Power Valve Actuator (PVA) Mod
- Peter Vee
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Power Valve Actuator (PVA) Mod
Saw the magic "PVA" abbreviation mentioned elsewhere on our forum as a means to get better consumption and responsiveness from a 4.8 auto... googled PVA mod and came up with this..
http://www.patrol4x4.com/forum/diy-modi ... ndex2.html
Looks like a no-brainer?
Regards,
Peter
http://www.patrol4x4.com/forum/diy-modi ... ndex2.html
Looks like a no-brainer?
Regards,
Peter
Peter Vee
2010 4.8 GRX fully rigged for overlanding
2010 4.8 GRX fully rigged for overlanding
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Re: Power Valve Actuator (PVA) Mod
Peter, I spent a bit of time reading up on this issue around the web and the conclusions I reached are that (a) there are wildly different outcomes reported by various people (some report significantly improved power and consumption, others the exact opposite and yet others no change at all – it is all just too inconsistent to be able to reach any proper conclusion) and (b) nobody who has been doing this fiddling seems to have a really thorough understanding of the systems behind what they are fiddling with; I got very much the impression of "experimenting in the dark". In the end it seemed to me that the Nissan engineers probably knew far more than the people who are doing the modifications and I decided I would rather place my trust in the engineers than the modifiers.
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Re: Power Valve Actuator (PVA) Mod
Huh?
Great, I was going to attempt doing this the weekend? Reason I spoke to a Patroller yesterday and they did the MOD and with the freeflow, they are getting 7 km/l. And the responsiveness of the vehicle is apparently very good.
Clem, considering that you did so much research, can you maybe say if there has been any negative results after doing this?
I also didnt want to originally do this mod, but the guys I spoke to says that it was put in place to prevent wheelspin etc at take off. After this mod the torque is there from start and you have to be a bit more careful.
Is there anybody on here that has done this mod? What is your take on this? Maybe someone with machanical background could shed some light on this?
I was excited to do this and now I dont know anymore?
Great, I was going to attempt doing this the weekend? Reason I spoke to a Patroller yesterday and they did the MOD and with the freeflow, they are getting 7 km/l. And the responsiveness of the vehicle is apparently very good.
Clem, considering that you did so much research, can you maybe say if there has been any negative results after doing this?
I also didnt want to originally do this mod, but the guys I spoke to says that it was put in place to prevent wheelspin etc at take off. After this mod the torque is there from start and you have to be a bit more careful.
Is there anybody on here that has done this mod? What is your take on this? Maybe someone with machanical background could shed some light on this?
I was excited to do this and now I dont know anymore?
God follows me where I tread.....
2007 Nissan Patrol 4.8 GRX = GRIZZLY!!!
2007 Nissan Patrol 4.8 GRX = GRIZZLY!!!
- Kagiso II
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Re: Power Valve Actuator (PVA) Mod
Would a Tyota Prado also have such a thng-a-majiggy PVA welfie [the V6 Praat-ou ??]
Don't bring God down to your level of faith ... bring your faith up to His level!
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Re: Power Valve Actuator (PVA) Mod
I can only tell you what I have read. If you start to search around the Internet you will find that there are other guys who have reported that the fuel consumption went up. I can also tell you that I am not sure that there is any proper explanation out there of exactly how it all works and fits together. My own perception (and I do stand to be corrected) is that if you have more torque (or power) it is only because you are burning more fuel. A petrol engine with an ECU detects the amount of air going into the cylinders and injects the correct proportionate amount of fuel. So if you increase the amount of air (by free-flowing) going into the cylinder, then the ECU must also increase the amount of fuel going into the cylinder. The only other possibility would be that if the free flow somehow improves the efficiency of the engine – perhaps by increasing air swirl in the cylinders or enabling a cooler airflow or something like that. On the other hand, nobody seems to have caused any harm to the motor by trying this so there is probably no reason you should not give it a try – it is after all completely reversible.NISMOnator wrote:Huh?
Great, I was going to attempt doing this the weekend? Reason I spoke to a Patroller yesterday and they did the MOD and with the freeflow, they are getting 7 km/l. And the responsiveness of the vehicle is apparently very good.
Clem, considering that you did so much research, can you maybe say if there has been any negative results after doing this?
I also didnt want to originally do this mod, but the guys I spoke to says that it was put in place to prevent wheelspin etc at take off. After this mod the torque is there from start and you have to be a bit more careful.
Is there anybody on here that has done this mod? What is your take on this? Maybe someone with machanical background could shed some light on this?
I was excited to do this and now I dont know anymore?
I would very much like to know and understand more about it if anybody has more information and a more comprehensive explanation. Perhaps one of the more technical guys on this forum will chime in.
- David
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Re: Power Valve Actuator (PVA) Mod
My understanding is that if you cable-tie the valve shut you are actually lengthening the intake duct which provides maximum torque. Don't know if any of you played around with side-drafts carburettors with different length trumpets?
With longer trumpets maximum torque will be available at lower revs. The negative is that the torque band gets narrower and maximum torque might drop off earlier than before.
With longer trumpets maximum torque will be available at lower revs. The negative is that the torque band gets narrower and maximum torque might drop off earlier than before.
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Re: Power Valve Actuator (PVA) Mod
Resonance ram air effect? Could be but wouldn't one then lose on HP? When does the PVA open in normal operation?
- David
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Re: Power Valve Actuator (PVA) Mod
Bit difficult to see when it moves. The butterfly is actually normally open and by doing the mod you cable-tie it closed. Can't remember the post but I remember somebody commenting on the Aussie forum that they did the mod and on the dyno it lost power On my car my revs are 99% of the time between 2&3k or below 2k so it doesn't feel like it lost anything - only gained low down according to my butt-so-meter.
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Stop Rhino Poaching Supporter!
ARB Bullbar, BZT rear bar, TJM 2" Suspension, Snorkel, LT 285/70/17 BFG KO2's, 40L Engel
Stop Rhino Poaching Supporter!
- Tinus lotz
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Re: Power Valve Actuator (PVA) Mod
i had a chat to graham and he said that the butterfly sits behind the airflow meter ,it allows more air into the motor and gives you more power faster .
all modern cars have them audi bmw toyota ect it is activated by vacuum after 3000rpm . on a 4.8 i hardly ever get to 3000rpm becouse i am doing 140 gps speed at 2400 rpm in 5 gear
my trottle response is much better also .the thing we must watch out for is going to lesotho highlignts you might be getting to lean but then u just cut the calble tie
my feul consumpsion on the new 4.8 is 6.1 to 6.2 at 140 gps speed and that with 35 takkies .........
all modern cars have them audi bmw toyota ect it is activated by vacuum after 3000rpm . on a 4.8 i hardly ever get to 3000rpm becouse i am doing 140 gps speed at 2400 rpm in 5 gear
my trottle response is much better also .the thing we must watch out for is going to lesotho highlignts you might be getting to lean but then u just cut the calble tie
my feul consumpsion on the new 4.8 is 6.1 to 6.2 at 140 gps speed and that with 35 takkies .........
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Re: Power Valve Actuator (PVA) Mod
Tinus,
So Graham approves this mod or just dont have a problem with it? Is it better to get someone like Graham to do this or can I do this myself? Vehicle is going for a service by G-TECH next week, maybe I should rather wait and let him do it?
Thanks
So Graham approves this mod or just dont have a problem with it? Is it better to get someone like Graham to do this or can I do this myself? Vehicle is going for a service by G-TECH next week, maybe I should rather wait and let him do it?
Thanks
God follows me where I tread.....
2007 Nissan Patrol 4.8 GRX = GRIZZLY!!!
2007 Nissan Patrol 4.8 GRX = GRIZZLY!!!
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