All commonly used automotive wastegates utilize manifold boost/vacuum to actuate and control the valve, and all wastegates control boost via bypassing exhaust energy on the turbine side. A blow off valve, BOV, is used on the compressor side of the turbo system. A BOV is always located in the system between the compressor housing and the throttle body. It can be between the turbo and the intercooler, attached to the intercooler end tanks, or inbetween the intercooler and the throttle body.

In the picture I posted above, you will see the HKS wastegate to the left of the turbine housing. It is angled off of the header collector to allow smooth flow into the wastegate - this is an external wastegate arrangement. Alot of OEM's and lower power level systems utilize an internal wastegate which utilizes a similar design but is attached to the turbo itself. It utilizes a hole on the turbine housing to bypass exhaust energy and control boost. It't benefit is it is more compact and works well in space limited setups, but it is limited in relative terms to it's ab ility to bypass enough exhaust energy as power levels increase. The result is boost creep, and if boost is allowed to increase beyond what it is mechnically capable of or tuned for, damage will result form an overboost condition.

 

The waste gate is on the exhuast part of the turbo. It is a valve similar to a fuel pressure regulator. this allows the exhuast to bypass the turbo's exhuast impreller and go down the exhuast pipe instead. think of it as a short cut I guess, from the motor to the muffler (going around the turbo).

You need this short cut to keep your impreller from over reving, or producing too much boost/controlling it.
When the wastegate opens, some exhuast goes around, and some continues on into the turbo maintaing the boost setting you set.

the internal waste gates are a simple round flap in the turbo. this also need an external actuator to open the flap.

An external waste gate is pretty big.
You can see it on Montys car, it is between the driver side turbo intake tube(Blue) and the driver side head/valve cover. this is a valve with and in and out port. you would route the exhuast into the waste gate from the header collector, and connect back into the turbo down pipe.




[Modified by bill mcdonald, 7:05 PM 2/11/2003]

 

Is there an advantage to an external or internal beside internal takes up less space??? Monty, what kinda of boost controller are you using?? Is the FAST system taking care of that??...

If it is, does anyone know how the HKS/Greddy/APEX i boost controllers are?.. They like and sound liek they are really nice...... The APEX i its the nicest i think.. but they are all about $500-600.....

What would I need with an internal wategate to controll it from inside the car?

Thanks in advance, and sorry about all the random questions.... Im kinda excitied.. I ran the idea past ym dad with a whole presentation, lol, he pretty much said its a go.. just have to worry about the headers, heat "Thats a lot of heat" and aluminum welding..... I think its really gonna happen and not just talk :yesnod: :yesnod:

 

Same questions ad Kevin, But I'm not sure what youhave to do to weld aluminum, I only welded steel and some other unknown metals, but I never touched Aluminum, do you have to take extra steps or get a special Wire for the welder and lower the current down even more with aluminum or something? How much do aluminum pipes come fr anyways? COuld we just use any type of aluminum pipe or does it have to have a special wall thickness to work?

ALso with the external Wastegate, MOnty you said that the wastegate only opens when it reaches a set point of PSI depending on the spring rating, so Where does the conrtoller nobe from the inside of the Car come from or how does that work? I get how a Wastegate works and all, but I dont understand that if it depends on Spring rate, then how does the boost controller change the max boost? Please help me out :confused: ;)

 

Is this the site your talking about? http://www.i-m-racing.com/profpercen.html IThey only have the settings in Bar, they dont have it in PSI? IF you do get this, does it really matter what kind of spring rate your get for your wastegate or not? LIke If I just want only 8psi MAX, so would I just get a #8 spring and not worry about boost controller?

OR later on if I build up my engine and I'm running 800-900 FLy HP then I could go say #20 spring and then get a boost controller so when someone else drives my car they wont feel the full Max POwer of it, Only as much I would allow, IS this some how the way O rdo I got it wrong? NO flames or repeating others, over and over again okay? :seeya :chevy

 

It doesn't work that way. The spring in the boost controller is the smallest amount of maximum boost you can run....if that makes sense. If you have an 8# spring and you add a boost controller you can not make the wastegate open up at 6#. However, you can make the waste gate open at any amount above 8#, like 10, 12, or 25 if you feel really ambitious :jester

The pressure from the intake manifold is what tells the wastegate to open. There is no way to increase that pressure, only a way to bleed some of it off to make it less. Hence why it will open at a higher rating than the spring and not a lower one. I hope this helps :cheers:

 

The aluminum welding isn't to big of a deal... just got to becare you dont stay in one place to long... woops theres a hole, lol.... You use less amps and a different gas..... Argon if im not mistaken, I prob am... (he has all the stuff nessarsay for it) just got to be careful, Steel tubing is going to be heavy and bulky.. My intercooling piping is going to be aluminum and Im going to buy a core and make my own intercooler...... The thinker the gauge the better I guess.... Dont want something flimsy.... Ill use steel where ever nessasary, but whenever i can Im using aluminum

 

The advantage of the external wastegate is that have higher flow and can bypass more exhaust energy than an internal wastegate. This is beneficial for larger turbos, higher boost/higher powered applications. Internal wastegates are more compact, integral with the turbo, and more economical. For most street applications, they are sufficient.

I'm currently still using a manual"dial a boost" boost controller, but I have an Innovative Turbo MSBC-1 electronic boost controller that I haven't gotten around to installing yet. I like the MSBC (Multi Stage Boost Controller) because it allows you to program up to 6 stages of boost, with a 0-60 psi range in 1 psi increments. It also allows you to custom tailor those 6 stages with up to 9 different boost ramps allowing you to control how fast boost builds in each of theose stages. It also includes a Launch stage for drag racing. Additonal features include shift or gear input allowing you to tailor the boost ramp and curve for different gears or for other conditions via the inputs. It includes a readout for actual, targeted boost, and boost ramp (increase rate). It uttilizes two solenoids - one to increase, and one to decrease boost - rather than one as with most EBC's. Most importantly, it incorporates an internal pressure sensor which will guarantee precise boost control despite changes in atmoshperic conditions, altitude, load, or mechanical variations. MAnual boost controllers cannot do this and are highly susceptibel to changes in baromteric pressure, temperature, humidity, altitude, etc. This will result in inconsistent boost control as atmospheric conditions vary. Alot of EBC do not have this feature.

Unfortunately, the current FAST system architecture does not incorporate the ability to integrate boost control, but the new FAST system will. It will feature user programmable inputs/outputs which will allow you top control boost, similar to the high-end Motec setups.

The new FAST system is supposedly in Beta and due out within the year and is promised to be more like the Motec.

Welding aluminum is more challenging, and requires gretaer skill than welding steel or stainless. I only TIG weld, and have never MIG welded, so I dont know all the particulars for that welding process. TIG is the preffered process for welding aluminum, and you will need to use a pure tungsten electrode, AC current with Squarewave starts for best results. The key to welding aluminum is cleanliness. The material must be clean, deoxidized and uncontaminated. New material is preferred over used, as it is mcuh easier to get a good, clean weld.

You can get aluminum from Burn's Stainless, Specialty Products Desings, aviation/kit plane supply companies, and most metal warehouses/distributors. Since aluminum will work fatigue, it's best to use something like 16 guage material, .065" thickness, for a street applicaiton where durability/reliability is highly desired. for a racing application, thinner material is used for weight savings, but it isn't exposed to as many work cycles as a street car would be.

Back to the wastegate questions, here's a schematic for how to plumb the typical twin turbo wastegate arrangement. A single turbo would be the same, only without the second wategate and plumbing. This should help illustrate wwhat I was trying to descibe in my previous post. An electonic boost controlled ssytem operates the same wy, except the electic solenoids take the place of the manual valve.

 

Thanks Monty & mn_vette for that, I understand it a whole lot better now, Umm where could I pick up an INtercooler for my Vette? KInda like yours where the Turbo compressor outlets go to the bottom of the intercooler and come up to feed into the intake. If I find an INtercooler from a Diesel Truck, like a BobCat and use it, will it flow enough so its not restrictive? Or is it not worth it and Intercoolers arnt too expensive? ALso could you post a link to the F.A.S.T. systems?

So that can control the Engine, Transmission and does it control the Guages as well? Like if you change your rear ratio and Transmission you plug in the FAST system and it will help correct them, from reading wrong numbers?

Now I just got to worry about my weak drivetrain :rolleyes:

 

Thats some good info guys.. Thanks a lot.... Today I went to the store and picked up a book called "Maximum Boost" by Corky Bell... it is $35 and worth every penny..... It tell you basicallly everything you will neeed to knopw about making and designing your own turbo system.... Its great, Im enjoying the read too. I suggest you guys pick it up :yesnod:

 

COuld I get this from "BORDERS"? I live abut 3/4 of a mile away. I'll try to pick one up, thanks for the tip :thumbs: :yesnod:

 

I picked mine up at Barnes And Noble.... Although it was listed out of stock, and said so for the rest of the stores on the island.. I looked and there was one left :yesnod: Very cool... You'll enjoy....

 

I'll leave to get it in about 1/2 an hour, but what kind of stuff does it have? Custom Turbo problems you will face tip? Or just everything that has to do with a Turbo setup explained andwritten out? Ohwell, by the time you read this I'll probably already have the book. :D

Anyways, so Now I think I'm going to go with an electronic Boost controll, Looks pretty cool to. But I dont want to rip out my CD player or A/C Controls. I think I could mount it where the cup holders are and just take them out and install the Boost Control. Also I could put a lock on it, so when I let someone else drive it it will be only limmited to what I set it to before I get out and let someone else drive it around( Highly unlikely anyway) :yesnod: What other places could one place thy Boost controller in thy cockpit? :lol: No for real's, any other places? ;) :chevy

 

Unfortunately, intercoolers are not cheap and often times cost more than the turbochargers themselves. Spearco/Turbonetics and Griffith are some of the more popular suppliers of aftermarket intercooler cores. However, they are generally the most expensive. My intercooler uses the largest air/air core available and it was around $900. I then had to fabricate and weld the end tanks and connection bungs on it to make the intercooler. A shop would probably charge around $300-500 to do this for you.

I am not familiar with what diesel or junkyard intercoolers would work, but I would suggest posing the questing to the JYTurbo group or the forced induction/power adder sections of the F-body forums. There are many guys over their doing home-made system using used parts. They can tell you what cars make good donors. More than likely, you will still need to modify the intercooler to fit your specific application. I've seen alot of guys used a Powerstroke intercooler and cut the end tanks off, and reweld new custom tanks on.

Here's the link to F.A.S.T.. If you have any specific questions regarding F.A.S.T. or other aftermarket EFI sytems, check out the EFI forums on the Turbobuick.com and Chevytalk.com sites. The moderators of the forums are employees of F.A.S.T. and Holley EFI.

Unfortunately at this time, F.A.S.T. or Accel DFI do not control the transmission (other than convertor lockup for the DFI). You'll need another stand alone transmission controller like the F.A.S.T./TCI T-com or equivalent if you have a 4L60E or 4L80E. However, your factory computer can still control the tranny even if you add the aftermarket ECU to control the engine.

Neither system interfaces with your gauges.

 

I'll check into the F-body forums. ALso I think I'll stick to the Stcok ECm to control all the other stuff and I''' use the one from the MPFI kit to run that system itself.

SO if I go this WasteGate stuff right, you could put the external wastegate before the Turbo and then I would have to make an extra pipe from the watsegate so when it leaks out the extra gasses they can escape, and go to the down pipe or something like that? ;)

 

Exactly. If you look at my setup, you will see that the wastegate is mounted at an angle off the header collector, right before the turbocharger, then it discharges via a 1.25" pipe back into the downpipe. This creates a smooth path for the exhaust energy to enter the wastegate gate when open. It's better to have the watsegate come off the collector becuase it provides a more even bypassing of the exhaust energy among all the primary's on that cylinder. Otherwise you'll end up with uneven flow and pressure among the individual primary's.

Then as you mentioned you need to handle the wastegate discharge. I routed my wastegate discharge back into the downpipe since mine is a street car, but for racing applications or for situations where maximum performance is prioritized over system complexity, weight, and noise, you can simply exhaust the wastegate into the atmosphere. An open wastegate under load or at WOT makes alot of noise though. If you didn't want to route the wastegate discharge back into the downpipe/exhaust system, you could built a seperate exhaust ssytem for the wastegates and include a muffler if noise is an issue, but you'll be adding even more plumbing, complexity, weight etc to your system.

 

Thanks for the help, but I couldnt get the book yesterday so I'll be able to get it around 6 today hopefully. Monty is this your first Twin Turbo car or have you built many before in the past? :confused:

 

This is my first custom twin turbo and I have helped a couple of other people build theirs. I used to have a turbo Rx7 when I was in Highschool and College. I guess I was a ricer before there was such a thing as a Ricer. I had a header on it and a custom exhaust with a Supertrap stainless steel muffler. It sounded like a WOT weedeater under water, LOL, but I thought it was cool and it was a heckuva fun car...nothing like spinning a turbo rotary engine to 8000rpms.





[Modified by Monty, 6:10 PM 2/13/2003]

 

Dang, what year was the RX? Anyways, could you post a couple of links of intercooler manufactures? BTW the diesel ones are kinda simple arnt they? All you would have to do is cut off the ends and then weld in the new covers for each side customly for the application. If I could find one I'll use it, but the ones I have so Far are like 4 ft wide and 4 ft tall and like 5 inches thick and its a 3 Core. That thing must really flow :yesnod:

 

light84, look for one from a small truck, like a bobtruck. or look at the diesel pick ups. if you cant score one there, check with your local radiator shop. most reputable ones have a catalog with every configuration you can imagine. since your dad has his own shop you should be able to get it for a little over cost.