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Location:
Lost in the K hole
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Fri, 15 October 2004 03:26
 
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Figure 1.1. Approximate point of wave reflection in a horn bell.
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According to "The Cambridge Companion to Brass Instruments"
Whether the other end of the instrument terminates abruptly (as in a bugle) or terminates in a flaring bell (as in a trumpet), sound waves are reflected by the bell mouth or by the flare. The sound inside an instrument is much more intense than the sound produced by the instrument in the surrounding air. The bell of an instrument has to be carefully designed so that it reflects enough sound to allow standing waves to build up, yet allows enough sound to escape to be audible at an appropriate intensity to be useful in music.
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Location:
Sydney
Registered:
July 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Fri, 15 October 2004 03:28
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checkmate then. I've no idea what the diagram is doing.
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Location:
Lost in the K hole
Registered:
May 2002
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Fri, 15 October 2004 03:55
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GTSboy is a champ.
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Fri, 15 October 2004 04:44
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Very annoying!
For some reason the Performance Forums site times out on me each time. I'm trying to get it from Malaysia though.
If you get a chance in one of the posts there, please mention that I can't pop in for a visit unfortunately.
It does this for a day or so at a time.
BTW, trumpet inlets aren't the way to go - Parallel is good. 
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Location:
Lost in the K hole
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Fri, 15 October 2004 04:50
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oooohhh... i feel controversy in the air
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Location:
nth ringwood, Victoria
Registered:
August 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sat, 16 October 2004 03:38
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also ed that toda 3sge is still in expermental stage the trd engine still has the injectors in the head and the only difference is that toda put a spacer with fuel rail and longer ram tubes for length
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Location:
Montrose, VIC
Registered:
May 2002
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sat, 16 October 2004 13:55
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Yeah - the runners sound like they'll be way too long.
Straight & short should be better. It doesn't matter is the engine is turboed or not, the Hemholtz thing works the same, as does the port velocity. The air still goes down the hole at the same speed, just with more pressure.
Best to use the info above to work out properly how long the runners should be so they work well.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sat, 16 October 2004 14:37
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Pretty much what I was thinking - however I never said exactly how long the runners would be  Just that from what I've seen, most multi throttle setups people have made, especially the few that use them with turbos, seem to always have the throttles as close as possible to the head, and stuff all runner on the other side too. While these seemed to work well, I always kind of figured they must be selling themselves short of what they might be capable of. As for air velocity, I'm thinking that while the air pressure is higher on the outside, there is also an increase on the inside due to the restriction of the turbo, and you'd bury yourself in nubmers even beginning to try and work out what the difference might be at any one time..
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Location:
South Australia
Registered:
July 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 08:29
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back to the 45mm port and throttle, mean intake velocity at 8500rpm is around 22m/sec - i figure thats fine. comments?
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btw - how did you get the 22m/s figure?
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Location:
Lost in the K hole
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 10:12
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that flow figure was based on average CFM
the more accurate "peak mean runner velocity" of 286ft/sec
was based on the mean peak velocity of the piston, the suface area of the piston, and the surface area of the port
cheers
ed
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Location:
South Australia
Registered:
July 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 11:12
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Ahh i get it -> that's based on an assumption that the engine gets the full ~500cc of air per second revolution?
ie air-speed = ((cylinder volume) * (rps / 2)) / throttle area
That's your inital method - the second one is as per just stated ???
So then how the crack did you come up with the runner length? I'm still scratching on this one...
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Location:
Lost in the K hole
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 12:13
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to be honest - calculating length is a MAJOR pita
ive just started reworking my theory using a new engine analyser bit of software. and im getting slightly different numbers.
and be damned if i can crack 100hp/L (just) !!! 
100nm/L on the other hand was easy enough.
and for those interested, i had a look at the port orientations in the stock 2jzge head. its actually quite steep. unfortunately the port shape is modified at about 10mm from the head surface (brown looking in the pic) in order to correctly align with the horizontal manifold runners. if you ignore (read 'die grind') this section, the overall port orientation can be seen to follow the rod (which for the best part is sitting FLAT on the floor of the port):
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 13:19
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| ed_ma61 wrote on Sun, 17 October 2004 22:13 |
and be damned if i can crack 100hp/L (just) !!!
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*snicker*
You'll learn, Grasshopper.
Accept nothing less that 120hp/L.
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Location:
Lost in the K hole
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Sun, 17 October 2004 22:55
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Bill...
just curious - what octane value do you input in EAPro ?? I was always under the impression that australian pump fuel was rated based on RON only, and was not averaged with the MON rating.
am i incorrect? is say, BP Ultimate 98octane actually (RON + MON)/2 = 98 ???
i seem to have a penchant for producing engine profiles with MEGA detonation!! im hoping its as simple as changing the fuel rating!
cheers
ed
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Location:
Brisbane / Gold Coast
Registered:
May 2002
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Re: ITBs & Port X-Sectional Areas + Lengths : Your Thoughts....
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Mon, 18 October 2004 02:40
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I use 97 to be on the safe side.
For the detonation index, under about 1.5 should be fine.
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