Flutter/Chatter sound. How do I get it??
10 August 2012, 03:48 PM
#32
He did ask how to get the noise, or remove the airbox resonator (forgot about that). Either way if the OE induction system is intact, it will hardly make any noise.
(ignoring the well documented MAF and VF turbo issues - as I already hinted at).
Anyhoo, a point to bring up of a commonly spouted statment about the turbo shaft speed slowing. Can you prove this? The air stalls, yes. And yes there are shock waves (of that we can clearly hear ) But the actual shaft slowing any faster than normal or even stopping? I think we need to properly debunk this. As there in conflicting information out there. Yes the shock loads place thrust and shock stresses on the compressor wheel and bearings, thats a given, but when people out there claim that the phsyical shaft is stalling or slows any faster. I don't think so - not of any significant magnitude anyway.
My simplified analogy of getting a electric ducted centrifugal fan and blocking its outlet...the motor actually speeds up. Remove the power, the fan takes longer to slow. Unblock the outlet and then remove the power, the fan slows down quicker.
Last edited by ALi-B; 10 August 2012 at 03:50 PM.
10 August 2012, 04:13 PM
#33
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Cheers
10 August 2012, 04:17 PM
#34
Its a intake silencer box in the corner of the front bumper on the driver's side. Acessible by removing the wheel arch liner (usually).
http://www.scoobypedia.co.uk/index.p...sonatorRemoval
http://www.scoobypedia.co.uk/index.p...sonatorRemoval
10 August 2012, 04:46 PM
#35
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thanks Ali, looking at the scoobypedia, is there any benefit to cutting the resonator off the bottom and keeping the pipework in the wing as a cold air feed?
10 August 2012, 08:36 PM
#36
Ali-B
Remove/bank off dump valve and fit cone filter.
Did you really mean to say this?
(H)
Remove/bank off dump valve and fit cone filter.
Did you really mean to say this?
(H)
Joke. Ali :
Anyhoo, a point to bring up of a commonly spouted statment about the turbo shaft speed slowing. Can you prove this? The air stalls, yes. And yes there are shock waves (of that we can clearly hear ) But the actual shaft slowing any faster than normal or even stopping? I think we need to properly debunk this. As there in conflicting information out there. Yes the shock loads place thrust and shock stresses on the compressor wheel and bearings, thats a given, but when people out there claim that the phsyical shaft is stalling or slows any faster. I don't think so - not of any significant magnitude anyway.
If there is no DV then where can the air go? It reverses back up the pipe from the throttle flap to the compressor wheel and shock loads it, acting as a brake on the rotating assembly. It is this reversal you here without a DV.
But the actual shaft slowing any faster than normal or even stopping? I think we need to properly debunk this. As there in conflicting information out there. Yes the shock loads place thrust and shock stresses on the compressor wheel and bearings, thats a given, but when people out there claim that the phsyical shaft is stalling or slows any faster. I don't think so - not of any significant magnitude anyway.
If someone has the time and inclination I guess they could devise a test to measure shaft RPM change but it would need a very specialised piece of kit that can measure up to 100,000 RPM and detect changes with an exceptionally high frequency sampling. Hardly worth the effort if you have already concluded that shock loading the compressor wheel and hence the shaft assembly and bearings is bad for the turbo.
Remember if your electric motor is not moving air it is not "working".
10 August 2012, 08:47 PM
#37
Some years ago I did some experiments involving resonator removal and different panel filters.
When we removed the resonator, (a large plastic reservoir located in the driver's side inner wing) we found power output dropped by about 7 bhp from 335 bhp to 328 bhp from memory. This was completely contrary to what we expected. The resonator box was replaced and the car was back to the original 335 bhp reading. I was so troubled by this result that we ran the same car on the rollers the following day and again observed a 7 bhp difference from running with and without the resonator and the car was left with the resonator in place.
Thinking this through further our conclusion was that the resonator ensured a smooth airflow to the MAF sensor.
No changes were made to the map to account for the resonator removal and no link pipe was fitted to bridge the inlet tract gap left by the resonator removal. Whether fitting such a bridge or remapping with no resonator present would have made any difference I do not know. I also wondered what the effect might be on any car running MAFless but never went further with this work as the car was destined for a Simtek and FMIC.
When we removed the resonator, (a large plastic reservoir located in the driver's side inner wing) we found power output dropped by about 7 bhp from 335 bhp to 328 bhp from memory. This was completely contrary to what we expected. The resonator box was replaced and the car was back to the original 335 bhp reading. I was so troubled by this result that we ran the same car on the rollers the following day and again observed a 7 bhp difference from running with and without the resonator and the car was left with the resonator in place.
Thinking this through further our conclusion was that the resonator ensured a smooth airflow to the MAF sensor.
No changes were made to the map to account for the resonator removal and no link pipe was fitted to bridge the inlet tract gap left by the resonator removal. Whether fitting such a bridge or remapping with no resonator present would have made any difference I do not know. I also wondered what the effect might be on any car running MAFless but never went further with this work as the car was destined for a Simtek and FMIC.
10 August 2012, 10:40 PM
#39
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Some years ago I did some experiments involving resonator removal and different panel filters.
When we removed the resonator, (a large plastic reservoir located in the driver's side inner wing) we found power output dropped by about 7 bhp from 335 bhp to 328 bhp from memory. This was completely contrary to what we expected. The resonator box was replaced and the car was back to the original 335 bhp reading. I was so troubled by this result that we ran the same car on the rollers the following day and again observed a 7 bhp difference from running with and without the resonator and the car was left with the resonator in place.
Thinking this through further our conclusion was that the resonator ensured a smooth airflow to the MAF sensor.
No changes were made to the map to account for the resonator removal and no link pipe was fitted to bridge the inlet tract gap left by the resonator removal. Whether fitting such a bridge or remapping with no resonator present would have made any difference I do not know. I also wondered what the effect might be on any car running MAFless but never went further with this work as the car was destined for a Simtek and FMIC.
When we removed the resonator, (a large plastic reservoir located in the driver's side inner wing) we found power output dropped by about 7 bhp from 335 bhp to 328 bhp from memory. This was completely contrary to what we expected. The resonator box was replaced and the car was back to the original 335 bhp reading. I was so troubled by this result that we ran the same car on the rollers the following day and again observed a 7 bhp difference from running with and without the resonator and the car was left with the resonator in place.
Thinking this through further our conclusion was that the resonator ensured a smooth airflow to the MAF sensor.
No changes were made to the map to account for the resonator removal and no link pipe was fitted to bridge the inlet tract gap left by the resonator removal. Whether fitting such a bridge or remapping with no resonator present would have made any difference I do not know. I also wondered what the effect might be on any car running MAFless but never went further with this work as the car was destined for a Simtek and FMIC.
10 August 2012, 11:24 PM
#42
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You guys know a scary amount about this stuff!
I'm not running enough power to warrant changing the panel filter (272 in a Bug WRX)
Thanks for all the info, not something that I'll be doing right now. Maybe when I upgrade to an STI though......
I'm not running enough power to warrant changing the panel filter (272 in a Bug WRX)
Thanks for all the info, not something that I'll be doing right now. Maybe when I upgrade to an STI though......
10 August 2012, 11:48 PM
#45
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strange this is, on my old classic I had an sti v4 recirc valve on + induction kit and fmic and the DV noise was VERY loud. Only thing I found was the fmic etc made the vf35 feel a bit laggy.
11 August 2012, 08:37 AM
#47
Properly mapped there should be no appreciable lag from an efficient FMIC system over a top mount. If you look at the air consumption of your engine per second and then compare it with the volume of the original system and the volume of the new system, from compressor outlet to throttle body in each case you will see how little effect the increased volume will have even in a worst case scenario.
When intercoolers were bar and plate (many still are) and had big pressure drops across the core and pipework with 90 degree sharp bends then there could be lag but not on a modern well designed system (read Hybrid).
Matty : Remember that air to the turbo enters the front of the turbo through the induction system. This is also the path of any recirculated air. Any reversed flow does not operate on the front of the turbo but goes backwards into the compressor through the compressor outlet acting against the operation of the turbo.
On a car with a mass air flow sensor there will be a momentary glich in fuelling if air is vented to atmosphere which is one reason why recirculating vales are used on cars with MAFs. Personally I don't think it matters too much but some mappers will tell you that to get the car smooth with a MAF sensor you need a recirculating BOV.
When fitting a front mount we will fit whatever the customer requests or go with the options, explain the pros and cons, and accept his decisions but on my own cars which are all MAP ie. no MAFs, I always use a Forge VTA and this is purely for ease of fitment and simplicity. If I had a car (well actually now I think about it - I do ) with a MAF sensor and recirc BOV I would not be looking to change it.
I hope this helps clarify for you.
In all the dump valves we have fitted I am yet to find a car that has shown a particular benefit from the change unless the original was defective. Yes the noise may appeal to some people and it is good if you want to frighten old dears at the bus stop and get them talking. You can start looking round too to see what caused the noise so I guess it is good for a laugh. What I don't understand is that guys are prepared to spend £200 and upwards for a heavily advertised all singing, all dancing, BOV that does make a lot of noise but is a source of continual problems because it leaks regularly.
When intercoolers were bar and plate (many still are) and had big pressure drops across the core and pipework with 90 degree sharp bends then there could be lag but not on a modern well designed system (read Hybrid).
Matty : Remember that air to the turbo enters the front of the turbo through the induction system. This is also the path of any recirculated air. Any reversed flow does not operate on the front of the turbo but goes backwards into the compressor through the compressor outlet acting against the operation of the turbo.
On a car with a mass air flow sensor there will be a momentary glich in fuelling if air is vented to atmosphere which is one reason why recirculating vales are used on cars with MAFs. Personally I don't think it matters too much but some mappers will tell you that to get the car smooth with a MAF sensor you need a recirculating BOV.
When fitting a front mount we will fit whatever the customer requests or go with the options, explain the pros and cons, and accept his decisions but on my own cars which are all MAP ie. no MAFs, I always use a Forge VTA and this is purely for ease of fitment and simplicity. If I had a car (well actually now I think about it - I do ) with a MAF sensor and recirc BOV I would not be looking to change it.
I hope this helps clarify for you.
In all the dump valves we have fitted I am yet to find a car that has shown a particular benefit from the change unless the original was defective. Yes the noise may appeal to some people and it is good if you want to frighten old dears at the bus stop and get them talking. You can start looking round too to see what caused the noise so I guess it is good for a laugh. What I don't understand is that guys are prepared to spend £200 and upwards for a heavily advertised all singing, all dancing, BOV that does make a lot of noise but is a source of continual problems because it leaks regularly.
13 August 2012, 07:33 AM
#53
Avoid copies and ensure entry and exit are sufficiently large to vent air quickly. ie bigger than 25mm.
You would not see a BOV leak on your boost guage but it will play havoc with tickover and smooth running in mixed traffic around town. Big culprits are Blitz, HKS and fancy twin cylinder Australian jobbies.
13 August 2012, 03:52 PM
#54
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I think i need that sound in my life, i am currently running a td04 on MY99 with a turbo smart DV boosting at 1.2 bar. I was advised not to take off the dv as it had been mapped with it on.
Where is it that the sound comes from? Is the wastegate for the turbo?
Where is it that the sound comes from? Is the wastegate for the turbo?
13 August 2012, 07:35 PM
#57
Harvey I got a sc40 billet people say I shouldn't run dv less as it not as strong as the sc42 etc as don't have the garret core and mine being sleeve bearing . But people running your s and af turbo fine dv less for long time and there both based on same turbo ain't they?
15 August 2012, 11:05 PM
#58
I have never taken an SC40 apart but I think they are sleeve bearing and that will be more tolerant to running without a DV than a roller bearing. I have no idea how much effect running without a DV will have on the life of a turbo but it must reduce the life because of the shock loading so just in the same way I go for shockless gear changes and some people go for a clunk almost every time my mechanical sympathy stops me wanting to run without a dump valve.
You could ask Scooby Clinic what they think?
You could ask Scooby Clinic what they think?
Last edited by harvey; 16 August 2012 at 01:40 PM. Reason: spelling.
16 August 2012, 05:10 PM
#60
What kev actually said he s never done it but he wouldn't recommend it due to sleeve bearing etc. I wanted Harvey's view .
It's like when people say u cant run over 350 bhp on standard classic Sti engine and box etc when Harvey's run 400 plus
It's like when people say u cant run over 350 bhp on standard classic Sti engine and box etc when Harvey's run 400 plus