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Old 16-01-2012, 09:15 PM   #1
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aftermarket exhaust manifold

im after an uprated exhaust manifold for my rb25de

now i know there isnt many options of manifold for the de lumps so the question i am asking is,

could i get say a turbo manifold like this one and would it fit i.e stud pattern the same on the head?

http://www.ebay.co.uk/itm/NISSAN-Sky...item2c599c4bb4

and then take my car to a local fabricator and get them to make me a downpipe that comes form the standard turbo outlet port on that manifold to meet my decat pipe?

or is the style of manifold more restrictive than a standard de one due to the bends and amount of gas pressure an NA has compared to a turbo?

thanks Andrew
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Old 16-01-2012, 10:12 PM   #2
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A turbo manifold is designed around getting a good even flow from all ports to the turbo, but as a turbo is the biggest restriction in the exhaust system, it would not really be suitable, and you would see no benefits, your best bet is to buy a dedicated N/A two or three into one type, however the gains are small.
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Old 16-01-2012, 10:28 PM   #3
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Seeing as it get equal flow to one certain point,would that not aid flow...as of I get a 3inch down pipe made to bolt up to the flange,would it be less restrictive than standard?i know On an na engine the gains are minimal,but every little helps lol
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Old 16-01-2012, 10:29 PM   #4
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Also I have been trying to find an aftermarket ready made manifold for the de lump but cannot seem to find any.
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Old 16-01-2012, 10:40 PM   #5
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Quote:
Originally Posted by morzyr33 View Post
Seeing as it get equal flow to one certain point,would that not aid flow...as of I get a 3inch down pipe made to bolt up to the flange,would it be less restrictive than standard?i know On an na engine the gains are minimal,but every little helps lol
Let me rephrase that, yes they are equal flow to the turbo, but turbos don't rely on exhaust pulse timing and extraction like an N/A engine does in order to extract power, thats why the designs are totally different, your welcome to try it but you will ultimately be wasting your money and time,
Have you tried some of the Japanese tuning sites like www.nengun.com?
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Old 16-01-2012, 10:46 PM   #6
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Oh rite I see,I've always been lead to believe that the more free flowing the better.i will have a look at nengun and search for a few others,May I ask what exhaust pulse timing is?Like I said I thought the
Quicker you can get combustion gases out the better
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Old 16-01-2012, 11:05 PM   #7
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Oh rite I see,I've always been lead to believe that the more free flowing the better.i will have a look at nengun and search for a few others,May I ask what exhaust pulse timing is?Like I said I thought the
Quicker you can get combustion gases out the better
That applies to turbo engines for the reasons i mentioned earlier, its also important with N/A but not in the same manner.
now i am no expert, but i have done a little reading, exhaust ideally should be designed to get the gasses out quickly, however with an N/A gas speed and timing are a critical factor if you want to gain power, an N/A performance manifold is usually designed around the overall flow of the motor and the cylinder timing order is also taken into consideration, and so the length's of the individual pipes vary to take advantage of the extraction effect of the firing order of the other cylinders, there is a little more to it, like reversion tuning which is more to do with the rest of the system, IE shape and length etc, but i haven't gone into that too much.

This is why a properly designed performance/race exhaust manifold can cost over 1k.
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Old 16-01-2012, 11:39 PM   #8
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Ah I understand what u mean now,obv in what certain order the cylinders fire at determines certain length or bore size of pipe on the manifold to achieve power!just been on nengun the fujibitsu manifold for my car is over 1k lol and I haven't got that much to spend!!would I be completely wasting my time do u think with no gains what do ever other than it looking really nice?also could it make my car slower?thanks for your help and explanations there great!
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Old 17-01-2012, 12:06 AM   #9
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Personally i wouldn't bother, on the grounds that you could just as easily loose power, and more importantly mess up the torque curve, just to look good, but its up to you.
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Old 17-01-2012, 12:15 AM   #10
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Yeah do you know if the bolt pattern is the same as the turbo one on an na?I've been looking at the standard na manifold aswell,the only thing I can see if length of pipes and it's in no special order cylinder 1 is pipe is longest as its te farthest away from the Downpipe and the pipes get smaller all the way to cyl 6!got me thinking now....
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