tial BOV spring question
 

hey guys i was wondering how i know what spring my tial 50mm BOV has in it... i recently blew a turbo and had frequent compressor surge and a loud "BARK" when fully letting off at 15psi. i'm assuming this is because i have the "piston" 9psi spring in my BOV and i need the "rotary friendly" 7psi spring since our motors pull less vacuum. mine is also streetported and pulls about 15inHg at idle.

my question is this: is there any way i can double check to make sure i have the wrong spring before i order a new one and take my BOV apart?

have you looked at the spring yet? They are color coated... Let me see if I can find the list.

edit: http://www.tialsport.com/documents/w3_tial_40_sp.pdf

there you go bud.

of course thats for a 40mm wastegate so maybe you could find the ones for the 50 or maybe they are they same :dunno:

unfortunately hondahater is confusing BOV with WG. here is the page for the BOV springs, but it looks like they're not color coded :(
http://www.tialsport.com/documents/w3_tial_bov50_sp.pdf
According to your vacuum, if the chart is right, you've got the 9psi spring. when i had the 7psi spring on my 2-rotor and ported motor, my vacuum was ~10 in/hg.

http://www.importevolution.com/defau...sort=2a&page=2

$30 just for a 7psi spring.

Jaker, Danny has the 7psi spring. You could always pull his apart to check/measure/compare/try. ;) Bill can get the springs in about 2 days.

ohhhh hahaha sorry :doh: thought you where talking about the wg.

I had a "piston " spring on one of my BOV's (I use two Tial BOV's) , I got it from a friend in a trade , I did not change the spring , I just cut off a few turns on it till it was nice and soft like the other one.

thats what i was thinking, because his opens partly at idle... do all the softer spring BOV's do that?

I have the 11psi spring on my BOV and it seems to be working just fine. At first I was getting compressor surge like crazy and I called chuck at RE, he said that he sold all of his Tial BOV with the 11psi spring in them with no problems so far. After a few days the compressor surge went away and the BOV works like its suppose to. Even though after looking at the chart I think a 9 psi spring wouldnt be a bad thing to change out to.

i think i have the 11psi spring. it compressor surges pretty bad unless i let totally off of the throttle and get it up to 25inhg vacuum. if i am running any kind of boost in the higher rpms, the BOV doesnt open fast enough to keep it from surging with a loud BARK

But remember jacob you dont want to use too soft of a spring (7 psi) in the BOV, because if do you might start leaking boost under heavy load which would essentially over spool the turbo. That will kill a turbo faster than compressor surge. Since my 11 psi spring does blow off under any positive manifold pressure and only surges alittle when I feather the pedal in vaccum, thats what makes me think a 9psi spring is right for me. Basically I dont want to leak any boost through the BOV under full throttle.

I doubt you're going to have a problem with the BOV opening under boost as long as you have even the lightest spring. The pressure on the intake tract (let's say 10psi) will always be less than the pressure in the BOV (spring pressure + boost pressure). In the case of a 7lb spring and 10psi you'll have 17psi pressure holding the valve closed. Even with a small boost pressure drop through the manifold and vac line to the BOV your pressure should always be greater in the BOV.

i cut 1.5 coils off of my BOV spring and it responds much better. i am thinking it still needs to have 1 more coil cut off, but it is much quicker to respond at lower boost and lower vacuum. however, it still barks at full load in the higher rpms

C. Ludwig I forgot about that part......then why would they sell a high psi spring at all. If the vaccum line is adding additional pressure w/ the installed spring on the BOV then everyone should be able to run a 7 psi spring (rotary/ piston). Is this correct?

I'm only theorizing. :) I would think the same thing and can't give you a good "I know exactly what I'm talking about" answer. I would suspect that you would want to balance the spring pressure with the amount of vacuum the engine can create to increase responsiveness. If the engine can create a strong vac signal you'd want to run a strong spring to help the valve close quickly at throttle tip in. You don't want the valve hanging open at cruise vac ranges. Is my guess anyway.

makes sense. Well since my 11 psi spring works good enough (but still get compressor surge occasionally on light throttle)...I think I will just step down to the 9psi spring.

You on stock ports?

Isn't a big factor of compressor surge related to turbo size (compressor trim).... usually too big of a turbo for the given engine CFM capacity at a given rpm & boost pressure? You can play around all you want with the BOV, if the turbo is too big for cruising around on low boost you will get surge, right?

No I am not

Let us know your results then. And the rest of the setup, mainly turbo size.

we're talking about compressor surge caused by the abrupt closing of the throttle plates. this is not the same as the surge caused by incorrect turbo/engine sizing.

No surge
 

No surge here with the 11psi spring in the Tial BOV.

Running a Gt40r and 17psi WG spring.

No surge...nothing...nada. Works better and faster than any other BOV I have used.

BOV is between the FMIC and the T-Body.