adrianreeve
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| posted on 18/3/11 at 08:49 PM |
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The effect of trumpet length?
The second hand jenveys I have bought came with 19mm stubby trumpets. Is there much to be gained from increasing the length of these?
Cheers
Adrian
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imp paul
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| posted on 18/3/11 at 08:52 PM |
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bottom end power so it seems me old fruit 
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HowardB
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| posted on 18/3/11 at 08:52 PM |
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they have a handy if long winded explanation on their website, in the FAQ section, worth a read.
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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imp paul
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| posted on 18/3/11 at 08:55 PM |
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but in the real world of driving your car can you even tell lol
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r1_pete
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| posted on 18/3/11 at 09:10 PM |
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quote:
Originally posted by imp paul
but in the real world of driving your car can you even tell lol
Anything less than WOT I'd doubt it, just my opinion of course.....
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snapper
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| posted on 18/3/11 at 10:17 PM |
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I have had some calculations done for my engine build, it takes in a lot of factors, cam duration, lift, etc, etc... If you have done or are
considering doing a serious engine build then intake length and exhaust primary lengths + the rest of the exhaust all come into play.
Find out what length of intake you need for your set up and use it but in the main it's all the factors together that make a real difference.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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cliftyhanger
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| posted on 18/3/11 at 11:03 PM |
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If you want some longer trumpets I have some to swap? assuming 45mm TB's of course. I have some at about 50mm, 65 and 90mm from memory
(don't ask, I keep getting things wrong )
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matt_gsxr
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| posted on 19/3/11 at 12:04 AM |
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quote:
Originally posted by r1_pete
quote:
Originally posted by imp paul
but in the real world of driving your car can you even tell lol
Anything less than WOT I'd doubt it, just my opinion of course.....
Anything less than WOT, then why bother starting her up??
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HowardB
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| posted on 19/3/11 at 07:50 AM |
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If I recall correctly, it is as said ^^^^, more than just trumpet length, and on the jenvey site they talk about the position of the injectors too,
either close to the head, or further out, for locost, I guess it will be a compromise unless you are able to have adjustable inlet lengths and
injection positions,...
I am going to fit TB's to my zetec, and it will be what fits in the engine bay, combined with anything I can read, and learn here.
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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balidey
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| posted on 19/3/11 at 08:17 AM |
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Here's an idea.
If you put on 2 short trumpets and 2 long trumpets, would this not give you some more low down power from a couple of cyclinders, more top end from
the other couple, so it wouldgive you a net effect of increase power all up the power band.
Go on, try and disprove that logic!
Dutch bears have terrible skin due to their clogged paws
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RazMan
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| posted on 19/3/11 at 09:21 AM |
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quote:
Originally posted by balidey
Here's an idea.
If you put on 2 short trumpets and 2 long trumpets, would this not give you some more low down power from a couple of cylinders, more top end from the
other couple, so it would give you a net effect of increase power all up the power band.
Go on, try and disprove that logic!
That's what a lot of the bike manufacturers do to spread the torque around the rev range a little.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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MikeRJ
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| posted on 19/3/11 at 09:40 AM |
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quote:
Originally posted by HowardB
If I recall correctly, it is as said ^^^^, more than just trumpet length, and on the jenvey site they talk about the position of the injectors too,
either close to the head, or further out, for locost, I guess it will be a compromise unless you are able to have adjustable inlet lengths and
injection positions,...
Engine design is always a compromise. You just need to the tip the compromises to best suit the intended use, and on a road car a wider spread of
torque is generally more useful than higher peak power.
You can effectively "adjust" injector positions, by having two sets of injectors which are staged.
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adithorp
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| posted on 19/3/11 at 10:17 AM |
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quote:
Originally posted by matt_gsxr
quote:
Originally posted by r1_pete
quote:
Originally posted by imp paul
but in the real world of driving your car can you even tell lol
Anything less than WOT I'd doubt it, just my opinion of course.....
Anything less than WOT, then why bother starting her up??
Like you're ever going to have the kahonas to WOT yours!
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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HowardB
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| posted on 19/3/11 at 11:28 AM |
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I like the idea of two sets of injectors, especially as I have two sets, so here is the question,....
could that be done with a Megasquirt ECU?
hmmmm, this ITB thing is growing more complicated by the minute.
thanks
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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dhutch
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| posted on 26/3/11 at 11:49 PM |
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quote:
Originally posted by imp paul
but in the real world of driving your car can you even tell lol
I spoke to a few companies about it at stands or over the phone, some talked around the subject, some didnt, but overall the clear overriding comment
was the difference is small at best. Burton power certainly said very much words to effect 'how much can you get in before it hits the bonnet,
20mm? That will do.' (DHLA 40's on a 1900cvh with a manifold lenght of about 80mm)
Daniel
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Nash
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| posted on 27/3/11 at 01:20 AM |
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I've seen the effect trumpet length has on mine on the RR at Dave Walkers place.
I have 20mm trumpets on mine. Dave set the car up and when he'd finished hje fitted sliding trumpets and then experiemented by adjusting them
and doing power runs.
Result is at 90mm I got the best gain. 10lb/ft of torque increase in the mid-range and a 6 BHP loss off the top end. It is all a compromise and on the
road that would be the best option for my car. On the track and at high revs the horses would probably be best.
HTH's................. Neil
It's What You Do Next That Counts.
Build It, Buy It, Drive It:
Southern Kit Car Club
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snapper
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| posted on 27/3/11 at 03:54 AM |
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2 long and 2 short trumpets unless properly set up with a plenum like some bikes would unbalance the engine.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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