Controling Turbo Boost--protecting Turbos

[robfrey]

I've been using chi-com waste gates for years. I've had boost issues but none traced to waste gate quality.
I just bought two 50mm GodSpeed units from Amazon. They are inexpensive and pretty nice. Actually the nicest cheap units I have seen so far. I know a bit about manufacturing and I have no idea how they could sell these that cheap. Material and machining must be free in China. I also like the flanges and they fit 2" O.D. tubing beautifully. I plan on buying two more as spares and will spring them differently. If you buy the same units, my spares will be available to you (as long as we are there).

[robfrey]

I also noticed that you went pretty big on your exhaust housings (1.32). That will optimize power but may give you problems at gear change. The engine can drop out of rpm range at gear change drop off target boost. Sometimes, blowing a little excess exhaust through waste gates by using a smaller housing will give you a wider power band with little loss to max hp.
I would not  worry about accidental over boost. Just hookup a Hobbs switch to your ignition box and deactivate the box if boost goes too high. McMaster has them cheap.
As far as trying to control boost in different gears, I wouldn't bother. It will just add to the complexity and give you more things to go wrong. That being said, I have never run a blow thru before in a situation that I had to pedal the throttle at all. Might be issues.with afr pedaling a blow thru carb.
I do not plan on varying boost on our liner. Just using two air pressure regulators, one on the top side of the waste gates and one on the bottom.

[CTX-SLPR]

I know this is bordering on a rules forum question but considering that most people reading this site for tech info will wonder if they can use it if they are in one of the OBC's (Other Backwards Classes, play on Hindu Brahmin term for lower castes) like I am in Classic.  I know there is a prohibition on electronic feedback type engine controls I would certainly see a boost controller as in the category.  What would be the suggestion for controlling turbos accurately if you can't use a HKS or AMS 1000?  Hobbes switches with a compressed air supply to "fire" the wastegates open?

Thanks,

[robfrey]

I know this is bordering on a rules forum question but considering that most people reading this site for tech info will wonder if they can use it if they are in one of the OBC's (Other Backwards Classes, play on Hindu Brahmin term for lower castes) like I am in Classic.  I know there is a prohibition on electronic feedback type engine controls I would certainly see a boost controller as in the category.  What would be the suggestion for controlling turbos accurately if you can't use a HKS or AMS 1000?  Hobbes switches with a compressed air supply to "fire" the wastegates open?

Thanks,

Wastegates springs, regulators, and your right foot. If you have enough spring, you can make a good supply of pressurized air without running a separate CO2 tank. If you need stages, use a couple of solenoids and regulators set to different pressures.
I have yet to see a accurate boost controller that monitors boost and adjust gate pressure to keep boost on target. Some claim they will do this but they always seem to work best by monitoring gate pressure and not manifold pressure. This was definitely the case with the MSD controller I ran on Vinny. I struggled with it for a long time until I moved the sensor to the gates. Then it worked pretty good. The MSD and the AMS are time based systems and I don't think they are very good candidates for LSR.
A good friend of mine that races Promods has tried and successfully used the AMS and the Hypercontroller but has gone back to timers and individual solenoids and regulators. Cost of hardware was definitely not a factor in this decision.
The MSD unit that we used on the 3838 Vette worked great on the chassis Dyno a week before we left for SpeedWeek  but failed to do its job when we got to Bonneville. Can't figure out why, everything looked fine.

[SPARKY]

different application but similiar physics:

lifetimes ago I flew high performance gliders, we had TOTAL ENERGY SYSTEMS variometers---very sensative RoC rate of climbs, they worked with static pressures, signal generstors ie a venturi, and a reseivor which we used a thermos bottle to compensate for the huge altitude "working range" we had in the mountainous west we had a normal and a high altitude.  these were  a needle through a hole---which we could control the flow rate to settle the units "needle quiver"
we switched back and forth with what we called a Clippered valve which was just a little pneumatic flip switch.
 If one had one switch to control the gate to "dump" pressure for a shift when you flipped back the rate of increase should be able to controlled by an orfice that controlled how fast the pressure was able to build back up.

[Richard 2]

They make manual needle valve boost controlers

[aut0m4tic]

I use a manual boost controller.  The cheap chi comm manual boost controllers can be dangerous.  I had one that adjusted exponentialy. 1 turn 1psi 2 turns 3psi 2.5 turns 5 psi   guaranteed to overboost.
  Mine is homebuilt (not by me) but works very linear.  A friend uses 2 electronic but manually adjusted  boost solenoids. One set at 10psi one at 22psi and switches between them on a dash mounted switch. 

Cory

[CTX-SLPR]

Sounds like really low pressure springs on the wastegate and then hobbes switchs firing Clippard or Swagelok, or whoever's pnuematic valves is the answer for "analog" boost control.  Good thing I work with that type of pnuematic valves on a daily basis and might even have some "junkers" laying around.

[NathanStewart]

Hey Sparky, one of our tech guys came over and told me a real nice Southern soundin' fellow from Arizona that's building a lakester called asking about a boost controller.  Think that mighta been you?      Shoot me an email at work: nstewart@aempower.com