blow off valves

The place for all technical car discussions. If you haven't already, read our Disclaimer first!

Moderator: The Mod Squad

blow off valves

Postby samlloyd » Sun Feb 24, 2008 4:30 pm

Just got a question in relation to bovs.

My car was on the dyno on friday, after getting a few things done to the motor (rb30det). The tuner says its getting heaps of compressor surge. Its a small turbo for the size of the motor; a T3/T4 .63exhaust (thats all i know at this stage :roll: )

Its got a genuine blitz sequential job on it at the moment. My tuner reckoned to run a standard type bov aswell as the one thats on there. Does anyone else do this. Would this just be because the standard ones have a lighter spring in them or something? How would a standard one be more efficient? And can i use any type of standard turbo vehicles bov?


Also having troubles with the internal wastegate not holding boost, i think the spring in it is just not quality enough. Currently 160kw at 3800rpm, then boost starts getting out of control there.

Car is still on dyno, will be on it all tomorrow.
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby IH8TEC » Sun Feb 24, 2008 4:55 pm

if your car does not have that good a vaccuum (like my car) then yeah a lighter spring helps, my bov's are slightly open at idle, but on throttle close up good. i beleive it can be a problem however if it's afm. not sure what your one is?

can you adjust your blitz one? do you run the line straight from the intake manifold? on it's own line.

and what form of boost control are you using? just the spring?
Current Rides: 1994 Hiace Custom
KTM 250sx

Previous Car: 1988 Toyota Levin 4agte
234kw atw and 12.5@183kmh
Sold to a muppit who wrecked it
Hmm
User avatar
IH8TEC
Toyspeed Member
 
Posts: 3128
Joined: Wed Nov 26, 2003 7:11 pm

Postby samlloyd » Sun Feb 24, 2008 5:03 pm

Its just had a link G3 installed, so no afm anymore. Boost control done by computer/wastegate. I think there is a Allen key type screw on the top, maybe ill try loosening it off?

I dont think it is on its own line but will check, (was installed before i bought car)
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Re: blow off valves

Postby Crucible » Sun Feb 24, 2008 6:47 pm

smithers wrote:The tuner says its getting heaps of compressor surge. Its a small turbo for the size of the motor; a T3/T4 .63exhaust (thats all i know at this stage :roll: )

Its got a genuine blitz sequential job on it at the moment. My tuner reckoned to run a standard type bov aswell as the one thats on there. Does anyone else do this. Would this just be because the standard ones have a lighter spring in them or something? How would a standard one be more efficient? And can i use any type of standard turbo vehicles bov?


ssq copies and genuine HKS ssq bovs dont vent very well....if any at all!. I had one on my car and got rid of it because it was surging quite bad. Others i know have had the same problem aswell.
User avatar
Crucible
Real Life Mechanic
 
Posts: 1438
Joined: Sun Jul 17, 2005 2:46 am
Location: Wellington

Postby samlloyd » Sun Feb 24, 2008 7:04 pm

Mines more like this, without the trumpet extension

Image

Its not like this,
Image



If i find another bov ill try swapping it and see if that helps
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby Dell'Orto » Sun Feb 24, 2008 8:57 pm

Might be that the Blitz one just can't dump enough air, they've got quite a small piston so that could be the issue.
1988 KE70 Wagon - Slowly rusting
1990 NA6 MX-5 - because reasons
2018 Ranger - Because workcar
1997 FD3S RX-7 Type R - all brap, all the time
OMG so shiny!

Quint wrote:Not just cock, large cock.
User avatar
Dell'Orto
** Moderator **
 
Posts: 17494
Joined: Tue Jul 08, 2003 5:07 am
Location: Straight out the ghetto, Lower Hutt

Re: blow off valves

Postby AJz » Mon Feb 25, 2008 12:11 am

True-No-Turbo wrote: ssq copies and genuine HKS ssq bovs dont vent very well....if any at all!. I had one on my car and got rid of it because it was surging quite bad. Others i know have had the same problem aswell.


Interesting you say that. Quite a few people recommend them as being one of the top because of the way they work. Baring in mind the genuine HKS would be of higher quality compared to the "no name" SSQV ones.

I used to run one i bought off Al @ Driven. Worked fine for me with standard boost. I got rid of it cos the noise drove me nuts after a while. Back to the factory one atm.
I had vtax :(
User avatar
AJz
Toyspeed Member
 
Posts: 3097
Joined: Sun Nov 14, 2004 2:11 am
Location: Dunners

Postby Bumpy » Mon Feb 25, 2008 5:26 pm

I have a genuine hks ssqv on my starlet, and those copies are S$%T!

I have never had any probs with mine and I've pulled it apart a couple of times over the 5 years i've had it to have a tootuu.

The only reason you'll be getting compressor surge is because the blow off valve isnt opening up enough, just find another vacuum source or get another blow off valve ...
User avatar
Bumpy
Toyspeed Member
 
Posts: 147
Joined: Thu Mar 09, 2006 9:08 pm
Location: Hamilton

Postby tsoob » Mon Feb 25, 2008 11:25 pm

i have the same blitz one on mine it is going on the dyno tomorrow arvo so will see if i have the same probs or not.
Platinum Wheels
15 Parkway Drive
Mairangi Bay
09 486 5317
WHEELS, TYRES & SUSPENSION!
www.platinumwheels.co.nz
User avatar
tsoob
Toyspeed Member
 
Posts: 3253
Joined: Tue Dec 05, 2006 7:37 pm
Location: 201.1kw on 19psi

Postby samlloyd » Tue Feb 26, 2008 7:14 am

Mines off the dyno and im picking it up today. The internal wastegate isnt working so well so boost does spike. The remedied it a bit and got the boost curve a bit flatter. But it really does need boring/external.

180rwkw at 4k though :)
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby TRD_ZERO » Wed Feb 27, 2008 8:59 pm

OK maybe its just my run of bad luck but ive had two of those blits ones they are the super sound version......they used to open up hecticly on idle and gave me bad leaks( you really notice it when you run afm). so i replaced it with a rebuilt one and it just jammed open. Thats two of the exact same bov........ so i went all out and paid top$$ for a new genuine hks ssqv as in the bottom pic and had no issues, that design is great i can definatly reccomend them.
User avatar
TRD_ZERO
Toyspeed Member
 
Posts: 1077
Joined: Sun Jul 16, 2006 12:24 pm
Location: Howick

Postby tsoob » Sat Mar 01, 2008 6:11 pm

it makes a little surge now was unsure its only if you take your foot off the gas slowly on boost but if you takt it off fast no probs.

Any luck with yours?
Platinum Wheels
15 Parkway Drive
Mairangi Bay
09 486 5317
WHEELS, TYRES & SUSPENSION!
www.platinumwheels.co.nz
User avatar
tsoob
Toyspeed Member
 
Posts: 3253
Joined: Tue Dec 05, 2006 7:37 pm
Location: 201.1kw on 19psi

Postby samlloyd » Sun Mar 02, 2008 12:04 pm

I havnt had much of a play with it. I got the internal wastegate bored out by roughly 9mm. I can hear the turbo chatter if you rev it up in neutral, with no load on the engine, but im not sure if it does it when it has some load on it and the b.o.v is actually venting.
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby escortman » Sun Mar 02, 2008 9:45 pm

do u have it set to hard? i played round wit mine 2day seems to be better now, had it set to hard
toyota supra 1996 2jzgte t64 turbonetics
Was 300hp on 10psi with stock twins, hopefully on similar boost be around 400hp

4x4 toyota blizzard offroader

widebody markII escort panelvan

RIP 13sec AE82 fxgt 4agte 5psi TD05 20g
escortman
Toyspeed Member
 
Posts: 1651
Joined: Thu Sep 29, 2005 4:14 pm
Location: West Auckland

Postby evil_si » Sun Mar 02, 2008 10:38 pm

who was your tuner? jason at infomotive?
User avatar
evil_si
Toyspeed Member
 
Posts: 2353
Joined: Sat Nov 01, 2003 6:19 pm
Location: TAURANGA, Pyes Pa

Postby samlloyd » Mon Mar 03, 2008 7:19 am

yes
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby cat007 » Mon Mar 03, 2008 11:00 am

What position is best for a BOV? Should it just be T'd into the pipe like this


Image


Or should the BOV pipe be like a Y like this


Image


That way the shock way bounces back INTO the BOV - but the air leaving the turbo has to do a 180degree turn to exit through the BOV
Or should the BOV be facing the other way, so the air leaving the turbo can go straight out the BOV
OR - does it not matter?

What are everyone's thoughts?
1:15.4 around Pukekohe
13.63 @ 169kmph at Meremere
Fastest MK3 at Suprafest 08
1G-GTE - Stinger 4424, T04B 60-1, 440cc injectors - 240rwkw @ 16psi
User avatar
cat007
Toyspeed Member
 
Posts: 3577
Joined: Sun Sep 01, 2002 7:29 pm

Postby touge rolla » Mon Mar 03, 2008 3:23 pm

I don't think it matters. Either way it's easier for air to flow through your bov than backwards through the turbo.
User avatar
touge rolla
Toyspeed Member
 
Posts: 781
Joined: Sun Jan 15, 2006 5:32 pm
Location: Wellington

Postby samlloyd » Mon Mar 03, 2008 9:32 pm

It doesnt really matter how the b.o.v is mounted, the rate at which pressure waves move is pretty quick.


just confirming this is my b.o.vImage

Do i want the top screw adjusted quite far in?
Karl Pilkington On seals - "Its between a fish and a dog."
User avatar
samlloyd
Toyspeed Member
 
Posts: 1047
Joined: Mon Feb 21, 2005 8:01 am
Location: Rotorua/gold coast/Bangkok

Postby tsoob » Tue Mar 04, 2008 9:19 am

if you screw it in it goes harder, mine is the same one
Platinum Wheels
15 Parkway Drive
Mairangi Bay
09 486 5317
WHEELS, TYRES & SUSPENSION!
www.platinumwheels.co.nz
User avatar
tsoob
Toyspeed Member
 
Posts: 3253
Joined: Tue Dec 05, 2006 7:37 pm
Location: 201.1kw on 19psi


Return to Tech Questions

Who is online

Users browsing this forum: Google [Bot] and 7 guests