Nissan K12 Back Box Delete

I have posted this little video with the sound of the Micra K12 with out the back box of the exhaust.
Soon i will straight pipe the K12 so stay tuned :)
 

John_D

Club Member
Radio Code Guru
I ran my K12 Sport + for a few days without a back box when the pipe into the box broke and while I wasn't averse to the exhaust note I found that the engine seemed to not want to rev as freely at the very top end. Replacing the back box cured this. I get the impression that the engine needed the back pressure in the exhaust system to run properly at max revs..........
 
I ran my K12 Sport + for a few days without a back box when the pipe into the box broke and while I wasn't averse to the exhaust note I found that the engine seemed to not want to rev as freely at the very top end. Replacing the back box cured this. I get the impression that the engine needed the back pressure in the exhaust system to run properly at max revs..........
In my opinion from what I have seen it does not affect me, my revs work with no difference and the car feels a bit faster but not too much.


Well as funny as this sounds, I am making my own cold air intake and I will be making a hood vent , as I have bee looking to see where can I try getting the coldest air. When this mod is done I will be making the full straight pipe and hopefully try see if there is some type of difference. At the end of the day is a 80hp car with a 1.2 engine that one day might blow up🤣.



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John_D

Club Member
Radio Code Guru
In my opinion from what I have seen it does not affect me, my revs work with no difference and the car feels a bit faster but not too much.


Well as funny as this sounds, I am making my own cold air intake and I will be making a hood vent , as I have bee looking to see where can I try getting the coldest air. When this mod is done I will be making the full straight pipe and hopefully try see if there is some type of difference. At the end of the day is a 80hp car with a 1.2 engine that one day might blow up🤣.



Sent from my SM-G973F using Micra Sports Club mobile app
My cold air inlet mod HERE.......
 

John_D

Club Member
Radio Code Guru
Thanks but I am doing it in a different way , I think oneone has done it yet. But is very helpful.

Sent from my SM-G973F using Micra Sports Club mobile app
I was working on the principle that Nissan and Renault designers, with their access to CAD design programs, who both seemed to come up with very similar locations for the air inlet to get cold air into the system, probably knew best, so followed their lead, removing all restrictions and increasing the duct size substantially, and it does seem to work.......
Sadly without said design aids (or a wind tunnel) it is almost impossible to work out where the high and low pressure areas on the body are at different speeds. (I speak as a retired design engineer with CAD design experience dating back to the late 1980's)
 
I was working on the principle that Nissan and Renault designers, with their access to CAD design programs, who both seemed to come up with very similar locations for the air inlet to get cold air into the system, probably knew best, so followed their lead, removing all restrictions and increasing the duct size substantially, and it does seem to work.......
Sadly without said design aids (or a wind tunnel) it is almost impossible to work out where the high and low pressure areas on the body are at different speeds. (I speak as a retired design engineer with CAD design experience dating back to the late 1980's)
Well I am not that professional and I dont think I am going to make the perfect intake for my car but at least I am going to try get some performance if is possible if not the sound will be at least there

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