Manifold problem

[CMF_Gallardo Escobar]

Hi i hope u can help me...
i would like to remove the first cat (the one under the extractors) but some1 told me that i have to connect the o2 sensor...but if i remove the cat where do i connect that sensor?? thanx

 

[CMF_jaxx]

if you remove the cat u will have to get a pipe made up and drill a hole for the sensor and do a bit of welding.

then to get the full effect you will have to remove the second cat.

i recommend:

the janspeed manifold which i think has a hole for the sensor anyway, then just either remove the 2nd cat or get a system (cat back) made up for you. our M.O.T's are quite strict. dont know what it's like in Italy, but be carefull.

 

[CMF_jaxx]

think this is the hole for the sensor...if its not please dont laugh at me...lol

 

[CMF_Gallardo Escobar]

thanks very much...i'm sorry but i still haven't enough money to get the complete manifold like in photo. i've already removed the second cat. now i know how i can remove the first too. do u think there will be problem with ecu?

 

[CMF_jaxx]

ECU: not at all, it will not think much different at all. hope you are not expecting alot of power gain here....are you? you doing any other mods at the same time?

 

[CMF_Gallardo Escobar]

sorry...but i think i will have to stop...u know...it was more easy if money grew on trees...everyway...i've changed the back cat and removed the second cat. i think that after removing the first, i should notice some improvements...i think...what do u think?

 

[CMF_Yom]

I'd be very suprised if you felt any improvement in power.

There are other things restricting the CG from breathing properly.

 

[CMF_Gallardo Escobar]

4 example?

 

[CMF_Brendon]

the entire exhaust system is very small. open whole thing up to 2 inch at the most and then make a cold air intake. that should be good to open it up a bit.

 

[CMF_Yom]

The standard cast-iron exhaust manifold. Very restrictive. The standard secondary from the 1st cat converter to the 2nd cat converter is also highly restrictive (it is physically smaller than the standard throttle body butterfly!). The standard UK-made air intake piping, again, quite restrictive once you've opened up the exhaust. Standard throttlebody butterfly is also very small and the GA15 TB can open up another 5kw on a micra with all the exhaust and intake modifications already.

The standard muffler is also very restrictive. The standard piping isnt so bad as its actually the same diameter as the standard throttlebody butterfly and infact the standard manifold wouldn't be overly stressing the standard piping if you chopped the rear muffler off.

If you replaced all the bends in a standard exhaust system with mandrel bends (pipe diameter stays the same throughout the bend) and placed a non restrictive muffler on the end I would put money on you getting the same results as a 2" exhaust system from the cat-back (that is asusming you keep the standard exhaust manifold).

Thats just my observations.

 

[CMF_Tuph]

Taking it back a bit- i just checked out a local exhaust place today and got told me the same thing, just to do one stage at a time -> so if it doesn't have to be done don't worry about it.

instead he quoted me for a 2" sports exhaust with a lukey muffler ($390), with this he said he would make a air intake ($250) and leave in the stock manifold. with this he expected +10-15 HP

i thought this was a bit strange because i went in asking about the 2" exhaust, 4-2-1 extractors and fuel sensor kinking like recommended in "$1500 factory micra Powerup". then i was going to make my own air intake... he sounded concerned about moving the O2 sensor.

just thought it was strange to not change the extractors

Thoughts?