Running without a DV- benefits other than noise..?
Std ECU and MAF. The only things none standard on the intake side are a green panel and a samco MAF tube to turbo inlet pipe hose.
I need to do a longer run to be totally sure, but I'm just waiting for Bob's thoughts about the overboost..
The 35 is certainly lively, even more so without the DV fitted..
Out of interest, what peak boost do you see and what gauge is that on..?
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AVCR, 1.35 normal peak, has got up to 1.5 when the weather was really cold! I knocked back the duty cycle at Bob's instruction to solve that.
Mine was mapped to kiss 1.55, but can reg 1.6 when really cold, defi's do over read somewhat IMHO.
IIRC, boost via something like romulation/ecuexplorer is usually about 0.1 bar or so lower. Haven't checked lately, so it would be a good idea to do a few data runs without DV. Silly, I should have thought about doing that the moment I blanked off DV..
IIRC, boost via something like romulation/ecuexplorer is usually about 0.1 bar or so lower. Haven't checked lately, so it would be a good idea to do a few data runs without DV. Silly, I should have thought about doing that the moment I blanked off DV..
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With the kit I thought I could alter the pressure required to open the valve to the point where on high pressure it will open but at lower pressures it doesn't.
Least thats the idea.
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My observation is:
Most Turbo charged cars have a Recirculated Valve, which must work the best if most manufacturers have chosen to use it. Because the Air flow/Mass Meter has measured the amount of air going into the engine, it helps if this doesnt escape after it has been measured and before it enters the combustion chambers or in other words via a Dump Valve. Without using one, It helps to keep the fuelling correct for the right amount of air in the engine.
My concearn with the Blanked off method would be as someone mentioned above, that as soon as the throttlebody closed (gearchange) the remaining trapped pressurised air (normally vented to atmos via dumpvalve or recirculated) would have nowhere to go and therefor force the compressor blades to slow down or stall. So this false, 'good power through gear changes' is because of said air being stuck waiting for the next opening of the throttlebody for it to force its way into the engine and thus a pressurised pipework into the engine. But surely the extreeme conditions of boost to stall must be wearing on the Turbo in so many ways that its negatives outweigh its positives the same as a dumpvalve.
Sensible and boring I know but reliability and less engine rebuilds surely are the ultimate performance figure everyone wants.
Most Turbo charged cars have a Recirculated Valve, which must work the best if most manufacturers have chosen to use it. Because the Air flow/Mass Meter has measured the amount of air going into the engine, it helps if this doesnt escape after it has been measured and before it enters the combustion chambers or in other words via a Dump Valve. Without using one, It helps to keep the fuelling correct for the right amount of air in the engine.
My concearn with the Blanked off method would be as someone mentioned above, that as soon as the throttlebody closed (gearchange) the remaining trapped pressurised air (normally vented to atmos via dumpvalve or recirculated) would have nowhere to go and therefor force the compressor blades to slow down or stall. So this false, 'good power through gear changes' is because of said air being stuck waiting for the next opening of the throttlebody for it to force its way into the engine and thus a pressurised pipework into the engine. But surely the extreeme conditions of boost to stall must be wearing on the Turbo in so many ways that its negatives outweigh its positives the same as a dumpvalve.
Sensible and boring I know but reliability and less engine rebuilds surely are the ultimate performance figure everyone wants.
^^^
Yes, I've been thinking about all the pro's and con's, but for me my VF35 is sort of 'expendable', given how cheap they are. It'll be well worth it for the gains I'm getting. Hopefully, as many have said, this turbo is up to handling it and it'll last without any probs.
I just need to deal with the slight 'overboost' I'm now getting and again if that means a £125 map tweak, so be it as the gains would be well worth it..
With regards to leak detection, if you go to your local plumbers merchants (or poss ebay) and get some 'Cotec' leak detection spray, it's bloody brilliant stuff and bubbles like hell on the slightest leak. Not cheap at around £10 a can, but it will last ages. If you know a plumber friend ask him for an almost empty can, as I did..
Going to try and do some data logging today, so will update later..
Yes, I've been thinking about all the pro's and con's, but for me my VF35 is sort of 'expendable', given how cheap they are. It'll be well worth it for the gains I'm getting. Hopefully, as many have said, this turbo is up to handling it and it'll last without any probs.
I just need to deal with the slight 'overboost' I'm now getting and again if that means a £125 map tweak, so be it as the gains would be well worth it..
With regards to leak detection, if you go to your local plumbers merchants (or poss ebay) and get some 'Cotec' leak detection spray, it's bloody brilliant stuff and bubbles like hell on the slightest leak. Not cheap at around £10 a can, but it will last ages. If you know a plumber friend ask him for an almost empty can, as I did..
Going to try and do some data logging today, so will update later..
My observation is:
Most Turbo charged cars have a Recirculated Valve, which must work the best if most manufacturers have chosen to use it. Because the Air flow/Mass Meter has measured the amount of air going into the engine, it helps if this doesnt escape after it has been measured and before it enters the combustion chambers or in other words via a Dump Valve. Without using one, It helps to keep the fuelling correct for the right amount of air in the engine.
My concearn with the Blanked off method would be as someone mentioned above, that as soon as the throttlebody closed (gearchange) the remaining trapped pressurised air (normally vented to atmos via dumpvalve or recirculated) would have nowhere to go and therefor force the compressor blades to slow down or stall. So this false, 'good power through gear changes' is because of said air being stuck waiting for the next opening of the throttlebody for it to force its way into the engine and thus a pressurised pipework into the engine. But surely the extreeme conditions of boost to stall must be wearing on the Turbo in so many ways that its negatives outweigh its positives the same as a dumpvalve.
Sensible and boring I know but reliability and less engine rebuilds surely are the ultimate performance figure everyone wants.
Most Turbo charged cars have a Recirculated Valve, which must work the best if most manufacturers have chosen to use it. Because the Air flow/Mass Meter has measured the amount of air going into the engine, it helps if this doesnt escape after it has been measured and before it enters the combustion chambers or in other words via a Dump Valve. Without using one, It helps to keep the fuelling correct for the right amount of air in the engine.
My concearn with the Blanked off method would be as someone mentioned above, that as soon as the throttlebody closed (gearchange) the remaining trapped pressurised air (normally vented to atmos via dumpvalve or recirculated) would have nowhere to go and therefor force the compressor blades to slow down or stall. So this false, 'good power through gear changes' is because of said air being stuck waiting for the next opening of the throttlebody for it to force its way into the engine and thus a pressurised pipework into the engine. But surely the extreeme conditions of boost to stall must be wearing on the Turbo in so many ways that its negatives outweigh its positives the same as a dumpvalve.
Sensible and boring I know but reliability and less engine rebuilds surely are the ultimate performance figure everyone wants.
I'd rather get maximum potential life from the turbo than the trade-off of a very slight performance increase (and even that might be Placebo anyhow(?)).
Plus, as said, if using the OEM recirc - or a stronger, but OEM pattern, all-metal Forge like I have - then the motor/ECU is behaving as Subaru intended...
Last edited by joz8968; Apr 8, 2009 at 10:37 AM.
Trust me, no-one is more cautious than me, the car is the family daily driver and we can't afford for it to be off the road with a failure..! That goes some way to showing how impressed I am, no placebo here..
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I removed my dv yesterday, when the turbo was on boost it was a lot better to drive, turbo coming straight back on boost after each gear change, but when driving off boost around 2000rpm it was very juddery i drove it for 25 miles and it felt like it was getting worse, so i have put the dv back on for the time been.
i drove it for 25 miles and it felt like it was getting worse, so i have put the dv back on for the time been.
I'm always cautious when people say how good things are. I like to be a pessimist, as then I cannot be disappointed! But really, from using my VTA then changing to being blanked off, it's fantastically smooth now. Granted you may get this with a recirc....but I haven't tried one to comment.
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There is an article about this in the new .....I think it's called "Redline" Magazine. Interesting results gained from the same car running the 3 different set ups.
Not much performance difference at all between Recirc, which was the fastest by about .1 second and no DV. Slightly bigger gap between those two and VTA, which was the slowest from 0-80.
Interestingly, recirc gave the best performance from 1st to second gear increment, but in the 2nd to third gear increment no DV came out trumps. There was also quite a bit of info a out compressor stall etc... interesting read!
Not much performance difference at all between Recirc, which was the fastest by about .1 second and no DV. Slightly bigger gap between those two and VTA, which was the slowest from 0-80.
Interestingly, recirc gave the best performance from 1st to second gear increment, but in the 2nd to third gear increment no DV came out trumps. There was also quite a bit of info a out compressor stall etc... interesting read!
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Nah, im not saying dont do it keep it standard etc, but rather,im just trying to understand what effects there are of each modification rather than modifying it because it sounds good or others do it. Ive just bought a Version 5 Sti Ra and it seems that these along with P1's they are seceptable to poping engines, and it seems fueling is a major candidate. Of course im not saying thats down to a dump valve alone but this mod must effect the fueling......... But it may in fact be helpful for my car, the MAF measures the air going into the engine, but along the way some is released to atmos before entering the engine but fueling is already allocated by the ecu from the MAF signal for said amount of air meaning that maybe this richens up the mixture? Although, lambda also plays its part, as does throttle position but which is more responsible for fuelling on an Impreza im not sure of yet? Of course the air lost im talking about is very minimal amounts and probably negligable, its really the ECU that needs mapping properly to sort this, but I do like to understand how these things effect the whole process.
Another thing I also find hard to believe is that the map is wholly responsible for P1 engine failures, as the P1 engine is the same as mine but I have a ecu which looks for ron 100 fuel the P1 has a prodrive modified map which should be good for UK fuel and therefor shouldnt pre ignite, anyway im getting waaay off the subject now.
I will be replacong the VTA dump valve for a recirc valve for the above reason and dont fancy the blocked method for Turbo wear reasons.
In an ideal world I would have anti-lag and a garge full of replacement turbos, straight cut dogboxes and all manor of Forged parts, a DV's would be the last thing on my mind but my work doesnt pay me enough and so Im left filling my head with socially un-acceptable trivia such as this, lol I love it really
Another thing I also find hard to believe is that the map is wholly responsible for P1 engine failures, as the P1 engine is the same as mine but I have a ecu which looks for ron 100 fuel the P1 has a prodrive modified map which should be good for UK fuel and therefor shouldnt pre ignite, anyway im getting waaay off the subject now.
I will be replacong the VTA dump valve for a recirc valve for the above reason and dont fancy the blocked method for Turbo wear reasons.
In an ideal world I would have anti-lag and a garge full of replacement turbos, straight cut dogboxes and all manor of Forged parts, a DV's would be the last thing on my mind but my work doesnt pay me enough and so Im left filling my head with socially un-acceptable trivia such as this, lol I love it really
^^^
It's no bad idea to 'know' your mods and put a little thought into them, even be prepared to try it and remove if there's no appreciable gain. That's why I like trying the small, usually cheap mods that a lot of people don't bother with.
Every mickle makes a muckle..
Lol, as long as you don't mention this kind of irrelevant trivia outside the realms of SN then you'll be fine. It's when you start to talk about it face to face with real live people that you have a problem..!
It's no bad idea to 'know' your mods and put a little thought into them, even be prepared to try it and remove if there's no appreciable gain. That's why I like trying the small, usually cheap mods that a lot of people don't bother with.
Every mickle makes a muckle..
Lol, as long as you don't mention this kind of irrelevant trivia outside the realms of SN then you'll be fine. It's when you start to talk about it face to face with real live people that you have a problem..!
Did you get any word back from Bob about if you needed a map tweak?
^^^
It's no bad idea to 'know' your mods and put a little thought into them, even be prepared to try it and remove if there's no appreciable gain. That's why I like trying the small, usually cheap mods that a lot of people don't bother with.
Every mickle makes a muckle..
Lol, as long as you don't mention this kind of irrelevant trivia outside the realms of SN then you'll be fine. It's when you start to talk about it face to face with real live people that you have a problem..!
It's no bad idea to 'know' your mods and put a little thought into them, even be prepared to try it and remove if there's no appreciable gain. That's why I like trying the small, usually cheap mods that a lot of people don't bother with.
Every mickle makes a muckle..
Lol, as long as you don't mention this kind of irrelevant trivia outside the realms of SN then you'll be fine. It's when you start to talk about it face to face with real live people that you have a problem..!
I still don't know where I stand with this subject. I do think though, if you are going to remove your DV Then you should have your car remapped afterwards or at least have the fuelling checked on a RR. Otherwise you are playing with fire IMO.
Fuelling is only altered when closing the throttle and coming off boost, and it happens to be rich (so 'safe') anyway. What's more, it prob only lasts for a second or so.
Last edited by joz8968; Apr 9, 2009 at 02:41 PM.
No word back from Bob yet, he's probably away as he normally get's back to me very quickly..
After more running today (no logging as I had to reinstall Romraider..!
) there is definitely a big improvement off/on throttle performance, as you'd expect given the IC is remaining pressurized. With swift full bore up shifts you can get seamless full power acceleration. I'm sold on that alone.
IMHO there are a few things I need to keep an eye on:
Boost peaking at smudge over 1.7bar (defi), however no KL activity at all. Makes me wonder if OE DV was leaking boost in some way..?!
The car is using more fuel. Normally average 22mpg (+/- 1mpg) which equates to 220miles per 44ltrs- same refuel every time after running to orange light. However, with just over 1/4 tank remaining I've only covered 130miles, so I doubt I'll get 180miles. That's 18mpg..!! That also corresponds to the extra pops and bangs, along with the fact that the tail-pipe is more sooty black, when it's usually brownish grey (I run 2ml of NF).
Having said all this, I'd still be prepared to pay to have (if required) a map tweak to keep the extra ommph (safely) that the bum dyno tells me I'm now getting..
After more running today (no logging as I had to reinstall Romraider..!
) there is definitely a big improvement off/on throttle performance, as you'd expect given the IC is remaining pressurized. With swift full bore up shifts you can get seamless full power acceleration. I'm sold on that alone.IMHO there are a few things I need to keep an eye on:
Boost peaking at smudge over 1.7bar (defi), however no KL activity at all. Makes me wonder if OE DV was leaking boost in some way..?!
The car is using more fuel. Normally average 22mpg (+/- 1mpg) which equates to 220miles per 44ltrs- same refuel every time after running to orange light. However, with just over 1/4 tank remaining I've only covered 130miles, so I doubt I'll get 180miles. That's 18mpg..!! That also corresponds to the extra pops and bangs, along with the fact that the tail-pipe is more sooty black, when it's usually brownish grey (I run 2ml of NF).
Having said all this, I'd still be prepared to pay to have (if required) a map tweak to keep the extra ommph (safely) that the bum dyno tells me I'm now getting..
The over fueling isn't that bad, in fact compared to how they come from the factory it's bloody lean.. et
Once I work out what's what with the latest version of Romraider (plus it's been a while since I last used it..
) I'll do some logging runs for a better idea of whats going on..
et Once I work out what's what with the latest version of Romraider (plus it's been a while since I last used it..
) I'll do some logging runs for a better idea of whats going on..
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Assuming the dumpvavle on the car when it was mapped was not leaking at all which it shouldn;t have been then there is not need for a remap due to removing the dumpvalve.
thougtht I may as well post rather than replying to your PM.
I much prefer the pick up and respool etc on gear change with no DV..
Simon
thougtht I may as well post rather than replying to your PM.
I much prefer the pick up and respool etc on gear change with no DV..
Simon
Assuming the dumpvavle on the car when it was mapped was not leaking at all which it shouldn;t have been then there is not need for a remap due to removing the dumpvalve.
thougtht I may as well post rather than replying to your PM.
I much prefer the pick up and respool etc on gear change with no DV..
Simon
thougtht I may as well post rather than replying to your PM.
I much prefer the pick up and respool etc on gear change with no DV..
Simon
The only things that are causing me a little concern is the apparent over boost of around 0.1bar and the extra fuel that it's definitely using
I might be being a little stupid here (not unusual..
) but could the 'over-boost' be caused by the fact that when the throttle butterfly closes completely, keeping the IC etc pressurised to a certain degree, you then get back on the gas, turbo creates usual boost pressure on-top of the 'stored' pressure and hence the over-boost..? Thinking about it, the minute you open the throttle the 'stored' pressure would be consumed by the engine, well before the turbo came fully on song..! Forgive me I'm thinking out loud..
I definitely prefer the sharper pick up after gear changes though..