Hey all,
As I understand the recommended way to set up the boost lines for the waste gate are as such.... from the turbo compressor housing to a "T"- one side of the "T" goes to the bottom side of the waste gate the other side of the "T" goes to( in my case) a boost solenoid "straight through" and then to the top side of the Waste gate. That is not my question. My turbo (an older garrett) doesnt have a nipple off the compressor. My question that is up for debate is, is it better to tap the compressor or in my case the first intercooler pipe right out of the turbo or the intercooler pipe right before the throttle bod?.
The reasoning for the later is that because of the intercooler, realized boost, after the intercooler that will actually be going into the intake manifold will be about 1 psi less than what would be read at the compressor giving the waste gate a discrepancy of ~1psi. It is a no, no to run a vacuum line/ post throttle body/ intake manifold as waste gates are not supposed to see vacuum and can be damaged.
What is everyone's recommendation and why?
Thanks

 

tap compressor for sure. assuming you have a quality ic core, its not going to be matter that much. let the wastegate do its work immediately by getting its source from the compressor.

 

When you say immediately. Can you back that up or explain further? The waste gate is doing its job right away. It has a spring keeping the plunger closed. Its not until it starts seeing positive boost via the line fed to it that it is then "tempted or made to open and that will not matter if the line that feeds it is further away as it is still doing its job, keeping the plunger closed until it sees enough boost to open, no?
Tell me if my logic is wrong....

What about best place for source for boost gauge for most accurate reading?

 

Depends, do you want the boost turbo is making or boost that your engine is seeing

 

That is an interesting question and one I hoped someone would have a point of view on.... I would assume that you want to know what the engine is seeing and could care less what the turbo was making. The turbo can blow all day long but your car is going no faster until it sees boost, right? That was my aim with the, "Where does the boost gauge get its reading from?". The intake manifold as you want to see what your engine is actually seeing.
Dont get me wrong i'm just looking for different perspectives and reasoning behind them?
What do you think?

 

You are correct. With one boost gauge, you only care about what the motor is seeing because that is the reading that could make or break a motor. If you were advanced enough and doing serious racing, you would want to monitor both the turbo and the motor to see what the delta is, similar MAP and EMAP to see how much backpressure exists. But, that is only for the advanced, you don't need to go that for for a street car. We're talking 9 and 8 sec 900whp cars there.

Yes, the best place for the wastegate to get its boost reference is the compressor housing. Its the most commonly used place because its the closest place to the wastegate with a suitable port. In your case (having a turbo with no port), it may be easier to obtain it from the hotside charge piping as that might be an easier place to tab (simple aluminum NPT bung) compared to having the compressor wheel tapped.

 

As posted above and to back up what I said above, if the wg is getting it's source from the compressor the hose will be one foot at most. If it gets it's source from the ic pipe(engine boost) it'll be a lot longer line. Keep hoses as short as possible when you can

 

 

Thanks a lot guys! That's just the kind of info I was looking.g for. So in capstone, for a race set up it would be good to monitor both the turbo and engine boost. But for a more conservative/street set up the compressor or for me the first ic pipe out of the turbo still hot side as close as I can get it is going to be best. Is this because the difference from turbo to engine boost will be very close or not matter that much?

 

I jsut realized you were talking about monitoring. Im concerned with the waste gate seeing the same pressure as what is going into the motor. Since i do have a choice and have to do the work to tap, Iam looking for the best and most accurate.... I guess i am just looking for clarity on if there is enough of a boost drop after the intercooler to make it worth while to have the barb on the cold side as closeto the throttle body as possible.

As redboost said it makes sense to have as short of pressure lines as possible but im unsure if that would be negligible?