how do i get this on my fd3s i used to get great chatter of my 200sx but all i seem to get is the dump of the resic valves will it work if i take them of and block the pipes?
Can i ask a question why do you want wastegate chatter when all you are doing is shortening the life of the turbo\'s.
Kevin
cos it sounds far better than a dump valve and im sick of pitsssshhh every time i come of the excelerator
No problem mate if you loose the dump valve then you should get the chatter you want how loud it is will depend on set up. The chatter noise you hear though is a reversion of flow going the wrong way over the turbo compressor blades this puts stress on the shaft with more likelyhood of turbo failure.
Kevin
i appretiate your help kevin thanks
Quote from: kev-yorksThe chatter noise you hear though is a reversion of flow going the wrong way over the turbo compressor blades
Had to be said! ;) :Laugh
But it sounds so good :rollin
I dont care how long my turbo lasts....it rocks :chat
Quote from: Red and SingleBut it sounds so good :rollin
I dont care how long my turbo lasts....it rocks :chat
Put antilag on your motor and a ignition based rev limiter you\'ll get a wonderfull collection of pops bangs and massive flames. Don\'t know how long the motor/exhaust will last though:2eek
Get a CD of the chatter and play it loud!!!
Then you have the sound and the Turbos are safe! :D
Quote from: Crazy EddieGet a CD of the chatter and play it loud!!!
Then you have the sound and the Turbos are safe! :D
:rollin :chat
There is no such thing as wastegate chatter - all you are hearing is the distress of the turbo stalling. It\'ll sound good until the turbo falls apart and you need to replace it. Which won\'t take long if you allow it to be stalled continuously.
It also reduces throttle response, causing a longer delay in spool up time, compared to running with a dump valve.
Personally, I always thought that wastegate chatter was a chav calling card :Giggle but maybe only on a nova or corsa :WaveBye
mine is loud and i love it..been on the car for 4 years with no problem at all, although i dont go out and floor it all the time..:3gears-rh
Quote from: TonyCThere is no such thing as wastegate chatter - all you are hearing is the distress of the turbo stalling. It\'ll sound good until the turbo falls apart and you need to replace it. Which won\'t take long if you allow it to be stalled continuously.
It also reduces throttle response, causing a longer delay in spool up time, compared to running with a dump valve.
Tony, this is true apart from the throttle response !
I don\'t care what anyone says drive a car with a dump valve then drive one without, the car without is soo much more responsive. The dump removes all pressure in the intake system so when your throttle opens again the whole intercooler and intake piping systems needs to re-pressurize.
I had no problems never running a dump valve on my cosworth and the turbo was in good condition after i removed it.
Throttle response after dumping is dependent on where the dump valve is placed in the system if I remember correctly.
Compressor stalling does place a lot of stress on the turbo, you may have just been lucky with the cossie. (Mind you, if it was a cossie it probably blew up every other week anyway :chat )
Yes you do Laeeq!
Its normal on single setups to get a flutter, even with a dump valve installed and when I was at .8 bar!
My cossie never blew up once during my ownership
did do a headgasket tho.
On cossies people tend to install the BOV close to the throttle however on a lot of jap machines i see them installed on the hotside before the intercooler.
Which did you hear was better ?
I\'ll have a look at my turbo notes at home and get back to you.
I was joking about the Cossie ;) I\'ll be racing agaisnt a couple of Escort cossies this year - Damn those things make power!
mine has always made this noise when you let off the throttle, along with the noise from the dump valve. it only does it at part throttle though-on full throttle eg. a gear change it doesn\'t make any noise and you only hear the dump valve.
i have been to tuners, garages etc and they have never commented on it in a negative way and say it isn\'t a problem. is there any chance peeps could have the noises mixed up? i\'m sure there is a thread on here from ages ago where \'wastegate chatter\' or \'compressor surge\' was actually something else.
i have standard twins btw.
compressor surge is something totally different.
This is caused by a restriction of gasses exiting the engine (usually a small turbo exhaust housing) while the turbo is still trying to force air into the engine.
This is very dangerous but is not the same as "chatter" or compressor stalling
Ok, the dump valve should help throttle response becuase it prevents the compressor stalling (making the \'chatter noise\').
When you shut the throttle you\'ve got compressed air in the intercooler/pipes leading up to the now closed throttle butterfly. That air wants to go somewhere as it is under pressure, and usually goes back through the compressor blades. This stalls the compressor, puts presure on the wheel and slows it down.
A dump valve allows that pressuruised air to escape, this means the compressor wheel is not stalled by the air and is spinning freely and gently slowing due to the reduction in exhaust gasses spinning the turbine - so when you get back on the throttle the compressor should spin up quicker than if it had stalled and been prematurly slowed by air being pushed back through the compressor - as happens with no dump valve.
The dump valve location does\'t effect the response as such (my mistake earlier), the reason for the different location is heat.
As air is compressed it gets warmer, and looses density. That\'s one of the reasons why we push air through the intercooler -to loose this heat and increase air density again (density is good for power).
If we vent after the intercooler than we are wasting intercooler efficieny). We are forcing the recently compressed and heated air to travel through the intercooler before it is vented. This is air we are not going to use as the throttle has been shut. This is extra heat the intercooler is having to soak up. By venting before the intercooler we are venting the heated air before it reaches the intercooler and therefore we are not wasting intercooler efficieny by having it cool air we are only getting rid of.
If you see what I mean.
It\'s going to be academic for a road car anyway - but it is little details that make up a good circuit car.
oh no not this story again about dumpvalves and bovs and recirc valves, not having one of these valves will not break your turbo blades etc, these valves are only fitted by manufacturers as noise suppressors to stop the so called "chatter" noise. Will post a link later from people in the know
HOGWASH TO DUMPVALVES
here is a link, take note from RICE RACINGs comments he knows his stuff and is a major tuner in Oz
http://www.rx7club.com/showthread.php?t=495277&page=2&pp=15&highlight=bov
Interesting stuff, but why is he banned from the forum? And I\'d need to know who he is to bring credibility to his comments. All I see is one post from a banned user in an internet forum. My reason for considering a BOV is based upon published techincal articles from people who make a living building, designing and installing turbo applications from scratch.
A discussion on BOV\'s always seems to prompt some strong feelings from people (for some reason).
There are applications where a BOV is needed to protect the turbo - usually when you start running high boost or go often from WOT to shutting the throttle down rapidly. From a racing prespective I\'ll fit one for this reason. A lot of turbos/boost levels get away without one. But the mechanics of what the BOV does and what it protects are still valid. It\'s up to the owner of the car to decide if they want to fit one based on the information available.
The reason why he was banned is there is a big fight about AI on the forum and other members on there, trust me he knows his sh*t
Tony in the 80\'s Formula One Turbos did not use BOVs, Rally Cars do not use BOVs.
Ask yourself why, the main reason why is the "drop" in performance, the repressurizing of the intercooler and pipes is the main reason as the BOV releases all the pressure that the turbo has built up, so the turbo has to work harder to repressurize therefore time is lost in building up the pressure again so this will cost you time in the quarter mile and Track.
There has been no real eveidence I have seen over the years on all these forums that has shown damage due to not running a BOV, plus a turbo keeps spinning even without a BOV there has been no real eveidence of turbo stall.
If there was Stall then this would hurt performance and Rally cars would run them.
With most tech arguements, you seem to get two distinct perspectives. However I find that the ones who are usually right are generally in the minority, and I think they should be more happy to let the others trundle down the path of blissful ignorance.
Just to add I have driven 10k Miles on my turbo no BOV, still like new the blades, my spool up time between gear changes has been practically instant
sweet someone who agrees with me for a change
so im not talking complete bollox.
I have some videos of my cossie at the nurburgring.
not only does it sound awesome but as in my previous comment my cars have drven sooo much better without a BOV
FYI... this fellow who i know http://www.rampage-hks.co.uk/remapping.php
runs a mahooooosive power scoob without any bov\'s etc. and neither do the rally cars that he tunes (as metiond in the page)
Rmaj
one of the arguements I have heard on the competition car front is that Rally cars, 80s F1 cars, etc is that the engines and turbos are rebuilt pretty much every race meet, lets face it if we ran cars for 800 miles between rebuilds we\'d get a little pi55ed off!
I\'m not saying I agree with either side, I would say that IMHO running without a BOV should reduce lag as there is more pressure in the system, however prolonged exposure to excessive pressure agaignst the turbine blades can\'t be a good thing for turbo life. Sounds to me as though we have the classic situation, a product has been developed to reduce engine/turbo wear, but potentially will increase lag and increase response time of the turbo. Like all things I guess, we have to make a compromise between logevity and performance.
That is ONLY my opinion, I am not stating fact so don\'t start flaming me! ;)
lol no flammage needed Mark.
I like evidence, never seen broken blades due to pressurised air of a cars turbo system.
OEM BOVs and recircs are designed in mainstream cars as noise suppressants as they stop chatter/compressor surge type noises
i have seen a snapped shaft on a gt rollerbearing turbo
on a cossie running over 2 bar, but was told the shafts on them are weaker
Interesting stuff again - this is how it should be: decent discussions. I understand about the loss of presurisation within the inlet system and the negative effect it can have.
But there is a lot of weight in the argument of why the major race teams don\'t use them - they are re-built frequently and long term wear isn;t really a worry for them.
And you must see that if you don\'t vent the inlet when the throttle is shut then that air has to go somewhere?
There is obviously more to this, why do so many technical discussions on turbo\'s advocate the use of a BOV (for road or competition). I don\'t like to copy what another tuner does - I like to understand why and make my own choice.
Have any of you who recommend no BOV got any information on the positives of no BOV, from a clear technical perspective - rather than from a experience/observational perspective.
Perhaps you are right, perhaps with the more modern turbo vanes and designs the backwash of presurised air doesn\'t cause premature wear, maybe it never did - but I\'d like to know more
i will try and dig up a post from a ford forum i once read from a tuner.
One thing i remember him saying was that BOV\'s can cause overspooling of a turbo should they become stuck open or faulty etc.
Dont quote me on that tho i will try and find the post.
That would be great, cheers.
It\'ll be something to read as I trundle my way down the path of blissful ignorance :D
There is a massive thread on Ausrotary on this from both sides of the fence.
Another thing to think about , Rally teams its all about reliablility that cannot afford to have a turbo go mid stage so surely a cheap BOV in respect of the cost of a turbo they would fit it to prevent this, they dont as they feel it does not contribute to reliability.
go outside of the rx7 market and lots of people run without bovs.the only reason to running a blow off valve or whatever u want to call it is to rlve reverse airflow over the turbo blades perf with or without will be fractional and 99% of us will not notice the performance difference manufacturers cant afford to have warranty claims so they fit bovs to rlve poss stress on the turbo.it wont happen over 1 week or 1 month but stress will occur.rally cars will be stripped and rebuilt far to regular for it to be an issue but road cars are different and i would be apprehensive buying a turbo car that hadnt been running a dump valve.each to his own but i wld rather have a safe car than take a chance to have what soundslike a horse blowing its nose everytime i change gear
is there any reason you couldn\'t have a more intelligent BOV which releases pressure up to a certain point but maintains pressure below a certain point? You could then balance the BOV lower cut-off point with the point at which the inertia in the turbo causes it to stall (if indeed it does stall)
BTW What actually makes the chattering noise?
(according to several encyclopedia)Motor sports governed by the FIA have made it illegal to vent unmuffled blowoff valves to the atmosphere.
see here for the pro BOV / CBV arguement: http://en.wikipedia.org/wiki/Blowoff_valve
http://en.wikipedia.org/wiki/Wastegate#Wastegate_chatter_myth
Quote from: rx7veilsideperf with or without will be fractional and 99% of us will not notice the performance difference manufacturers cant afford to have warranty claims so they fit bovs to rlve poss stress on the turbo.
Dis-agree with the minimal performance difference, Had a single turbo 300zx and it took ages to spool up in gears it had an after market HKS seq BOV fitted, as soon as I disabled it the performance was returned. The 300zx twin turbo had recirc valves fitted as standard due to the MAF system of metering air as not to spoil the tune and to suppress the noise of the turbo chatter this is stated in the Nissan literature no mention of it to protect the turbos.
IMO opinion on modern Single turbo Rexys you dont need a BOV
Until I see back to back quarter mile times proving that an RX7 is quicker without a dumpvalve and conclusive evidence there\'s no negative effects of compressor surge then I\'ll err on the side of caution and keep the dumpvalve.
Quote from: MillSpeedUntil I see back to back quarter mile times proving that an RX7 is quicker without a dumpvalve and conclusive evidence there\'s no negative effects of compressor surge then I\'ll err on the side of caution and keep the dumpvalve.
well cant prove it on a RX7 but on my single tubby 300zx a few years ago I posted consistant 15.4s as soon as I disabled my BOV my in gear boost response improved and my quarters improved to 14.8s no other mods were made
Daym, that\'s quite an improvement. I wonder if someone would be willing to do a little experiment at one of the drag meets? Say do five runs with, and then 5 runs with the BOV removed/disabled.
someone must be up for this! would be nice to actually put this to rest. I have a G-Tech Pro if someone\'s willing to try it on the road at a meet rather than wait for the strip
"There is a common myth in the automotive world about so called "wastegate chatter", a noise created on lifting off the throttle in a turbocharged car. The sound is commonly described as a chipmunk or a rattlesnake and is often stated incorrectly as being a result of the turbo\'s wastegate closing.
The noise is in fact the air compressed by the turbo passing back through the compressor housing of the turbo after having hit the now closed throttle plate.
A blow-off valve (BOV) will usually eliminate this noise, but in some cases, i.e. where it doesn\'t open fast enough or is setup to only react to high boost, some chatter will remain.
The chatter noise is very noticeable on WRC Rally cars, where no BOV is allowed."
Quote from: DRAGON"There is a common myth in the automotive world about so called "wastegate chatter", a noise created on lifting off the throttle in a turbocharged car. The sound is commonly described as a chipmunk or a rattlesnake and is often stated incorrectly as being a result of the turbo\'s wastegate closing.
The noise is in fact the air compressed by the turbo passing back through the compressor housing of the turbo after having hit the now closed throttle plate.
A blow-off valve (BOV) will usually eliminate this noise, but in some cases, i.e. where it doesn\'t open fast enough or is setup to only react to high boost, some chatter will remain.
The chatter noise is very noticeable on WRC Rally cars, where no BOV is allowed."
thank you! this is an interesting discussion, but at last someone has answered my question as to why i have both!
the chattering noise is turbo stall
think of a propeller when it spins one direction air flows one way due to the orientation of the blades on said propellor. If it were to spin the other way the air would flow in the opposite direction.
When the throttle closes on a turbocharged car the air has no were to go apart from backwards through the turbo.
The turbo is spinning one way and the air is trying to go the wrong way this is what stalls the turbo and makes the chatter noise.
bah i was too slow Ross allready posted it.
Quote from: CraigNi have seen a snapped shaft on a gt rollerbearing turbo
on a cossie running over 2 bar, but was told the shafts on them are weaker
Bang on.... was waiting for a comment like this. Running the standard turbos with no BOV will result in severe shaft damage!! No blades snapping, or nuts shearing and no squirrels having kids! The REW turbo pack uses 4mm shafts. These are tiny, and will snap if there is no charge relief...espeacially if run high enough to produce in the region of a bar of boost.
Now when you go single, the shafts are alot bigger. For example a To4e is 7mm in diameter, and is a fair bit more robust than the twins. Move onto the larger Mitsubishi and Garrett turbos, and you will find these sporting 8-12mm shafts. the inherant strength of the thicker shafts lends them to be more suited to running without any charge relief, hence the shouts of \'its been fine on my setup!!\'
Peace,
John
got to say i wouldnt touch a car thats been running with no dump valve but each to there own
Right just to add a bit more to this one this is a section taken from a garret turbos tech paper.
Blow-Off (Bypass) Valves
The Blow-Off valve (BOV) is a pressure relief device on the intake tract to prevent the turbo’s compressor from going into surge. The BOV should be installed between the compressor discharge and the throttle body, preferably downstream of the charge air cooler (if equipped). When the throttle is closed rapidly, the airflow is quickly reduced, causing flow instability and pressure fluctuations. These rapidly cycling pressure fluctuations are the audible evidence of surge. Surge can eventually lead to thrust bearing failure due to the high loads associated with it.
Blow-Off valves use a combination of manifold pressure signal and spring force to detect when the throttle is closed. When the throttle is closed rapidly, the BOV vents boost in the intake tract to atmosphere to relieve the pressure; helping to eliminate the phenomenon of surge.
Quote from: BlitzBoyThe reason why he was banned is there is a big fight about AI on the forum and other members on there, trust me he knows his sh*t
Tony in the 80\'s Formula One Turbos did not use BOVs, Rally Cars do not use BOVs.
Ask yourself why, the main reason why is the "drop" in performance, the repressurizing of the intercooler and pipes is the main reason as the BOV releases all the pressure that the turbo has built up, so the turbo has to work harder to repressurize therefore time is lost in building up the pressure again so this will cost you time in the quarter mile and Track.
There has been no real eveidence I have seen over the years on all these forums that has shown damage due to not running a BOV, plus a turbo keeps spinning even without a BOV there has been no real eveidence of turbo stall.
If there was Stall then this would hurt performance and Rally cars would run them.
greer sports a respectable tuner backs this theory aswell i dont want a big rammy started i just wanted to no how to get it thats all
If you are concerned with the effect if has on the drag strip then my mate used to change gear so fast that the dump valve never had time to fully open before he was on the power again. The dump valve effectively welded itself shut! :Laugh
Of course I am no use to the argument which method is best! :King
Quote from: 88GT-RBang on.... was waiting for a comment like this. Running the standard turbos with no BOV will result in severe shaft damage!! No blades snapping, or nuts shearing and no squirrels having kids! The REW turbo pack uses 4mm shafts. These are tiny, and will snap if there is no charge relief...espeacially if run high enough to produce in the region of a bar of boost.
Now when you go single, the shafts are alot bigger. For example a To4e is 7mm in diameter, and is a fair bit more robust than the twins. Move onto the larger Mitsubishi and Garrett turbos, and you will find these sporting 8-12mm shafts. the inherant strength of the thicker shafts lends them to be more suited to running without any charge relief, hence the shouts of \'its been fine on my setup!!\'
Peace,
John
Now that\'s the kind of think I like. And makes perfect sense regarding the different experiences of people. Different turbo\'s different sizes, different strengths.
You can easily see how tuners who run larger, stronger turbos can say \'i never have a problem without a bov\', and you can understand why manufacturs fitting smaller cheaper mass market turbos have to do something to protect the compressor.
There seems no doubt that without venting it does stall the compressor, and it can have a negative effect on turbo longevity - but the overal \'wear\' is going to dependent on the turbo size and quality.
Interesting as well regarding the experience on the strip with and without bov - I\'d cerainly like to see a few runs with and without on the same day and same car.
damn it ive started world war 3:Hammer :chat
Quote from: rx maddamn it ive started world war 3:Hammer :chat
Nah, you\'e started a decent debate.:Thumbsup!
Quote from: 88GT-RBang on.... was waiting for a comment like this. Running the standard turbos with no BOV will result in severe shaft damage!! No blades snapping, or nuts shearing and no squirrels having kids! The REW turbo pack uses 4mm shafts. These are tiny, and will snap if there is no charge relief...espeacially if run high enough to produce in the region of a bar of boost.
Now when you go single, the shafts are alot bigger. For example a To4e is 7mm in diameter, and is a fair bit more robust than the twins. Move onto the larger Mitsubishi and Garrett turbos, and you will find these sporting 8-12mm shafts. the inherant strength of the thicker shafts lends them to be more suited to running without any charge relief, hence the shouts of \'its been fine on my setup!!\'
Peace,
John
I know Rice Racing runs his stock twins without BOV or charge relief at stupid amounts of boost (using WI) and has done for a long time with no problems.
It must be possible to \'tune\' the BOV to release only at and seal at certain pressures. It could then be setup to only let go when there is a large amount of pressure in the system that \'might\' cause problems, but would effectively not open at all at when only light boost and throttle plate closure occurs.
I presume the bigger turbo\'s may also have different shaped compressor blades that are designed to reduce the effects of charge backwash - much like in the modern turbofan engines on airplanes which have to take bird strike in their stride.
I\'ll be keeping my BOV as I only have a small Turbo, but that has the advantage that it respools pdq anyway.
Cheers.
Please correct me...but am 100% positive that Rice WAS running BNR stage 3\'s with no BOV. Now looking along the lines of Garratt TO4Z
Quote from: ProfIt must be possible to \'tune\' the BOV to release only at and seal at certain pressures. It could then be setup to only let go when there is a large amount of pressure in the system that \'might\' cause problems, but would effectively not open at all at when only light boost and throttle plate closure occurs.
I presume the bigger turbo\'s may also have different shaped compressor blades that are designed to reduce the effects of charge backwash - much like in the modern turbofan engines on airplanes which have to take bird strike in their stride.
I\'ll be keeping my BOV as I only have a small Turbo, but that has the advantage that it respools pdq anyway.
Cheers.
The upmarket BOV\'s are tunable for pressure Prof also the some of the bigger turbo\'s are now coming with ported shroud compressor housings which may help.
Here\'s a pic of the ported shroud housing instead of stalling the air bypasses via the ports in the shroud four of them around the compressor wheel and back into the compressor to keep everything spinning.
Kevin
Cheers Kev - btw is that turbo running the engine or the other way around !
Heheheheheheheheheheheheheheheheh......:god :evillaugh :cool
Here\'s a cutaway of the ported shroud prof. Lowers the efficiency of the turbo slightly but means that the surge line moves way over to the left on a compressor map.
Kevin
It\'s not going to make much of a dent in the power that thing must be able to provide. I like the idea of that though - it makes a lot of sense - bit like a built in recirc valve.
Quote from: 88GT-RPlease correct me...but am 100% positive that Rice WAS running BNR stage 3\'s with no BOV. Now looking along the lines of Garratt TO4Z
Sorry, you\'re wrong. I can\'t get on to Ausrotary at the mo\', it seems to be down but I don\'t think he\'s even got the BNR specced engine in yet (he didn\'t at the beginning of December anyway). I think the T04Z is for a different car as he\'s trying to keep the SP close to stock.
Just realised I sound like a stalker! I\'ll stop now.
Sounding a bit of an Anorack myself.......
ported shrouds also make the turbo sound like a jumbo jet is about to take off :god :god :god :god
is there any BOV or dump valves that sound like the chatter sound?? :(
Quote from: kev-yorksThe upmarket BOV\'s are tunable for pressure Prof also the some of the bigger turbo\'s are now coming with ported shroud compressor housings which may help.
Here\'s a pic of the ported shroud housing instead of stalling the air bypasses via the ports in the shroud four of them around the compressor wheel and back into the compressor to keep everything spinning.
Kevin
jesus h thats a big turbo were did he get that of a jumbo jet
No...he\'s just showing off!!!!
I\'m sitting on the fence here, but the reason the rally cars don\'t use BOV\'s is because they use anti-lag, so the turbo stalling is not a problem.
Also remember reading somewhere that the F1 cars in the 80\'s use to blank the wastegates off during qualifying and throw the turbo away after qualifying. Anybody willing to try this?
sorry to bring this one back from the dead but i have this chatter noise and i have a bov fitted should i try to adjust my bov to eliminate some of the chatter noise as it really is very very load
your bov is sprung too hard, loosen it off a bit and it should help. if not, the spring may be too hard. :)
Quote from: Jimjitsusorry to bring this one back from the dead but i have this chatter noise and i have a bov fitted should i try to adjust my bov to eliminate some of the chatter noise as it really is very very load
IMO, and after reading these posts I\'d say you only *need* to eliminate the chatter if your on stock twins... If you\'re running a single, it\'s a matter of personal taste.
I\'m absolutly gutted tbh I have to run one on a RX7. (mine has uprated twins). I hate dump valves with a passion.
John (88-GTR), with refrence to your post about shaft sizes... you wouldn\'t happen know the shaft size on a 200SX T28 would you? I\'m from a SX background and on both mine I ran perfectly fine with no BOV @ 15psi & I\'ve never heard of a single failure put down to that cause. I\'m guessing they must have a thicker shaft. Infact with them, I think more people have problems fitting large bore exhausts causing low backpressure and dragging oil through the rear oil seals...
Quote from: RAWthank you! this is an interesting discussion, but at last someone has answered my question as to why i have both!
Mine chatters on low boost (I mean if I lift off early, rather than control the boost) but sounds like a normal psssssshhhhhtt when driving hard..
no idea if its OPk to do that though... :confused:
Quote from: RAWthank you! this is an interesting discussion, but at last someone has answered my question as to why i have both!
Mine chatters on low boost (I mean if I lift off early, rather than control the boost) but sounds like a normal psssssshhhhhtt when driving hard..
no idea if its OK to do that though... :confused:
well ok if it does not do to much damage to the to4e then ill leave it i kinda like the noise and my bov is working i have the pffffff and fffffftthththththt
mine does it at any level of boost if i let off the throttle quick i get the hannibal if i let it off easy i get the bus putting its brakes on
I\'ve got a to4e and been running 0.85 bar without a BOV/ dump valve for over a year and had no probs... plus the wastegate chatter sound is intoxicating :D
Quote from: Kash_I\'ve got a to4e and been running 0.85 bar without a BOV/ dump valve for over a year and had no probs... plus the wastegate chatter sound is intoxicating :D
Good enough answer for me i like the noise so it stays :Thumbsup!
Quote from: Kash_I\'ve got a to4e and been running 0.85 bar without a BOV/ dump valve for over a year and had no probs... plus the wastegate chatter sound is intoxicating :D
Mine\'s sweet as a nut with no BOV (Pip didn\'t fit one when he fitted my single - Not got much good to say about them either...) t04e @ 0.87bar (389.9@flywheel) ran a 12.54 despite terrible starts all day due to the stock clutch, tired stock suspension, 30PSI in the tyres, a full tank of fuel and no diff bracing.
AND...
It\'s my daily car and has been for 18months ! :driving
does the stock car have a BOV?
Stock FD has a recirulating bov for each turbo.
My greddy bov is adjusted so that at low boost I get a little chatter, but at good boost levels it will all vent to atmosphere.
Good thread !
i had a series 2 rs with a t3 that was at 20psi with a dump valve decided to bin it for the chatter had no problems whatsoever with the turbo and that was always driven hard then after that a s13 origionally a 1.8 with t25 ran that with no bov with no problems then swapped to sr20det with t28 again with no bov and no probs (except for the w"£$y variable valve timing)
the one thing i noticed with the escort was it was slightly quicker picking up
also if i remember right a magazine (maybe fast car/max power????) did a test on the new-at the time mk4 golf turbo that was dyno\'d which HAD more power and response without the bov
havent had time to read past page one up to yet but for reference about why rally cars dont have BOVs, theres a good reason for this, its not to save the turbo or anything like that, its because they run anti-lag, when the driver lifts off the throttle instead of the engine taking no more charged air and it either being \'dumped\' or passing back through the blades it is continually pumped into the engine, the ignition is timed right back so the fuel is almost ignited as it leaves the cylinder head hence expanding and keeping the turbo spinning so when the throttle is opened the timing is adjusted back and full boost is avaliable instantly.
If a BOV was installed all that pressure would be lost and anti-lag wouldnt work, since most people run without anti-lag i can see the benefits of having it
the times when isnt as efficient on a road car is in extreme full throttle times when the car is running a large cooler and pipe work.
Its been mentioned that the loss of pressure will cause a lag in full boost between gear changes, now this is all down to the driver to be fair and how fast he changes gear.
It takes longer for the pressure to escape back through the turbo and the system to revert back to zero pressure/vacuum than it will through a BOV as it has two options on how to get out and will use both.
If the driver is very slow on gear change then most likely the pressure will fully escape through either the turbo or if a BOV is fitted before full throttle is applied
If no BOV he will just slow the turbo down which will then take a very small amount of time to spool back to full speed, if hes running a blow off valve obviously the turbo will be slowing down but not at the rate of which is was without a BOV.
So it does depend on the situation the driver is in, very fast full throttle changes i would advise not to run a BOV(drag, maybe some circuit) but for street use id advise to run one as the benefits out weigh the potential negatives as you wont be able to tell enough for it to make a difference
hope this helps, any questions or comments im happy to discuss:Talking1