ok on the link you had posted there are no multiple sizes of wastegate's or blow-off-valve's,

get the kit it comes with a 38mm external wastegate. you then pick the SPRING PRESSURE from the list so being that you are new to this i would say get a 3-4psi (.250Bar) spring, and purchase an electronic boost controller which will allow you to go up higher. This way you will still be able to run the car at low boost with the controller turned down

the optional 50mm bov goes in the intake and is there to keep the turbo compressor from building up to much pressure in the intake pipe when you shut the throttle so i would order it too.

one set of valves controls the turbo(wastegates) and one set keeps them from damaging themselves when you shut the throttle(bov's)

I thought the link I provided did. I've been reading the book and rereading on here what Nix said. Things are becoming far more clear now. Hopefully I'll be :driving: soon.

A couple of points: Both the BOV and the Waste Gate can run the excess to atmosphere, OR back into the exhaust or into the intake.

It is more complicated with piping for either to recirculate, but the options are there from GTM. For me, limiting at only 8-10 psi, it gets LOUD to dump waste exhaust out of a pipe unmuffled. I opted for an internal redirect back into the exhaust.

And the same goes for the BOV. The Tial's are the 'standard' which look great and give that unmistakable PPPSSShhhhhhhh when you let off the throttle.

Loud.... :stirthepot:

I chose to have (2) Synchronic BOV's installed from GTM and we recirculated the outlet back into the intake duct. Quiet release.

Do they affect power plumbed back in or out to atmosphere? Most will say there is more power to be had uncorked, but mine is the quietest and one of the quickest in the land.

So, you have to decide what you want.

Hope this helps.

Coop

I think you may have accidentally made a mistake. You most certainly would not ever run the wastegate output back into the intake. That would be fiercely hot exhaust gases going back into the intake tract, which is crazy. Notwithstanding the heat, most of the oxygen is gone. You would never do this.

Likewise, with the BOV vent, there would be no reason to ever run it into the exhaust tract. In fact, hooking the exhaust tract up to the BOV could cause some serious issues as BOV valves are not meant to be used at that temperature. Furthermore, with a post-MAF bov, you really need to run it back into the intake tract to keep AFR correct. Otherwise you are venting air that the MAFs have metered and expect to be combusted. You can tell a car running a VTA BOV post MAF because it will usually backfire after a shift because of the temporary super rich mixture.

Accordingly, your logical options are as such:
WG -> vent to atmosphere or reroute back to exhaust post-turbo
BOV -> vent to atmosphere or reroute back to intake post MAF (assuming BOV is post-MAF)

This is to prevent the sound of the WG I would think?

How would this effect overall pressure after the MAF, and engine performance?

Sorry I'm still learning. I want to make very educated decisions before I get my car so I'm ready to start when I get it. I'm a computer scientist with a math minor so I'm guessing the math part won't be overly difficult for me.

I have talked with my wife about it and I might try to reverse engineer the ECU if I get bored. Which would of course let me flash my own firmware onto it :)

Again thanks to everyone for answering questions and helping me. I know from experience helping new people can be a hassle.

EDIT: Also for any other noobs reading this post, I highly recommend that book I posted. It's less than 20 bucks and it has very up to date information on turbocharging. It's very noob friendly. You have to know "basically" how an engine works. If you do then the book will guide you from that. I think it's a good book even if you don't want to turbo honestly. You learn about displacement and compression and all that.

What is to prevent the sound of the wastegate? The wastegate doesn't really make any sound. It's just a valve. What makes a ton of noise is if you vent the wastegate to atmosphere because it's like a direct path from your engine to the outside with no muffler in-between. It's running a portion of your exhaust open which is LOUD.

I can't really answer your second question because I don't know that it makes sense.

I don't think you are going to have any luck reverse engineering the ECU so I would spend the time learning basic turbocharged engine operation instead. Luckily most of the kits out there are already well engineered so you don't really need to make any educated decisions about wastegates or BOVs.

^^ you're, of course, 100% correct. It's what I meant. Semantics.

One of the challenges of written text is to be precisely clear. My statement could have been misconstrued, and for a described n00b thread, it's important to not allow this.

Thanks.

I may have misunderstood you. When you said back to intake I thought you meant after the turbo and intercooler. Since the air is already pressurized and cooled. But you meant maybe back to before the compressor perhaps?

Am I still confused lol.

You would need to vent back to pre-turbo (unpressurized), post-maf to maintain proper metering. Because of the pressure drop through the tract and in particular after the IC, if you tried to route the BOV back to the post-turbo (i.e. pressurized) side, then the BOV may actually flow the wrong way. You need to think of everything in terms of pressures and note that high will always move to low.

Haha, as I am an attorney, I am used to trying to be precisely clear in all my written communications. For better or for worse (e.g. ask my gf her opinion :shakes head:).

I know this is an old thread, but I figured it beats opening a new one.

===

Maybe I am thinking about this wrong. A boost controller basically works to control the air pressure in the line going to the wastegate. By venting some (or for this example all) you can bypass the wastegate all together and run whatever boost you wish correct?

So if lets say you ran the lowest spring you could find is 5PSI, you cannot control your boost till you hit 5PSI, but then you have complete control over your boost (based on rpm and tp% with the EVC6 with its 3D mapping).

So why not run a 3PSI spring? This would allow complete control over and above 3PSI. I am sure there must be a tradeoff, would the valve open under higher manifold pressures due to the softer spring? If so do companies list a maximum manifold pressure for their springs?

If this was possible then you could (if you wanted) have the boost come on just like it would a supercharger and not so much like an off on switch. This would be beneficial to keep the tires from spinning and the power to the ground.

Unless I am thinking about it wrong?

There are a couple of reasons. First of all, practically speaking, you are going to want to make low-end boost under almost all circumstances since boosted cars can be under powered NA (ever watch Top Gear when they run the Evo in 6th gear?). Thus, a spring is there to help with that. Second, you would likely wear the boost control solenoid out significantly quicker if you did not have a spring because it would have to work harder. Third, my guess is that the spring actually helps to smooth out the action of the boost control solenoid, which is essentially just a bunch of pulses timed to achieve a target (i.e. a duty factor).

Thanks NXlimited for your reply,

First - You could go about setting the minimum boost to achieve say stock HP numbers down low (whether it be 3psi or 5psi). But I do see what you mean.

Second - The spring would still be there and would serve the exact same purpose as say a 9psi spring. The solenoid is a duty type designed to switch on and off very quickly to control boost, its going to cycle anyways and I am sure there is a maximum duty cycle set by the EBC which might be out of range to be able to do something like this.

Third - The spring as a response rate much the same as a boost control solenoid, in fact the solenoid will have much faster times. Running without (or with when the EBC requires) your spring opens and closes the valve continually to regulate pressure.


Here is a link to the 3d table that you have access to,

http://image.importtuner.com/f/tech/...+boost-map.jpg

Just thought I would put my 2 cents in here as I saw a post on the 1st page with some bad info.

A wastegate is possibly the only component in your whole engine package that can actually be made smaller as you increase your boost/horsepower output.

Big Turbo/Low Boost = Bigger Wastegate
Big Turbo/High Boost = Smaller Wastegate
Small Turbo/High Boost = Smaller Wastegate
Small Turbo/Low Boost = Bigger Wastegate

If I may jump on topic with GLOKWORK; my high boost is set to roughly 10.4 PSI and the Greddy supplies a 4.5 PSI WG spring. I hit the target boost level, but it is not steady. From what I have learned over the last two weeks is to get a WG spring that is close to your target boost (or low boost setting in my case), but no less than half of your high boost target.

To the OP:

If you are looking at GTM TT kits, you will have a hard time going wrong parts-wise. I would just suggest going with an Electronic Boost Controller if you plan on going with External WasteGates. As long as you can communicate your intended use or power goal, GTM (or any competent builder/tuner) can get you where you need to be.........with the right budget of course.