Donate to the MX-3.com Forums
View unanswered posts | View active topics It is currently July 14 2020, 5:30 AM



Reply to topic  [ 35 posts ]  Go to page Previous  1, 2, 3
 FAQ: Superchargers 
Author Message
Senior Member

Joined: November 07 2000, 3:01 AM
Posts: 2516
Location: Gainesville, FL USA
Reply with quote
Post Re: FAQ: Superchargers
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by ProtegeSTS<BR>Jeff, Im clearly just a moron and bow down your intellectual power, so answer my questions so that all of us lemmings/idiots/morons/toyota owners can learn.<P>a) Ok, so Corky and Pat disagree on certain aspects.... who is right? Also, how does it not apply to your system? <P>b) Where does Pat's math go wrong? IIRC, ALL compressors build compression the same way, square of the blade tip speed.(ignoring VE) If this is incorrect, whats the correct?<P>c) "My boost curve is not a long exponential swoop as your math would have it because of the blower sizing." Where is ANY data to back this up? Looking at a stock KLDE dyno vs yours would show that the supercharger does indeed give more power as you reach higher rpm.<P>d)
Quote:
Its not that "I don't believe you", but, rather, that what your are stating is wrong. Again, you are confusing what "boost" is. A Roots type will displace EXACTLY the same amount of air in every revolution. How much "boost" that amounts to is dependant on the requirements and VE of the motor at that RPM. The flow reqirements of a motor are not linear, so the "boost" (which is really a measurement of the inefficient relationship between a supercharger and its host - a properly sized and set up system would never show any "boost" at all) CAN'T be the same at a wide range of RPM. If your Roots type hit its full "boost", meaning pressure differential, at 2000 RPM, you would be in deep trouble before you even hit 3500 RPM<HR></BLOCKQUOTE><P>Again, please, how are you going to discount owner's of these systems? Yes, a roots displaces the same amount, so youre correct in your VE argument, but the roots blower increases its own rpm with engine rpm, and is geared to always supply X amount of extra manifold pressure (again, ignoring VE, which in a well designed motor wont change THAT much). And my definition of "boost" is positive manifold pressure. Keep in mind that a roots blower's efficiency isnt linear either, and ALL of our "basic calculations" are just first cuts of the real deal.<P>e) Ok Mr. Semantics, please explain boost threshold as opposed to lag for the rest of us.<P>f) please take the time to actually explain how the previous dyno that Ive posted is wrong, and why it is. See, thats what ive seen, and it makes sense to me. But you seem to think that nothing works like that. So id like to hear your ideas on whats is actually wrong, rather than spouting off that "thats imaginary, and doesnt exsist in the real world."<P>[ October 23, 2002: Message edited by: ProtegeSTS ]<BR>

_________________
David Coleman
I used to know alot about MX-3's, but not so much anymore. Oh well.


October 27 2002, 8:59 PM
Profile ICQ WWW
Senior Member

Joined: November 07 2000, 3:01 AM
Posts: 2516
Location: Gainesville, FL USA
Reply with quote
Post Re: FAQ: Superchargers
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by ProtegeSTS:<BR><STRONG><P><BR>I said that a Centrifugal (Vortech) was a poor choice. I never said it didn't work. It just doesn't work as well as other options, IMO. It's still a way to get good power gains (We wont get into "where" those are located), and the packaging isnt horrible. It's just nothing I would ever do to a KL engine, as I see better options, again, in my opinion.</STRONG><HR></BLOCKQUOTE>

_________________
David Coleman
I used to know alot about MX-3's, but not so much anymore. Oh well.


October 27 2002, 9:00 PM
Profile ICQ WWW
Senior Member

Joined: November 07 2000, 3:01 AM
Posts: 2516
Location: Gainesville, FL USA
Reply with quote
Post Re: FAQ: Superchargers
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by big mike<BR>
Quote:
A Roots type will displace EXACTLY the same amount of air in every revolution. How much "boost" that amounts to is dependant on the requirements and VE of the motor at that RPM. The flow reqirements of a motor are not linear, so the "boost" (which is really a measurement of the inefficient relationship between a supercharger and its host - a properly sized and set up system would never show any "boost" at all) CAN'T be the same at a wide range of RPM. If your Roots type hit its full "boost", meaning pressure differential, at 2000 RPM, you would be in deep trouble before you even hit 3500 RPM. Furthermore, this does nothing to advance your argument that...<BR> <HR></BLOCKQUOTE><BR>Not to be a jerk, but as far as I can tell from this argument you don't even understand the fundamental theory of how forced induction works. Any blower, regardless of type, only forces more air into the motor using its positive manifold pressure. If you didnt make any "boost" in pressure you'd be barely gaining any power, a normal high output motor can get to very nearly 0 vac all by itself just on the suction created by its pistons. The positive pressure FORCES more air into the cylinder than the motor can mechanically move using its vacuum. You're also completely ignoring the CFM part of the equation, roots blowers make full boost pressure at very low RPM, because the ammount of CFM of air they displace relative to the engine's VE is very close to constantly relative, engine VE doesnt vary THAT much.<P>To make a simplier example of WHY your completely wrong about the need for boost pressure, imagine taking an air compressor and hooking it up to a standard blow gun attatchment. Does it move as much air through the tip at 40 psi as it will at 120? No, the higher pressure in the tank FORCES more air through it, just like boost pressure forces more air down the intake manifold and into the cylinders.<BR> <BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR> Typical N/A Honda motor<BR>Do you see the "hump" at 4.5k or so and how there is a long RPM strech beyond the torque peak before you get to the HP peak? That is what "peaky" means.<BR>Typical centrifugal chart on a small displacement motor (2 liter Honda)<BR>That is what a "typical" centrifugal plot looks like. Not similar to:<BR>my dyno<BR>Do you see how the torque is flat over most of its range and the HP is a long sweep up until it runs out of fuel? The only thing "peaky" is the little hump where the mix crossed the 13:1 A/F range. <HR></BLOCKQUOTE><BR>Did you actually LOOK at your own dyno plot? I dunno where you grew up, but last time i checked FLAT torque meant it was constant, not constantly making a linear rise, which UNEQUIVAQALLY shows that your centrifugal's displacement of air rises as the speed rises. If you want a FLAT torque curve, maybe you should go look at a stock 1.8t audi/vw, or a tuned BP like mine, my BP makes 90 ft/lbs from 2000 rpm to 6000 with a peak of 108, its a very slow rise to 108 and slowly backs down until you get much above the magic flow limit at 6000 and it starts dropping away again. It's not pefectly flat, but its way flatter than the curve from your motor. <A HREF="http://groups.yahoo.com/group/escortgt/files/Dyno%20Data/Big%20Mike%20Dyno/bigdyno.jpg" TARGET=_blank>Mike's Dyno</A><BR>Take a look for yourself.<BR>

_________________
David Coleman
I used to know alot about MX-3's, but not so much anymore. Oh well.


October 27 2002, 9:00 PM
Profile ICQ WWW
Senior Member

Joined: November 07 2000, 3:01 AM
Posts: 2516
Location: Gainesville, FL USA
Reply with quote
Post Re: FAQ: Superchargers
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by lazzyie:<BR><STRONG>Regardless of your arguing I thank the four of you for the sheer amount of information that has been thrown out in this thread.</STRONG><HR></BLOCKQUOTE><P><BR>I echo the sentiments of lazzyie here. Which is why I put this information here, at the suggestion of Jarid [cjthor].<p>[ October 27, 2002: Message edited by: David Coleman ]

_________________
David Coleman
I used to know alot about MX-3's, but not so much anymore. Oh well.


October 27 2002, 9:03 PM
Profile ICQ WWW
Senior Member

Joined: November 07 2000, 3:01 AM
Posts: 2516
Location: Gainesville, FL USA
Reply with quote
Post Re: FAQ: Superchargers
<A HREF="http://www.project33.com/start.cfm" TARGET=_blank>http://www.project33.com/start.cfm</A> <P>8 part pictoral series on how to rebuild a roots blower. Good stuff.

_________________
David Coleman
I used to know alot about MX-3's, but not so much anymore. Oh well.


December 09 2002, 2:24 AM
Profile ICQ WWW
Display posts from previous:  Sort by  
Reply to topic   [ 35 posts ]  Go to page Previous  1, 2, 3

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.