Duke

I agree, with that system it sounds great to have it after the IC!
The reaction time would still be slower, but if it works it works.

NZ951

I can actually adjust the sensitivity and base expected duty cycle of the opening as well, also can hold boost to a preset level say 80% before the EBC vents. Do you think the reaction speed would be noticably slower???

Ahmet

In theory there is a difference, in practice it may not be worth moving it. If you'd like I'll try to give you more input later. For the time being, I'm off to go take some more exams...
Ahmet

NZ951

Good luck.

cpt_koolbeenz

<<<The car is tuned using manifold pressure, boost can be regulated using a line from the intercooler pipe, nothing wrong with that. There will be a boost controller in line. I think the sooner you have pressure available to the boost controller the better. As I've noted before, there will be more pressure to work with from the intercooler pipes as well. Both of these points are plusses, in my opinion.>>>

The innercooler's flow rate is not linear... That's why...

NZ951

Chris, whats your opinion on my setup for the lines?

Ahmet

Thanks, I think I did really well!

cpt_koolbeenz, like I said earlier you're not trying to tune the engine from the intercooler pipe, just getting a signal to the wastegate (earlier than the intake manifold). The banjo bolt is located between the intercooler and the turbocharger so the flow through the intercooler is not a consideration either. The intercooler pipe (besides the compressor housing) is simply the point to have the most pressure, and earliest in the system. THAT is why I'm suggesting using a line from there (well there are other reasons I mentioned in my earlier posts) to control boost with. It will be available earlier, and it's got more force...
Ahmet

NZ951

How is the signal earlier? The pressure is in the entire system though at different levels, and the length to the controller the same, in fact very short in my case...

Do you have figures or analysis that shows the benefits of the IC banjo and its assumed earlier signal? I would be pretty interested in seeing something scientific on it.

cpt_koolbeenz

<<<cpt_koolbeenz, like I said earlier you're not trying to tune the engine from the intercooler pipe, just getting a signal to the wastegate (earlier than the intake manifold).>>>

You are right... nobody is trying to tune the engine from the intercooler pipe.

<<<The banjo bolt is located between the intercooler and the turbocharger so the flow through the intercooler is not a consideration either.>>>

That is precisely the reason the intercooler is a consideration... Theoretically, there will be a higher pressure before the intercooler than after. This difference in pressure will increase as boost does.

<<<The intercooler pipe (besides the compressor housing) is simply the point to have the most pressure, and earliest in the system. THAT is why I'm suggesting using a line from there (well there are other reasons I mentioned in my earlier posts) to control boost with. It will be available earlier, and it's got more force...>>>

You may or may not prevent boost spikes (if that is your intent) by plumbing it earlier in the line.

My only question (suggestion for taping off the intake) is why control the wastegate with a signal that only it uses? For example: If you have two electrical sources (both with a positive and a ground (or reference)), you tie the grounds together to have a common reference. Same idea here...

Basically both ways work but with taping off the intake, you are ensuring the wastegate is getting the same reference pressure as the engine. Tapping off the pipes can (again theoretically) cause side effects like the wastegate closing too soon at high boost levels due to intercooler inefficiency. We overcome these (not necessarily apparent) side effects by just turning up the setting on the boost controller. This can cause overboosting at "lower" (I say "lower" since they are, by now, actually higher than before, since you turned up the boost controller) boost levels. I intend to do some experimenting when I get my car back together... I am going to remove the ISV like NZ and tap from there. Then take some readings and then try it from the pipes...

BTW Ahmet make sure you are getting your just rewards for working tirelessly on Randy's car... I think $90 an hour is fair (plus his "spare" parts)...

BoostGuy951

Ahmet is correct on this one. The amount of pressure where you are getting your Wastegate signal is not a concern. Its the Quickness that the signal gets to the wastegate port. Placing the signal line closer to the turbo outlet shortens the feedback loop. If you consider that what you are really controlling with the boost controller is turbine speed, you need to have the signal as close to the source as possible. Due to the lag from when the pressure gets from the turbo outlet to the manifold, you may be overspinning the turbine by the time the Wastegate gets the signal to open. This may cause a slight boost spike (Even if your manifold side gauge doesn't show it) before the pressure gets around back to the wastegate. You can still set the controller to whatever PSI, where you plumb the WG signal doesn't have anything to do with that, just with the quickness the wastegate will respond.

NZ951

Interesting that every turbo charged car I have seen has not got the banjo on that side of the IC... In fact many tuners and turbo-heads ask me about why its on that side from factory. I just dont see how it is slower,and the physical distance to the controller and WG is the same.

BoostGuy951

NZ-

Why not whip up a datalog of the boost curves on each? Theory is one thing, but we can see if there is actually any difference.

Laust Pedersen

Alright, I have been sitting on the sideline long enough for this one.

It may be a good idea to take a look at the tables and graphs I have generated for the pressures in the Intercooler (banjo bolt), Manifold and Exhaust (test tube). At WOT it does not matter much if the WG control is taken from the banjo bolt (on the IC inlet tube) or the manifold. Only the IC pressure drop, which I believe to be small, makes the difference.

However under partial throttle there can be a significant pressure built up in front of the throttle plate, making the turbocharger work harder than necessary. Granted it is nice to have an excess pressure reservoir (volume between the turbo compressor and throttle plate) so the manifold pressure immediately jumps if the throttle suddenly opened from maybe 10-15 psi. In addition to making the turbo work (unnecessarily?) harder it also may work the BOV (diverter valve) beyond its capacity.

After having driven around with a closed wastegate and not (willingly) exceeded 25 psi, I have popped a few hoses and felt some power pulsation when lifting the throttle for gearshift from high rpm. As a consequence I would like to limit the pressure difference across the throttle plate to 5-10 psi, something not possible with the WG control at the manifold.

Maybe the above were at least partial the reasons why Porsche tapped the WG control signal where they did.

Laust

NZ951

Stop signing your name Laust and put Mad Scientist like you should.

Darius Juca

AAAAAHHHH so he's the Mad Scientist!!! I also eliminated the banjo bolt and cycling valve.....should I go back to the IC pipe?