10-30-2007, 09:10 PM #1
With a Stage I, is it pointless to get a BOV?
I've heard mixed things about the BOV-
Is it good for the ski? Bad for the ski? Does it help supercharger reliability, or does it just sound cool..?
10-30-2007, 10:46 PM #2
- Join Date
- Dec 2006
- Crest Hill, IL
****Below is my opinion. The BOV debate is a for/against item on this board...I am for it, and here is my reasoning why...
The BOV gets a bad wrap, but its all in how you look at it...
The above BOV setup was designed when the ceramic clutches DID NOT have metal replacements.
A BOV is designed to REDUCE, NOT PREVENT, wear on clutches...whether they are metal or ceramic...
When the motor is spinning at high RPM's, and either the throttle is closed quickly/abruptly, or if the ski becomes "unhooked" and then reenters the water (without letting off the throttle), the BOV is designed to vent excess surge of compressed air, allowing the SC wheel to gradually reduce its speed and sync up with the engine and its current rpm...
IF the SC wheel is made to abruptly change speed (no BOV), the clutches will slip (as designed) and the SC wheel will gradually slow and sync back up...
BUT this slip causes friction, and friction is heat...
Heat will transfer to the spring washers, which keep tension on the clutches. When the spring washers are heat cycled repeatedly, they loose their tension, and thus the clutches slip even more...And with slippage comes wear, with wear comes heat, etc, etc...
If they were ceramic, they would shatter eventually from becoming brittle over time of constant heat cycles...Even the metal units will slip...its better than shattering and clogging your oil passages and killing the oil pump...
Therefore, MY THEORY, a BOV reduces slipage by venting excess pressure that can cause heat cycles on the spring washer....Thus REDUCING the time between spring washer replacement...If they are not wearing/slipping as much, they are not heating up...If they are not heating up as much, the heat will not transfer to the spring washers, WHICH, keep tension on the metal clutches...etc, etc...
I have been running a BOV on my RXP...I originally installed the above BOV setup on the SC when it had 30ish hours on it...At 70 hours theclutches were changed to metal, and upon inspection, the ceramics showed signs of fatigue...HAD I NOT put a BOV on, they could have shattered at any time before that......The metal clutches were run for the next 50 hours with new spring washers. When I had a new SC wheel installed, the tension on the washers was down, but not enough to cause slippage...
I suggest getting the metal units first if you haven't swapped yet...And if you have swapped, then get a BOV and prevent heat build up to ensure you get the longest life out of those spring washers....
10-30-2007, 11:03 PM #3
that BOV acts on vaccuum, does it not? so essentially when the manifold side of the Throttle body is under vaccuum, the BOV is open/venting...
at idle, you are venting excess compressor air...
at cruise you are venting excess compressor air...
when you are in BOOST, the BOV closes and stops venting, right?
if you answered yes to all the above, then IMO... the BOV pictured above does NOTHING except for when the throttle is chopped closed
think about it.... again, hinges on the fact that the above three answers are all yes
10-30-2007, 11:14 PM #4
Wow Danny said a lot!
I say this:
10-30-2007, 11:18 PM #5
im dealing with this asshole i mean a guy in FL about an issue with a blow off valve and a boost leak! we have DINNER riding on it! hahahahahaha BET!
10-30-2007, 11:32 PM #6
10-30-2007, 11:42 PM #7
I am N/A guy myself, and Danny is correct, so is shibb except that u don't just need vacuum to open the valve. If the throttle is snapped shut at high rpm, the valve will still vent the boost. Ever mess w/ a vacuum operated fuel press regulator? Same deal here, vac=vent, no vacuum no vent untill overcoming the spring in the valve, which is harder on the clutch. This also leads me to think a bad/weak spring in a bov would cause low boost pressure as well. Wonder what Stickem's take on this is, I have a guess....stock, leave it off, rude and turbo boost, gotta have it, but then again the only s/c I have these days are greenwheel and rude, I spray everything else. (well the wife's mini is s/ced, but it don't count)
10-30-2007, 11:44 PM #8
10-31-2007, 12:03 AM #9
- Join Date
- Dec 2006
- Crest Hill, IL
Like I said, its ones own opinion...
On my custom piping I installed an adjustable unit, nothing major. I can dial in the spring rate, or swap it for a differnt spring...I noticed a MAJOR difference on its first fire that goes against the first 2 things Shibby listed...
When I fire it up on the trailer, no load, the BOV's plunger gets sucked DOWN...Which shows a vacuum is present...Wrap the throttle a fiw times, it plunges further, then pops up when throttle is released...NOW I did it in the water, with the seat open, and it reacted that same WITH a load...
BUT the forum is here to help aid in one's knowledge, and the more you know what goes on, the more you can make your own judgement...
10-31-2007, 12:34 AM #10
Well butter my ass and call me toast, goin' to crash.......
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