How does a smaller up pipe help spool up?
09 July 2011, 01:03 AM
#1
How does a smaller up pipe help spool up?
I've got a biggish turbo for my new 2.0 engine and my mapper say it's going to be laggy on a 2.0 and says I should get a narrower up pipe to help spool and bring full boost down by a couple of hundred rpm.
That's all great but how does that work? Is it the same principle as putting your finger over the end of a hose pipe?
That's all great but how does that work? Is it the same principle as putting your finger over the end of a hose pipe?
09 July 2011, 08:20 AM
#4
Scooby Senior
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At low flow rates a narrowing ( venturi ) causes the gas velocity to increase.
To turn the turbine wheel it's a product of the mass of gas multiplied by it's speed ( momentum).
At higher flow rates the slight restriction is not an issue as most turbos can produce loads more boost than the engine can withstand.
All IMHO.
dunx
To turn the turbine wheel it's a product of the mass of gas multiplied by it's speed ( momentum).
At higher flow rates the slight restriction is not an issue as most turbos can produce loads more boost than the engine can withstand.
All IMHO.
dunx
09 July 2011, 10:57 AM
#6
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I used to have RCM headers & up pipe ... replaced the up-pipe with one of Harveys which did make a difference. I have rr results somewhere before & after which I'll attempt to post up. Harveys pipe starts the same width as the RCM one but narrows to help spool up.
TX.
Edit - the after is 1bar at 4000rpm, 1.8bar at 4600rpm. The before is 1bar at 4100rpm, 1.7bar at 4600rpm. Both runs at same dyno. Small win I guess! The car "feels" much better though, well worth it for a modest outlay imho.
TX.
Edit - the after is 1bar at 4000rpm, 1.8bar at 4600rpm. The before is 1bar at 4100rpm, 1.7bar at 4600rpm. Both runs at same dyno. Small win I guess! The car "feels" much better though, well worth it for a modest outlay imho.
Last edited by Terminator X; 09 July 2011 at 11:23 AM.
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09 July 2011, 11:06 AM
#8
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Think it's £149 wrapped. Might even incl install if you get Harvey to do it.
Just trying to find old graph now.
TX.
Just trying to find old graph now.
TX.
Last edited by Terminator X; 10 July 2011 at 10:03 AM. Reason: price correction after seeing Harveys post
Won't be getting Harvey to fit it because we'll fit it when we build the engine.
10 July 2011, 09:54 AM
#13
I've got a biggish turbo for my new 2.0 engine and my mapper say it's going to be laggy on a 2.0 and says I should get a narrower up pipe to help spool and bring full boost down by a couple of hundred rpm.
That's all great but how does that work? Is it the same principle as putting your finger over the end of a hose pipe?
That's all great but how does that work? Is it the same principle as putting your finger over the end of a hose pipe?
yes exactly the same except you dont get wet
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