Why do bridgeports change their rhythm?
02-20-07, 09:31 AM
#1
Why do bridgeports change their rhythm?
So every time I've listened to a bridgeport idle they always change back and forth from brap brap brap brap to brrrrrrrrrrrrrrrrrrrrrrrrrr.
I've just fired mine up and it does the same thing, here is a video of it:
http://www.indyhp.com/vids/zinx-halfbridge_starting.wmv
The idle changes at 1:01 and 1:16.
Anyone have any insight into this? I'm guessing its something to do with the overlap.
I've just fired mine up and it does the same thing, here is a video of it:
http://www.indyhp.com/vids/zinx-halfbridge_starting.wmv
The idle changes at 1:01 and 1:16.
Anyone have any insight into this? I'm guessing its something to do with the overlap.
02-20-07, 12:00 PM
#2
3rd motors a charm I hope
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in your ecu map, at different temperatures, your car will adjust the amount of fuel and the idle level depending on water temps.... This could have something to do with it...
02-20-07, 02:57 PM
#7
Originally Posted by Doc Holiday
My guess always was that it had something to do with the plugs fouling slightly. On my carbed car, the car would start to run like that, and after I revd it up to "clean it out" it would idle with strong sharp braps again.
You'd think if that were happening you could see the idle drop or fluctuate, but it doesn't. If you couldn't hear the car do this, you'd never know it way happening.
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02-20-07, 11:10 PM
#9
3rd motors a charm I hope
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Originally Posted by cdaleracer669
my stock port you could hear it change rythyms. never stayed the same. maybe its a rotary thing
yes, it was the same for my car when i had stock ports and with the street port.... i just figured it was the position on the map changing and the temps adjustments... either way, if your looking to fix the problem, put an ls1 in there... lol... or just deal with our crazy rotaries...
02-23-07, 10:00 PM
#11
Old [Sch|F]ool
When it's brapping "solid" the rotors are in phase. When it's just sorta rrrrrr then the rotors are brapping out of phase of each other, so it seems smooth.
Because of the plenum volume on my P-port, it almost always was "smooth" at rest. When coasting, it would brap (buck).
Because of the plenum volume on my P-port, it almost always was "smooth" at rest. When coasting, it would brap (buck).
02-24-07, 01:56 AM
#12
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Originally Posted by zinx
Its not just my car, every bridge i've heard does this. I don't think its something in the tuning. The idle is rock solid, as well as the all temps. Its not moving to any other bars on the coolant adjustment map.
I have always wondered the same, although even stock rotaries do it too.....
02-24-07, 09:13 PM
#13
Originally Posted by peejay
When it's brapping "solid" the rotors are in phase. When it's just sorta rrrrrr then the rotors are brapping out of phase of each other, so it seems smooth.
Because of the plenum volume on my P-port, it almost always was "smooth" at rest. When coasting, it would brap (buck).
Because of the plenum volume on my P-port, it almost always was "smooth" at rest. When coasting, it would brap (buck).
ya stock ones be like pprrrrrrrrrrrrrrrrrrrrrrrrrrrrr pr ppr pr pppppppprrrrrrrrrrrrrrrrrrrr
or something like that
02-26-07, 05:52 AM
#18
Stay tuned...
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Your exhaust sounds awesome. Can you elaborate more on the exhaust. This has to be the best sounding 4 inch exhaust without a silencer in the tailpipe. Is it really that quiet at idle?
Anthony
Anthony
Originally Posted by zinx
So every time I've listened to a bridgeport idle they always change back and forth from brap brap brap brap to brrrrrrrrrrrrrrrrrrrrrrrrrr.
I've just fired mine up and it does the same thing, here is a video of it:
http://www.indyhp.com/vids/zinx-halfbridge_starting.wmv
The idle changes at 1:01 and 1:16.
Anyone have any insight into this? I'm guessing its something to do with the overlap.
I've just fired mine up and it does the same thing, here is a video of it:
http://www.indyhp.com/vids/zinx-halfbridge_starting.wmv
The idle changes at 1:01 and 1:16.
Anyone have any insight into this? I'm guessing its something to do with the overlap.
02-26-07, 09:18 AM
#19
Engine, Not Motor
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You get the "brap" with high overlap ports (like bridge) because the engine misfires rhythmically due to exhaust contamination of the intake charge. Sometimes that rhythm changes as no two combustion events are the same so the engine may change it's tune for a few seconds.
02-26-07, 11:44 AM
#22
Double Ds for me to share
My bridged 12a does the same thing goes back and forth from smooth streetport idle to brap brap idle of the bridge. I'm running a 48IDA on my bridge. I dont care it seems fine to me, but with the p-port going in i cant wait to hear its idle
02-27-07, 08:20 AM
#23
Originally Posted by AnthonyNYC
Your exhaust sounds awesome. Can you elaborate more on the exhaust. This has to be the best sounding 4 inch exhaust without a silencer in the tailpipe. Is it really that quiet at idle?
Anthony
Anthony
02-27-07, 08:22 AM
#24
Originally Posted by Aaron Cake
You get the "brap" with high overlap ports (like bridge) because the engine misfires rhythmically due to exhaust contamination of the intake charge. Sometimes that rhythm changes as no two combustion events are the same so the engine may change it's tune for a few seconds.