hp, dual exhaust, dual mufflers) = xxx hp at the wheel.

Wouldn't the 135i (300hp, dual exhaust, single muffler) make less hp at the wheels due to the restrictions of a single muffler? :iono:

[atr_hugo]

Originally Posted by Zonian22

335i (300hp, dual exhaust, dual mufflers) = xxx hp at the wheel.

Wouldn't the 135i (300hp, dual exhaust, single muffler) make less hp at the wheels due to the restrictions of a single muffler? :iono:

Possibly - but there are a couple of other things going on with this engine that mitigate any loss of HP based on exhaust. BMW uses an electrically assisted power steering rack which means no pulley for a hydraulic pump (no parasitic HP loss) and the water pump uses an electric motor (no parasitic power loss with a pulley for the water pump).

To be honest I'm not sure if the effect of a true dual pipe/single muffler would be in HP but its impact may be felt in where the peak HP would be. I read that a 335i customer of Vishnu requested an X-pipe (crossover pipe) for his custom exhaust and that did have some effect on HP - but the X-pipe was much closer to the turbos in that application, IIRC. Again someone needs to keep me honest here.

[ein-er]

Just get the Vishnu exhaust, along with PROcede V2 and you'll have a rocket.

ein-er

[Drillslinger]

As far as flow goes, didn't someone post that a single, large diameter pipe actually flows better than 2 smaller ones

[dumesday4u]

quad exhaust like hte e46 m3 i love =]

[eMINI]

OK, I'm not sure what I'm missing here. 335 HP & TQ = 135 HP & TQ, right? Since they're equal, I think it's fair to assert that the exhaust is functionally equivalent as well. I certainly have room for the possibility that the torque curves may be different and/or that the peaks are slightly different. But I suspect they're pretty much the same, ya know?

[menotakoala]

I think BMW may be doing a 2-2-1 setup. Both headers may lead into two separate catalytic converters and then into a 2.5 inch Y connection and lead out as a single 3 inch piping. And that will lead into a muffler that will have a dual output on the left side of the car.

[adc]

Change the muffler on a turbo car and get what? 3-4BHP maybe? That is easily accounted for via software.

Any significant exhaust improvements on turbocharged cars have to happen at the exhaust manifolds, turbos and downpipes. Even catback exhausts only seem to liberate only around 15RWHP on the 335.

In other words, I think it's all a wash between the 335 and 135, exhaust-wise.

[SpoolMasta]

My evo IX MR had a 3" all the way from the o2housing, not any farther and it gained at least 20HP, but i did have a downpipe.

If the 135 needs to be single sided, i hope they at least can offer a true duel aftermarket for flow, backpressure is the enemy for a boosted car. but the 135 is also running low boost compared to my evo(21 psi). So im not sure if it would benefit from a High flow cat somwhere during the piping for mid-range.

Travis