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Discussion Starter · #1 ·
Just reading the posts concerning this trick and thought I would mention I'm playing around with this at the moment. I have removed my HKS Seq.

Fitted the O.E. and no difference is performance. Next I reveresed the O.E.
valve and what a difference.

Car is boosting higher and feels a lot quicker.
The sound is fantastic too.
I'm running HKS forged pistons and ARP rod bolts, Blitz filter but when I see peak 1.9 bar is does worry me.

My car normally peaks 1.6 with the HKS.

I was told to try this from a rally team who got rthe idea from Gems.
They use this trick on their group N cars but they do retain standard air box which will dampen the noise.

R and amp;D told me that the turbo actually spins the opposite way with the valve reveresed and could cause the nut on the shaft to come undone.

I only use the car for Hillclimbs so will this be a problem.


Thanks

Paul Scutt ( Scutty )
 
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Discussion Starter · #2 ·
They told you the compressor spins in reverse when you turn the valve around?
Forgive me but that sounds like the biggest load of horseshit I have heard in a long time. Does it also mean that your exhaust has magically become the intake system and the turbine blades have suddenly curved themselves in the other direction? I am no expert as the Evo is the first turbo car I have had but if what they say is true then I will eat my hat (if I had one http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >).
I think you may have got the wrong end of the stick with that one.

Can someone explain how reversing the valve makes any difference and what do you exactly mean by reversing the valve? (turn it around 180° or swap the intake around with the outlet?) If the inlet is swapped with the outlet then the valve won't work (or won't work anywhere near as effiently) unless my diagrams deceive me. If the valve is rotated and the diameter of the inlet and outlet remain the same then I don't see how it will make any difference or does the rotating it alter the diameters slightly?
 
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Discussion Starter · #3 ·
I have no wires cross Heave Ho.

That is what R and amp;D Told me today. I have to come clean and explain I'm a graphic designer and no engineer but enjoy learning how my car works .

Could someone please explain to me what is happening when I reverse my O.E dump valve.

I was advised to change back to O.E. as re-circulating was better than dump to atmosphere.

Thanks

Scutty
 
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Discussion Starter · #4 ·
Hi,
Reversing the Valve does help if you're running higher boost than normal. By turning the valve around the boost pressure forces the valve shut on to its seating, because the pressure is acting behind the diaphram. With running the valve the normal way the pressure is pushing against the front of the diaphram and when running high boost the pressure can push the diaphram off its seating and cause you to lose pressure.
Only thing that bothers me with reversing the Valve is that normally the valve is actuated by vacuum and opening the valve with the boost pressure infront of the diaphram assisting the the speed of the valves action, but by reversing the valve the vacuum has to pull the valve open with boost pressure trying to hold it shut. This would lead me to think that there could be a slight case of compressor stall and that's the whole point of a dump valve being fitted in the first place!, to stop this happeninghttp://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >.
As for the story of the turbo spinning the other way!.........Well less said about that comment the better[img]http://www.ltregister.f9.co.uk/graphics/biggrin1.gif border|EQU| 0 align|EQU| absmiddle >.

Regards,
Paul.C
 
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Discussion Starter · #5 ·
Just buy a good quality recirculating dump valve from forge motorsport.
It holds more boost and doesn't have idle problems for 120£.
 
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Discussion Starter · #6 ·
GSRed,
That is exactly what I thought, the vacuum that opens the valve would have to overcome the boost pressure pushing against it hence thats why I said the valve wouldn't work or work as well as the valve around the correct way. The fact that Scutty can hear a difference also suggests that the valve is not openning as designed (see below).

Scutty,
If you are running high boost and you think the OE valve is restrictive then do as Maxi suggests, an aftermarket recirculating valve should have a stronger spring or better valve closure without compromising fueling by venting to atmosphere.
The main reasons why manufacturers fit dump valves (always recirculating) is to stop the noise that you are now hearing and to improve fuel metering as it prevents the air rushing back and confusing the air flow meter when the throttle is shut. It's very little to do with preventing the turbo 'stalling' as people forget that as soon as you shut the throttle the exhaust gases drop suddenly, little exhaust gas flow means the turbo will slow abruptly anyway. There may well be a case that an uprated dump valve would be beneficial if a large turbo is fitted to a small engine and it was running a high boost level but other than that just stick with what is supplied (unless its faultly).

If you are running that high a level of boost have you had any trouble with detonation?

If you want to know more about modern Turbo cars then can I suggest '21st Century Performance' which is available mail order from Autospeed in Australia. You should get it within 5 working days for roughly £44 inc P and amp;P (I think mine only took 4 days). If you don't like the idea of getting stuff from Oz then WH Smiths can order it for you for £38 inc P and amp;P but you will have at least a 2 week wait, look here for details.
 
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Discussion Starter · #7 ·
just a small question needing answered . do all Evos come with a recirculating dump valve as standard ?? thanks . |EQU|)
 
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Discussion Starter · #8 ·
http://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >
HH6
For the air to rush back to the air flow meter would only be possible by the trapped pressurised air to force the turbine to reverse in rotation and letting the air back past the turbo into the intake system. If this happens it is called COMPRESSOR STALL [img]http://www.ltregister.f9.co.uk/graphics/biggrin1.gif border|EQU| 0 align|EQU| absmiddle >.
Just thought i'd clear that as both symtoms are in actual fact part of stalling the turbo.
The main reason a recirc valve is fitted is as you point out to stop the noise but also to prevent unmetered air being drawn in under certain throttle positions.

Negri,
Every lancer from the 1800 GSR to the evo VII has a recirc dump valve as standard[img]http://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >.

Regards,
Paul.C
 
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Discussion Starter · #9 ·
if you are running with the standard ecu it s no use to change the dump valve the other way around because i have already fuel cuts

qoute me if i am wrong

regards

andre
 
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Discussion Starter · #10 ·
I think I have standard ECU but will check later.

I'm not sure because I bought my RS with 7,000 miles on the clock.

I have never had fuel cut in my RS or my last car Evo 5 GSR. I did get fuel cut in my Integrale and it's not nice.

I fitted a bigger fuel pump to my RS but have not yet fitted bigger cable to carry constant 12 v.

I have removed the grommet which sits in the boost solnoid, car is running low comp HKS forged pistons. I have fitted the ARP bottom end bolts too.

Aart from these mods and a Blitz filter my engine is standard.
I always see 1.5-1.6 psi.

With my dump vale reversed I can see 1.9 peak, I either have a different ecu or faulty boost gauge.

I plan to fit Gems management very soon anyway.

I would like to thank all of you who have given me advise on this subject.

Thanks guys

Paul Scutt ( Scutty )
 
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Discussion Starter · #11 ·
GSRED, you say that from the 1800GSR through to the E7, they all have the Recirc BOV's. I was under the impression that the recirc was only from the E4 on?? My E3, has the OEM BOV, and I get the ppssshhhhhhh noise, so am thinking this is not recirc?

Agree?? Disagree???
 
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Discussion Starter · #12 ·
GSRed,
Once again I failed to check my reply carefully enough. You are quite right. What I meant to say is the main reason for fitting a recirculating BOV is to prevent any reversion pulse messing up the the air flow meter readings when the throttle is closed. If a BOV wasn't fitted then you would get the reversion pulse messing up the metering and it would also stall the compressor. The main reason though is the air flow meter thingy.

As for the umetered air bit I assume you mean when idling (for example) a vacuum is created and the VTA BOV will be openned allowing unmetered air to enter? That is why some VTA BOV cause rough idling? Am I right? Just theorising as I am not an expert like you yet
 
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Discussion Starter · #13 ·
From my experience the idle problem just happens after acceleration, not when you let the engine idling for a few seconds.
The problem is that with a vta blow off valve, the air is not recirculated in the air intake, so there is less air, but the ecu think that this air is going in the intake, so it gives the appropriate fuel for it. But as the air of the blow off valve is not there anymore,the mix is too rich causing idle problems.

A recirculating blow off valve will give a better turbo response after a release or after braking, so it's much better in rally or fast road use.

The only good side of a vta blow off valve is that it can release the air that would cause the turbo to slow down when you release the gas much faster then a recirculating one, and would be useful in a car that have a high turbo pressure if used in drag racing.
When you change the gears at 7000rpm one after another.
 
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Discussion Starter · #14 ·
E3xtc,
All the Evos have a plastic recirc valve. If you have an induction kit fitted this will allow you to hear the OE valve venting back into the system.http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >

As for unmetered air being pulled into the system. Well my experience is that most after market VTA valves have a weaker spring tension compared to the OE unit, When coming to a stop the intake manifold is on high vacuum and holds the VTA valve open even after all the boost pressure has been released thus allowing air to be pulled in through the open valve. I found this to be the case on my Blitz valve, but it has an adjusting screw so i can alter how much it opens.

Another theory for fitting a VTA unit is that the OE lets already warm air back into the system only to be heated again. By fitting a VTA valve it means that only fresh cold air is always being used and not recycled air. More power from changing the Oe valve???.... HH6 will not be happy with that one [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >.

Regards,
Paul.C
 
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Discussion Starter · #15 ·
...but there is also the school of thought that due to the pressure drop the recirculated air cools down anyway (bit of physics involved there) and it has to pass through the intercooler again anyway. If you could notice the performance difference over the two just by this then I would eat my hat http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle > (I am getting a taste for hats [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >)

1'57s you git! you wait mate [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >
 
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Discussion Starter · #16 ·
Even with the standard airbox you can hear the recirc valve to it's business but having travelled in Hunty's Mak at Croft, with an induction kit it is much more noticable
 
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Discussion Starter · #17 ·
GSRed

what model do you have (1800gsr or an EVOgsr)
If it is an 1800 what boost and ignition timming are you running
 
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Discussion Starter · #18 ·
akiwi,
I don't mean to be a pain in the @rse here but you've asked that same question a few times and i've given you the info, But it's starting to get on my nerves with you butting in with a totally off topic (auto-reply) type question!. Please respect the thread topics and if you have a question post your own threadhttp://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >.

As for you HH6,
I'll let you have the last word on this topic, NOT because you're right but just that you seem to like typing more than me [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle >[img]http://www.ltregister.f9.co.uk/graphics/happy1.gif border|EQU| 0 align|EQU| absmiddle >.

Regards,
Paul.C

p.s 1:57 [img]http://www.ltregister.f9.co.uk/graphics/wink1.gif border|EQU| 0 align|EQU| absmiddle > catch me i you can!
 
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Discussion Starter · #19 ·
I have the valve reversed on my Evo for the time being. The valve does operate but when backing off at higher boost levels it does cause some compressor surge.

Regarding vent to atmosphere valves, in my experience they always come with stiffer springs than the OEM valves, and the spring tension is adjustable as well. If you have ever tried to vent an OEM valve to atmosphere you will see that it doesn't work at all, the car stalls because the valve opens wide open causing a lot of air to bypass the mass air flow meter.
 
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