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Location:
sydney
Registered:
November 2003
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 Plenum size
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Wed, 18 February 2004 07:05
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Due to the fact i am already going spastic on this engine i dont see the point in using the shitty old tvis plenum on my 4agte so am going to make a new one.
My question is.....What size should it be? (Volume size i guess)
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Location:
sydney
Registered:
November 2003
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Re: Plenum size
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Wed, 18 February 2004 07:16
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Oh yeah......Will the 4agze throttle body be enough or shoud i go bigger with that too?
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Location:
Brisbane
Registered:
May 2002
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Re: Plenum size
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Wed, 18 February 2004 07:19
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I think the rule of thumb is 1.5 times the engine capacity, ie 2.4 litres in your case. I'm sure someone will correct me if I'm wrong. 
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Location:
sydney
Registered:
November 2003
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Re: Plenum size
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Wed, 18 February 2004 07:27
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Would it matter if i went a little bigger ( 2.5L - 3L )?????
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Location:
PNG
Registered:
June 2002
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Re: Plenum size
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Wed, 18 February 2004 07:41
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Throttle response. You have to fill it up.
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Location:
Brisbane
Registered:
May 2002
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Re: Plenum size
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Wed, 18 February 2004 07:54
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That's exactly it. The plenum size affects the inlet tuning and thus torque characteristics of the engine. A larger plenum is more suited to low-rpm torque but throttle response will suffer, while a smaller plenum (or no plenum in the case of ITB's) is better for high-rpm flow and sharp throttle response but low-rpm torque suffers. Obviously I'm generalising here, there are many factors to be considered and I'm not an expert by any means!
Anyway, the 1.5x rule (or whatever it is) is the best compromise, but not necessarily the best for your purposes.
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Location:
Lost in the K hole
Registered:
May 2002
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Re: Plenum size
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Wed, 18 February 2004 08:50
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i think the magic number is x3 norbie (for NA anway - the numbers for FI still elude me)
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Registered:
February 2004
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Plenum size
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Wed, 18 February 2004 12:11
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kinda depends where you have your TB. if you have ITB's with turbo, you may want a larger plenum (like a pressure reserve). if you have single TB maybe smaller..... as Norbie said it depends on lots'o'stuff, like runner size and length, how everything merges together.... and particularly, how much airflow you are expecting..
that speed event AE86 is designed for peak power only (40 psi, need i say more  ) and does it well... may not be so good for tootling tho.
some drag turbo apps don't have plenums, just extractor looking pipes from TB to each cylinder (that V8 monster posted up somewhere)
i'd suggest having a look around at OEM plenums on things like 200SX, skyline, supra, starlet etc.. give you a bit of an idea (since they have done a lot of testing for you)
Cya, Stwart
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Plenum size
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Wed, 18 February 2004 12:12
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as for TB sizing
300ft/sec
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Location:
Bundaberg, Qld.
Registered:
May 2002
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Re: Plenum size
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Wed, 18 February 2004 12:57
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| fatmr2 wrote on Wed, 18 February 2004 17:16 |
Oh yeah......Will the 4agze throttle body be enough or shoud i go bigger with that too?
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 use the 4age throttle body it bigger than the gze one, or a 3sgte one which i think is a little bigger than the 4age one......
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Location:
sydney
Registered:
November 2003
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Re: Plenum size
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Wed, 18 February 2004 21:29
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Looks like this is going to be a bit of a challenge 
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