A question about exhaust notes
#26
Rotor Head Extreme
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Originally Posted by snub disphenoid
240rwhp NA with the stock CR? Wonder what it could do streetported with 9.7:1 CR rotors...
I'll have an answer for everyone this summer. I'm installing 9.7 rotors w/ turbo II exhaust sleeves and will dyno my NA 20b to see what the power difference is compared to the 9.0 with stock ports. Reted and Bcool made around the same amount of hp (232 rwhp) w/ stock block and intake manifolds. I'm very curious to see what I'll get with better sleeves and higher compression. Then i'm going to install my custom made intake manifold, re-tune and dyno again. I'm going go try to give as much info about what hp one can expect with varying combinations. Then finally I'm going to open the engine again and do a half bridge and re-dyno with old stock manifold and new one.
Hey I like experimenting. What can I say.
DIY will save me a **** load of money as well.
Last edited by t-von; 04-21-06 at 10:02 PM.
#27
Old [Sch|F]ool
Originally Posted by BLUE TII
Another thing that makes a racecar scream is the straight cut gears of a race transmission. On turbo cars it is not uncommon for the gear whine to be louder than the exhaust!
http://wrc.no/filer/atle_vik_inboard..._bergen_04.wmv ?? port 13B, naturally aspirated. You can pretty much only hear the exhaust if he's in 4th gear. (5.85:1 rearend!)
Plenty other cool videos there, pretty much all hillclimbs or Euro-style rallycross.
#28
Senior Member
peejay: Links aren't working
One of my favorite sounding 20B FD's is this one here:
http://mrec.rotary.net.nz/media/ts_bat.mpg
On the track you really only hear the yellow car right up until the FD passes it and then the 20b is louder. I read somewhere that the car was burnt in a fire.
One of my favorite sounding 20B FD's is this one here:
http://mrec.rotary.net.nz/media/ts_bat.mpg
On the track you really only hear the yellow car right up until the FD passes it and then the 20b is louder. I read somewhere that the car was burnt in a fire.
#29
Rotary Freak
Originally Posted by t-von
Hey I like experimenting. What can I say.
DIY will save me a **** load of money as well.
DIY will save me a **** load of money as well.
#30
Collections Hold
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Originally Posted by snub disphenoid
240rwhp NA with the stock CR? Wonder what it could do streetported with 9.7:1 CR rotors...
Last edited by GtoRx7; 04-22-06 at 01:45 AM.
#31
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My favorite sounding 20B http://media.putfile.com/Mazda-LMP2
peejay, your descreptions sound good but the links both bring up the same non moving page.
peejay, your descreptions sound good but the links both bring up the same non moving page.
#32
Rotor Head Extreme
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Originally Posted by GtoRx7
Hmmm maybe T-von and me can go hit up the streets.......
That would be tight 20b domination baby. So you about ready to unleash the power of the semi PP's? I can't wait to see the results. I have a slightly different idea when I ultimately get underway. You guys will have to wait and see.
Last edited by t-von; 04-23-06 at 02:47 AM.
#34
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Originally Posted by t-von
That would be tight 20b domination baby. So you about ready to unleash the power of the semi PP's? I can't wait to see the results. I have a slightly different idea when I ultimately get underway. You guys will have to wait and see.
#35
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Here's a question related to the original post:
Does a 4 rotor with 180 degree lobes on the e-shaft (like 2 2-rotors) sound like a pissed off 2 rotor, or like more like the 787b (it has 90 degree separation between lobes).
Does that 10 Bryan Mckewan's red 4 rotor p-port on Streefire have 180 degree or 90 degree lobeing on the e-shaft?
Any theories or thoughts?
Does a 4 rotor with 180 degree lobes on the e-shaft (like 2 2-rotors) sound like a pissed off 2 rotor, or like more like the 787b (it has 90 degree separation between lobes).
Does that 10 Bryan Mckewan's red 4 rotor p-port on Streefire have 180 degree or 90 degree lobeing on the e-shaft?
Any theories or thoughts?
#36
Old [Sch|F]ool
Originally Posted by GundamExpo
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peejay, your descreptions sound good but the links both bring up the same non moving page.
peejay, your descreptions sound good but the links both bring up the same non moving page.
I *have* the videos on my computer, but they're too big for me to host and certainly too big to e-mail...
#37
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This is a good thread. Pardon my gravedigging, but I just found it (and I don't think you guys will mind ).
God yes that car is awesome. Or, was awesome. That's a hell of a clutch too.
Fatty, I'm fairly sure that firing two rotors 180 degrees apart will sound like a twin-engined 13b car. The 4-rotor you referred to, if it's the one I think it is, is almost certainly 90 degrees phased because of the unique sound.
I do think it's interesting that some 20b's sound higher pitched (than a 13b) while some sound lower. There is definitely some harmonics coming into play on the lower pitch that can be either muffled or accentuated by the exhaust. I'm sure that the exhaust itself plays the biggest part in the tone (actually, the correct musical term would be timbre, and yes, it IS music to my ears!) of the engine.
I really love the multitude of 20b sound clips in this thread (a few I haven't heard before). T-von, your car sounds interesting and I look forward to hearing more about it. I personally am thinking about sticking an NA 20b into a Miata... that sound coming from that car would be really freaking awesome.
Originally Posted by soloracer951
Fatty, I'm fairly sure that firing two rotors 180 degrees apart will sound like a twin-engined 13b car. The 4-rotor you referred to, if it's the one I think it is, is almost certainly 90 degrees phased because of the unique sound.
I do think it's interesting that some 20b's sound higher pitched (than a 13b) while some sound lower. There is definitely some harmonics coming into play on the lower pitch that can be either muffled or accentuated by the exhaust. I'm sure that the exhaust itself plays the biggest part in the tone (actually, the correct musical term would be timbre, and yes, it IS music to my ears!) of the engine.
I really love the multitude of 20b sound clips in this thread (a few I haven't heard before). T-von, your car sounds interesting and I look forward to hearing more about it. I personally am thinking about sticking an NA 20b into a Miata... that sound coming from that car would be really freaking awesome.
#38
Lapping = Fapping
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Here's an audio clip from when I was test firing it with a temporary carb setup and modded 12A dizzy. https://www.rx7club.com/forum/attach...hmentid=105273
Here's another. This time the tape recorder was placed in the garage about 20 feet from the (closed) garage door. You can barely hear the starter! That's what an open header will do for you. https://www.rx7club.com/forum/attach...hmentid=105274
Here's another. This time the tape recorder was placed in the garage about 20 feet from the (closed) garage door. You can barely hear the starter! That's what an open header will do for you. https://www.rx7club.com/forum/attach...hmentid=105274
#39
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Originally Posted by peejay
http://www.wrc.no/filer/konsmo_Stein.wmv Peripheral port 20B, naturally aspirated. Gearbox about neck-and-neck with the exhaust.
http://wrc.no/filer/atle_vik_inboard..._bergen_04.wmv ?? port 13B, naturally aspirated. You can pretty much only hear the exhaust if he's in 4th gear. (5.85:1 rearend!)
Plenty other cool videos there, pretty much all hillclimbs or Euro-style rallycross.
http://wrc.no/filer/atle_vik_inboard..._bergen_04.wmv ?? port 13B, naturally aspirated. You can pretty much only hear the exhaust if he's in 4th gear. (5.85:1 rearend!)
Plenty other cool videos there, pretty much all hillclimbs or Euro-style rallycross.
I had all of the movies on my computer, but they went away on a harddisk crash. I'd love to get my hands on them again.
Regards,
Frode
#40
Rest In Peace Dave
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Here's another video of my car, this time its at Auto-x but it kind of gives you a better idea of what the sound is like.
http://myweb.cableone.net/mjbless/idahorotary/autox.wmv
http://myweb.cableone.net/mjbless/idahorotary/autox.wmv
#42
Rest In Peace Dave
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Drag radials in the rear spinning off the start and it was plowing like a hoe in the corners, belive me there was enough lack of grip there. Now if only if my 5zigens would show up i'd have something to mount these Azenis's too
#44
S3 RX-7 - 20BT 450 RWHP
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Originally Posted by GundamExpo
That's what everybody says, but I don't get it. You are on stock ports in your video but your car gets high pitched, in the video I supplied the car is on stock ports as well.
Header maybe? Muffler? Are you running stock rotors?
Edit: I'm concerned with it just because its something im curious about. Its really weird to me how a motor can have so much variation in its pitch when its still being revved to the same limit. I will also say that the exhaust note on a car is a big piece of how much I enjoy driving it, im a little strange that way.
Header maybe? Muffler? Are you running stock rotors?
Edit: I'm concerned with it just because its something im curious about. Its really weird to me how a motor can have so much variation in its pitch when its still being revved to the same limit. I will also say that the exhaust note on a car is a big piece of how much I enjoy driving it, im a little strange that way.
The car in the video actually has a large extend port, 2 1/2" exhaust (soon to be 3") and a single straight through 3" s/steel muffler. I think at that time I was running a stock cat though, have since pissed the cat off.
Not sure what revs it was pulling in the video but would estimate around 8500 rpm, it makes power just over 8000 rpm
I'm running 4.4 gears in it too
#45
S3 RX-7 - 20BT 450 RWHP
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Originally Posted by GtoRx7
A n/a engine vs. a turbo one will sound quite different due to the turbo making the exhaust much more quiet. Rpms also matter, that First gen sounded like he was shifting at 6800, and was turbo? If you listen to mine, I shift at 8,600 and has 3 mufflers, no turbo.
http://videos.streetfire.net/Player....5-64809850FAD0
http://videos.streetfire.net/Player....5-64809850FAD0
I think it was running the stock cat then, didn't have it on for long, just to pass engineers.
Stock intake.
Here's another video of it from behind taking off, same day
http://www.rotary20b.com/20b-2.WMV
Last edited by Rotary20B; 05-20-06 at 10:13 AM.