Moderator: The Mod Squad
jondee86 wrote:I like the idea... it's different and it looks cool
And apparently some serious motorcycle manufacturers like it too.
Cheers... jondee86
Vertigo wrote:It would probably flatten your torque curve a little.
A better idea, if made of money, would be a variable length runner.
https://www.youtube.com/watch?v=JMVioC2XGO0
Vertigo wrote:A flat curve is great, IMO!
ae111 corolla gt wrote:I've heard some people say long trumpets are good for both low and high end power.
jondee86 wrote:ae111 corolla gt wrote:I've heard some people say long trumpets are good for both low and high end power.
The complicated theory for calculating the optimum length of intake trumpets involves
such parameters as the overall length from valve head to open end, diameter, velocity
and at what rpm the ram effect should peak. The simplified theory just says 110mm long
trumpets work best on 20V 4AGE's
And that may well be true for engines with the OEM intake manifold and ITB's. The Toyota
factory engineers (who of course know fcuk all about intake design) went to a lot of trouble
to come up with a trumpet that kept noise down, preserved a bit of low end torque, and
could fit inside an airbox with some decent volume. Not to mention a cold air intake and
a filter that actually keeps all the wear particles out of the engine.
[RANT] Fortunately, it is easy enough to fix the factory fcukup by ripping all that shit out
of the engine bay and whacking on some Trademe trumpets with wire mesh screens on the
end. Now you have a race engine that sounds like someone strangling a Turkey when you
give it a bootfull outside the netball courts on a Saturday afternoon... bewdy aye
Truth is you just lost some power, your engine doesn't idle too good, bogs in the midrange
and sounds like a Honda... stink aye When you get tired of all that (and it won't take long),
you might get lucky and be able to find all the shit you ripped out and put it back. [/RANT]
So the point that I'm trying to make is that trumpets are tuned to have a pressure wave
arriving at the inlet valve at the correct moment to creat a ramming effect that helps get
a bit more charge into the combustion chamber. More charge equals more power. However,
the ram effect peaks at certain frequencies, and you have to choose the rpm range band
where you want to get that extra power... for example 5000 to 6000rpm. When the physical
dimensions of the intake tract are fixed, the only variable you have available for tuning the
ram effect is trumpet length.
Can it work at both high and low rpm ? For a fixed length trumpet the simple answer is NO.
You tune for the strongest ram effect to occur at where you want peak power. There are
weaker harmonics that occur in other (lower) rpm ranges, but their effect would be negligible.
There are some on-line calculators that predict the best length for trumpets under a known
set of conditions. For your experiment with two different lengths of trumpet, you should
try to select lengths that work in overlapping bands... for example 4-5000 and 5-6000rpm.
And when fitting trumpets inside the factory airbox, you will need to keep at least 20mm
clearance between the end of the trumpet and the airbox wall. Better if the wall is angled
as that will help prevent reflected pressure waves from interfering with the tuned wave.
Good luck !!
Cheers... jondee86
Vertigo wrote:Dont forget, the head is where the power is made. Port it and cam it, if you are serious about power.
Or turbo.
Flannelman wrote:Second that Lith. I found on my Silvertop that making a bigger plenum helped filling the mid-range dip with an extra 3kW from 5800-7800rpm.
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