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why does the 4-2-1 on the frp lump make a hissing noise almost like a dumpvalve......... i have always wondered what causes this, does anyone know???
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4-2-1 Manifold Noise
#2 Guest_Matt and Tiggr_*
Posted 23 March 2005 - 10:54 AM
You sure you aint got a leak?
Could be a sharp bend causing airflow noise
Could be a sharp bend causing airflow noise
#3
Posted 23 March 2005 - 02:24 PM
its only when i let of the throttle.....its not just mine as its the same noise on all frps
just wondered what causes this???
just wondered what causes this???
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#4
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Posted 23 March 2005 - 03:44 PM
QUOTE
just wondered what causes this???
All FRP's crackle & pop from the tail end of the exhaust, it was a Ford design feature, if you get this noise anywhere else then investigate :?:
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#5
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Posted 23 March 2005 - 04:15 PM
QUOTE
its only when i let of the throttle.....its not just mine as its the same noise on all frps
just wondered what causes this???
just wondered what causes this???
Know exactly what you mean.. No idea what's making the noise but it sounds fairly cool.
Quite often get a few pops & crackles, followed by the tsssss noise until you accelerate again.
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#6
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Posted 24 March 2005 - 12:52 AM
Yes, I also get the "Tschhhhhhh!" noise on throttle-off after hard accelerating (std 1.7 with 4-2-1 manifold)
It does sound like a bit of a dump valve, lol
I think it sounds ok, it was a bit strange at first but I am kind of fond of it now, especially when (cough) "booting it"
I'd speculate (cos I don't know for sure) that it's to do with the changing frequency of the gas-pulses inside the pipes. Isn't the stainless 4-2-1 metal a lot thinner&lighter than the original manifold? Therefore you would hear the gasses more...?
It does sound like a bit of a dump valve, lol
I think it sounds ok, it was a bit strange at first but I am kind of fond of it now, especially when (cough) "booting it"
I'd speculate (cos I don't know for sure) that it's to do with the changing frequency of the gas-pulses inside the pipes. Isn't the stainless 4-2-1 metal a lot thinner&lighter than the original manifold? Therefore you would hear the gasses more...?
#7
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Posted 24 March 2005 - 10:55 AM
Can I assume we all have the PS Miltek 4-2-1 manifold??
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#8
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Posted 24 March 2005 - 11:07 AM
I remember correctly, it's the 'overrun' set by the ecu .....
the 421 manifold just acts as an amplifier .... the stand. puma overruns too, to a much lesser extent..... but doesn't have the same amplification system..... i.e. cat in the manifold etc instead of cat back racing exhaust..
hope that clears it up a bit...
Chris
the 421 manifold just acts as an amplifier .... the stand. puma overruns too, to a much lesser extent..... but doesn't have the same amplification system..... i.e. cat in the manifold etc instead of cat back racing exhaust..
hope that clears it up a bit...
Chris
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#9
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Posted 24 March 2005 - 11:51 AM
There's no cat on mine... 
Yes, it's the PS 4-2-1 :rock:
Yes, it's the PS 4-2-1 :rock:
#10
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Posted 24 March 2005 - 12:20 PM
Hmm - my cat is safely tucked away in the garage... But I think it did it when it was still attached.
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#11 Guest_Cooler King_*
Posted 24 March 2005 - 04:20 PM
mine does it too!!!!!! a mate of mine said, " why have you put a dump valve on your un-turbod car? although i though it wouldnt be as loud as that!" he mwas obviously talking about the manifold!
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Posted 25 March 2005 - 01:14 AM
ive got the full millteck/ps system on mine, and (aside from the cool popping noises on lift off) after booting it, if you leave it in gear and let the revs drop naturaly, it makes a zzzzzzzzz sound, i think its just the vibrations, gasflow in pipe...correct me if im wrong because i did wonder...
#13
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Posted 25 March 2005 - 01:16 AM
mine dosnt sound anything like a dump valve???????
#14 Guest_lesinge2k_*
Posted 25 March 2005 - 01:26 AM
mine too... reminds me of some of the sounds that were coming from Nicos Focus RS... to a lesser extent 
I quite like it... when thrashing it hard, then some t***er pulls out in front of you, lifting off makes some nice agggressive racey noises, and scares them into moving out of the way
I quite like it... when thrashing it hard, then some t***er pulls out in front of you, lifting off makes some nice agggressive racey noises, and scares them into moving out of the way
#15
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Posted 25 March 2005 - 10:12 AM
QUOTE
ive got the full millteck/ps system on mine, and (aside from the cool popping noises on lift off) after booting it, if you leave it in gear and let the revs drop naturaly, it makes a zzzzzzzzz sound, i think its just the vibrations, gasflow in pipe...correct me if im wrong because i did wonder...
There's kind of 2 noises on mine..
One is a very short 'sopps' sopps sound which I assume is what people are talking about. Usually happens when changing gear on hard acceleration.
The other is the pops followed by a long tzzzzzzzzzzzz sound when you let the revs drop. There's a couple of long hills I often drive down, and can get the car to make that sound for ages
ex Silver 1.7 / ex FRP #416 / Astra SRi CDTI 150
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