Controling Turbo Boost--protecting Turbos

[SPARKY]

A blow of valve is to protect the turbo if one closes the throttle

A waste gate controls the exhaust energy to the turbo to control air delivered.

What would be the consequences of using a "wastegate" to bleed off boost-- to control power output --as a form of traction control---a run away turbo?

[Stainless1]

Sparky, the blow off will also bleed boost, they have a control port

[SPARKY]

Well, if anyone doubted I was "dumber than a box of rocks"  about turbos  I have removed all doubt---lol

[John Burk]

Waste gate traction control is what Ron Main uses . Boost preset by trial and error for each gear and steps up at each shift . The advantage with preset is that traction can always be maximum . With closed loop TC that maintains wheel slip at x% traction is always past peak .

[Jon]

The downside of using the blowoff valve to control boost pressure is that you heat the air more than you need to.

Ideally the blowoff will only open on a spike when you take your foot of suddenly e.g. a manual gearshift.

I will be setting up to flat shift and most likely not run a blowoff, will probably run a burst panel for backfire though.

Cheers
Jon

[Rex Schimmer]

You have to be careful using "pop off" valves to control boost. The design of the valve gets to be real important. Most of us think of a pop off as being some sort of spring loaded plate covering a hole in the inlet plenum, this type of valve has a couple of faults if you want to use it to closely control plenum pressure. When it is open, even a small amount, it presents a very large area for the pressurized gas to escape and it is very difficult to modulate the amount of the opening to provide very accurate pressure control. The other characteristic of this type of valve is that it closes at a different pressure than it opens, as the pop off plate is larger than the hole it covers the pressure to open is based upon the area of the hole that it is covering. When it is once open a larger area, that of the cover plate, is presented to the manifold pressure and it may require that the manifold pressure drop substantially to allow the plate to reset. All of this makes it a very difficult way to control manifold boost. This was one of the challenges that the Indy guys had with the USAC pressure control pop off valve, it would open at say 50 inches of pressure but would not reseat until the pressure was down to 40-45 inches. The drivers would  actually run 1/8 inch plastic tubing from the valve  to their ears and listen for the valve to just start opening and they would dial down the boost with the waste gate before the pop off opened completely. The type of valve that you would want would be one with a piston sliding in a sleeve with probably some sort of vertical slot or vee that is opened gradually as the piston moves up the sleeve. Because the piston is always presenting the same area to the plenum pressure there is no hysteresis in its action and is much easier to control. Using a waste gate with either a servo driven pressure control valve or with multiple control valves set at different pressures that are selectable seems to me to be the best way to accurately control boost..

I have only been associated with turbos on road racing cars, 935 Porsches and a turboed V6 Chevy that Ryan Falconer built for us and each used the waste gate for pressure control.

Rex  

[panic]

Very nice, thanks - like a big OPRV.

[bak189]

On our LSR Turbo sidecar (now retired and for sale) we always had a big problem with traction.....we controlled traction with controling the wastegate pressure
We did use a pop-off valve for safety................................................................

[SPARKY]

Rex-- do you have one in mind  I found  a supplier here in Phoenix to buy some T4 blanks to make my exhaust manifold to the turbine inlet.
hwy69rqcing.com  Clint Hudgeons most helpful

He told me that some of the drag race teams are using wastegates to stage their power levels--they are using multi stage wastegate controlers.

Exhaust wategates control turbo impeller speeds;  the power level is controled by how much air pressure is bypassed out of the intake  system before the throttle blades.

[Jon]

Did you get an email Sparky?

Maximum Boost by Corky Bell as PDF

[SPARKY]

I read it once a long time ago---I need to find my copy and read it again ---then read it again---thanks Jon!

I am looking at a TurboSmart unit from down under Jon!!

[maj]

That the e-boost 2 Sparky ?
Boost control has come a long way with the various electronic controllers now

Another to consider is the AMS-1000

They work differently, so one may suit you more than the other

E-boost presets a pulse width modulation (duty cycle) to a solenoid,
 the solenoid can be used in different ways, but the most common with an external wastegate is to divert some of the air used to activate the wastegate  and send it to the spring side of the diaphram , this adds to the spring pressure in a controlled manner, the higher the duty cycle the more manifold pressure adding to the spring pressure and more boost
you set it and then test the result for each stage, our bikes run a similar system and some previously were running the E-Boost
10% DC would raise the boost level a couple of psi, and 80% was about the max we used on a 6 psi wastegate spring to get ~28 psi in the plenum
Good thing about the eboost was the dc was not necessarily a set rate through the whole gear , you can tailor the boost curve to ramp up after a gear change and not be a big step at the change, or pull some boost out at the top of the rpm range , all you had to do was understand the instructions.... that was the difficult part

Ams-1000, probably more experianced guys with these than me here  .
But basically its reactive, you set a boost level and it aims for it , has 2 solenoids , one to add air and the other to release

[maj]

Page was giving me difficultys

Both use external triggers to change boost levels, not sure how it would work for traction control,
the eboost has 2 wires for the trigger, giving various combos as a direct trigger , no wires, green, orange, green and orange gives 4 levels of control
or using it sequentially where the orange may be a reset and green the trigger to step up a level

Probably easies to download the manuals and get an overview on what they may or may not do that suits your application

[SPARKY]

MaJ the Eboost 2 is what Sum and I are looking at for the exhast wastgate control.
 We are planning on stepping it like you say especially in Low and direct. Both I will have a 3000 rpm "Climb" and nearly 100 mph once the turbos are "LIT". 

These are the gears  I "need"  some type of variable power control-- not  throttle related  just how much boost .
Squirle Performance turbo graphs say I am going to double my power in about 500 rpms between 37-38 and 4200.  With my old car I know from experience that only a 150 hp jump in 200 rpm on a less than "good" track momentarialy asks for the driver to pay attention

 Tom Burkland told me how Don Vesco tried to control it years ago on the Yamahas with a foot throtle that sereved a diffrent function in the last 1/3 of its travel.

Once I shif into high with a good track I do not think I will have much of a traction problem-- the stepped boost should be able to handle the problem.

[Stainless1]

Bill, in the later Kawasaki bike I think Don just had a knob, IIRC a regulator that he just turned up for more boost.  There are a lot of ways to skin this one, a MoTec could be set up so your throttle controlled boost. 
Any way you do it I would put a blowoff valve on it.  We had the waste gate stick once, interesting problem, run to 18psi dump to 0 run to 18, that run didn't last long.