Removing bosch reserc valve to reduce in gear lag?

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Removing bosch reserc valve to reduce in gear lag? #198456 25/09/2006 04:08 25/09/2006 04:08
A Anonymous Unregistered
Anonymous Unregistered A	In gear lag is not the best. Want to reduce it and heard that removing the bosch recirculation valve and blanking the holes will keep the turbo boosting between gear changes? Apparently this is the way Cosworths are done? Anyone know anymore about this?

Re: Removing bosch reserc valve to reduce in gear lag? #198457 25/09/2006 04:10 25/09/2006 04:10
Joined: Dec 2005 Posts: 19,939 North wales pinin_prestatyn Forum veteran
pinin_prestatyn Forum veteran Joined: Dec 2005 Posts: 19,939 North wales	The recirculation valve is designed to keep the turbo spinning between gearchanges, so no Idea why removing this would help lag. I'd wager that it would increase it. I've also read on other forums of people removing their Dump valves for that cool rally chatter sound, this is silly. Coopless!

Re: Removing bosch reserc valve to reduce in gear #198458 25/09/2006 04:11 25/09/2006 04:11
A Anonymous Unregistered
Anonymous Unregistered A	As in, have no dv?

Re: Removing bosch reserc valve to reduce in gear #198459 25/09/2006 05:44 25/09/2006 05:44
A Anonymous Unregistered
Anonymous Unregistered A	Yeah alot of the Cosworth boys run with no DV.

Re: Removing bosch reserc valve to reduce in gear #198460 25/09/2006 06:10 25/09/2006 06:10
Joined: Dec 2005 Posts: 1,897 New Zealand Saint My life on the forum
Saint My life on the forum Joined: Dec 2005 Posts: 1,897 New Zealand	No-sorry it has the opposite effect - it will actually increase lag, Basically when you change gear the throttle body slams closed (as you lift you foot off the accelerator), the BOV give the compressed air somewhere to go (that pish as the air escapes) while it can't go through the throttle body and keeps the turbo spinning as fast as possible. with no BOV the air "fulls up" the IC plumbing and then basically once it is full it stops the turbo - well trys to as the air backs up and slows the compressor wheel. a BOV is the best way to keep the turbo spinning short of an Anti-lag system like the rally WRCc ars use, this system injects raw fuel into the exhaust to keep the turbo spinning (simplistically) and this is why they backfire on overrun - they are not actually running that rich , Antilag is very hard on turbo's and can destory a turbo within no time - hence the WRC changing top of the line turbos often to only get 300hp (restricted) Are you sure your BOV/DV is working O.K.? Hope this helps

Re: Removing bosch reserc valve to reduce in gear #198461 25/09/2006 17:07 25/09/2006 17:07
Joined: Dec 2005 Posts: 1,513 Banbury stevo My life on the forum
stevo My life on the forum Joined: Dec 2005 Posts: 1,513 Banbury	Or some wrc cars just let air into the exhaust which causes the unburnt fuel to ignite and turns the turbo into a mini jet engine to keep it spinning. Most WRC cars are running 330+ BHP now which is amazing when you see the size of the restrictor and have more torque than a truck engine. 362bhp of warble

Re: Removing bosch reserc valve to reduce in gear #198462 27/09/2006 03:38 27/09/2006 03:38
A Anonymous Unregistered
Anonymous Unregistered A	Nice write up 'Saint'. Just going at what I heard from Keith at Auto Integrale Stand this weekend at Auto Italia Gaydon, however I also know he runs an external wastegate, does this change things? He also uses a GT roller turbo and said that in gear turbo lag will be reduced and that the roller bearing turbos can take the abuse? I am still a little confused on this?

Re: Removing bosch reserc valve to reduce in gear #198463 27/09/2006 04:56 27/09/2006 04:56
Joined: Dec 2005 Posts: 19,939 North wales pinin_prestatyn Forum veteran
pinin_prestatyn Forum veteran Joined: Dec 2005 Posts: 19,939 North wales	At the Prodrive Brief, they showed a cutaway of their ALS (anti lag system) It was basically a combustor section in the exhaust that ignited the unburnt fuel and kept the turbo spinning. He reckons the only reason we don't see this system in europe is as every car has to have a Cat convertor fitted, and the ALS would not work with one, despite it being cleaner than a normal engine with cat. I asked how they got around the severe strain on the engine this produces, but he didn't give me a straight answer Coopless!

Re: Removing bosch reserc valve to reduce in gear #198464 27/09/2006 05:17 27/09/2006 05:17
Joined: Dec 2005 Posts: 1,897 New Zealand Saint My life on the forum
Saint My life on the forum Joined: Dec 2005 Posts: 1,897 New Zealand	Having an external wastgegate won't effect this - the wastegate lets exhaust gas escape under boost conditions to stop the turbo overboosting - a BOV let intake air escape under conditions of Vacum in the plenum camber (ie when you have your foot off the gas) If he said "GT turbos can handle it" it sounds like he is talking more about an Anti lag system of some type, even running no BOV is not that hard on turbo's (it's not ideal) but won't kill a turbo superfast or anything (just make them stall and increase lag) I'll try and find a link to a site with a more detailed explaination cheers

Re: Removing bosch reserc valve to reduce in gear #198465 27/09/2006 07:21 27/09/2006 07:21
A Anonymous Unregistered
Anonymous Unregistered A	hi pietch. first of all you didnt have so much lag in your graphs. i saw 100 hp at 3000 rpm and i think thats "logical" for that engine. about your quote i read lotus entusiast add DV and the reasons, good review here http://www.espritfactfile.com/Procedures.html#InstallingaBOVEasyWay regards

Re: Removing bosch reserc valve to reduce in gear #198466 27/09/2006 21:31 27/09/2006 21:31
A Anonymous Unregistered
Anonymous Unregistered A	Quote: No-sorry it has the opposite effect - it will actually increase lag, Basically when you change gear the throttle body slams closed (as you lift you foot off the accelerator), the BOV give the compressed air somewhere to go (that pish as the air escapes) while it can't go through the throttle body and keeps the turbo spinning as fast as possible. with no BOV the air "fulls up" the IC plumbing and then basically once it is full it stops the turbo - well trys to as the air backs up and slows the compressor wheel. a BOV is the best way to keep the turbo spinning short of an Anti-lag system like the rally WRCc ars use, this system injects raw fuel into the exhaust to keep the turbo spinning (simplistically) and this is why they backfire on overrun - they are not actually running that rich , Antilag is very hard on turbo's and can destory a turbo within no time - hence the WRC changing top of the line turbos often to only get 300hp (restricted) Are you sure your BOV/DV is working O.K.? Hope this helps Hi Saint, This is what I believed to be true too, however have you ever run without a d/v there are interesting things to be found.. read on.. The theory is sound as to why it should keep the turbo spinning, and i am sure it does, it also causes a vast amount of compressed air volume to be ejected, so then when you go to accelerate again the turbo has to fill up all the extra pipework with compressed air again, causing lag. I have done tests before with 1 d/v 2 d/v's and no dump valves, 2 d/vs was worst for lag and No d/v is the way to go for lagless gearchanges however its not nesessarily the best way for the turbo!! In a wrc car all you hear is compresser surge when they change gear (compressed air hitting the blades) and obviously the crazy anti lag systems but then their turbos only have to last one race!!! Dave

Re: Removing bosch reserc valve to reduce in gear #198467 27/09/2006 21:44 27/09/2006 21:44
Joined: Dec 2005 Posts: 3,158 Near Reading JohnS I need some sleep
JohnS I need some sleep Joined: Dec 2005 Posts: 3,158 Near Reading	If you don't dump air you get compressor stall - as there is negligable pressure on the turbine wheel and a load of compressed air in the intake it forces the compressor to stall. Not all dump valves work in the same way Dave, if you look at the HKS SSQV it only reacts to pressure changes and can be adjusted quite substantially to affect how it reacts to going off boost. John

Re: Removing bosch reserc valve to reduce in gear #198468 27/09/2006 21:49 27/09/2006 21:49
A Anonymous Unregistered
Anonymous Unregistered A	How, John ? I thought the SSQV was non-adjustable ?

Re: Removing bosch reserc valve to reduce in gear #198469 27/09/2006 21:55 27/09/2006 21:55
A Anonymous Unregistered
Anonymous Unregistered A	Indeed john, they are adustable, mainly to bleed off a smaller amount of air, so its inbetween no d/v and a very small one, just taking the edge off the shock wave about to hit the compressor and not removing all the air from the pipework thus reducing lag but still looking after the turbo

Re: Removing bosch reserc valve to reduce in gear #198470 27/09/2006 21:58 27/09/2006 21:58
A Anonymous Unregistered
Anonymous Unregistered A	As with most things in life its very difficult to have your cake and eat it, No D/V = no lag but the pressure on the turbo after a time can cause the thrust bearing to wear, and eventually leak oil / fail. With a d/v is laggy but a healthy turbo for many years!!

Re: Removing bosch reserc valve to reduce in gear #198471 27/09/2006 22:01 27/09/2006 22:01
A Anonymous Unregistered
Anonymous Unregistered A	I have heard that a recirculating SSQV is available but I do not know where to get one? Would this be the kindest option I wonder? Anyone know where to get one as most are atmo ones!

Re: Removing bosch reserc valve to reduce in gear #198472 27/09/2006 22:27 27/09/2006 22:27
Joined: Dec 2005 Posts: 3,158 Near Reading JohnS I need some sleep
JohnS I need some sleep Joined: Dec 2005 Posts: 3,158 Near Reading	you can buy an adapter to make it recirc. Of minor benefit but it is possible to make your recirc pipe point towards the compressor wheel so that when the dump valve opens the air is pushed over the compressor wheel to aid its continuation of spinning and to make it take marginally longer to go into vacuum. You'd need a bespoke induction pipe to achieve this. John

Re: Removing bosch reserc valve to reduce in gear #198473 27/09/2006 22:34 27/09/2006 22:34
A Anonymous Unregistered
Anonymous Unregistered A	Quote: I asked how they got around the severe strain on the engine this produces, but he didn't give me a straight answer "Well Mr Prestatyn, we get around engine fatigue issues by changing the damn engine after every rally"

Re: Removing bosch reserc valve to reduce in gear #198474 27/09/2006 22:48 27/09/2006 22:48
A Anonymous Unregistered
Anonymous Unregistered A	I'm pretty sure they frequently rebuild turbos Last edited by Nobby; 27/09/2006 22:49.

Re: Removing bosch reserc valve to reduce in gear #198475 27/09/2006 22:50 27/09/2006 22:50
Joined: Dec 2005 Posts: 19,939 North wales pinin_prestatyn Forum veteran
pinin_prestatyn Forum veteran Joined: Dec 2005 Posts: 19,939 North wales	"Thanks Mr T.Bird, however it was road cars you were reffering to in your brief and this is what I'm also reffering to. " Coopless!

Re: Removing bosch reserc valve to reduce in gear #198476 28/09/2006 02:28 28/09/2006 02:28
Joined: Dec 2005 Posts: 1,897 New Zealand Saint My life on the forum
Saint My life on the forum Joined: Dec 2005 Posts: 1,897 New Zealand	have to agree with John on this one - the lack of pressure on the exhaust turbine and the massive pressure on the comp wheel with no DV/BOV will cause the turbo to stall due to the pressure pushing back on the comp wheel. I would have thought it would take alot longer to re-spool the turbo than it would to full the plumbing with an already spinning turbo. I'm no expert so would be keen to read more if you have a link Cheers

Re: Removing bosch reserc valve to reduce in gear #198477 28/09/2006 02:42 28/09/2006 02:42
A Anonymous Unregistered
Anonymous Unregistered A	Bosch has special BOV for Porsche, that has smaller and faster opening than the VW and Audi ones, which provides less lag and quick response on gear changes. I think is to avoid early damages on the comp blades. No DV/BOV, short turbo life. Cheers Sydney

Re: Removing bosch reserc valve to reduce in gear #198478 28/09/2006 02:59 28/09/2006 02:59
Joined: Dec 2005 Posts: 1,513 Banbury stevo My life on the forum
stevo My life on the forum Joined: Dec 2005 Posts: 1,513 Banbury	Why doesn't someone just try it one day and report back on the effect. P.s. I can't because my car needs to be fixed. WRC engines have to last two race distances + shakedown mileage. 362bhp of warble

Re: Removing bosch reserc valve to reduce in gear #198479 28/09/2006 13:58 28/09/2006 13:58
A Anonymous Unregistered
Anonymous Unregistered A	So a reserc SSQV ( http://users.ox.ac.uk/~ohare/hks2_s.jpg ) would not be that benificial? My biggest problem is my in gear lag, 2nd>3rd etc. Found this: http://www.overboost.com/story.asp?id=1067 Snip: "We did a data logging run with our VAG-COM, and were initially stumped by the results: The MAF was detecting a slight drop in airflow, yet the vehicle was accelerating more quickly, and there was a huge improvement in throttle response. As it turns out, the SSQV was sealing the charge pipe so well that the MAF was indirectly showing us this because there was a smaller loss in the system; less air through the MAF means more is staying between the turbocharger and the throttle body. Additionally, with MAF intake down, the ECM was holding the throttle body to 100 percent for a longer period. (During our Injen intake install, the torque numbers we logged seemed "off" because the ECM was closing the throttle at an earlier period.) Neat-o. We can't wait to dyno this puppy." Anyone got a reserc SSQV to comment or know of where to get one cheap? I found this one so far as a kit to replace the Bosch for $275 (£146): https://935motorsports.com/catalog/produ...7daa72a1b3af7b5 Also if I remove the vacume pipe from my existing bosch style reserc valve will this be the same as running no DV? I may give it a try. Last edited by pietch; 28/09/2006 14:15.

Re: Removing bosch reserc valve to reduce in gear #198480 28/09/2006 14:52 28/09/2006 14:52
Joined: Dec 2005 Posts: 3,158 Near Reading JohnS I need some sleep
JohnS I need some sleep Joined: Dec 2005 Posts: 3,158 Near Reading	pietch - you should be able to plumb that straight in. There is a filter you have to put on the vacuum pipe (supplied with the valve) which is the only (Very slight) difference.

Re: Removing bosch reserc valve to reduce in gear #198481 28/09/2006 15:20 28/09/2006 15:20
A Anonymous Unregistered
Anonymous Unregistered A	Quote: have to agree with John on this one - the lack of pressure on the exhaust turbine and the massive pressure on the comp wheel with no DV/BOV will cause the turbo to stall due to the pressure pushing back on the comp wheel. I would have thought it would take alot longer to re-spool the turbo than it would to full the plumbing with an already spinning turbo. I'm no expert so would be keen to read more if you have a link Cheers Hi Saint, I have no links only experience, as i've said done this lots of times and the D/v always produces more lag, the compressor blades make a noise (compresser surge) but this does not stall the blades, the wrc boys dont have d/v's! Honestly, try it and you will see! Dave

Re: Removing bosch reserc valve to reduce in gear #198482 28/09/2006 15:26 28/09/2006 15:26
A Anonymous Unregistered
Anonymous Unregistered A	Quote: So a reserc SSQV ( http://users.ox.ac.uk/~ohare/hks2_s.jpg ) would not be that benificial? My biggest problem is my in gear lag, 2nd>3rd etc. Found this: http://www.overboost.com/story.asp?id=1067 Snip: "We did a data logging run with our VAG-COM, and were initially stumped by the results: The MAF was detecting a slight drop in airflow, yet the vehicle was accelerating more quickly, and there was a huge improvement in throttle response. As it turns out, the SSQV was sealing the charge pipe so well that the MAF was indirectly showing us this because there was a smaller loss in the system; less air through the MAF means more is staying between the turbocharger and the throttle body. Additionally, with MAF intake down, the ECM was holding the throttle body to 100 percent for a longer period. (During our Injen intake install, the torque numbers we logged seemed "off" because the ECM was closing the throttle at an earlier period.) Neat-o. We can't wait to dyno this puppy." Anyone got a reserc SSQV to comment or know of where to get one cheap? I found this one so far as a kit to replace the Bosch for $275 (£146): https://935motorsports.com/catalog/produ...7daa72a1b3af7b5 Also if I remove the vacume pipe from my existing bosch style reserc valve will this be the same as running no DV? I may give it a try. Hello mate, removing the pipe will not be the same DONT DO IT. You will cause a boost leak. The vac hose becomes presurised on boost, pushing the valve closed, with this hose disconnected and sealed off the boost will be able to push the valve open as it is only closed by the pressure of the return spring. This in turn will cause the turbo to spin up more as it thinks its not up to pressure, causeing turbo failure (in prolonged applications) Cheers Dave

Re: Removing bosch reserc valve to reduce in gear #198483 28/09/2006 15:32 28/09/2006 15:32
Joined: Dec 2005 Posts: 3,158 Near Reading JohnS I need some sleep
JohnS I need some sleep Joined: Dec 2005 Posts: 3,158 Near Reading	Quote: Hi Saint, I have no links only experience, as i've said done this lots of times and the D/v always produces more lag, the compressor blades make a noise (compresser surge) but this does not stall the blades, the wrc boys dont have d/v's! Honestly, try it and you will see! Dave I think what you are describing is because the dump valve stays open briefly after dumping so the pressure differential that should exist between the boost side and non-boost sides of the inlet does not exist and it consequently takes longer for the boost to build (ie. there is a delay). If you remove the dump valve then in the same period the effect of compressor stall is less. But that still just means it's because of the type of dump valve you're using. The same would apply to most vent to atmosphere dump valves. Former low boost hero - 616BHP@1.5 bar. 2.4 20VT RIP

Re: Removing bosch reserc valve to reduce in gear #198484 28/09/2006 15:40 28/09/2006 15:40
A Anonymous Unregistered
Anonymous Unregistered A	In a way yes, by "Dumping" the air you are lowering the presure in the boost circuit, this needs to be built up again after the vacuum drops back towards atmospheric pressure, hense Lag. At high revs the car is consuming a vast amount of air, this, coupled with the boost circuit being opened to the atmosphere (or intake), causes a massive drop in pressure. I can only go on experiments, and D/V's cause lag, some more than others, but only because some let out more air than others!! Baileys is a prime example big openings with dump the compressed air very quickely!! dave

Re: Removing bosch reserc valve to reduce in gear #198485 28/09/2006 20:24 28/09/2006 20:24
A Anonymous Unregistered
Anonymous Unregistered A	FTODave: So you suggesting I do away with the DV? How do I block it?My ball bearing turbo will take the surge abuse right? How is the drivewithout DV, does the car react in the usual way? Have you ever tried a SSQV reserc valve yourself? What do you run, no DV I presume? Advice appreciated.

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