Wrighty
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Registered: 28th Feb 04
Location: Howden
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Im lookin for information regarding throttle bodies, with regards to the variations you can get and how they will affect power delivery. Iv read on here before regarding different length trumpets and perhaps angle of them? not sure
Any technical people in the know who can give me an idea how a TB can affect power, if it is made longer etc
Cheers!
Jon
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broster
Premium Member
Registered: 6th Dec 02
Location: Drives: E39
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what engine is it?
On the 1.6 16v engines and 2ltr it gives a nie spread of torque and power is linear, they tend to make the engine "revvy" to make the most you need to look at cams aswell and exhaust manifolds
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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Subaru EJ20T
Looking at possible spacing / enlarging my throttle body on it, just wondering how it would affect power if spaced differently, it at all.
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andyc1234
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Registered: 7th Nov 06
Location: Lancashire
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so just a single tb then on a turbo car would make no difference at all. The trumpet length and angle is for individual tbs and the length of the ram pipes going into them which affects the torque/bhp spread
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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How do you know though
if length can affect individual TB's (which one is, right) why wouldnt it work andy?
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broster
Premium Member
Registered: 6th Dec 02
Location: Drives: E39
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sorry, i see so your after info on enlarging your throttle body a subaru, keeping a single body?
how much boost are your running and what size are you boost pipes
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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1.2bar (18psi) at the mo, boost pipes, id have to go measure but i think theyre around 70mm.
wondering what enlarging and spacing the TB further from the manifold would do!
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DizzyRebel
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Registered: 2nd Jan 09
Location: Lincoln
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Basically the longer the trumpet the higher up the rev range the peak power is, the shorter the trumpet, bottom end/midrange power and torque is increased more at the sacrifice of high rp, power.
Depends on the application and desired engine characteristics really, its not a simple equation to make though and i wouldnt want to mess about with trumpet lengths and tb spacing at home without the proper techinical knowhow.
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DizzyRebel
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Registered: 2nd Jan 09
Location: Lincoln
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quote:
Originally posted by Wrighty
1.2bar (18psi) at the mo, boost pipes, id have to go measure but i think theyre around 70mm.
wondering what enlarging and spacing the TB further from the manifold would do!
Not much on a turbo car, you dont require on harmonic pulses to fill the cylinders with air as the turbo creates boost pressure. so short distance and a large tb would be your best bet. No doubt its already like this from the factory though.
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Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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The main reason you space the inlet manifold away from the block on the EJ20 is to help prevent heak soak between the two, not really to increase the volume of the plenum although I do think there are spacer kits out that are about 25mm thick so probably would increase the volume a little bit!
If you want to go nuts then go for a Magnus intake manifold but only really any good with supporting mods!
http://www.magnusmotorsports.com/intakemanifolds/subaru.htm
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gazza808
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Registered: 30th Jun 08
Location: Peterborough
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quote:
Originally posted by DizzyRebel
Basically the longer the trumpet the higher up the rev range the peak power is, the shorter the trumpet, bottom end/midrange power and torque is increased more at the sacrifice of high rp, power.
Depends on the application and desired engine characteristics really, its not a simple equation to make though and i wouldnt want to mess about with trumpet lengths and tb spacing at home without the proper techinical knowhow.
got that the wrong way round.
shorter trumpet power higher up, long gives more mid range etc
[Edited on 08-06-2009 by gazza808]
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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Cheers for that link stu, that manifold looks the nuts as do the cosworth ones! They also space the manifold from the block for heat soak reasons, but i arnt taking my inlet off just for that.
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Stu
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Registered: 3rd May 00
Location: Madchester UK Drives: 2014 BMW M135i
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quote:
Originally posted by Wrighty
Cheers for that link stu, that manifold looks the nuts as do the cosworth ones! They also space the manifold from the block for heat soak reasons, but i arnt taking my inlet off just for that.
Yeah, they are mega! Always wanted one myself but without a fairly high level of tune and some complimentary mods you are wasting your time! Manifold is a ballache to take off too so never even did the spacers!!! 
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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dreading doing my fuel rails in parallel as inlets gotta come off also 
there was a 700bhp impreza on youtube running a cossie inlet and it previously only made in the 600's without it!
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Wrighty
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Registered: 28th Feb 04
Location: Howden
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Looks like the rs25 lads over the pond are into it..on N/A though. Surly the same principle should apply for forced induction
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