Standard Dump Valve

[jerry phipps]

Hi everyone

At the meet yesterday and wow what a meet that was i noticed that all the mr2 turbo owners had removed there hose from the dump valve. So no longer was it a silent dump sound. This quick little mod had changed your humble standard dump valve into a very loud but pleasing sound.

So today i decide to try this mod. I removed the hose and tried it to. I found that it worked a treat. But my concerns are it this a safe mod to do??? Sure it sounds wicked and you can spend a few hours racing around enjoying the sound. But will this cause and damage to my engine after awhile.

Looking at aftermarket dump valves they do not have one end exposed to the element like this. Which makes me think. Does the standard valve suck air back into the valve?? If so is it safe to have the valve exposed like that??

Could someone advise me as if it's not safe for my engine i will replace the hose back onto the valve and in the future buy a proper after market dump valve.

cheers jerry!!

[GiJoe90]

Imoc discussion

TOC discussion

I'm still unsure!!

Joe

[jerry phipps]

Hi Joe

Thanks for the heads up there buddy. Well there are some mixed views there about this. What i dont understand is why the bov is venting hot air back into the airbox Wouldn't it have being better to vent the hot air into the engine bay instead of the airbox??

Well i think i will replace the hose and carry on as normal. But wow what a sound it makes. Perhaps i might email rogue systems on some advise

Cheers jerry!!

[KiwiMR2]

Venting the OEM valve to the atmo is the WORST thing you could do with regards to the bov issue. If you want the pssshhhhtt you need to get an aftermarket bov. Don't listen to hard to Imoc....they have been known to be wrong about things before.

Cheers

KiwiMR2

[CozmoNz]

i cant see whats wrong with it.

attach a filter to the end of that hose.... and plug the airbox (where it returns).

so it can suck air in. hell, even run a hose down to a cold location, so it runs cold air in....

i might try that...

blocking / shutting off bov is silly, thats why you fit a bov.

running that hose to a different location, so it expels the air to a different place, THROUGH A FILTER will only make it make a different noise.

if you dont use a filter, it will suck air back through, and hate you for it.... dust + combustion chamber = VERY bad.

[jerry phipps]

Well at the end of the day it was a bit of fun and i think i will be replacing the hose back on. I will have to buy a proper bov instead. At the end of the day i dont want to damage my engine really ah ;)

jerry!!

[KiwiMR2]

On Gen II engines the air passes through the AFM before getting to the turbo, so if you vent some of it back to atmo then it's already been metered, and, since there is now less air than the ECU thinks there is, it runs rich. Any BOV vented to atmo will do this.

Where the stock BOV differs from aftermarket is that it also functions as a bypass valve, bypassing the turbo off boost, if the stock BOV is vented the incoming air that flows (when it's functioning as a bypass valve) is not metered and the engine will run lean. However, as this is only off boost, and reduces as the manifold pressure increases, it will not IMO be sufficient to melt pistons. It runs rough because there is only a limited range of AFR's where combustion is possible, go too lean and no combustion event takes place (same if you go too rich). When it doesn't ignite because it's too lean you don't have a high cylinder temp problem, but you can cause backfires and damage to the cat as the unburnt mixture accumulates in the exhaust, when there is sufficient fuel it is ignited by the residual heat in the exhaust system. Simple answer is don't vent the Stock BOV, if you want the pssst noise by and aftermarket one.

[jerry phipps]

KiwiMR2

Cheers for your well explained answer mate. Well i have reattached the hose now and like you said i think thats it's better to invest in a after market bov.

cheers mate ;)

jerry!!

[CozmoNz]

sorry man, i keep thinking they are all map sensored *doh*.

but its cool to do that on ours :D having no afm :D.

[Fizz]

On Gen II engines the air passes through the AFM before getting to the turbo, so if you vent some of it back to atmo then it's already been metered, and, since there is now less air than the ECU thinks there is, it runs rich. Any BOV vented to atmo will do this.

Where the stock BOV differs from aftermarket is that it also functions as a bypass valve, bypassing the turbo off boost, if the stock BOV is vented the incoming air that flows (when it's functioning as a bypass valve) is not metered and the engine will run lean. However, as this is only off boost, and reduces as the manifold pressure increases, it will not IMO be sufficient to melt pistons. It runs rough because there is only a limited range of AFR's where combustion is possible, go too lean and no combustion event takes place (same if you go too rich). When it doesn't ignite because it's too lean you don't have a high cylinder temp problem, but you can cause backfires and damage to the cat as the unburnt mixture accumulates in the exhaust, when there is sufficient fuel it is ignited by the residual heat in the exhaust system. Simple answer is don't vent the Stock BOV, if you want the pssst noise by and aftermarket one.

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The Rev 3 tubby has a map sensor though? :bookworm:

I think im going to take Jerry's option of adding a filter at the end of the tock BOV..

[CozmoNz]

The Rev 3 tubby has a map sensor though?  :bookworm:

I think im going to take Jerry's option of adding a filter at the end of the tock BOV.. 

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rev 1,2 afm

rev 3,4,5 map

if you have a 1,2 dont touch the bov.... if you have a 3+, go for gold.

i plan on it in the future :D

[KiwiMR2]

I think im going to take Jerry's option of adding a filter at the end of the tock BOV..

What will that do?? thats were the air vent's OUT, why filter it??

The Rev 3 tubby has a map sensor though?

Your right...I didn't read it properly :P didn't click he had a Type III. All the same I wouldn't use the OEM one for atmo venting, aftermarket is better in that sense.

Cheers

KiwiMR2

[Fizz]

I think im going to take Jerry's option of adding a filter at the end of the tock BOV..

What will that do?? thats were the air vent's OUT, why filter it??

The Rev 3 tubby has a map sensor though?

Your right...I didn't read it properly :P didn't click he had a Type III. All the same I wouldn't use the OEM one for atmo venting, aftermarket is better in that sense.

Cheers

KiwiMR2

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If you read above.. some people are saying it sucks in air as well??? But how these people know this i aint got a clue?

Is it word of mouth?

And why is it bad for the stock BOV to vent to air if you think it only blows air out?

[jerry phipps]

Well this is it mate. You have only got to take peoples advise on here really or seek professional advise. I was thinking of contacting rogue systems and asking them. But for now i have put the pipe back to normal until I'm more wiser. But what a sound it makes. I really dont think that a after market bov will ever sound as loud as the standard bov??

jerry!!

[Jimlad]

if you have a 1,2 dont touch the bov....

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Don't agree with you there mate.. a few of us with AFM's easily run BOVs with no problems whatsoever.

[Mister2]

no prob here. rev1 usdm motor w/ hks bov. never had stalled after shifting or studdered.

but anyways, jerry since ur running on speed/density, running an open bov wont affect your car. only reason y it is advised not to is exactly what kiwi said about the afm. that air is supposed to go back into the intake. ecu thinks it is, so it dumps fuel in.

[jerry phipps]

no prob here. rev1 usdm motor w/ hks bov. never had stalled after shifting or studdered.

but anyways, jerry since ur running on speed/density, running an open bov wont affect your car. only reason y it is advised not to is exactly what kiwi said about the afm. that air is supposed to go back into the intake. ecu thinks it is, so it dumps fuel in.

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So what you saying that it's ok to have the standard bov dumping into the atmosphere then?? This is becoming very complicated now

jerry!!

[Mister2]

hmm.. ohh yeah.. forgot that u had the standard... hmm.. im not too sure. i mean, it was made to recirculate, so maybe it has to? i dont know, i never had the standard one on my car.

[CozmoNz]

Why filter the air?

it does open the bov @ idle, because its not vent to atmo, it can be as loose as it wasnt to be, where as an aftermarket one MUST be tighter, not to *suck in* at idle.

if you put a filter on, then it can suck in air at idle, and vent it on throttle drop.

[KiwiMR2]

I ran an atmo aftermarket on my 90 GT back in the day...as mentioned the issue there is as the type I & II is equipped with the afm the air is supposed to be measured and fuel adjusted accordingly etc, no air to measure and it dumps more fuel and you run super super rich.......but I did it and the owner after me...right up to 200,000 km's plus. I TRIED the oem vented and it would stall when comming to a stop.

Jerry...you think the OEM is loud vented....try the Turbo XS H-RFL ;)

Adding the filter is a nice touch but doesn't do anything.

Cheers

KiwiMR2

[jerry phipps]

Hi kiwi Mr2

Some sound advise there Now when you are talking about the turbo xs dump valve you talking about this one are you ;)

In my potn magazine they claim thats this is one of the loudest dump valves around infact the quote Extremely F**kin loud!

Sounds like a laugh I see that you are running this bov how would you rate it mate. In the magazine it sells for £170 plus you have to buy a adapter. And is it easy to fit?

Jerry!!

[KiwiMR2]

That is indeed the one, I LOVE it....IMO if your gonna vent the do it properly, they are indeed LOUD :)

Yep with the MR2 fitting kit it takes like 10 mins to fit and all ya need is a socket set or spanner.

Cheers

KiwiMR2

[jerry phipps]

That easy yeah? Perhaps if you are coming along to one of the meets perhaps i could hear how yours sounds like

Cheers jerry!!

[KiwiMR2]

That easy yeah? Perhaps if you are coming along to one of the meets perhaps i could hear how yours sounds like 

Cheers jerry!!

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You pay for the shipping of both myself & my MR2 to the UK Im up for it :P

Do a search for the bov on here....Im SURE someone in your part of the world recently got one :)

Cheers

KiwiMR2

[jerry phipps]

That easy yeah? Perhaps if you are coming along to one of the meets perhaps i could hear how yours sounds like 

Cheers jerry!!

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You pay for the shipping of both myself & my MR2 to the UK Im up for it :P

Do a search for the bov on here....Im SURE someone in your part of the world recently got one :)

Cheers

KiwiMR2

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Sorry mate

I didn't realise that you weren't from england mate. Oh well i will have to just imagine how it sounds like mate So where are you from then mate?

jerry!!