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Discussion Starter · #1 · (Edited)
So last night I was working on the car last night, tying up some loose ends. I started thinking about ways to tweak the system and came up with the idea of plumbing the wastegate signal from the charge piping right before the ETM rather than from the compressor housing. My thought was that by locating the source further downstream it would allow the WGA to stay shut longer and improve throttle response and spool time. It would still work with the regular TCV but would account for the drop across the intercooler and piping.

Has anybody ever done this or heard of it? Any reason it wouldn't work other than the chance ME7 won't like it?

What do you guys think?
 

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I did this years ago, on a big turbo/big boost fwd Mopar. Made a noticable difference. I did it for same reason as you mention. Now that said, I used a MBC, so no idea if there would be a difference, being that these are controlled by the ECM. Be easy to try though.
 

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So last night I was working on the car last night, tying up some loose ends. I started thinking about ways to tweak the system and came up with the idea of plumbing the wastegate signal from the charge piping right before the ETM rather than from the compressor housing. My thought was that by locating the source further downstream it would allow the WGA to stay shut longer and improve throttle response and spool time. It would still work with the regular TCV but would account for the drop across the intercooler and piping.

Has anybody ever done this or heard of it? Any reason it wouldn't work other than the chance ME7 won't like it?

What do you guys think?
Make a pitch to Dougy in the R forum. I bet he'll try it and report back.
 

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Discussion Starter · #4 ·
I did this years ago, on a big turbo/big boost fwd Mopar. Made a noticable difference. I did it for same reason as you mention. Now that said, I used a MBC, so no idea if there would be a difference, being that these are controlled by the ECM. Be easy to try though.
Thanks for the reply, I know it should work in theory but was curious if anybody had actually tried this on the S60. Surprised there hasn't been more discussion about this topic though. I'll give it a shot over the weekend and see what the story is.
 

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So last night I was working on the car last night, tying up some loose ends. I started thinking about ways to tweak the system and came up with the idea of plumbing the wastegate signal from the charge piping right before the ETM rather than from the compressor housing. My thought was that by locating the source further downstream it would allow the WGA to stay shut longer and improve throttle response and spool time. It would still work with the regular TCV but would account for the drop across the intercooler and piping.

Has anybody ever done this or heard of it? Any reason it wouldn't work other than the chance ME7 won't like it?

What do you guys think?
Brandon,

I don't seem to follow your thought process. Are you looking to reroute the wastegate vacuum line (yellow) to the TCV to come from the charged air pipe? Or do you want to reroute the raw compressor vacuum line (red) to the TCV to come from the charged air pipe instead?

If the latter, the ECU may no longer have the ability to detect metered air leaks (post MAF), since it won't see a variance between the raw compressor line pressure (sent to ECM via TCV) and the inlet manifold pressure (via MAP sensor).
 

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Discussion Starter · #6 ·
The latter George, I am looking to feed the TCV from the charge air pipe right before the ETM rather than the compressor.

I wasn't aware the TCV could even measure pressure? I was under the impression the TCV had two signals, a power and pulsed ground from the ECM, not sure how boost pressure would be measured or fed from the TCV. Wouldn't the EMC use the readings from MAF and compare to the MAP and AIT sensors to determine air loss?
 

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The TCV does receive input from the ECU on how much boost pressure to re-route from the compressor (red) line to the wastegate (yellow) line to operate the wastegate actuator and open/close the WG flappoer port, but I'm not sure actually if it can measure boost itself. the ECU may calculate expected boost from the MAF, and compare it to the MAP/AIT sensor(s) readings to determine the signals to send to the TCV..
 

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Discussion Starter · #8 ·
Pretty sure the TCV is just a solenoid valve that bleeds what it's told to and it wouldn't know the difference anyways, boost pressure is boost pressure as long as far as the TCV is concerned. The only concern at this point is how the ECU will react to the slight delay due to extending the vacuum hose to the charge pipe prior to ETM. I suspect the longer line might have a tendency to increase surging/spiking but we'll have to see how the system reacts. Might be a finer balance with the WGA set pressure, rather than running a tad bit over stock it might really need to be spot on to react as best as possible with the rerouted line.

I'll follow up when I get a chance to try it, otherwise anybody that happens to do it let me know how it goes!
 

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The more I think about this, the more unsettling it is in my head.

If you re-route the red vacuum line to the charge pipe, are you not introducing the existence of vacuum pressure to the TCV, when the throttle plate is closed? Whereas the raw compressor line will always provide charged boost pressure to the TCV, which would just get rerouted through the fresh air hose (blue) if it's not needed to operate the WG flapper.
 

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Discussion Starter · #10 · (Edited)
No vacuum is seen in the charge piping before the ETM, only behind the plates in the manifold. The piping is essentially exposed to the same pressures as the compressor housing but it's delayed as the pipes and core take a moment to pressurize. That's the whole point of this, to use the latent signal at the end of the charge pipe to feed the TCV, almost like a precharge to reduce lag and increase spool rate.

However, I have seen instances where the signal is taken from the intake manifold, and there is controversy as to whether the WGA should see vacuum or not. Some say the vacuum will essentially help to keep the WG closed during shifts to reduce lag, some prefer to run a check valve to block vacuum. I have not considered going past the throttle plates for my setup, just not something I want to try.

I have done a bit of research and it's not as uncommon as I had thought, just not used much in these types of cars. With the ECU controlling boost and such small turbos I don't know how much there is to gain with this, on a large turbo with manual boost control this is a pretty good mod from what I have read.
 
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