jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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am i right in thinking that the length of the trumpet determines the torque/power of the engine?
longer - less power/more torque?
shorter - more power/less torque?
seeing as if gotta pay for a full remap when the engines done again, i thought it might be worth it if it helps gain abit more torque from the engine
cheers
james
[Edited on 12-03-2008 by jamesvalver]
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Warren G
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Registered: 14th May 06
Location: Kent
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just run no trumpets or filters, thats what im doing, well untill i get some made up
but apparently yes,you are correct
only minimal difference can be expected,
think its more about throttle responce, bit like having a airbox, you have air stored in it, for that first blip of the throttle, so longer trumpets will do similar but less amount
or am i talking rubbish again james?
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jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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ur prob talking alot of sence warren. i dont have a clue at all. i also heard they sound better with longer trumpets lol
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Warren G
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Registered: 14th May 06
Location: Kent
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me making - making sence, thats a rare site lol
well the sound shite with a induction chamber on
my 1.4 was louder with a K&N on, but need it still on becasue i have an AFM still, was hoping to be rid of the crappy standard managemnet by now 
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csweatherston
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Registered: 16th Jan 06
Location: Devon
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your 1400 has an afm/maf??
thought it would be map?
anyhow, its more than the length of the trumpets that determin power/torque.
its also angle of the flare, length of tube, total distance from valve etc..
every engine will be different.
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jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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anyone else?
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Warren G
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Registered: 14th May 06
Location: Kent
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quote:
Originally posted by csweatherston
your 1400 has an afm/maf??
thought it would be map?
anyhow, its more than the length of the trumpets that determin power/torque.
its also angle of the flare, length of tube, total distance from valve etc..
every engine will be different.
who has a 1400!! 
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csweatherston
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Registered: 16th Jan 06
Location: Devon
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you??.. well you said "my 1.4 was louder with a k+n, but need it still on because i have an afm still"
[Edited on 13-03-2008 by csweatherston]
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Warren G
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Registered: 14th May 06
Location: Kent
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ahhh got ya
i have an induction chamber on (which is realy quite) due to i still have a AFM on my 1600 you see
no air filter thou
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bieransri
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Registered: 13th Apr 06
Location: Kidsgrove, Staffordshire
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quote:
Originally posted by jamesvalver
am i right in thinking that the length of the trumpet determines the torque/power of the engine?
longer - less power/more torque?
shorter - more power/less torque?
seeing as if gotta pay for a full remap when the engines done again, i thought it might be worth it if it helps gain abit more torque from the engine
cheers
james
[Edited on 12-03-2008 by jamesvalver]
thats pretty spot on james, however Q Dave A to enlighten us
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sand-eel
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Registered: 15th Mar 07
Location: carluke/braidwood--IRNBRULAND
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it's quite a science to it really, the best way will be to get custom ones made to suit your actual engine, generally the longer it is the more torque but less power and vice versa but also if you get pulse tuning which is sort of "shock waves" of air you can have trumpets which will stop this "shock wave" increasing as much. you want the waves in phase
[Edited on 13-03-2008 by sand-eel]
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jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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hmmm... well its goin to be remapped by jamsport so im guessing they could just remap it to suit? im not too bothered about makin more power as 232bhp is plenty but i would like abit more torque if poss
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Richardhhha
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Registered: 29th Sep 07
Location: Croydon, Greater London
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talk to dave a he was experementing on trumpet length for the 1.6 he should be able to give you some insite..
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bieransri
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Registered: 13th Apr 06
Location: Kidsgrove, Staffordshire
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im sure dave had both on his engine and sure theres graphs in his project thread.
something inbetween the standard 40mm and 90mm (think thats what dave tried) ones so roughly retains the power figure but may produce more torque?
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jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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ive u2u'd dave and beardy
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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felt me ears burning 
trumpet length is an odd thing, some engines work a lot better with shorter trumpets, others with longer.
Theres no diffinitive answer to 'whats best' as it comes down to manifold design, camshaft spec, quality of the headwork etc....
I always keep a selection of trumpets on the shelf so that I can try different setups on different engines when on the dyno, I prefer longer trumpets on both the x16 and c20 engines, they tend to give much flatter torque over a longer period of revs.
On my engine I found that the 40mm trumpets had less lower down torque but at 4000 rpm the engine came to life and the rate of acceleration through the revs was a lot quicker (on both road and dyno) whereas the 90mm trumpets seemed to pick up slower and smoother and rate of acceleration was slower but was a lot nocer to drive on the road.
heres a more difinitive giude:
What is the correct overall system length?
Induction length is one of the most important aspects of fuelling performance engines.
In our experience an under-length system is the greatest cause of disapointment, with loss of up to 1/3 of power potential. There are a number of good books on the subject and the serious developer is referred to these and, in particular, dyno trials. A guide figure, from the face of the trumpet to the centre of the valve head is 350mm for a 9,000 RPM engine. Other RPM are proportional, i.e. for 18,000 RPM the figure is ca 175mm.
Any air feed system to an airbox or filter can have a large effect on the power curve and must be considered carefully - particularly if the airbox is small.
The induction system is part of a resonant whole - from air inlet or trumpet to exhaust outlet - and the ideal length is heavily influenced by the other components.
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csweatherston
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Registered: 16th Jan 06
Location: Devon
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looks like the difinitive guide from jenvy...with a few words changed 
to put it simply, its the volume of air stored in your trumpet, before it has to draw more will give you better torque.
also the 'free air space' around the trumpets, from which to draw the air.
short trumpets have less distance, therefor can build up quicker
long trumpets, have the immidate source, but a longer distance to travel.
its a science, you cant say long = hp, short = torque
[Edited on 14-03-2008 by csweatherston]
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jamesvalver
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Registered: 21st Feb 03
Location: Bury St Edmunds, Suffolk
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hmmm... its only when you start to fine tune an engine that you find out just how much is envolved. how much am i lookin at for trumpets so i can have a play when it goes back on the rollers?
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RCS
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Registered: 26th Jan 05
Location: Lichfield/Dundee
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quote:
Originally posted by csweatherston
looks like the difinitive guide from jenvy...with a few words changed
to put it simply, its the volume of air stored in your trumpet, before it has to draw more will give you better torque.
also the 'free air space' around the trumpets, from which to draw the air.
short trumpets have less distance, therefor can build up quicker
long trumpets, have the immidate source, but a longer distance to travel.
its a science, you cant say long = hp, short = torque
[Edited on 14-03-2008 by csweatherston]
Disagree with all of that, apart form the science statement
The torque an engine produces is proportional to the mass flow rate of air. Nothing to do with volume in trumpet etc.
Have a read of this James
http://www.lesoft.co.uk/files/Bratislava2001.pdf
You have to 'tune' the pressure waves, as sand-eel has already said.
The best length of trumpet will depend on your cams. Your best bet is to speak to companies that have experience with this engine...SBD,SRE etc. They will have done extensive testing on this and be able to give you advice.
'hmmm... its only when you start to fine tune an engine that you find out just how much is envolved.'
Thats when you become a thermodynamacist, not an engineer.
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Dave A
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Registered: 10th Dec 03
Location: County Durham
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quote:
Originally posted by csweatherston
to put it simply, its the volume of air stored in your trumpet, before it has to draw more will give you better torque.
also the 'free air space' around the trumpets, from which to draw the air.
short trumpets have less distance, therefor can build up quicker
long trumpets, have the immidate source, but a longer distance to travel.
completely wrong I am afraid.
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