carnut
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| posted on 29/5/03 at 08:43 AM |
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Tuned length exhaust
Is it worth paying the extra to get one made?
How much difference does it make to power and torque?
Ive been told that a 4-2-1 system would be better than a 4-1, how much difference does this make?
any help would be gladly recieved
Carnut
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carnut
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| posted on 2/6/03 at 12:41 PM |
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Come on, someone must know a bit about tuned length exhausts!
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David Jenkins
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| posted on 2/6/03 at 01:08 PM |
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Casting my mind back to model planes, I think you'll find the problem with 'tuned pipes' is that they're tuned for specific
engine speeds. For a car, there is an element of tuning involved, but it's more a case of 'this length will roughly match the way you plan
to use your engine' rather than anything else.
I think that you need to use a more general description, and 4-2-1 & 4-1 is a good place to start. What I've been told is that a 4-1 setup
is very good for helping the engine at high revs, but not so good at lower revs - in other words, good for a racing car engine. On the other hand, a
4-2-1 is good for helping the engine at the low end rather than at the top.
It's horses for courses, but I'd guess that the 4-2-1 is more use for general driving.
BUT, and it is a big BUT (who's got a big butt?  ), unless you're tuning an engine to a fairly high degree, you probably won't
notice a great difference, IMHO. Pick whatever you can get and/or whichever takes your fancy!
rgds,
David
P.S. these are entirely my own opinions, and they may not be worth 2p. 
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kingr
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| posted on 2/6/03 at 03:06 PM |
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Sounds very much right to me, another thing to bearing in mind is that while tuned length exhausts may add power to one place, they also take away
from another, so they're great for constant rpms but not particularly suitable for variable speeds. I used to fly model helicopters, where the
engine maintain pretty much constant speeds, and people would go to great pains getting the distance from the exhaust manifold to the first baffle
millimetre perfect for the RPMs they were running, and it did make a small difference, but then they're high revving 2 stokes, where clearing
the cylinder is much harder than in a four stroke. I can't see that it's worth spending much time over in a car, less still much money.
Kingr
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carnut
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| posted on 2/6/03 at 03:54 PM |
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thanks guys, thats all very interesting.
I was just thinking that if i got a good exhaust it may be a good way of getting power on the cheep. ie cheeper than other types of tuning.
Looks like i may just go for what I can get for a decent price.
Just one more question. Would a straight through race can give much more if any power increase? For post sva purposes obviously.
thanks
Carnut
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locodude
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| posted on 2/6/03 at 05:18 PM |
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quote:
Just one more question. Would a straight through race can give much more if any power increase? For post sva purposes obviously.
Don't do it, my ZX9 on a Micron race can is hellishly loud. One more job to do B4 le mans is fit a baffle
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andyd
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| posted on 2/6/03 at 05:45 PM |
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Carnut,
Most people fit "race cans" to their bikes because they think they sound better. Without doing anything else to the engine I'd bet
90% or these people wouldn't notice any difference in performance. On a bike it tends to be a point and squirt operation which means that the
revs are always changing. Even when you ride through town etc. the sound is exiting the tailpipe quite a way from your ears not to mention the crash
helmet blocking out sound too. In the car you may be emulating the bike on twisty backroads and it'll sound sweet but during the town journeys
(or main road cruising) it'll be bloody loud and very irritating after 5 minutes. Besides am I right in saying that you are using a blackbird
engine? If so that's plenty of power I'd have thought.
HTH
Cheers.
Andy
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