Does it matter if the boost line is before or after the intercooler
I would imagine you want it after, actual boost, depending on the drop
are you guys mounting a man. wastegate controller in the car, or
just mounting it in the engine comp.

 

I see what you mean but if the wastegate is opening by the boost signal that's past the intercooler already, then at that point it's too late and your engine will see way more boost than you are trying to control. Every time you go from 0 boost to spooled, you would be overboosting for a little bit. The key with the boost reference line at being at the turbo compressor is that there is a very short delay and the pressure signal is sensed and the WG opens very early on in the piping path.

 

Unless you're talking about the boost gauge line itself....if that's the case then at the intake manifold so you get true boost that your engine sees and you can utlilize the vacuum reading off your gauge as well

 

I had my wastegate referenced on the intake for about a thousand miles and my boost would always spike 4/5 lbs on initial spool up. I switched it to the compressor housing and the spiking issue went away and it seemed more responsive all around. It will work either way it's really about preference.

 

reference the gates from the compressor housing or as close to it as possible.

 

I'm referencing after the IC just ahead of the throttle blade.
I've seen no boost spikes at all.

I'm not really sure why the engine would see a spike?

 

Holy crap that's scary stuff you guys lol... if you are trying to play it safe and know on a certain sized turbo on 15 psi will be way too much for your engine to handle and only want 10 psi (X amount of expected power on that sized turbo)..and it spikes to 15 then your motor will be gone.
Of course you may get away with it but if you have a certain amount of ignition timing or are using a certain fuel or are aware of any other restriction or limit, you wouldn't want to exceed that limit by a huge amount by surprise.
If you put a 14 pound wastegate spring in, you understandably want to limit to 14 psi and not have a surprise amount of spike, frightening stuff as that's gambling with your engine.

 

I have always reference from the intake, but this time around I plan on in the charge pipe. I was going to go off the compressor housing since its like 8 inches from my gate, but my buddy recommended in front of the throttle body. I never really thought of it much, but I think Ill make him weld the bung in the compressor housing.

Should I be referencing the Boost controller from the intake or compressor housing as well? I'm gonna go with an innvoate SCG-1 (basically a tru-boost with Wideband)

Jay

 

Again, for the wastegate signal line, if you have it going from the intake, when the certain boost figure from the intake reaches the wastegate it says ok that's at our limit so let's open the wastegate to relieve any excess boost past your limit(such as the spring). It won't matter for a short while that the wastegate is open as you already have way more boost pressure inside your intake and feeding your engine which will be fatal if you didn't plan on it.

Beanslsxnova already mentioned how he was seeing about 4 to 5 lbs higher boost on initial spool so you see a real example of what happens with this routing. If you really don't want to drill a nipple into the compressor housing even though many turbos have one from the manufacturer and that's frustrating if yours doesn't, you could still screw in a nipple into the piping just before the intercooler but the sooner after the turbo outlet the better so you can actually control boost.

 

Did your buddy maybe mean in front of the throttle body for your boost gauge?
Also as far as the intake manifold referencing, that's for your BLOW OFF VALVE just incase you guys might be thinking of the right location but wrong part.
If your buddy truly meant wastegate reference from in front of tb, please don't ever take advice from him again. I may have a low post count because I just started going on this forum for my swap but please hear me out on all this. I had a turbo setup in my other car last for over 6 years (10psi) on the original engine (non turbo-bone stock bottom end) and it's still doing great with the new owner

 

You guys must have boost leaks somewhere as the most pressure drop I have ever experienced with 3 inch piping and a giant front mount intercooler was under a pound unless my spring wasn't a true 10 psi spring despite reading 10 psi on my gauge.

I understand how you guys are referencing to the intake for the WG as if you put in a 14 pound spring into the wastegate , you are doing so because you want 14 psi at the engine. That's not a safe method though as if you are compensating for boost pressure drop along the piping, get a boost controller and start at low boost and read what your boost gauge says and adjust as necessary until you see your target boost on the gauge(boost gauge referenced to intake manifold aka true boost engine sees). If you reference the WG to the intake you could see a huge unexpected spike because even if the wastegate opens after reading the intake manifold pressure, it won't slow your turbo fast enough...that's what I'm getting at. Proceed at your own risk if you route it differently but don't be surprised if your engine can't handle the short burst of the surprise amount.

Get a manual boost controller but remember that you can't boost lower than what your wastegate spring is rated for so go for the smaller spring so you have more control. The boost controller will only be able to boost higher than the WG spring as it will mask any boost pressure from your wastegate(depending on your controller style) and thus achieve higher pressures until the setting you enable starts sending signal to your WG..but please test it out in small increments until you see what you want on the guage. With boost controllers ALSO make sure the routing is in between the compressor and the wastegate, there shouldn't be any routings past the intercooler .

 

Well most on here put it near or in the intake bc they want to get the closest to actual pressure. That's how I always did it on past build but all of them were fairly low boost and I never noticed any issues.

However this time around I will have the bung welded on the compressor housing. it doesnt bother my drilling it since its a ebay GT45 and im already cutting off the outlet to weld on a V-band.

Jay

 

That's a good plan Jay and on low boost setups I see how there is leeway in case you see more boost. What I was stressing is that let's say you are boosting an engine that you know can't see more than 500 rwhp on whatever rods and bottom end you have. Let's say you know that on a certain turbo, 13 psi makes 470 rwhp and that's your limit. Then with your 13 psi WG spring you go for a pull and as the pressure is coming out of the compressor it's still building and building past 13psi as your turbo hasn't slowed down yet as the wastegate is still closed.
Now the first bit of pressure reaches your engine and then that first 13 psi reference from the intake manifold starts heading to the wastegate to tell it to open up....the wastegate opens but now all through the rest of the piping you have way over 13 psi and now the turbo starts slowing down and the pressure is maintained at 13psi due to the open WG.

For the short while of the delay, your engine may have seen 540 rwhp. It's a short while but if that bottom end is limited to 500 rwhp then I don't see why you wouldn't cause damage even if it wasn't a long time at that power level.

 

You may have not seen a spike with your turbo and piping combination but a different combination will see different results and either a much larger spike or no spike at all. Beanlsxnova saw a 4 to 5 psi spike on initial spool as he most likely has a completely different setup from you. I'de say you were extremely lucky with your setup not spiking because if you were at your injector duty cycle maximum and fuel pump output maximum based on the power you suited for, any more air flow from the turbo would cause a lean condition. I personally don't know if a 1 or 2 second lean condition would be enough for terminal damage but it might cause some damage if you did see spikes over time.

***I read the sticky and how it says boost reference for the WG should be a pre throttle body source but that is too vague, misleading and dangerous. Source from as close to the compressor as possible, even drilling a hole in your intercooler inlet hose and screwing in a nipple is good enough. Million times better than being closer to the intake manifold as the delay may bite you one day.***

 

I ran mine from the turbo housing and was getting about 9#to the engine with a 10 spring so I added a port after my intercooler but before the throttle body.and that got me back to 10 lbs. I whould'nt hook to the intake I don't think you want the wastegate closing that fast.with the rpm high and vacuum sucking the wastegate closed.

 

There we go see, 1 pound of pressure drop is pretty fair. If you get any more pressure drop then even a little $30 manual boost controller properly routed (compressor housing or piping --> controller --> wastegate) will compensate for any pressure drop SAFELY. No need to cheat and gamble by hooking it up closer to the TB. The faster your turbo spools the more boost spike you will see on initial spool-up. I realize I've repeated myself 50 times haha just trying to save people from possible engine damage

 

On the compressor or as close as possible you want the strongest source that way the wastegate is opened faster. Lets say you drop 3 psi from the compressor to the intake so the engine is seeing 9 instead of 12. Now if you use the compressor to feed the wastegate your using 12psi to open it resulting in the gate opening faster and giving you the lowest amount of boost for that spring. With the 9 psi you are putting less force on the spring to open so your going to have more of a chance of a spike because its not opening as fast and higher minimum boost.

 

I pull from after intercooler before throttle body.
0 spikes, runs 9psi with 9 lb springs, when I add 2 pounds with the ams I have 2 more pounds over spring.
This is on a stock ls3 with twin 6266, DKT 1.06 a/r spools at 3600...

 

I could see shortly after the intercooler not being too much of an issue but right by the throttle body despite being before it seems risky.

I just wonder how much of that extra pressure dissipates when it is past the intercooler and by the tb when the wastegate opens up. If the WG is open then the turbo is only pushing that lower amount that the spring or regulator is set to...but if at some point 14 psi was created within the piping on initial spool then it would seem that the closer to the intake manifold (pre TB), then the higher chance you would see that larger pressure temporarily.

Still seems silly that people can spend thousands on their engine and turbo kit but can't buy a boost controller and properly route their damn signal lines. If you get pressure drop from the compressor housing as your signal line, then turn up the boost..problem solved!!!

 

Risky?

Read your posts... I fail to agree with your choice to not use a reference close to the tb. I have used the same setup up to 24 psi on a set of 6266s and 1300whp. Guess I like to live on the edge...