Corky Bell's "Maximun Boost"

[Guest Anonymous]

Does anyone want to sell there copy of this book. If so, can you accept PayPal? There is/was only one on ebay, but it costs as much as it does at Barnes and Nobles.

 

I also have another newbie question. There is a valve between the intake turbine and the cylinder head to help keep the turbo spinning while shifting right? So, is there a similar set-up on the exhaust side or does the waste gat take care of that?

 

[ May 04, 2001: Message edited by: KS73Z ]

[Guest Anonymous]

I don't know why you'd need one unless you've got a butterfly in your exhaust that closes when you let off the gas.

 

Wastegates bleed off exhaust once your turbo is producing the amount of boost you set it to. They effectively function as a boost limiter so you don't continue to produce more and more boost and ultimately blow your engine up. They allow exhaust to bypass the turbo when opened up so the engine can still vent the exhaust gasses but not produce any more boost once the pre-set limit is reached.(At least this is what I've always been under the impression they do. If I'm wrong by all means someone smack me upside the head and correct me.)

[Guest Anonymous]

I had a decent grip on that part but:

 

When driving hard the turbo is spinning like a madman, right? So, when you lift off the gas to shift, the TB closes which causes back pressure on the turbo which will cause it to slow. This makes the pop-off or blow-off valve(not sure what this one is called)to open and let the turbo keep spinning. How am I doing so far?

 

So, if you restrict the air from going into the engine you also restrict the air coming out of the engine. With less air coming out of the engine and the turbo still spinning "like a madman" would you not create a vacuum in the exhaust manifold which would also slow the turbo? Or is this simply not a problem due to the design of the turbo housing?

 

These questions are a direct result of too much windsheild time. Ya see I drive about an hour to work one way and my mind wanders during this time.

[Owen]

I'm most likely misinterpreting your question here, but you're saying a vacuum is created in the exhaust side when the TB is closed? I'm sure the turbo slows, that's what turbo lag is.

 

As for the vacuum, I don't think it would be a total vacuum since air in constantly being bled in, even at idle...what was your question again??

Sorry, nevermind...

 

Owen

[Cody 82 ZXT]

The Blow of Valve is installed bewteen the throttle plate and the outlet of the compressor housing. It is used to releive the pressure that is caused by the throttle plate closing when you shift or whatever. In racing conditions it helps the compressor wheel to keep spining for quicker spool up instead of being hit by the reversion of air after it hits the throttle plate upon closer. It also is used to help releive pressure from the bearings in the turbo. The sound it makes is just an after effect of the air rushing through the valve.

 

If you look you can see one on also every serious turbo car out now days. The supercharger guys are even starting to use them.

[randy 77zt]

for those people that have the darius video on your hard drive if you watch the engine pics you will see a blow off valve.

[Guest Anonymous]

quote:

---

Originally posted by Owen:

I'm most likely misinterpreting your question here, but you're saying a vacuum is created in the exhaust side when the TB is closed? I'm sure the turbo slows, that's what turbo lag is.

 

As for the vacuum, I don't think it would be a total vacuum since air in constantly being bled in, even at idle...what was your question again??

Sorry, nevermind...

 

Owen

---

 

Well to clarify, I doubt it's even close to a full on vacuum, but if your throttle plate is closed and you're not pulling in air but the engine's still spinning, you're going to probably have a low pressure area in the exhaust manifold or worst case atmospheric pressure. This is contrasting the usual pressurized condition when there's actual exhaust gasses being pushed through the manifold. This wouldn't cause turbo lag though, turbo lag is the delay in a turbo spinning up when you open the throttle and subsequently start sending more exhaust gasses to the exhaust side of the turbine. It's not going to go from 0-100,000 RPM instantly.

[Guest Anonymous]

I don't see it as a problem, never heard of anyone using one. The hot side will keep spinning in a vacuum, just that it won't be powered and will begin slowing down.

 

Actually it would probably slow down less in a vacuum due to less friction from less air I would think.

 

In any case the fact that to the best of my knowledge nobody worries about it and I've yet to ever see one even on serious turbo'd cars tells me that it's not an issue.

 

If any of this makes sense.

[Cody 82 ZXT]

The resaon for the BOV has nothing to do with exhaust gases. Leave that out of the equasion(sp).

You stated that the turbo can't instantaiously go from 0 to 100,000 thats right and that is one reason you would put the BOV in. It helps to keep the turbo spinning by not letting it get hit with the pressure wave coming back from the throttle plate. This would stall the turbo and not let it spool back up as fast as it would other wise.

As far as the exhaust part being in a vacum so it would still be spinning. I can see what your thinking is but, remember the compressor wheel is connected on a common shaft to the turbine wheel. What one does the other does. If the compressor wheel gets stalled then the turbine wheel gets stalled. When you open the throttle up again, your going to be putting heat and exhaust gas pressure back on the turbine wheel causing the wheel to spin and create boost if the conditions are right to do so.