Alright guys I am looking for suggestions here. I have a built automatic and my turbo is milled out to a 57 trim. My question is what BOV are you using and is it vented to the atmosphere or recirculated? Mine is vented to atmoshere and under high boost the BOV acts like it is supposed to. But under low boost the valve seems to flutter a bit and not give a solid Pssst sound. Is this normal and will it cause damage to the turbo? I was told by the local tuner shop to put all the washers in it to stiffen it up but it still does it. It is a knockoff RFL so if I broke down and bought good one would this problem go away? Thanks Keith
Calling Anyone with Turbo'd Automatic
- Thread starter toyzforme
- Start date
You have it backwards you need less spring tension for low vacuum operation, it surges when the valve isn't opening.
I use a pair of TurboSmart type 3's and run a large bore hose to them and had to cut 1/3 from the springs to cure my part throttle surge.
The large bore hose allows them to received a good supply of boost to the back of the valves to help keep them closed under boost with the light springs.
The light springs allow them to be very active off boost preventing the surge when on/off the throttle on winding roads.
I use a pair of TurboSmart type 3's and run a large bore hose to them and had to cut 1/3 from the springs to cure my part throttle surge.
The large bore hose allows them to received a good supply of boost to the back of the valves to help keep them closed under boost with the light springs.
The light springs allow them to be very active off boost preventing the surge when on/off the throttle on winding roads.
Ive never been a fan of knock off bovs or wastegates... I would buy a real one regaurdless. Tial, most greddy, HKS isn't too bad. When you say flutter is the bov fluttering or the turbo? if your getting compressor surge then adding washers or tightening it should make it worse.
FYI. even real turbo xs bov's are known to leak right out of the box.
FYI. even real turbo xs bov's are known to leak right out of the box.
If the valve is the design variety where the intercooler pipe is plumbed to one side of the piston and a vac line is plumbed to the opposite side of the piston, the boost pressure will be equal on both sides of the piston.
The spring only keeps it closed at idle and off boost circumstances. The spring is basically a preload, it should be just strong enough to keep the valve closed at idle.
If the spring is too tight it will not open, if its too loose it will stay open at idle and off boost. Though even if the spring is too loose, as long as its there it wont leak under boost.
This is because the boost pressure is on both sides of the piston. This makes the pressure differential on either side of the piston equal, leaving the spring preload as essentially the only differential of pressure keeping it closed just as if the engine was not running.
The spring only keeps it closed at idle and off boost circumstances. The spring is basically a preload, it should be just strong enough to keep the valve closed at idle.
If the spring is too tight it will not open, if its too loose it will stay open at idle and off boost. Though even if the spring is too loose, as long as its there it wont leak under boost.
This is because the boost pressure is on both sides of the piston. This makes the pressure differential on either side of the piston equal, leaving the spring preload as essentially the only differential of pressure keeping it closed just as if the engine was not running.
Judging by the 3 posts it looks like I need to remove the washers and try it from there. I didn't know about the pressure being on the other side of the valve under boost. I figured it would leak and needed to have the extra tension to keep it shut. Hmmmmm ok I will have to give this a try and see if it works when I get back from my deployment. I am counting the days as I am down to 14 left. Well if I get any BOV other than a turboxs I will have to get a flange welded on and cut the other one off. I like the Tial but I am thinking of recirculating the air back like it was suppose to be.
I have what looks like the factory BOV, which is recirculated, but I get compressor surge. Might be because I'm only running 6psi or maybe because I just need a new BOV, don't really know.
My setup is similar to yours. (built auto trans, .57 trim CT26, 7M-GTE) I use a new style HKS SSQV on the HKS steel pipe un-recirculated. I've never had any of the idle/stalling problems that some people get when running their BOV un-recirculated and my BOV always blows off. Many of the guys I know around me have used HKS BOVs with success and I've yet to hear any compressor surge with mine!
blk92suprat;1476052 said:
Yea that is what I am thinking as well and it must relate to the auto's that are turbo'd because if you think about it, most times the manual guys are getting into the higher boost so they might not hear the flutter as much. I could be wrong in my thinking as well. But I am going to try what IJ said and see what happens. Only 14 more days till I am out of this sandbox