Exhaust Pipe diameter

[CMF_malindags]

for 1.0L K11, what would be the best exhaust pipe diameter for a complete exhaust mod?

 

[CMF_Ghetto Micra]

probably 2", it's common, and it's probably one of the cheapest due it's "common'ness"....

 

[CMF_malindags]

if i use 2.5" will it cause a negative performance?

 

[cisco]

Yes theoretically. Loss of torque - reduces exhaust gas velocity. There's no point in a 2.5" if you're not installing a turbo any time soon.

 

[CMF_evade]

2.5 is huge. use 2" ..you want SOME backpressure.

2.5 is what ive got on my turbo setup

 

[CMF_w8upforme]

Probably with running a 1.0, 40mm or 45mm would be sufficient, for most low down torque..

 

[CMF_Polar]

the OMP 1.3 grp N micra rally cars used just over 1.5" (40mm) diameter exhaust system. so on a 1.0 no point in going bigger than 1.5". this is mandrel bent system. if your thinking of getting a powerflow, which i think are terrible, it wont be mandrel bent and will be smaller than what you asked for on the bends. i would recomend the omp as i have one, it also decats starting from the front pipe back.

 

[CMF_Napster]

after reading this i was a little confused??

so the smaller the backbox tip, the better performance u should get??

or have i got that all wrong??
cheers
napster

 

[CMF_w8upforme]

No it is the pipe diameter of the whole system (cat back) that matters, tip is just there for the looks...

What I mean is, standard micra exhaustdiameter is about 35-38mm, and especially on the 1.0, if you put an exhaust on the car with say 50mm diameter, you will lose a lot of torque and power in the lower revs, which could mean you would have to rev to 2500rpm (this is an example) to actually be able to drive away smoothly.

so I guess 40-45 mm would see some gain there, but if you would go for 50mm and upwards you would lose an awful lot of driveability on your car...
It would be all sound and now performance (which would be a shame)

 

[CMF_Napster]

well i learnt sumting new 2day thanks to u great people!!

so the smaller the "pipe" from the "manifold", the better performance?? Yes/No or am i still wrong lol??

i didnt know that u could lose power and torque from having a to-bigger exhaust??

napster

 

[CMF_NotAnotherSSS]

Napster, take the time to read these webpages:

http://auto.howstuffworks.com/engine.htm
Then:
http://auto.howstuffworks.com/question172.htm
and
http://auto.howstuffworks.com/muffler.htm
and may as well read this
http://auto.howstuffworks.com/question636.htm

They may help you improve your understanding of how exhausts work and why backpressure is a major issue.

Cheers

 

[CMF_Napster]

"NotAnotherSSS" Thankyou very much

very apprecaited!!!

cheers
thanks everyone else aswell

napster

 

[CMF_lam.666]

didn't want to creat a new post, as my question is along the sames line as this.

what would be the best exhaust pipe diameter for a non turbo micra
1 7/8" (48mm) or 2" (51mm)?

the system will look something like this:

extractors > cat > 1 7/8 straight through no muffler or;

extractors > cat > resonator > 1 7/8 straight through no muffler or;

extractors > cat > resonator > 2" straight through no muffler.

keeping in mind its just a 1.3 litre...

does anyone here run a 1 7/8 diameter exhaust system?

 

[CMF_egSi]

my mate has a 2 complete system on his and he tells me there was definate gains.