basic questions about turbochargers

[badkuk]

couldn't find an appropriate thread for this...


the impression i'm getting is that on turbocharged engines, you cycle through periods of boost(once max pressure is reached) alternating with sudden drops(once pressure drops down, and while you wait for pressure to build up)

is there a way of controlling the turbo? is it like NOS systems where you have this button you push, and zoom, off you go? Or are you at the mercy of come sort of cycle, so you'd just have to cope and time your moves accordingly?

[OTEP]

The transisition in most everyday turbo vehicles is not as sudden as your explanation suggests. Boost usually gradually builds up along with your revs.

Only the largest turboes feel like they are cycling on and off because of the amount of exhaust needed to turn the turbines.

There are manual boost controllers that can elevate the wastegate's opening pressure. I'm not sure if you can indeed control boost. You are still at the mercy of how much exhaust is passing through the turbine.

[nugundam93]

MBCs or manual boost controllers usually only control the opening of the wastegate, which is the safety valve of the turbo system to prevent overboost (garantisabog, so to speak).

and like what otep said, you're not actually at the mercy of the cycle, but more of at the mercy of the turbo size (which is dependent on your needs). after all, a smaller turbo could spool up quick, but doesn't have too much top-end power, and a big turbo could spool up pretty slow, but has the top-end power.

there is also an anti-lag solution in situations where there is no throttle input. fuel is injected into the exhaust manifold itself and ignited, allowing for a combustion which still allows the turbo to keep spooling in its "sweet spot", even if there is no throttle input.



hayyy...yun lang muna, sakit na ulo ko dito sa work. heheh.

[airshaq20]

Boost doesn't go in cycle. Boost is produced by your RPM..and unless you are pumping your gas pedal like a drummer, it wont be an up-and-down cycle (or else you will be driving a car that is running out of gas).

One way of "controlling" the boost is using a BOV or a DV.

If you have a car that uses an OEM DV and you use a BOV, i would suggest you to change it to a good aftermarket DV. A DV (Diverter Valve) and a BOV (Blow Off Valve) are very similar devices. The only difference is that a BOV vents most of the boost
pressure the the atmosphere when you shift, whereas a DV will only
vent EXCESS boost pressure to the atmosphere when you shift.. the rest
of the pressure it "diverts" back into the system, preventing you from
having to rebuild all that boost pressure when you enter your next
gear. BOV's sound "cooler" (shift-pfffttt-shift-pfffftt), but DV's are usually more useful to build your boost.

[nugundam93]

then again, there are also 2 main types of BOVs, one that vents to the atmosphere the pressure, or one that recirculates it back into the system after a very short time. and there are also hybrids of those 2 types.