Legion_2

So after all this time, I finally replace the RFL BOV on my car because I was worried about attracting too much attention. I replaced it with a TiAL BOV, which I'm assuming came with an 11 or 12lb spring.

And now I have slight compressor surge ("slight" meaning at low boost, or when I slowly let off the pedal during boost). The RFL was slightly open at idle, and the Tial is firmly closed at idle (but doesn't take much effort from one finger to open it), so that's the difference. I'm sure with a 9lb spring the TiAL would be wide open at idle.

So now I'm wondering, is this slight surge harmful in any way? I hate the sound it makes, but I was thinking it might actually be beneficial under partial load, because less air is being "wasted" so to speak.

Input? Should I go to the 9lb spring?

19slocivic97

First i"ll give you the old HT lecture......SEARCH!!!(haha)

Second i have the same problem and when i searched i found from posts that its not surge, its just a slight compressor "back pedeling" and that it shouldnt be harmfull to turbo.
Hope this helps

Legion_2

Well I sure as hell wouldn't want the compressor to "back peddle," that would imply that it instantaneously stops spinning and reverses direction between shifts. I'm sure the vanes would all break off if that were the case. Not to mention the lag it would induce after each shift.

And semantics aside, we all know what surge is - a shockwave of air pressure reverberating between the compressor and throttle plate. I'm just wondering if it's harmful or beneficial. And searching revealed surprisingly little intelligent response on the matter.

Boosted_B_Series

You need to size the spring correctly, how much vacuum are you pulling at idle?

Do you have a newer tial q 50mm or a older tial 50mm?

Match up the spring accordingly to your vacuum using tial's charts on their website.

My Q is slightly open at idle.

Also make sure you have a large diameter vacuum line hooked up to a non restrictive fitting.

Legion_2

A large diameter line actually slows the response time, as there is a larger volume of air to remove from the vacuum space to raise the piston. And the question isn't whether I have the proper spring... Rather, it's whether the current situation has positive or negative effects on performance.

Is this place really so devoid of knowledge these days? Where the hell did everyone go? 5 years ago, this thread would have been one page 2 by now. Anyone out there know anything about turbo theory? Heck, anyone just willing to throw around some terminology and sound knowledgeable? Like maybe something about the venturi effect, or laminar flow?

Geez, this place is a wasteland. Who here actually knows about cars? More specifically, who has data collected from empirical testing, as opposed to simply regurgitating info that they've read from the archives? I'm looking to pick the brain of say, someone like TheShodan (if he's still here) as opposed to say... someone like Tony413.

If everything you know about cars you've learned here on h-t, don't bother responding, because that only makes you as useful as the search button.

Turbo-LS

iTrader: (4)

Well if you have all the answers then why are you asking for help smartass, the guy was helping you out.

YES its bad for the turbo plain and simple, how much its doing is how bad it is. theres your answer, now appologize to the nice man that was giving great advice LOL

LastGenEK

Look at your question? what th hell would you like someone to say to you that you already dont know!!!

Boosted_B_Series

We'll lets applause for a snot nose little *****. I'm trying to help you out you need not let your arrogance get away from you. I wouldn't have came in here and asked such a stupid ignorant question to begin with nor would I have wanted to waste everyone's time before I yanked out a silly question.

Sounds like someone likes to read and actually knows jack ****. Who are you trying to impress, guys that build hondas?

If you knew the people you obviously want to blow; obviously you'd know how to get a hold of them to ask your brilliant question.

Get a grip little tike.
dk

HiProfile

Maybe by a fraction of a millisecond, but not enough to outweigh the negative effects a small line will cause. When you've seen boost gauges bounce around like on a scifi movie while the MAP reads a steady PSI, you'll understand. You'd have a slower response with a large-plenum manifold than you would by doubling the line's diameter, think about it. Also, each accessory should have its own vac source, thats another big issue with parts that require 'clean' vacuum.

Legion_2

I"m not being a smartass, I'm simply stating in advance that I'm not interested in retarded responses. I'm looking for educated input. I'm optimistically hoping for a technical thread in this era of tech devoid, archival regurgitation which has become the FI forum.


It's not exactly a "yes or no" type of question; I'm looking to discuss the theory behind the subject at hand. Saying "YES it's bad, plain and simple" is an outrageous, unfounded claim with no empirical evidence to back it up, therefore your answer doesn't exactly help me.


I would like to know if the benefits of my scenario outweigh the cons. Benefits: a higher instantaneous volume of air available to enter the IM, once the throttle plate re-opens after shifting. Cons: reverberating shockwave puts backpressure on the compressor, possibly decreasing the turbo RPMs and promoting a "falling out" of boost between shifts.


And yet, you've provided no insight to help in my quest for answers. How about this: THANK YOU for stating that TiAL has different springs available for their BOVs, depending on the vac pressure you pull at idle. I appreciate the response, however, as indicated in my original post, I'm aware of the repercussions of swapping higher/lower pressure springs.


?


Sorry grandpa, I didn't realize that being 3 months your junior made me such a young, ignorant child. Again, for the sake of diplomacy, thanks for your input. Now since you've already blown your intellectual load, how about you stand aside and let someone else voice their opinion.

Legion_2

That does make sense. I've also wondered how much the walls of the vacuum line collapse under full vacuum, as vacuum tubing is simply non-reinforced rubber. I think the vac line for my BOV is actually a windshield-washer fluid line, or some other such Pep Boys Chinese made crap that isn't meant to endure high pressure or vacuum.

As for my IM, I do have a giant plenum, but I have every vac source tapped directly into the plenum. So the BOV line goes directly to a nipple on the plenum.

HiProfile

A vac manifold as you described counts as individual vac sources, as long as the main feed is big enough. I usually use thick-walled fuel line as vac hoses, and its never collapsed enough to see.

BTW real washer fluid line will be PVC, as the methanol in the fluid breaks down most rubbers (both syn & non-synthetic), so I doubt its that stuff. Most smaller 1/8 or 1/4" rubber hoses can take 25 Hg" of vacuum, although Hondas can pull quite a lot at higher-rpm decel. I've never seen issues with 1/4" ID lines, and my boost gauge is responsive enough with the 1/8" OD nylon crap.

TiAL

not hurting anything

yes size makes a difference

Legion_2

Ironically enough, the lame freeware tuning software I use goes out of range when I do what you've described and it throws a CEL. So every time I decel in 5th at 75+mph I have to turn off the engine and crank it back over to clear the phantom CEL. This is with an old-school version of Uberdata BTW.



What exactly is the fluttering noise? Is the BOV itself fluttering open and closed, or is the sound coming from the compressor? And do you suppose this surging backpressure will slow down the turbo between shifts? I have enough problems already with falling out of boost beetween shifts, as I'm comically far from where I should be when I view the compressor maps for my SC50. The last thing I want is to make the re-spool issue worse with the new BOV setup.

Tony the Tiger

The fluttering is indeed coming from the compressor, but the surging is so light that the air just bounces back and forth and leaks through the compressor blades. You will notice the compressor wheel still spins freely while it is lightly surging.

The worse form of surging is running the turbo past the surge line. A BOV related surge only occurs at a brief moment, and it is also the time when exhaust gases slow down, throttle is closed, therefore, nothing is pushing the turbo to go further. On the other hand, running a turbo under surging conditions is forcing the compressor with air going opposite directions as well as the turbine accelerating at full speed. I've seen turbos running on malfunctioning BOV's (meaning stuck closed), and these turbos lasts for years anyway. BOV related surging is so minor, so I won't even worry about the slight surging from low boost/0-vac.

Legion_2

Got it. Thanks for the reply!