Compressor Surge on s14 sr20

[s15 sr20 guy]

I have a s14 sr20 and i am having a little surge problem. I am running a Sard r2d2 bov. Running my car at 7 psi everything is fine and there is little to no compressor surge. When I up my boost to 12 psi i I am getting compressor surge when i shift around the 10 psi range or higher. the compressor surge is very noticeable too. The weird thing is that my bov is still blowing off. i tried adjusting the bov softer but it didnt seem to help. do i need to set my bov to be tighter? what should i do? by the way this is my first turbo car. i also looked though alot of the threads and none of them seem to have my problem because my bov is blowing off fully but its surging to.

[jspaeth]

There is always a compromise between compressor surge, and how "easily" it blows off.

IF you tighten it, it will mean that it takes more boost and subsequent throttle let off to blow off.

If you loosen it, too much, your idle will be bad and you will run really rich, but the looser you make it, the easier it blows off.

Again, there are a ton of variables....how much boost you are at, and how quickly you let off the throttle.

A little surge under light loads isn't too bad.....if you try to make it blow off too easily, it will probably leak to easily

[s15 sr20 guy]

so if i tighten the bov will it lessen the compressor surge at higher boost levels and increase compressor surge at lower boost levels?

[jspaeth]

If you tighten the bov, you will in general have more surge.....the "break-even" point where the bov opens will be slightly higher, requiring a larger difference between manifold pressure and hot pipe pressure.

Tighten---->requires larger pressure difference to blow off.....too tight, and it won't blow off for medium amount of boost build up, leading to more surge.


Essentially, tightening it always creates more compressor surge (well, it shifts the regime where you get surge down farther to lower boost levels).


Try LOOSENING it first to eliminate surge, but you don't want to completely get rid of surge....in other words, at very light boost levels with easy throttle let off, some surge is okay...

IF you loosen too much, you aren't going to hold boost well and might have bad idle.

[s15 sr20 guy]

ok. i will losen the bov as much as i can and then adjust from there.

[tt99ol]

really you should loosen it as much as you can just so it wont leak at idle, then leave it there, thats as good as its gonna get, well loosen it all the way, then tighten it back up until it doesnt leak anymore

[s15 sr20 guy]

I have adjusted my bov every which way and nothing seems to help the compressor surge. i also took apart my bov and made sure it was working good and it is. the bov is opening all the way and blowing off hard. like i said earlier, it only surges at any boost at or above 10 psi. it still bows off hard. the thing that gets me is that i have seen cars running a higher boost then mine and they dont have compressor surge. i am only running 12 pounds of boost. the only thing that i can think of is that i am running a ball and spring manual boost controller and that may be the cause of the compressor surge. one time i rigged up a turbonetics boost controller made for an external waste gate and had it set for 10 psi and there was no compressor surge. could it be my boost controller or am i just reaching?

[garagelu]

My car actually does the same thing. I have a sard r2d2 mounted on the cold pipe. It actually surges and then blows off when you let off at partial throttle. I bet yours acts the same as mine. I dont really consider it a problem because I think it sounds completely awesome. I run a ball bearing turbo so I am not too worried about it.

My theory is if you mounted the bov on the hotside, you will get less compressor surge. Where do you have yours mounted?

[khilgers]

I had an issue with my Blitz BOV surging. I took it all apart, cleaned the piston walls, re oiled the seal, RTV'd the top back on and it has worked great from that day. It may help to take it all apart and give it a good cleaning. I bought mine used from a friend that had only around 6K miles on it, but it did help to give it a good cleaning. They are not hard to take apart, just watch out for the large spring when you take the top of. Good luck.

[s15 sr20 guy]

My bov is mounted on the cold side as well. i realized after i took it apart that i didnt take one part off so i am gonna take it aprat right now to nothing and rebuild it again and hopefully my problem will be solved.

[khilgers]

I've got mine mounted on the cold side for my S14 sr and after I cleaned the BOV my problems went away.

[tt99ol]

it actually could have something to do with the boost controller, if it bleeds out air too fast the wastegate slams shut and all the exhaust gasses spool the turbo more, where is your vaccuum source to your actuator? from the manifold?

[s15 sr20 guy]

all of my vacuum sources come from the intake manifold. i have taken my bov apart, what is the best thing to oil it with? i have a sard r2d2 bov.

[khilgers]

I just used a very small amount of 5/30 oil. Just enough to coat the cylinder walls lightly so that the piston can move freely.

[garagelu]

well I know exactly what your blow off valve is doing because I have the same one. Honestly I dont think coating it with oil will do anything. I bought mine brand new and even before I installed it, I took it apart to make sure the piston moved freely. And the problem isnt that the bov isnt releasing any air at all. It actually surges and then blows off. It kind of acts like there is too much preload on the bov but I have the screw as loose as it will go and it still does it.

I think placing the bov closer to the turbo will fix it. Try oiling the piston wall barely and see if it fixes it. I cant remember when I took mine apart if it was already prelubed. Its been a while. But if that doesnt work its either the placement of the bov or just the design of the bov.

[khilgers]

now that I think about it the SARD bov on my buddys STI swapped impreza does the same thing. It will first make the fluttering sound like compressor surge, then the woosh of the air being released. Like garagelu said, you can try moving it to the hot side, oiling it and go from there. But from my understanding you are supposed to put the BOV on the cold side of S14 SR motors.

[s15 sr20 guy]

its not the bov making the fluttering sound. it is the turbo compressor surging. the bov is clearly blowing off. it blows off and surges at virtually the same time. it will blows off and then a split second later it will surge, but it is blowing off and surging at the same time. am i making sense?

[s15 sr20 guy]

I also want to know will the surging damage my turbo. it's not horrible compressor surge because my bov is still blowing off. i just want to make sure that i dont hurt my engine or turbo in any way.

[jspaeth]

maybe if you could take a video and post that, it would help....

if it's surging when you have a lot of boost built up, that isn't good.

minor surging at small throttle inputs/letoffs isn't terrible and is practically unavoidable

[GabeS14]

The little compressor surge you are hearing, is fine....it will not damage the turbo..It mostly happenes when you release at a pressure so low that the BOV didn't even open....(too low to cause any damage).. many guys run no bov with much bigger turbos, for a few years with no prob, so if you have a stock turbo, dont worry.

I had comp surge for 2 years on the Stock T28(S14), till I upgraded the turbo, and the turbo was in almost perfect condition when I pulled it out.
I boosted about 14-17 psi all the time.
Whenever you do boost hard the majority of the air is released by the BOV so the little surge you hear, actually is very light.

[s15 sr20 guy]

i'll post a video tomorrow after i put my bov back together

[tt99ol]

try running your wastegate actuator vacuum source from a nipple on the coldpipe because once your throttle plate closes your wastegate gets 0psi or even vacuum readings and shuts completely, on the charge pipe it will only close once there is no pressure in the pipes, or after the bov lets it all out, it wont have as harsh of a boost spike either so it will feel smoother coming on to boost

[s15 sr20 guy]

here is a video: the bov is blowing off and i could hear it when i was driving but u cant hear it in the video because the compressor surge is louder.

the video is on youtube

http://youtube.com/watch?v=GmDpxmSHCHQ

[GSXRJJordan]

Doesn't sound like it's blowing off much at all. Ready for the shocker...

It has nothing to do with your BOV.
(as long as the BOV is blowing off at all, it's working. Note about the SARD: no rubber seals. It's just a metal piston against a metal wall, and gets lubricated by the small amount of oil blown through the hotpipe. On the first boost after a long period of sitting, it'll stick. Once it opens, you're in business.)

Now back to the issue: your vacuum setup. Either you've got your BOV tee'd off on some other vacuum source (like the MBC), or your manual boost controller is absorbing some of the change in pressure. MAKE SURE YOUR BOV HAS IT'S OWN VACUUM SOURCE FROM THE COLDPIPE/INTAKE MANI.

Oh, and one more thing - BB turbos are weaker than journal bearing, not stronger. That doesn't mean you've permanently damaged your S14 BB turbo - as Gabe said, many people run their turbos hard (with compressor surge) for years before it becomes a problem.

Fix your vacuum source, and your problem will go away.

/thread. That's one more Zilvia tech problem solved before breakfast :)

[jspaeth]

hhah

Yeah I agree.....although your video doesn't really show you building much boost before letting off the throttle, but either way, it doesn't sound like it's blowing off.


Your MBC in should be connected to a nipple as close to the turbo as possible, and the out should go to the wastegate nipple

Your bov nipple should run to a vacuum source in the intake mani, as previously said.

It doesn't sound right at all....I would loosen the spring and make sure you have everything set right.

Also, a video where you floor it and hold, and THEN let off would be helpful I think


Also, some people said to run the wastegate source from the coldside, and I guess that maybe this is better for MBC????......for an electronic boost controller, which can respond quickly, you are better using a boost source as close to the turbo as possible, as pressure changes coming from the turbo are picked up the CLOSER you are to the turbo

[s15 sr20 guy]

I know you cant hear the bov in the video but it is blowing off hard. remember the turbo is right in front of me and the bov is on the cold pipe side that why it cant be heard in the video. nothing is tee'd off everything has its own source. the bov source is the manifold, and the MBC source is the nipple on the intercooler. does the surge sound bad and should it be something i worry about?

[jspaeth]

i mean your turbo isn't just going to all of a sudden blow up, but over time it adds wear on the turbo....try to reduce it

[GabeS14]

I dont think it sounded bad at all man...
Mine sounds like a lazer...almost like i had a giant turbo on a supra!(exageration:eek: ) but something like that

so yea, yours is minimal!

[McRussellPants]

Oh, and one more thing - BB turbos are weaker than journal bearing, not stronger.


BB turbos don't have the same issues with surge.


I don't see surge as an issue, this isn't the stone age, half the people rabbling about surge read it out of SCC who read it out of Maximum Boost which was written in the 70s.


Fucking Buzz words.

[jspaeth]

^ I'm sure you are right, but it OBVIOUSLY isn't great for the turbo to have a force acting on it suddenly trying to make it move in the opposite direction

[s15 sr20 guy]

earlier today i put on a different MBC and it did not solve the problem, so we can eliminate the MBC as a possible cause. i am guessing i needt to try a different type of BOV. so i am gonna try to borrow one from someone because i dont want to spend $200 on one if it wont fix the problem. before i do that i will try is recirculating the BOV to see if that makes a difference. i have a hose that fits around the bov and all i need is a reducer to put it back to my intake. i am hoping recirculating it will fix the problem since it is the cheapest fix

[garagelu]

Are you not listening to everyone thats posting on this thread?

First of all the boost controller has absolutely nothing to do with this situation. Second, recirculating the bov will do absolutely nothing also. Third, a different bov will fix it. If you want absolutely no compressor surge, go with a hks ssqv. They have two valves that work pretty well.

You know, me and two other people have already told you that the r2d2 bov acts the same as yours. So does it not make sense to you that its not anything else but the bov. Why would you think to recirculate or check the boost controller.

Here are really the only choices you have. Try to lube the inner piston wall of the bov, change the location of the bov closer to the turbo, or get another bov. And like I said before compressor surge doesnt hurt BB turbos that bad. Journal bearing turbos get messed up from it the most. As long as the bov is releasing air, there is nothing to worry about. Its blowing off so its doing its job. If you are so worried about it, just sell your r2d2 and buy another bov.

[sbanzer123]

i sort of have the same problem with my s14. i have a s14 sr20 with a tial bov. as you know there is no way of adjusting the tial, besides swapping out springs. my bov will go off everytime, but the more pressure i make or the faster i shift and get back on the throttle the less surge there is. i have my bov ran on its own seperate line off the throttle body, my boost gauge is t'd off of the fuel pressure regulator, and my wastegate is on its own seperate line off the hotpipe.

[s15 sr20 guy]

I have been listening to everyone and i have been doing everything that people have been suggesting to me, but you have to understand that i want to try everything possible before spending $200-$300 on a new BOV. I have been talking to other people about my issues as well and they have suggested recirculating the bov which i will gladly try because it cant hurt anything. trying other things wont hurt anything but i will try a new bov and see how that goes.

[s15 sr20 guy]

i sort of have the same problem with my s14. i have a s14 sr20 with a tial bov. as you know there is no way of adjusting the tial, besides swapping out springs. my bov will go off everytime, but the more pressure i make or the faster i shift and get back on the throttle the less surge there is. i have my bov ran on its own seperate line off the throttle body, my boost gauge is t'd off of the fuel pressure regulator, and my wastegate is on its own seperate line off the hotpipe.

thats how mine is except i am on the cold pipe.

[garagelu]

I can guarantee that recirculating the bov will do absolutely nothing for you. It will be even worse because you wont be able to hear the bov and all you will hear is the surging. Plus good luck running a hose all the way from the cold pipe over to the intake. And please try to understand the concept of recirculating the bov. Once you understand you will figure out that it has nothing to do with compressor surge. And yes it cant hurt anything but if you want to fix the problem, you are just wasting your time and energy.

And how are you spending 200-300 dollars on a bov. Go buy a used hks ssqv for around 100-130 dollars. You should be able to sell the sard for 100-130 or even return the r2d2 if you bought it new.

I have run my r2d2 on my 2871r for over a year and my turbo is still perfect.

[johngriff]

I didn't read the whole thread, just the first post.

That BOV is garbage can material.

Wrecked a friend new 50 trim in about 75 miles.

I am sure the damage is less on a stock turbo, but it makes sense that once you let the turbo create more volume, it cannot vent it, HENCE FORTH, creating surge.

So get a better blow off valve.

[s15 sr20 guy]

i am looking for a hks ssqv bov now. hopefully i will find one for a good deal.

[McRussellPants]

^ I'm sure you are right, but it OBVIOUSLY isn't great for the turbo to have a force acting on it suddenly trying to make it move in the opposite direction

lol.

turbos don't just flip it and reverse it. Turbos are not missy elliot.



you get small boost spikes.

interestingly enough, you get the same first spike with a blowoff valve.

without the bov you just get little tremors and it doesn't bleed boost as quickly.

[GSXRJJordan]

^^^ Yup. McRuss esta correctamente otra vez.

I don't agree that the R2D2 is trash, as John so elegantly put it, but I will say that for what a BOV does (vent boost in an efficient manner), the SSQV is technologically superior. I just hate the sound, and for the most part, it's all the same to my 'stock' turbo.

[jspaeth]

^^ I understand they don't just change direction hahahah....that would be kind of hard for something to go from 100000 RPM to 0 in a tenth of a second

I was just saying that clearly with the BOV not opening, it puts more backpressure on the compressor wheel

[sbanzer123]

I didn't read the whole thread, just the first post.

That BOV is garbage can material.

Wrecked a friend new 50 trim in about 75 miles.

I am sure the damage is less on a stock turbo, but it makes sense that once you let the turbo create more volume, it cannot vent it, HENCE FORTH, creating surge.

So get a better blow off valve.

i am having the same problem with my tial as i said above. and i know thats not a garbage bov and yes it is genuine, i ordered it from full-race. i was thinking of putting some washers on top of the spring on mine to preload it and see if that helps at all, this would be the same thing as loosening a adjustable one.

[Matej]

I thought compressor surge was cool. :aw:
http://www.zilvia.net/f/showthread.php?t=162024&highlight=compressor+surge

[GSXRJJordan]

i am having the same problem with my tial as i said above. and i know thats not a garbage bov and yes it is genuine, i ordered it from full-race. i was thinking of putting some washers on top of the spring on mine to preload it and see if that helps at all, this would be the same thing as loosening a adjustable one.

Pre-loading the spring will actually make it take MORE change in vacuum to get it to open, not less. Order up the spring set, and try the softer spring; most likely, you'll go back to the suggested spring and learn to live with a little compressor surge. And like Matej says... its cool =P

[sbanzer123]

i dont really mind it too much i was just adding my .02

[johngriff]

Well I like to shit can stuff as soon as it breaks things 3 times its cost.

Like afc's.

But just by looking at the R2D2 valve, its just too small for larger serious setups. I like the HKS in THEORY, BUT, it wears after about 2 years of regular use, since the internals are made of plastic.

Or you could go twin or triple bov!! Three R2D2 valves, just add more until you dont have surge.

And yes, the tial is a tricky SOB.

[s15 sr20 guy]

What is a bigger bov that would help eliminate compressor surge besides a hks ssqv. would a greddy bov be better than my sard r2d2

[GSXRJJordan]

I don't understand why everyone thinks they need bigger BOVs. Bigger valve means they can blow off more air, true, but at the expense of response time. The first boost spike (as soon as the throttle plate closes, before there's much vacuum change) is the most harmful - you're going to get that regardless. The only reason you'd need a bigger BOV (like a Greddy type R/etc) is if you had a bigger turbo pushing a ridiculous amount of air - and all the big turbos have anti-compressor-surge housings.

[s15 sr20 guy]

ok....i didnt know that, this is my first turbo vehicle. so if i am understanding you correctly getting a greddy rs bov will help surge but will hurt response. sorry if i sound like a slow idiot but i am with this turbo stuff. my last car was an all motor honda.

[garagelu]

no he is talking about the greddy type r bov not the type rs. The type r bov will hurt response because it is designed to move a lot of air for high horsepower cars that run more than 25-30 psi. The type rs would be another good candidate for a bov. Basically what everyone is trying to tell you is that if you arnt happy with the r2d2 just buy another one. Pick one and stick with it. All bov basically do the same thing, just two different designs...push type and pull type.

And also I disagree with johngriff about the r2d2 being too small for larger setups. I used to have a blitz DD and I have taken apart both. Both are basically the same design and same component with a different housing. The spring size and rate and the piston size are both about the same. But really I dont know what you consider a larger setup. If I was pushing a big turbo with 30+ psi of course I would run a greddy type r or a tial.

[s15 sr20 guy]

thanks that was very helpful and informative

[Koopa Troopa]

no he is talking about the greddy type r bov not the type rs. The type r bov will hurt response because it is designed to move a lot of air for high horsepower cars that run more than 25-30 psi. The type rs would be another good candidate for a bov. Basically what everyone is trying to tell you is that if you arnt happy with the r2d2 just buy another one. Pick one and stick with it. All bov basically do the same thing, just two different designs...push type and pull type.

And also I disagree with johngriff about the r2d2 being too small for larger setups. I used to have a blitz DD and I have taken apart both. Both are basically the same design and same component with a different housing. The spring size and rate and the piston size are both about the same. But really I dont know what you consider a larger setup. If I was pushing a big turbo with 30+ psi of course I would run a greddy type r or a tial.

Uh, I have a Greddy Type R and I have tightened it down quiet a bit and it has no problem opening with .5kg on a T04S....

My friend tightened his Type R down so much the screw snapped and it still opens with stock turbos and boost on his GTR...

I also know plenty of people who are very happy with their Type R's on close to stock motors.

[johngriff]

Yeah, a larger bov isn't going to hurt response.

Because both valve's will close when pressure is equalized between the intake manifold and the charge pipe, and open when there is a difference.

Oh and blitz DD? AYFK?! I am not fond of the smaller valves that force the air to make a 90 to vent. I like the tial, and the PWR which I sell:
http://www.rpsport.net/c=tcbai3h4ecT3PmZi8qTw48WNO/product/RPS-PWR-BOV/PWR_Blow_Off_Valve.html

If you look at the exploded view, you can see that air exits from all sides at a variant rate based on the cut in the body, allowing varying amounts of air to be released as equality is realized. The reaction time on this and the tial valve is fast because it does not need to open as much to vent the same amount of air as the smaller 90deg valves.

[SoSideways]

Uh, I have a Greddy Type R and I have tightened it down quiet a bit and it has no problem opening with .5kg on a T04S....

My friend tightened his Type R down so much the screw snapped and it still opens with stock turbos and boost on his GTR...

I also know plenty of people who are very happy with their Type R's on close to stock motors.

I'm one of those guys that are running a Greddy Type R w/ a close to stock motor.

Stock T25 finally blew up on my yesterday. Oil seal is gone, giving me the infamous 007 smoke screen.

However, I highly doubt it was my BOV's fault that my craptastic T25 blew up.

[garagelu]

I never said the greddy type r would ever have problems opening on stock boost or stock turbo. I just said its designed for bigger setups due to the larger body and stiffer spring.

And I disagree about running the type r on stock setups. If the spring is designed be say a 14 psi spring, then 7 psi will open it up at a slower rate resulting in slower release of the pressure. And of course stock boost will open the bov, but like I said it will be at a slower rate. I think there are cheaper and better bov when running stock boost.

And honestly why is everyone making such a big deal about which bov is best. Choosing one bov over another isn't going to make a significant difference in horsepower or even response gain. And given that bov like the greddy, sard, or blitz moves air at a 90 degree angle, the air is being pushed out at such a fast rate that the radius wouldnt affect it much at all.