evopowned

iTrader: (3)

I have an 03 evo and believe im getting compressor surge and don't really know how to stop it but it only happens when half throttle. example if im getting on the freeway cruising not giving much gas and start to boost like five pounds of boost steadily the car will start to flutter (bov)? flutters like crazy and will get worse until i either let off the gas or give it more gas. bov does not flutter under high boost (32psi) and as long as i dont half it steadily it doesn't do it which is a pain for city driving. but ive tried putting different springs in the bov tried low 14-18psi spring and also tried high 28+ spring now running 20-28 psi spring. it is a forge recirculating bov. and i just dono what else to try? or if my bov is even the problem? i just know its horrible on the life of my turbo anyone have any suggestions i could try?
ps ( my filter has oil on the back of it guessing from the compressor surge )
incase matters.
turbo mods:
fp green
forge bov
injen piping and intercooler
hks filter

(car is built for 32 psi no worries)
anyways car performes great when giving it gas but she does not like to go slow haha Thanks for any input im gonna keep searching for similar issues

sktng22

iTrader: (3)

my car does this too. ive learned to deal with it and just full throttle everywhere or barely any throttle lol

EvoJoeRacing

iTrader: (2)

Your Blow off Valve is too stiff... Which forge bov is it? The type rs or the non adjustable on?

sktng22

iTrader: (3)

o wait what filter has oil on the back of it? wtf? are your seals going bad in the turbo?

EvoJoeRacing

iTrader: (2)

Just reread your OP... If you build boost up to 20lbs or so and slowly back off the gas and let your PSI slowly drop... what PSI does the flutter begin?

evopowned

iTrader: (3)

hahaha fair enough

evopowned

iTrader: (3)

its a FMDVEVO15 closed loop dump valve. i tried the low psi springs and still get the same issue

evopowned

iTrader: (3)

dont want to think about that part haha its not much and herd theres always a little oil in your intake on turbo cars? very little oil

evopowned

iTrader: (3)

it doesnt when im letting boost out. only if i slowly building boost up and lets say try to hold steady at a low boost. doesnt flutter at max boost and doesnt when increasing boost only until boost gets steady in mid range does it flutter. so say pushing on gas 4th gear just to slowly speed up boost will start to build tell your not giving enough gas to boost more and boost starts to stabilize. thats when it starts to flutter if that makes sense? was talking to someone ounce and we think it has something to do with the oposite pressures on the valve? from the pressurized side to the no pressurized side its unstable? causes it to flutter but dono why its unstable? tried the four different springs and had same result with all didnt try the 8-14psi spring cause i dont see how that could hold my valve cloosed under 32psi? dont want to over work my turbo which i might be already

EvoJoeRacing

iTrader: (2)

The cause of this occurance is simply a pressure differential at certain partial throttle situations. You are reaching a point at which there is pressure in the charge piping, however there is still vacuum in the intake manifold, which will pull the valve open via the vacuum line reference to the top of the valve. While it may not appear so at the time it occurs, this is actually a positive attribute of the valve's operation indicating that it is reponding properly to changes in pressure and vacuum.

The OEM Evo valves, however, have a small channel or rib up the back side of the valve that serves to create a small internal leak within the valve body. This serves to dampen the valve's operation at such partial throttle conditions. It actually limits the valves ability to respond to changes in pressure and vacuum, which is why this "problem" doesn't occur with the OEM valve. The issue, though, is that this small deliberately incorporated leak also severely limits the valve's boost holding capability, which is the main reason for swapping it for an aftermarket valve.


I have a Forge Type RS Diverter valve and i do get surge like that but it is not violent. I only get it up to about 8psi or so. If you are surging anything higher then that your spring is to stiff and you should soften it. You will not eliminate the surge but will reduce the PSI at which it happens. I would say i only feel it between 5 - 8 psi. And honestly is a rare occasion for me since when i cruise in 5th gear i am at atmosphere (0psi / 0 vacuum) and if i get on the gas i usually boost around 14-15psi.

I have a Tomei Arms 7960 which is comparable to your green and my peak boost is about 32-33psi

evopowned

iTrader: (3)

Nice info! good to know my bov is doing what is suppose to then maybe i do need to put a lower spring in just worries me on pushing such high boost cant tell if its holding pressure well sense turbo is so loud as is. what spring do you have in yours? i believe all forge springs are same? i have the blue one in mine right now if i remember right think its rated 22-28psi been ahwile sense i looked at the specs

EvoJoeRacing

iTrader: (2)

When you put a softer spring in it just keep an eye on your boost gauge. Make sure that you are still hitting your peak boost that you were with the stiffer spring.

I have the Type RS DV which has the twist top on it so I can adjust my spring by just turning the top.

Ian0611

iTrader: (41)

What boost controller and wastegate are you running? I'm dealing with a similar issue with my Synapse and my stock WGA but I think the problem is that my WGA is at the end of it's rope it's not playing nicely with the Grimmspeed 3 port.