To cross pipe or not?

[Mikefirefighter]

Im going to get a new set of headers and Im wondering if I should get ones with or without the cross exhaust pipe.

Some say if you dont have a cross pipe it reduces low end torque. But on the other hand if its not there it cant be damaged or holed.

Opinions ?

 

[Pukmeister]

But on the other hand if its not there it cant be damaged or holed.

Opinions ?

I'd be more worried about holeing the front engine cover than the cross pipe.

If you cause damage in that area I'd say you must be doing something extreme with the bike anyways.

Personally I'd rather have bottom end grunt than top end power. It seems Akrapovic agrees, apparently their headers keep the cross link pipe.

If you do a site search, you'll see that some people have cut open their cats and ripped the restrictive catalyst out then got it tig-welded again. Looks stock, costs very little, breathes much more freely.

 

[Mikefirefighter]

Thanks for that but it doesn't answer my question. Protecting the front cover is not the function of the cross pipe. If it needed protecting Im sure there would be a mech guard available.

Further the fact that Akrapovic just copied the original BMW design is immaterial. Iv read somewhere that the only function of the cross pipe is to aid emission control.

 

[Sgt Bilco]

Mike

As you know we retain the balancer pipe on the keihans. It`s there because it helps with the low down grunt and apart from anything else, it looks "right".

As far as we are concerned, BMW put the balancer pipe in there for a reason and that`s another reason why we retain it. It`s cheaper to manufacture it without the balancer pipe and I`m guessing that`s why others don`t.

Oh, the Keihans are stainless steel and if you will have to be doing something really, really dull to damage it...........

 

[GS Chris]

My aftermarket headers don't have a cross pipe.

I noted a distinct improvement in throttle response, low end torque, and tank range. Plus you get that true twin exhaust note

Chris

 

[Greg Masters]

Im going to get a new set of headers and Im wondering if I should get ones with or without the cross exhaust pipe.

Some say if you dont have a cross pipe it reduces low end torque. But on the other hand if its not there it cant be damaged or holed.

Opinions ?

I did a search on 'exhaust reversion' and found this interesting article.

A few points from the article caught my attention:

• most systems are a compromise - where do YOU want to sit on the compromise line?
• the quickest cars and bikes are those with a flat power curve
• the cross pipe DOES aid low end torque

The choice is yours!

Greg

 

[pathfinder]

The 08 engined 1200 runs very lean at certain revs and care must be taken when considering an aftermarket exhaust as this can lean out the mixture even further.Some tossers have noticed their bikes are cutting out when coming to a stop I believe this could be due to running too lean.Did I tell ya about mi wippet?

 

[Mikefirefighter]

mmmm

Sgt Bilco,

Thanks for the reply. Sorry I did not know your pipes had a balancer pipe as I did not know of your company.

I cant find any actual data that proves that the balancer pipe help low down grunt. Some claim that it evens out the power curve but Im skeptical. At the moment I am of the opinion that its only function is to aid emission control by a secondary heating of the exhaust gases by the opposing down pipe prior to entry to the catalytic converter. It would further follow that a balancer pipe on a none cat system would be redundant. Despite it looking right.

Don't take this last comment the wrong way but retaining the balancer pipe on your system so it costs more is more to do with marketing than engineering.

The article that Greg found is right and sound tuning practice. The relevant section being that which deals with the diameter of the exhaust and its affect on lower and upper rev ranges.

Large diameter pipe low grunt but high end power
Small diameter pipe increased grunt but reduced high end power.
You cant have both without a variable exhaust system.
Yamaha have done some work in this area ;-)

Maybe this will have to wait till I get hold of a dyno and thats not going to happen any time soon.