R32 Gtr Blocking Of Blow Off Valves

[DS-ZILR]

Gday crew im crap at searching and only found people making a mock of the subject so i have to ask. What are the bad and good points of blocking them off. im sick of me dumb mates doin it and saying its awesome and then the other mates trying to be technical heroes and saying its bad but never saying why cause they dont know. could anyone tell me why you would do it and for what gain? where i stand at the moment it seems people only do it to make the flutter but also that it isn't to bad for your turbos.

please help and sorry for bringin up an age old question. if someone wants to post me a link to somewhere that tells me then we could consider this post done and would make it quick and easy.

cheers again crew

Dion

[Shaun]

Im not sure why you'd block them off. Ive heard of compressor wheels flying off due to the reversion created by doing such a thing. One of the nuts that holds the wheel on actually went throught the windscreen of another car like a bullet. This was on a 1500HP drag car though.

BOV's are there so that when the throttle snaps shut during a gear change (and the compressor wheel is still spinning and forcing air into the plenum), the excess air can vent out the blow off valve. It typically goes back into the inlet before the turbo (plumb back BOV), but the highly audible ones vent to atmoshpere (illegal).

Hope that helps. Your dumb mates are as you say, dumb.

Shaun.

[R31Nismoid]

Its simple with GTR's

GTR BOV's leak @ idle/low RPM, they are not fully shut.

This is to lessen/avoid compressor surge, its not really noticeable with stock turbos, although with larger ones (HKS2530 etc) it seems to rear its head a reasonable amount. (i have heard it like... once with stock turbos, so not often)

Blocking them therefore = no leak. This has two issues.

1. Idle & return to idle is affected, the car potentially will stall when 'clutching in' after a big of a rip through the RPM if you dont engage the next gear

&

2. Comp sure (as mentioned earlier)

As for the rest of the arguments you'll read, it goes both ways and people will never see eye to eye - but the above is the technical points, for GTR/RB26 only.

[Rekin]

Its simple with GTR's

GTR BOV's leak @ idle/low RPM, they are not fully shut.

This is to lessen/avoid compressor surge, its not really noticeable with stock turbos, although with larger ones (HKS2530 etc) it seems to rear its head a reasonable amount. (i have heard it like... once with stock turbos, so not often)

Blocking them therefore = no leak. This has two issues.

1. Idle & return to idle is affected, the car potentially will stall when 'clutching in' after a big of a rip through the RPM if you dont engage the next gear

&

2. Comp sure (as mentioned earlier)

As for the rest of the arguments you'll read, it goes both ways and people will never see eye to eye - but the above is the technical points, for GTR/RB26 only.

so this means my newly installed gtr bov still leaks with my 2530?

[R31Nismoid]

i think the stocker gts-t does too?

i was just talking GTR tho, thats all he asked about, as if you apply to other cars, im not sure

[R31Nismoid]

Not that it would matter anyhow, its plumb-back. there is no drama there

[DS-ZILR]

Its simple with GTR's

GTR BOV's leak @ idle/low RPM, they are not fully shut.

This is to lessen/avoid compressor surge, its not really noticeable with stock turbos, although with larger ones (HKS2530 etc) it seems to rear its head a reasonable amount. (i have heard it like... once with stock turbos, so not often)

Blocking them therefore = no leak. This has two issues.

1. Idle & return to idle is affected, the car potentially will stall when 'clutching in' after a big of a rip through the RPM if you dont engage the next gear

&

2. Comp sure (as mentioned earlier)

As for the rest of the arguments you'll read, it goes both ways and people will never see eye to eye - but the above is the technical points, for GTR/RB26 only.

thats awesome info cheers mate. i am having a problem with my car venting on acceleration. i cant find any split pipes or leaking connection but i haven't had a great look down the turbo side of the engine yet. i have high idle about 1500rpm bugger all power and it surges when i put the boot into it and sounds like its doseing all the time where it should be boosting. any particular area i should be looking into? AFM not working? Vacuum lines (so far cant find any)? this is why i was trying to block off my blow off valves just to see if i am getting any leak by throuhg them.

cheers

Dion

[_K1NGTR_]

Mine have been totally blocked for some time now idle is 100% ok it don't stall it dun run shit it runs 100% fine nothing wrong with blocking them off you get less noise and have noticed no change in my dyno sheet man your fine to block them off.

[TTT]

less noise?

[DS-ZILR]

i would have thought there would be more noise.

[paulr33]

http://www.skylinesaustralia.com/forums/Bo....html&st=20

page 2 onwards

[joeyjoejoejuniorshabadoo]

i think the stocker gts-t does too?

i was just talking GTR tho, thats all he asked about, as if you apply to other cars, im not sure

the stock skyline bov's have a tiny hole in them to bleed a little and keep boost linear that you can block off... i did this a year ago and it works fine.

there's a thread round here somewhere

[MrStabby]

BOVs allow the turbo to spin more freely after the throttle snaps shut during a gear change, so when you snap the throttle open again for next gear you will be on boost quicker. If you block it off the pressure build up between the shut throttle and the compressor will slow the turbo down considerably.

So, blocking off BOVs is for posers. If you don't have homosexual tendencies, and prefer to go fast, leave it as it is.

[DS-ZILR]

i blocked em off yesterday to see if thats where i was getting my boost leak but its not and yes it ran like shit and yes it took ages to recover from a reving back to idle and nearly stalled whenever i came off the gas and clutched in. i really see no advantage at all from doing that and if it keeps ya turbo spinning to have it on there then ardvark blockin it off.

really makes no sense at all to block them dont know why people do it. (GTR only not assuming its bad on everything)

thanks for everyones input

catch

Dion