MR2 Bypass valve install, recirculated. A couple questions..

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Re: just musing...

Postby BriinumsBo » Fri Aug 08, 2008 7:03 am

grip addict wrote:i'm running a recirc'ed ssqv. i'll try to get pics up. its a little ghetto for now, but i want to get a bigger flange (Read-correct size) welded onto my intake pipe. the car definately drives better, doesn't backfire as much, on/off boost is much more transparent.
now the question of the day-
i wonder if the 18 psi that i'm moving would be enough to spool the turbo momentarily? or at least keep it spooled. if you plumbed the line to the exhaust man and had it push air directly onto the turbo blades, i wonder how fast they would spin. you'd probably have to use a check valve or something...


not sure if you could keep the ssqv. probably you would need additional dumpvalve that would work as a check valve on the exhaust side. but it should be better then recirculating.
i did my sssqv recirculation a week ago, also pretty ghetto :D but it works, though i miss the ssqv sound.
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Postby johndgt4 » Fri Aug 08, 2008 10:39 am

Just a thought guys, as far as I am aware, the MR2 bypass valve is meant to be open under vacuum conditions to improve throttle response by allowing some air to bypass the intercooler etc.

I may be completely wrong on this but if not I do not think it would be a good idea to leave these venting to atmosphere.

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Postby BriinumsBo » Fri Aug 08, 2008 10:53 am

johndgt4 wrote:Just a thought guys, as far as I am aware, the MR2 bypass valve is meant to be open under vacuum conditions to improve throttle response by allowing some air to bypass the intercooler etc.

I may be completely wrong on this but if not I do not think it would be a good idea to leave these venting to atmosphere.

John


while i do totally agree with you, that optimal BOV SHOULD be that way, i dont think any BPV or BOV acts like that, since there must be enough vacuum to open the valve. when you have open throttle the vacuum is almost at 0, and too little to press against the valve spring and open the valve. if you vent to atmosphere you can actually see it work: if you use simple setup blowoff valve that opens at any vacuum situations ( not like ssqv or similar that open at vacuum/boost combination), the valve is open and as soon as you just tap on the gas while idling it sucks some amount of air in, but it closes fast since there is no more enough vacuum to keep it open. this is probably where the MR2 bypass valve`s special checkvalve comes in, but i cannot assure, since ive never seen one.
of course if you vent to atmosphere and have valve open at idle, you`re probably using some piggyback to control the fuel flow.
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Postby smog7 » Sat Sep 27, 2008 7:02 am

so how has this held up maxaud?
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Postby maxaud » Sat Sep 27, 2008 7:27 am

good, haven't had an issues as of yet.
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Postby vash169 » Thu Nov 20, 2008 2:43 pm

What's the size of the Samco T-hose you used?
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Postby maxaud » Thu Nov 20, 2008 3:32 pm

I believe it's 51mm (part #STP51)
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Postby Rick89GTS » Thu Apr 16, 2009 6:06 am

Very helpful info for setting up a BOV or BPV. Great thread :)
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Re:

Postby GT4RC » Mon Jun 07, 2010 3:58 am

BriinumsBo wrote:
johndgt4 wrote:Just a thought guys, as far as I am aware, the MR2 bypass valve is meant to be open under vacuum conditions to improve throttle response by allowing some air to bypass the intercooler etc.

I may be completely wrong on this but if not I do not think it would be a good idea to leave these venting to atmosphere.

John


while i do totally agree with you, that optimal BOV SHOULD be that way, i dont think any BPV or BOV acts like that, since there must be enough vacuum to open the valve. when you have open throttle the vacuum is almost at 0, and too little to press against the valve spring and open the valve. if you vent to atmosphere you can actually see it work: if you use simple setup blowoff valve that opens at any vacuum situations ( not like ssqv or similar that open at vacuum/boost combination), the valve is open and as soon as you just tap on the gas while idling it sucks some amount of air in, but it closes fast since there is no more enough vacuum to keep it open. this is probably where the MR2 bypass valve`s special checkvalve comes in, but i cannot assure, since ive never seen one.
of course if you vent to atmosphere and have valve open at idle, you`re probably using some piggyback to control the fuel flow.


This is exactly how the synapse engineering BOV acts. I am running one with the anti-stall kit (it's a spring loaded stopper that opens only by air blowing off. I suggest using a stronger spring than they supply as it does not shut fast enough and causes stalling issues.) It reacts very very quickly and is very sensitive, and I cannot wait to get a straight intake made up so I can run it recirculated. I will definately be making comparison videos when I finally get it done.
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby MWP » Mon Jun 07, 2010 8:09 am

Or... how about just not running a BOV at all?
They are not needed, and were only ever introduced in factory cars to help with noise emissions (turbo flutter is louder than a recirc-bov).

It also does not help with performance, as contrary to common belief, having pressure in the IC pipes after a gearchange does help with power, and it doesnt slow the compressor turbine greatly.
Not having one also wont noticeably shorten a turbos life.
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby aus jd 2703 » Mon Jun 07, 2010 9:11 am

MWP:turbo flutter sounds cool but so many people say its bad for your turbo i just cant see that many ppl being wrong..... but i can deffinately see them being miss informed :D
imo the idea of having a by pass valve to by pass the turbo when bellow boost makes sense ur effectively running a stright intake with no turbo= no restriction.. good idea im surprised its not more common.
to take it further why not bypass the inter cooler?
though i cannot see a 30mm hose supplying enough air for a 4cylinder even if its below 3000 rpm but i think having to paths for air will greatly decrease restriction.
cool thread should have read it earlier
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby MWP » Mon Jun 07, 2010 10:39 am

aus jd 2703 wrote:MWP:turbo flutter sounds cool but so many people say its bad for your turbo i just cant see that many ppl being wrong..... but i can deffinately see them being miss informed :D


Yup, and it has been proven with test results & the fact that turbo racing cars (proper million $ cars, not track day warriors) dont run BOVs.

imo the idea of having a by pass valve to by pass the turbo when bellow boost makes sense ur effectively running a stright intake with no turbo= no restriction.. good idea im surprised its not more common.
to take it further why not bypass the inter cooler?


Turbos and intercoolers can flow so much air, that when the engine is not boosting (and drawing little air), there is very little restriction.
The air filter creates a hell of a lot more restriction than the turbo and IC do.
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby built2run » Tue Jun 15, 2010 3:12 pm

dude what era are you getting your info from?? all newer turbocharged cars since 1996 or so have some sort of bypass/blow off valve. thats racing cars and street cars all of them. even the verion. and a good "setting" on the bov/bpv will leave some pressure in the system, but not enough to let it all back up and cause those pressure waves that DO happen when you close the throttle. those pressure waves do revert into the compressor where the pressure is already high. your right that it won't make the turbo lose hardly any more rpm than not having as much exhaust flow. thats exactly why when that higher pressure hits the compressor it can eventually break off bits of the compressor. million dollar race cars don't care about the turbo as long as it does its job for the qualifying run and the actual race, then remove and replace. they have the funding but even still all those expensive race cars do have a bov/bpv at least newer ones do and thats a fact, keep up with technology if they all use them now there must be a reason right? or else why bother investing in it?
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby MWP » Wed Jun 16, 2010 4:39 am

built2run wrote:all newer turbocharged cars since 1996 or so have some sort of bypass/blow off valve. thats racing cars and street cars all of them. even the verion.


Yes, because they are needed to meet noise emission laws. Even the Veyron (get your spelling right) has to meet these laws.
Before noise emission laws became more difficult to pass (mid 90's), few factory turbo cars had BOVs... like 165's and 185's didnt.
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Re: MR2 Bypass valve install, recirculated. A couple questions..

Postby johndgt4 » Thu Jun 17, 2010 10:51 am

Some people here need to research high power turbo cars such as WRC etc.

Needing pressure in the pipes idea is wrong. Flutter is caused by reverse airflow going supersonic over the turbine blades when running high boost.....not good for a stock turbo.

Most WRC cars, pre-antilag, used blow off valves but these cause issues when running anti-lag and hence now don't tend to and why you now hear flutter on most modern WRC cars.

Too much detail to go into here but some research will get you the info.

Don't always beleive what you read on the NET.

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