as a blow off valve is operated by the neg. pressure drawing open the valve - or more accuratly is allowed to be pushed open by the boost pressure contained before the throttle butterfly. wouldnt it make sense to have the spring in the blow off valve rather low - requiring less vacuum to open it...thusly any time the throttle is closed the valve opens and as soon as pressure is introduced reducing the vacuum it closes and remains closed until it goes again to a state of vacuum. as stated earlier the vacuum i'm getting at idle and really anytime i take my foot off the gas is in the 20 range . because a supercharger produces pressure linearly rather than a turbo which can quickly spike a high pressure and upon shutting the butterfly would have more momentary pressure in the '' before throttle '' plumbing so it could open a rather stiff spring valve mine is only producing the pressure corresponding to the rpm and upon shutting down (even with the vacuum assist) it has a hard time opening the valve - which is causing cavitation between the blower and throttle butterfly - no where to go ! any real downside to lowering the spring tension in my blow off so it opens....after all it will slam shut at the first sight of pressure - even neg. 10 lb

 

You are the first Integra owner I've met that actually has the Vortech system.

I didn't quite understand your post. What's wrong with the current spring tension? You said it's "hard to open the valve", perhaps you could clarify whether this is after throttle lift-off at redline or lower?

I'm no expert on F/I but here's my stab at it. A less stiff spring will mean the valve won't close shut as quickly once you get back on throttle. I'm not positive on this next statement but I'm almost certain you need a stiffer BOV spring to run higher boost levels (to prevent yourself from "leaking" boost).

You'd get a better/faster response on Honda-tech's F/I forum, but the last time I posted a topic with "Vortech" in the title, all the replies I received were "you should've gone with turbo centrifugal chargers suck etc.".

Shingo

ps. Any times or numbers? How do you like the system? I had my eyes set on the Vortech Supercharger + Si aftercooler but decided to wait out this little recession we're having and set aside my funds for post-graduation needs.

 

well i can't speak on turbo's , but this thing kicks ass. i got the std. vortech and complemented it with a payn tech 8 rib belt/pulleys which eliminate pwr steering and A/C. the system not only eliminates extra drag but tom payn uses a 'big to big' pulley ratio to achieve any boost you want , but does so with less rolling resistance (plus the pulley's - including crank - is aluminum) anyway back to the question at hand....and thanks for responding by the way...i don't seem to be taken so seriously here......my tial blow off was not seeming to open at anything less than a full boost shut down (around 12 lbs.) mid throttle and idle would seem as it should open....it's got 21 lbs. vacuum behind the valve with about 1 lb. pushing it to open - it should open. i agree with you the stiffer spring would definetly give better response getting back on throttle. over the weekend it seemed to work perfectly - don't ask me why - i tightened the belt to assure no slippage and removed the valve...looked it over..reinstalled it - very carefull with rubber 0 ring...hooked it to manifold pressure and it seems to be perfect (of course this after i ordered a lighter spring , but i'll just return it un-opened) i'll put up some pics of a seriouse combat ride as soon as i get a few mor details done. the vortech is plumbed through two small saab intercoolers with nitrouse injected in a very small qty. mostly to super cool the intercoolers - and a matching fuel addition to the manifold by tiny jets hooked to the same trigger as the nos.

 

A soft BOV spring will leak or flutter.

 

well it opens fine now that i'm getting good boost but at constant throttle(freeway)it does flutter. tial says it has thier stiff spring 11 lbs. i'm just sending back the other lighter one - i over reacted.
thanks guys

 

Took me a long time to find some good doco on BOV's to tune mine properly.. I will share it with you..
At idle, if you feel a slight breeze coming out of it, then it needs to be tightened till you dont feel a slight breeze... At 2k rpms, if you feel a slight breeze coming from it, tighten 1-2 whole turns more..
If its the opposite and you dont feel no breeze both times.. loosin the shit until you do and tighten slowly until it stops.
Thats all folks.

now for some bad advice:
always run from the cops.

 

Given the inherent nature of supercharging, I don't see why it would ever open. I've often wondered why supercharger setups started using BOV's? I really don't see how they serve any useful purpose? I'd say, if it's not opening, that's probably a good thing. Someone correct me if I'm talking out of my ass here.

 

I asked the same question.. Ever hear a toilet flush and the water pressure in the place that holds the toilet have HIGH water pressure? And as soon as its done filling the bowl the pipes go BAM! in the walls? Well that could be your superchargers hoses popping off if there no way to quickly alter all that pressure when the throttle plates suddenly close. There is so much pressure it can and will damage your supercharger especially turbos. Its a very important device to a forced induction intake! oh one more thing.. definitely causes a lag idle then back to normal when just reaching stop lights etc.. and sometimes causing small backfires.

 

What are you talking aboot? I don't really think the fluid dynamics of my city water system has much to do with supercharger design. I shut my tap at the point of use, but have no control over the source (unlike a supercharger). Anywhoo, I've given this some thought, and I believe 'supercharger manufacturers' are attempting to use the conventional 'turbo bred' BOV as a 'bleed valve' (ie. hit 9 psi, open a bleed to atmosphere). I always thought the max boost was controlled by the size of the pulley, right? If my motor can safely handle say 9 lbs, then I use a 9 psi pulley. Why would I want to use a 25 psi pulley, and bleed off the excess back down to 9 psi?


Ummm, yeah.

 

I guess you missed the point..
Your right about your pullys controlling what psi you can max. when you have lets say 9psi at full throttle and suddenly let go the throttle.. What do you think all that pressure is going to do at that instant? Where is it going to bleed? Believe me if it doesnt find a place to go. It will MAKE A PLACE TO GO.. Pop goes the pipe off your intake and tornado your engine compartement possibly?
Try this,.. shut your blow off valve off and tighten the screw so it dont open.. then drive your car fast and come back to this board and tell us what happened. lol
There are many web sites describing what a Blow Off Valves purpose.