Re: I got a 7kw gain mate your a/f ratio is important because headers aka extractors; increase your fuel economy. so if you dont notice a increase there, or even more power. id say something is not running, maybe give your afm a clean, yet i too think a 2.5 exhaust would help you with more gain, with the results you got i would think something isnt connected/working.
its not a stock exhaust, its replaced before i got the car. Could this be viable? Build a pipe that cones down from 2.5 inches at the headers to 2 inches before the cats. So there is no obvious restrictionand the reduction occers over a meter or so of pipe. Or just use 2.5 all the way?
I had only the mufflers and air pod It was on a low reading dyno too. 100kw with air pod and mufflers, 107kw with added headers, 114kw with UD pulley, full exhuast and superlight flywheel added. On another dyno with same mods around same time got 128kw. On a hub dyno got 134kw or so.
DREDZ has a 2.5inch cats-back system, and 135rwKw pre-header fit Although dyno at Berri after the fit still only showed 137rwKw, the difference in performance is noticeable on the track... At Heathcote pre-headers, temp about 15degrees, on a proper drag surface, 660ft time 9.9secs; at Berri after headers fitted, temp about 30degrees, rough hotmix airstrip, 660ft time 9.9secs. Given the temperature difference, and the fairly slippery surface at Berri (wheelspin off the line in an NA auto?) I would have expected a slower time than at Heathcote, so the headers do made a difference. Also, at Heathcote I was using more advanced timing and an octane booster. And also contrary to expectations, the exhaust sound is quieter with the headers!
High flow cats will make NO difference, and a 2" exhaust is overkill for a 1.5L output pushing only 130rwkw, you would be wasting your money going larger IMO.
Could these be useful to find the extra kw engine pipes from uas then use 2 inch from behind 2.5inch cats?
what type of mufflers do you have? if you dont have straight-through style mufflers that can restrict the flow of air through the system. If that is the case, it is no surprise you didnt get any gain from installing headers. A system can only flow as much air as it's most restrictive point.
Yes i understand that but how can there be no change at all in the figures? From what I understood 90% of the restrictions are in the front of the exhaust (headers to cats), the gasses have slowed sufficiently at the tail pipe. My thought would be 2.5 inch to the cats then 2 inch fter the cats.
I think you'll find that your Torque figure has increased with little change to the actual power output.
dude sorry if i'm still confused..... but why persist with a 2inch exhaust?? the stock exhaust out of Mr Nissan factory is 2 1/4 inch, so your exhaust is smaller than stock. Seriously, just go 2.5 inch all the way through. Either that, or at least put some pipes on that are the same size as stock..... what you have now (if I understand you correctly) is smaller... Cheers
damn this is interesting.... IN THOERY.. cos i havent tried it... TTZ say 9kw headers upgrade gain with sotck pipes... Mark has a high or (highest output NA in the country with 155kw) and has 2.5" twins...high flow cats, headers and good rear muffers AN 11sec HQ small block v8 doesnt even need that kind of system to flow 550hp.. but were talking a quad cam, higher reving motor not a low reving small block v8.. The zeds have a twin 2.25" stock setup but isnt that harshly reduced to 1" in some places? especially in the H pipe?.. hence it makes it wisper quiet and good on fuel? My zed has got stock pipes atm... i had a run with my mates NA that ran a single 3" (that barked badly i dare say) AND we were deadly close... his was a light weight 2+0 and i got the aussie 2+2.. both with pods, both stock headers... SO MAYBE the single 3" lost him back pressure just enough so i could stay ahead in a heavier Z with more kms ect... For only 150+ rears twin 2.5" sounds foolish but it seems to work fine on Marks car.... any engineer would say twin 2.5" is too big for that sort of output... twin 2" would be smaller than the near perfect stock exhaust but without all the restrictors in it... but it didnt work out on this dyno.. ID say the fuel mix is the biggest problem with only pullin 130 rears... or the position of your pod can affect the low RPM kw.. On the stock ecu advance the timing to lean out the mix.. or get a re-map to advance the timing via the software in the ECU. this can make HP..
advancing the timing does not lean out the mix. 2 inches is killing you. 2.5 the whole way and a tune and you will have mid 140's i reckon
Ive fitted 2-1/4 This gave me an improvement to the bottom & mid range but made no difference to the top end. I spent several months asking around and looking on the internet what was required, all the info I got said 2-1/2" was to big. Spent the next 6 month designing and drawing the thing. If you are interested I will sent you a copy of the drawing of the cross-over I designed and built
did your design>> Include undercar mufflers and a x over pipe? some of the expensive systems "off the shelf" have under car mufflers not just rear mufflers.
