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R75/6 crosspipe
Posted: Mon Nov 21, 2016 7:39 pm
by Googledave
Are there any pros or cons in removing cross pipe? Thanks all!
Re: R75/6 crosspipe
Posted: Mon Nov 21, 2016 8:29 pm
by Kurt in S.A.
My understanding is that engine performance as it relates to the exhaust is basically a zero-sum game. What I've heard is that the cross over pipe helps with mid range power. Likely removing the pipe will help say top end speed/power but sacrificing mid range power. You have to decide what you eventually want. I make the assumption that BMW knew what they were doing when designing in the intake and exhaust systems for engine performance. YMMV.
Kurt in S.A.
Re: R75/6 crosspipe
Posted: Mon Nov 21, 2016 8:55 pm
by robert
" I make the assumption that BMW knew what they were doing when designing in the intake and exhaust systems for engine performance. YMMV."
The R 50/5 and the R100rs had exactly the same part number exhaust head pipes.
How can an engine half the size of the other have an exhaust system designed
for performance with the same size pipe?
Re: R75/6 crosspipe
Posted: Mon Nov 21, 2016 9:30 pm
by Kurt in S.A.
robert wrote:The R 50/5 and the R100rs had exactly the same part number exhaust head pipes.
How can an engine half the size of the other have an exhaust system designed
for performance with the same size pipe?
It's all about air flow and pulses of air that come out of the engine. As in the case of the intake, I suspect there are pulses of air that are pushed out from the exhaust valve. The shape of the header and exhaust system have something to do with how well those pulses work within the cavity of the exhaust system. Is the stroke the same? Are the valve sizes the same? Maybe that's your answer?? Plus I wasn't referring to specific power levels, but rather to the optimization of power.
It's pretty complicated stuff and I didn't stay at a HIE last night, so that's the best I got!!
Kurt in S.A.
Re: R75/6 crosspipe
Posted: Mon Nov 21, 2016 11:49 pm
by Rob
Holiday Inn Express?
Is their continental breakfast, brain food for you?
Re: R75/6 crosspipe
Posted: Tue Nov 22, 2016 7:20 am
by Kurt in S.A.
Rob wrote:Holiday Inn Express?
Is their continental breakfast, brain food for you?
Sounds like you've never seen their run of commercials a few years back.
Kurt in S.A.
Re: R75/6 crosspipe
Posted: Tue Nov 22, 2016 11:20 am
by Rob
Kurt in S.A. wrote:Rob wrote:Holiday Inn Express?
Is their continental breakfast, brain food for you?
Sounds like you've never seen their run of commercials a few years back.
Kurt in S.A.
I avoid ANYTHING with commercials like the plague.
Re: R75/6 crosspipe
Posted: Tue Nov 22, 2016 11:25 am
by Rob
Rob wrote:Kurt in S.A. wrote:Rob wrote:Holiday Inn Express?
Is their continental breakfast, brain food for you?
Sounds like you've never seen their run of commercials a few years back.
Kurt in S.A.
I avoid ANYTHING with commercials like the plague.
YouTube = Ah!
Re: R75/6 crosspipe
Posted: Wed Nov 23, 2016 1:37 pm
by pkboxer
Just my $0.02
I removed my crossover on my '74 R90/6 (single crossover)
It was in bad shape after fighting with it removing the exhaust one time.
I cut off the stubs off and welded the holes shut.
I didn't make a point of doing before and after comparisons when removing it but my impression is that there really wasn't much, if any, difference.
That's just my experience.
It makes taking the exhaust off much easier too!
