Post #1
Anyone know what the Volumetric Efficiency for our engines is?________________________________________
Ex SC-6Now in a Megane R26
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displaying posts 1 to 21 of 21
| Author | Subject: Volumetric Efficiency??? |
 smegal
Seasoned Pro  Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Now in a Megane R26 |
 Posted 15th Jan 2010 at 23:03
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phillipm
Seasoned Pro  Location: Rotherham Registered: 15 Oct 2006 Posts: 20,607 Status: Offline |
Post #2
Peak?________________________________________ - Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM meEmail me! Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces. |
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Posted 15th Jan 2010 at 23:10
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smegal
Seasoned Pro Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Post #3
Yeah please, I'm trying to fathom out how to use a turbocharger compressor map.________________________________________ Ex SC-6Now in a Megane R26 |
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Posted 15th Jan 2010 at 23:12
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phillipm
Seasoned Pro Location: Rotherham Registered: 15 Oct 2006 Posts: 20,607 Status: Offline |
Post #4
I've never measured it accurately but IIRC it's just under 89% around peak torque.________________________________________ - Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM meEmail me! Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces. |
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Posted 16th Jan 2010 at 00:21
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smegal
Seasoned Pro Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Post #5
How do you measure it?________________________________________ Ex SC-6Now in a Megane R26 |
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Posted 16th Jan 2010 at 00:23
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phillipm
Seasoned Pro Location: Rotherham Registered: 15 Oct 2006 Posts: 20,607 Status: Offline |
Post #6
You need the mass airflow and the BMFC figures.________________________________________ - Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM meEmail me! Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces. |
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Posted 16th Jan 2010 at 00:25
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r*byb
Regular  Location: Tamworth Registered: 15 Sep 2007 Posts: 421 Status: Offline |
Post #7
89% is good really, most performance cars now run around 80% i believe.________________________________________ Team Low Compression |
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Posted 16th Jan 2010 at 01:54
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phillipm
Seasoned Pro Location: Rotherham Registered: 15 Oct 2006 Posts: 20,607 Status: Offline |
Post #8
BMW M5 peaks about 110%...________________________________________ - Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM meEmail me! Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces. |
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Posted 16th Jan 2010 at 02:49
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rich_w
Seasoned Pro  Location: Havant, Hampshire Registered: 29 Jul 2004 Posts: 5,412 Status: Offline |
Post #9
Volumetric efficiency is the engines actual flow divided by the theoretical maximum flow.As you say, 80% is a good figure to use for a modern performance engine. If you're looking at Rotrex compressor maps - be very careful - they aren't particularly accurate. This is because Rotrex use maps straight from the compressor wheels they use in their 'chargers, which are generally derived from turbos by Holset, Garrett etc. Obviously, the same compressor wheel will vary in performance when used in a S/C compared to a turbo application.  ________________________________________ Contact Details:rich@lynxpowerengineering.co.uk 07732 822546 |
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Posted 17th Jan 2010 at 03:52
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smegal
Seasoned Pro Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Post #10
I was looking at compressor maps for a turbocharger as a uni project. I did look at the rotrex map and was confused but I didn't give it a second thought.________________________________________ Ex SC-6Now in a Megane R26 |
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Posted 17th Jan 2010 at 03:56
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bobdylan_55
Seasoned Pro Location: derby Registered: 28 Mar 2009 Posts: 1,466 Status: Offline |
Post #11
be careful about if you need peak or at redline or at max power etc, peak is often mid way up the rev range. ________________________________________ 309 GTi6-T |
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Posted 17th Jan 2010 at 04:10
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rudolf
Seasoned Pro Location: Skelmersdale Registered: 07 Apr 2004 Posts: 2,769 Status: Offline |
Post #12
phillipm wrote: BMW M5 peaks about 110%... rich_w wrote: Volumetric efficiency is the engines actual flow divided by the theoretical maximum flow. So it can't be more than 100%  ________________________________________ S Reg Diablo standardsSpec SORNEDR Reg Nile standard spec written off then repaired X Reg Astor in need of TLC R Reg Nile to restore Set of Lions to fit. |
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Posted 17th Jan 2010 at 04:58
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chris with a pug
Seasoned Pro  Location: Southampton Registered: 16 Feb 2003 Posts: 5,366 Status: Offline |
Post #13
it can if the theoreticalmaximum is less than actual |
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Posted 17th Jan 2010 at 05:34
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phillipm
Seasoned Pro Location: Rotherham Registered: 15 Oct 2006 Posts: 20,607 Status: Offline |
Post #14
rudolf wrote: phillipm wrote: BMW M5 peaks about 110%... rich_w wrote: Volumetric efficiency is the engines actual flow divided by the theoretical maximum flow. So it can't be more than 100% It can, google resonance supercharging  ________________________________________ - Bespoke rollcages/additions/adjustments. Half cages right up to complete custom spaceframes - MSA/FIA spec, CDS, ROPT, T45, etc - PM meEmail me! Custom-made polybushes available - need an odd size or fitment? - anything from batch work to one-off pieces. |
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Posted 17th Jan 2010 at 05:54
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smegal
Seasoned Pro Location: Leeds Registered: 26 Dec 2005 Posts: 5,940 Status: Offline |
Post #15
bobdylan_55 wrote: be careful about if you need peak or at redline or at max power etc, peak is often mid way up the rev range. I'm using Steve's lecture notes and am finding the imperial calculations confusing. I was aiming for peak efficiency to be between 4-6k and am liking some form of Garrett gt2860 turbo. ________________________________________ Ex SC-6Now in a Megane R26 |
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Posted 17th Jan 2010 at 07:54
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osm2121
Regular  Location: Montevideo Registered: 02 Nov 2012 Posts: 229 Status: Offline |
Post #16
Sorry to revive the thread, but didnt wanted to open an other.Talking about resonance, this is only when the inlet has a plenum? Where the vibe rebounds back into the cyilinders in the plenum? Or with throttles bodies also matters? Cause if it doesnt have a plenum, theres no rebound back to the cylinder. I assume the shorter would be better to get rid of the resonance going out as soon as possible so it doesnt affect the air coming in. Although I´ve read in the forum, people said is the other way round, the larger the better, up to a limit. I think 370mm was said as the best measure for it, without going to a fine tune. Im just talking without any studies or background, just wondering and wanting to know a ittle bit more about this |
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Posted 11th Nov 2014 at 20:52
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jamiek_uk2000
Seasoned Pro  Location: Llanelli Registered: 18 Apr 2009 Posts: 1,925 Status: Offline |
Post #17
Only Rich is still in this thread from the original post. The forum is flat out!________________________________________ 205 GTi Red - G939 RTU - Died!306 GTi 6 Diablo - Being resurrected! Project Thread Looking for: VTS P1 Rack PR1.2 16" |
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Posted 11th Nov 2014 at 21:12
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allanallen
Seasoned Pro Location: Buxton Registered: 01 May 2007 Posts: 1,399 Status: Offline |
Post #18
The 370mm inlet runner length was a length derived by sandy brown to give the best torque curve IIRC. No idea what resonance was like at that length though. ________________________________________ www.bridgecraftmotorsport.co.uk |
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Posted 12th Nov 2014 at 22:35
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pete_rallye
Seasoned Pro  Location: Yorkshire Registered: 12 Dec 2002 Posts: 5,253 Status: Offline |
Post #19
You don't need a plenum to benefit, but I have always thought it would help. Very basically the air waves that bounce of the back of the closed valves and resonate back up the inlet leave a vacuum behind them, as soon as they are out of the inlet and into open air, there is a rush of air back into the inlet to fill the vacuum, and the idea is you time this rush of air getting to the valves at the same time the valves are fully open. There is no real 'ideal' length. It depends on what cams you are using (as the valves will open at different times depending on the cams) and where you want you're power, you can alter the length to move the power up and down the rev range, although you may well see a jump in power at certain revs with a certain length. This is how you get VE above 100% also, by using the ram effect to fill the cylinders. ________________________________________ Oulton Park in a BTCC 306 vid 1Oulton Park in a BTCC 306 vid 2 Lap of the 'ring |
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Posted 12th Nov 2014 at 23:31
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Puggitt
Regular Location: New Zealand Registered: 07 May 2012 Posts: 293 Status: Offline |
Post #20
pete_rallye wrote: This is how you get VE above 100% also, by using the ram effect to fill the cylinders. The ram effect? Able to elaborate? |
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Posted 12th Nov 2014 at 23:39
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pete_rallye
Seasoned Pro Location: Yorkshire Registered: 12 Dec 2002 Posts: 5,253 Status: Offline |
Post #21
I'm speculating here but I would expect VE to be calculated using air speed calculated from piston speed and port size and the associated air velocity, and not taking into account any effect of ramming the air in caused by the above explanation. So if you can design an engine to have as close a VE to 100% as possible, the 'ram' effect caused by the above would not be included in the calculation, and so when the engine is actually run, the VE at certain points in the rev range may exceed 100%.... ________________________________________ Oulton Park in a BTCC 306 vid 1Oulton Park in a BTCC 306 vid 2 Lap of the 'ring |
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Posted 14th Nov 2014 at 22:35
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