Turbo Idea - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Titan · 07-07-2002, 01:47 PM

I was sitting in church today, and as per usual, I was thinking about cars the entire time. I was just considering turbo setup's in my head and I wanted to know how to reduce lag for spool up. I realize BOV's reduce dangerous back pressure, but I though of another way.

What if the exhast turbine was spring loaded for variable surface area? What I mean is that what if each blade was composed of a retractable blade which would normally be held within due to a spring setup. Yet, once the exhast flows by and the turbine begins to spin, the centripetal force would pull the blade further outwards and thus increasing its surface area. Although, the more I think about this, the more I realize it wouldn't really help the spool-up as much as the flow of the exhast and back pressure.

What if the shaft between the intake and the exhast turbines on the turbo had a gear reduction system? Much like a transmission, which would promote proper spool-up acceleration.

These are just random idea's I had, where I do realize the impracticality, yet I'm just wondering about it hypothetically.

mrdirty · 07-07-2002, 02:04 PM

To #1:
You're now adding significant weight to the compressor wheel which will reduce efficiency; second, you would need near identical masses for springs and moving blades individually in order to maintain ballance. Thirdly, you would need springs of near identical spring constants and pre-loading to keep the spring loaded fins from moving independently and offsetting the centroid of the compressor wheel and vibrating to destruction. The cost of this type of precision is astronomical, shit, turbo's are expensive enough w/ the amount of dynamic balancing that needs to be done.

I'm not saying that this is impossible, just not cost effective as you've described it; plus, there are many ways people get around lag such as putting a nitrous jet before the compressor and spooling that way, or setting the cam timing to backfire into the exhaust stream at low rpm to keep the turbine spooled.

AKADriver · 07-07-2002, 07:42 PM

Garrett developed a similar idea in the late '80s called the Variable Nozzle Turbo.  Chrysler used it in some of their 2.2 SOHC turbo engines.

It worked okay, but it was expensive and they didn't make enough different sizes for it to become popular.  It had a side benefit of not needing a wastegate, boost control could be done internally by fully opening up the vanes.

Kreator · 07-07-2002, 08:58 PM

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Titan @ July 07 2002,2:47)</td></tr><tr><td id="QUOTE">What if the exhast turbine was spring loaded for variable surface area? What I mean is that what if each blade was composed of a retractable blade which would normally be held within due to a spring setup. Yet, once the exhast flows by and the turbine begins to spin, the centripetal force would pull the blade further outwards and thus increasing its surface area.</td></tr></table><span id='postcolor'>
Ok, if i understand this correctly... when the blade goes out and you increase the area, the exhaust has now much more resistance to the flow. Thus you have a positive force of the wheel spinning up and the negative of more area that slows the esxhaust down... My guess would be that there will be no affect to the system, or the rpms of the turbo would jump back and forth.... although i suck at physics  <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt='

'>

*SaintlyCharBoy* · 07-07-2002, 10:23 PM

if you read maximum boost by corky bell, he talks about a variable vane turbo compressor wheel

acura used a variable turbo setup in the first generation japanese legend, though i am not precisely sure how it worked, it was called a "wing turbo"

07-07-2002, 08:58 PM	#4
Kreator Nissanaholic! Join Date: Mar 2002 Location: MD Age: 41 Posts: 1,975 Trader Rating: (0) Feedback Score: 0 reviews	</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Titan @ July 07 2002,2:47)</td></tr><tr><td id="QUOTE">What if the exhast turbine was spring loaded for variable surface area? What I mean is that what if each blade was composed of a retractable blade which would normally be held within due to a spring setup. Yet, once the exhast flows by and the turbine begins to spin, the centripetal force would pull the blade further outwards and thus increasing its surface area.</td></tr></table><span id='postcolor'> Ok, if i understand this correctly... when the blade goes out and you increase the area, the exhaust has now much more resistance to the flow. Thus you have a positive force of the wheel spinning up and the negative of more area that slows the esxhaust down... My guess would be that there will be no affect to the system, or the rpms of the turbo would jump back and forth.... although i suck at physics  <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=''> __________________ кто болеет за Зенит, у того всегда стоит!

07-07-2002, 10:23 PM	#5
SaintlyCharBoy Premium Member Join Date: Jan 2002 Location: Bow, NH Age: 43 Posts: 849 Trader Rating: (1) Feedback Score: 1 reviews	if you read maximum boost by corky bell, he talks about a variable vane turbo compressor wheel acura used a variable turbo setup in the first generation japanese legend, though i am not precisely sure how it worked, it was called a "wing turbo" __________________ 92 vert - KADE + VH41 + GM MA5 = too many parts in the garage 95 base - retired

07-07-2002, 01:47 PM	#1
Titan Zilvia Junkie Join Date: Apr 2002 Location: Ontario, Canada Posts: 421 Trader Rating: (0) Feedback Score: 0 reviews	I was sitting in church today, and as per usual, I was thinking about cars the entire time. I was just considering turbo setup's in my head and I wanted to know how to reduce lag for spool up. I realize BOV's reduce dangerous back pressure, but I though of another way. What if the exhast turbine was spring loaded for variable surface area? What I mean is that what if each blade was composed of a retractable blade which would normally be held within due to a spring setup. Yet, once the exhast flows by and the turbine begins to spin, the centripetal force would pull the blade further outwards and thus increasing its surface area. Although, the more I think about this, the more I realize it wouldn't really help the spool-up as much as the flow of the exhast and back pressure. What if the shaft between the intake and the exhast turbines on the turbo had a gear reduction system? Much like a transmission, which would promote proper spool-up acceleration. These are just random idea's I had, where I do realize the impracticality, yet I'm just wondering about it hypothetically. __________________ Sleep Doesn't Drink Beer

07-07-2002, 02:04 PM	#2
mrdirty Zilvia Addict Join Date: Mar 2002 Location: Thunder Bay Ontario Age: 47 Posts: 650 Trader Rating: (0) Feedback Score: 0 reviews	To #1: You're now adding significant weight to the compressor wheel which will reduce efficiency; second, you would need near identical masses for springs and moving blades individually in order to maintain ballance. Thirdly, you would need springs of near identical spring constants and pre-loading to keep the spring loaded fins from moving independently and offsetting the centroid of the compressor wheel and vibrating to destruction. The cost of this type of precision is astronomical, shit, turbo's are expensive enough w/ the amount of dynamic balancing that needs to be done. I'm not saying that this is impossible, just not cost effective as you've described it; plus, there are many ways people get around lag such as putting a nitrous jet before the compressor and spooling that way, or setting the cam timing to backfire into the exhaust stream at low rpm to keep the turbine spooled.

07-07-2002, 07:42 PM	#3
AKADriver Post Whore! Join Date: May 2002 Location: Springfield, VA Age: 43 Posts: 3,518 Trader Rating: (1) Feedback Score: 1 reviews	Garrett developed a similar idea in the late '80s called the Variable Nozzle Turbo.  Chrysler used it in some of their 2.2 SOHC turbo engines. It worked okay, but it was expensive and they didn't make enough different sizes for it to become popular.  It had a side benefit of not needing a wastegate, boost control could be done internally by fully opening up the vanes.