guys my mate has a vlt with a straight gas setup and a to4e turbz. the mechanic said coz its manual it needs a bov and u cant take it off is this true?will it do much damage or he better off keeping it on? mechanic said if its auto then no prob coz in manual the throttle body closes and can stuff up the turbo? cheers ps not sure which section to post in so i did few diff ones soz

its generally a tech issue so best put it there... Turbos are pretty robust these days, sure you will hear the surge and it might flutter but unless you are pushing high boost it is likely to be ok without it - the manual factory setup doesnt have a bov and car makers wouldnt want warranty problems from a broken and expensive turbo... However, as its gas, where is the gas feed, presumably its not liquid injection but vaporised then it will get vented with a bov - do you want to do that ?

hrmmm.... this debate is old...but i dont know what to beleive i say just look at what workshop cars use, not only here.. but i'd use the JAPANESE workshops as a reference, because they DO KNOW their sh*t... but having said that im not quite sure if they use bovs hmm... go to bed niche! lol ;p

Im pretty sure turbos can generally take a fairbit of 'surging' before they give up, I mean... Dixie has had his same turbo for like 4 years isnt that right? he dose's more then anyone... ever.

Quote: Originally Posted by SXC - 747 Im pretty sure turbos can generally take a fairbit of 'surging' before they give up, I mean... Dixie has had his same turbo for like 4 years isnt that right? he dose's more then anyone... ever. yes.. but what turbo is he running (hiflow isnt it?) and how much boost is he running? comparing a T3 unit, thats been modded even, to a T04e is like chalk and cheese (well not really but u get what i mean) what about ppl with larger turbos, and running 20+ psi? does the surging matter? Some original photos have not been recovered yet.

I think he is more worried about the gas escaping to the atmosphere, rather than just air on a normal setup.

Quote: Originally Posted by pete_3178 guys my mate has a vlt with a straight gas setup and a to4e turbz. the mechanic said coz its manual it needs a bov and u cant take it off is this true?will it do much damage or he better off keeping it on? mechanic said if its auto then no prob coz in manual the throttle body closes and can stuff up the turbo? cheers ps not sure which section to post in so i did few diff ones soz Not true, it will help but is not a manditory requierment. I didn't run a BOV to start with but threw one on to remove the stress on the throttle (not for the turbo sake), so I would say leave it on if you can put up with the noise.

you can just put an extra spring on the throttle wheel thingo apparently, which will stop the throttle from sticking open, theres a few on here that have done that

I would put a plumb back BOV on. They're legal and bugger all noise.

i think he means that the throttle will open and close more on a manual then auto with gear changing, personally i think its better off having one as it doesnt backspin the turbo and eventually spinning the front nut off the turbo wheel which i have done before in a manual myself. however it is debateble if you search there will be a milliion discussions on people who like and dislike them as some people also believe its wasting energy by venting and is for rice burners only.

so when you back off an auto does the throttle body not shut? mechanic is gay, it will make no difference if he runs no fully hektik bov... Eventually it may cause damage to the turbo if running huge boost, but its no different to a standard setup... Take it off, make it dose...

I have run manuals with and without BOV's. As stated everyone has a different opinion - I personally don't think it does any harm without one on lower boost. Once the throttle closes, air in the pipes has no where to travel putting back pressure on the compressor wheel which is why the mechanic told him to run a BOV. Although during gear changes compared to an auto the throttle would be closing, I along with a lot of others are sceptical of how much of an effect this has on the compressor wheel.

Good thing about an auto is it can change gears fast with no clutches, the wonders of planetary gears @dvl Are you nuts, nuts coming off, huh ? Did you put not on, even spinning it back which is *very* unlikely as there is no sustained force as its also against flow of exhaust wont have the nut come off - they are torqued up pretty well Some original photos have not been recovered yet.

The problem he would be refering to is that as the throttle butterfly is closed, the turbo is still spinning building pressure, the excess pressure will need to port somewhere which is what a BOV is used for. Without one the pressure will vent out through the turbo causing it to surge. When it surges it will put extra pressure on the Journal and Thrust bearings causing them to wear out quicker. Not really much of an issue on ball bearing turbos. The wear it causes wouldn't really a major issue on low boost, and even the lecturer who taught us about turbos doesn't run one mainly because he prefers the compressor surge noise. If it is really that much of a concern though, and you don't want the BOV noise then get a plumb-back BOV. From what I understand they aren't really that loud at all...

The old BOV debate has been raging for years. I too have had manual setups with and without BOV's. I'm not running one with my current setup, mainly because I became skeptical as to the benefits of running one, along with the fact if just gives another place for problems to occur. I had a plumb back BOV on my old T3 setup, and it was basically silent. So if you dislike the noise they make and still want to avoid any possible damage to the turbo (however debatable), that would be the way to go.

The turbine won't actually backspin, the interia at 100K + RPM of the blades, even given their minimal mass, is too great for the pressure to overcome in that short period of time. The blades merely cavitate due to the airflow/pressure changes. I believe I saw somewhere that Niche had a turbine wheel speed sensor...if you've got a manual mate you could solve this backspin debate once and for all :P I don't have a BOV on my manual atm, was thinking about getting a plumb back though, just to add a bit more stealth-ness Some original photos have not been recovered yet.

I've heard of the air (under some conditions) acting like an incompressible fluid and putting such stress on blades that they shatter... There is some physical evidence that the blades do get scoured by reverse flow to 'some' degree However, that was 25+ years ago, in terms of what we have now that idea might be real in some isolated instances but is not applicable to the sorts of flow and pressures we are running here The turbo makers use up todate alloys, have tested turbos for surge and flow and spin and de-acceleration rate and thrust and many many tests to destruction etc etc etc They dont have any warnings or notices about having to use a BOV for any particular boost ratings for any particular engines, factory engines dont seem to come with BOVs, that should tell us a heck of a lot about the real need edit: Just to add one minor note, the BOV is more really a performance item to keep the turbine speed at max during gear changes in racing/rallying type environments and not as a protection mechanism. Some original photos have not been recovered yet.

I think quite a few cars have factory fitted BOv (pulsars,mazda's etc) and going on niche's theories of factory R&D maybe they do have some benefit. Also with the nuts coming off the turbine shaft it ,maybe a backfire might be the culprit.

Quote: Originally Posted by Darryl I think quite a few cars have factory fitted BOv (pulsars,mazda's etc) and going on niche's theories of factory R&D maybe they do have some benefit. Also with the nuts coming off the turbine shaft it ,maybe a backfire might be the culprit. Yes, the wonders of marketing by the uneducated to the badly informed And re nut *no* shouldnt come off with any backfire ever, there is this thing called torque or rather a mechanics questionable competence using a checklist. Some original photos have not been recovered yet.

Would make for an interesting dose if there was a local ignition source Some original photos have not been recovered yet.