Controling Turbo Boost--protecting Turbos

[SPARKY]

absolutely will have a blowoff valve.

[Rex Schimmer]

When Vesco started running the turboed Kawasaki 900 cc engines I understand that he started at a relatively low boost and short shifted to high gear then used the "knob" on the boost control to increase boost and therefore horse power and was able to control wheel spin. When he ran the TZ750 Yamaha engines they, being two strokes, would "come on the pipe" so hard that it would spin the tire and was the reason that they probably never ran at their  full potential.

The control system that Maj described is a proportional control of the boost using a variable voltage command signal. I am sure with some fairly straight forward electronics it could be made into a type of closed loop traction control. Another method would be to have several remote pressure control valves, which are really just air pressure regulators, set at different boost levels, connect them all in a parallel circuit and have a normally opened solenoid valve between the regulator and the pressure header to the waste gate. You start with all valves unenergized, so that the boost pressure is now controlled by the lowest set regulator and then as you need more boost you close the valve on the low set regulator and then the boost is then set by the next highest regulator and you do this for as many boost settings as you desire. If you loose electrical or shut off the engine all of the valves open and the boost goes to the lowest setting. Just another way to skin the cat.

Rex

[maj]

Yep the solenoids and regulators works well, used them for a few years on my roadbikes,
as good as a flat rate in an electronic controller , just a bit bigger than a single solenoid

its when you want to change the boost curve during a gear that you need the electronics

How were you looking to trigger the controller ? cars can be a bit trickier than bike with there gear position sensors easily modified for a gnd circuit/gear
or variable voltage from the sensor readable by the controller like the AMS1000

Actually a lot of drag car guys here are changing from the e-boost to the AMS

Also, commonly called blow off valves that use a pressure reference line to open on decelleration and hold closed on positive pressure will not save an overboost, they just seal tighter, you want a preset dump valve , usually ~1inch diameter spring loaded screw in to manifold type , probably find them on  some of the mid 80's turbo gm cars (our gm cars that were rebadged nissan had them ) ,   
Or a smaller BOV with a range of springs available and dont connect it to a pressure reference , and have it set quite a few psi above your intended level

[SPARKY]

jon, why are the guys changing?

[maj]

Greg =Maj 

The ams operates differently with its increase and decrease solenoids putting air from an external source directly to the wastegate top or spring side  and holding it at the desired pressure allowing a better control, for example you can throw away the wastegate spring and use air pressure only
Try giving Seb at Next Level Racing a call , http://www.nlrsystems.com/nlr_contact.html
nothing like getting your information direct from the supplier

[Rex Schimmer]

From a servo control stand point what Greg has described makes a lot of sense as the external pressure supply combined with a responsive proportional pressure control valve should make for a very responsive system and accurate. Used in drag racing or land speed racing it would certainly appear to be the best system for adjustability, response and accuracy and the ability to customize the boost curve to the requirements of the car/bike. Neat idea.

Rex

[NathanStewart]

Sparky, you planning on running blow thru carbs?  While I've heard the AMS is great I think you could actually pick up a small stand alone EMS for less and get more out of it.  I know of a system that does closed loop boost control with boost targets for engine speed, throttle position, gear, and vehicle speed.  Same system also does engine acceleration rate traction control, nitrous control, data logging, etc.  PM me if you're interested.   

[CTX-SLPR]

Are the electronic and feedback style boost controller legal in Classic?

[Richard 2]

I have tried TurboSmart at Bonneville. Get the AMS 1000

[Hellcat Customs]

Dunno if it matters much... I don't use electronics to control boost, it's all mechanical. We do run a bov in our system but at Bonneville we never had it blow off until shut down at the end of the run.... never heard it during shifts because we never really backed out of it while shifting. So could you run without it probably but I'm paranoid about these things and since it didn't hurt anything to have it we just left it in line.... the electronic world has come leaps and bounds in the turbo world, I just haven't tried any of these possible features because I'm not at that level just yet

[SPARKY]

We appreciate all the feedback--We may well be over thinking this---but I am trying to anticipate this:  We have had around 700 hp available--B'ville  corrected---we hope to double that.

 I know from the past that on avg tracks you NEED to be a driver at least part of the time.  Ruts, potholes, wet spots, loose areas, soft areas and the first shift, Salt Devils--ie thermals.  I just know that I have a LOT of new areas to learn mostly the X 2 of the torque availble to the rear wheels---there is a wing in the works--noo in my dreams-- but most likely will not be availabe this year .
The turbo works at Squirrel Perf. say that I will have 14-15-psi at 4000  that is above my shift rpm---so I THINK I am going to have to "curtail" the power some way when I shift and bring it back up on both shifts .
From what I have been told about the way turbos "pull" my wide ratio with only 2 shifts should make the "driving" easier--only SALTtime will tell.
Please keep posting your experiences we are all helping each other!!

So far what I think I have learned:
1. Wategates control turbo speed to manage output and from overspeeding.
2. BOV protect the turbos when the throttle is closed from excessive pressure that can damage the turbos and can be used on the compressor side to control boost levels
3.  Some are using another "wategale like" valve between the turbos and the throttlebody to momentarily "dump" boost at shifts or to address traction issues.

[maj]

Close

but using a bov to dump air while the turbo is loaded will contribute to overspeeding of the turbo  and wastegates do little to stop turbine overspeeding
 basically if your putting a lot of energy into the exhaust side you should be using it on the compressor

so releasing air from a bov or dump valve under power is a last resort for motor safety not a planned means of  boost control

If you were using a centrifigal supercharger that had mechanical control of compressor speed you could use the inlet side to control boost pressure

When you shift , you will take the load off the turbo briefly, and it will take a moment to pick up speed and pressure again , so your not going to have a lot of wheelspin at the shift, but at the rapid torque rise soon after the shift as you load the turbo exhaust again , thats where you can control the rate of pressure rise with electronic management  

Richard 2 , can i ask why you did not like the turbosmart unit at Bonneville ??

[SPARKY]

maj---so for we have not lifted when we shifted, we just shifted the PG once and the GV once--both without lifting---should we just think about lifting and getting back in it???

[maj]

Sorry more thinking of a manual,
you could put trigger switches on the pg and a relay off the gv switch and let the controller manage how the power is delivered

At least i have an understanding of the gv now , realy keen to see how its baby brother works on our liners   

[SPARKY]

I highly recomend setting it up where it freewheels when you lift or blow it up---we have been to that movie two times ---its nice to just ROOOOOLLLLL out instead of flat spotting the tyres.  also you can get a nice clean cut for a plug read