Independent Throttle Bodies
03-27-2004, 10:41 PM
#51
Senior Member
Thread Starter
Join Date: Jul 2002
Location: Fayetteville, Georgia
Posts: 2,483
Originally Posted by mazdaspeed7' date='Mar 27 2004, 09:21 PM
Just for future reference, the problem with the stock intake manifolds isnt the runner length, its the runner cross-section. Its optomized for a stock engine. All of Mazda's careful design starts to go down the ******* when you start modifying other parts.
I appreciate your time explaining these things to me...you gotta learn somewhere.
03-28-2004, 01:45 AM
#52
Senior Member
Join Date: Jun 2003
Posts: 406
The stock manifold is great for stock ports. the X-section area isnt a problem untill you port the motor, in which case you can make the runners in the plates bigger aswell. MS7 is right in that it is a big problem, the ports im looking at now have 2.5 square inches, where as the stock secondary LIM runners are about 1.3 square inches. Ive though about bandsawing the whoile manifold and hogging it out, but the casting is only so thick.
03-28-2004, 03:58 AM
#53
Senior Member
Join Date: Dec 2003
Posts: 162
Drago86,
I've tried being nice about this and you appear to be too stupid to notice that you are digging yourself deeper into the hole. So I'll just call you 'otto' as in a fish called wanda.
Now please leave this discussion to people who actually want to learn about it rather than quote one paper they do not even understand. Hint: Reversion is not good. Using it as you primary tuning method is not a way of getting a performance engine.
I've tried being nice about this and you appear to be too stupid to notice that you are digging yourself deeper into the hole. So I'll just call you 'otto' as in a fish called wanda.
Now please leave this discussion to people who actually want to learn about it rather than quote one paper they do not even understand. Hint: Reversion is not good. Using it as you primary tuning method is not a way of getting a performance engine.
03-28-2004, 07:17 AM
#54
Senior Member
Join Date: Dec 2002
Location: Bayou-self Louisiana
Posts: 947
I have a basic ignorant question. Pulse tunning I assume would be the fine tunning
after the CFM / flow design. I see box plenums for charged air systems that seem to reflect little thought to flow. Is this because the intake is charged? It was my assumption that I would want a continual uninterupted flow (least possible) for maximum CFM . So does it matter about the design before the plenum chamber which then ties into individual runners?I thought these designs with the throttle body before it would disrupt the inherent flow.
Ex: after the FD ,TB, my friend removed some section of casting from the middle that caused some sepration. It now becomes a chamber of no flow but rather a box/space before the runners .I thought this would hurt flow characteristics.He did it just because.
And in pulse tunning ....do you use a designlike a balance pathway or pipe such as in the exhaust?
after the CFM / flow design. I see box plenums for charged air systems that seem to reflect little thought to flow. Is this because the intake is charged? It was my assumption that I would want a continual uninterupted flow (least possible) for maximum CFM . So does it matter about the design before the plenum chamber which then ties into individual runners?I thought these designs with the throttle body before it would disrupt the inherent flow.
Ex: after the FD ,TB, my friend removed some section of casting from the middle that caused some sepration. It now becomes a chamber of no flow but rather a box/space before the runners .I thought this would hurt flow characteristics.He did it just because.
And in pulse tunning ....do you use a designlike a balance pathway or pipe such as in the exhaust?
03-28-2004, 11:11 AM
#55
Super Moderator
Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Originally Posted by l8t apex' date='Mar 28 2004, 09:17 AM
I have a basic ignorant question. Pulse tunning I assume would be the fine tunning
after the CFM / flow design. I see box plenums for charged air systems that seem to reflect little thought to flow. Is this because the intake is charged? It was my assumption that I would want a continual uninterupted flow (least possible) for maximum CFM . So does it matter about the design before the plenum chamber which then ties into individual runners?I thought these designs with the throttle body before it would disrupt the inherent flow.
Ex: after the FD ,TB, my friend removed some section of casting from the middle that caused some sepration. It now becomes a chamber of no flow but rather a box/space before the runners .I thought this would hurt flow characteristics.He did it just because.
And in pulse tunning ....do you use a designlike a balance pathway or pipe such as in the exhaust?
after the CFM / flow design. I see box plenums for charged air systems that seem to reflect little thought to flow. Is this because the intake is charged? It was my assumption that I would want a continual uninterupted flow (least possible) for maximum CFM . So does it matter about the design before the plenum chamber which then ties into individual runners?I thought these designs with the throttle body before it would disrupt the inherent flow.
Ex: after the FD ,TB, my friend removed some section of casting from the middle that caused some sepration. It now becomes a chamber of no flow but rather a box/space before the runners .I thought this would hurt flow characteristics.He did it just because.
And in pulse tunning ....do you use a designlike a balance pathway or pipe such as in the exhaust?
Plenum tuning is seperate from runner tuning. I dont want to get into specifics on it though. I know my limits, unlike some people here...
03-28-2004, 11:14 AM
#56
Super Moderator
Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Originally Posted by bill shurvinton' date='Mar 28 2004, 05:58 AM
Drago86,
I've tried being nice about this and you appear to be too stupid to notice that you are digging yourself deeper into the hole. So I'll just call you 'otto' as in a fish called wanda.
Now please leave this discussion to people who actually want to learn about it rather than quote one paper they do not even understand. Hint: Reversion is not good. Using it as you primary tuning method is not a way of getting a performance engine.
I've tried being nice about this and you appear to be too stupid to notice that you are digging yourself deeper into the hole. So I'll just call you 'otto' as in a fish called wanda.
Now please leave this discussion to people who actually want to learn about it rather than quote one paper they do not even understand. Hint: Reversion is not good. Using it as you primary tuning method is not a way of getting a performance engine.
03-28-2004, 11:43 AM
#57
Super Moderator
Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Originally Posted by Dysfnctnl85' date='Mar 28 2004, 12:41 AM
If you fab'd a new manifold with wider cross-sections, wouldn't the problem lie in the actual intake ports on the motor? I'm assuming that the intake runner cross-section is the cross-section of the intake port on the housing itself...Does that make any sense?
I appreciate your time explaining these things to me...you gotta learn somewhere.
I appreciate your time explaining these things to me...you gotta learn somewhere.
The intake runners need to be sized so the mean speed of the airflow is 100 meters per second (3937 inches per second). Ill get to the runner length part at the end. Next, you want to make sure the runners in the block can flow enough for the ports, and that the flow is smooth. Everywhere there is flow, you want the flow path as straight as realistically possible. The intake and exhaust are street ported, as we said earlier. Next comes the header. You want the pipe sized properly for the hp you plan on making. A good rule of thumb is 0.025 in^2 for each hp. Thats the cross section, but a little math will get you the ID of the pipe you should use. Remember to divide the first number by two for the header, since theres 2 pipes. And of course, you want to make sure the rest of your exhaust, including the mufflers flows enough to not be a restriction.
If you change one thing, it will have an effect on everything else. And its not always positive.
Heres an excerpt from an article on the AREEP site. Its on composite intake manifold construction for a rotary powered aircraft.
Originally Posted by Brent Regan' date=' from the AREEP site
Brent Regan wrote:
> The following facts are based on empirical knowledge, direct observation and
> published data.
> After the intake port opens, a low pressure pulse is produced. This pulse
> propagates along the intake runner until it reaches the end (the end being the
> point where the diameter of the runner increases significantly) where it inverts
> and returns as a high pressure pulse. It has been demonstrated that the
> characteristics of this pulse (amplitude, duration, slope) are proportional to the
> air requirements of the engine at that throttle setting and RPM. The runner length
> should be set so that the returning pressure pulse coincides with the closing of
> the intake port. For proper wave reflection the runner must terminate in a full
> radius bell mouth (Radius >25% ID for >90 degrees). The absence of the bell mouth
> will result in a vena contracta significantly smaller than the runner ID and
> attendant flow losses.
I specify a one inch radius bell mouth on the latest design but that is
easily changed.
> The intake tube ID should be selected so that the mean air velocity during the
> intake period is 100 meters per second (3937 inches per second). For a 40 cuin
> rotary at 6000 RPM and a Ve of 1.0 the intake runner diameter should be 1.313 (1.50
> tube with a 0.065 wall). For a Ve of 1.3 you want an ID of 1.497 inches.
Is 1.5 close enough? :-)
> At 6000 the port open duration is 0.0075 seconds. Sea Level speed of sound is 1100
> ft/sec so the propagation distance for the port open period is 99 inches. The peek
> amplitude of the of the induction pulse occurs between 25% and 30% of the initial
> port opening, therefore the optimal propagation length should be between 40% and
> 50% of the total. The runner length is 1/2 the propagation length or, in this case,
> between 19.8 and 24.75 inches. Actual length must be determined empirically.
> Variable length induction is pointless on an aircraft engine.
I suggest slightly longer so torque peak occurs closer to cruise RPM for
BSFC improvement reasons.
> Exhaust lengths always seem to end up between 26 and 31 inches (regardless of RPM)
> and their diameters are proportional to the amount of horsepower they are flowing
> (0.025 square inches per horsepower seems about right).
> Paul's pig tail induction, while cleaver, suffers two drawbacks. It has no bell
> mouth on the end of the induction runner and the large angle the flow is turned
> through will cause the wave front to skew, reducing it's peek amplitude. This is
> because the path around the ID is shorter than the OD. This is the same effect that
> requires track and field runners to start in a stagger, so they all run the same
> distance, and finish in a line.
I added the bell mouth in the last design. What can I do to adjust for
the skew or is it something one must live with? What do you estimate
this wrap up is going to cost in the way of HP?
> Get whatever turning you need to do done as close to the port as possible and then
> run a straight, parallel wall pipe for the remainder.
> In 1984, the peripheral port 12As we were building for Daytona were making 200
> horsepower and 175 ftlb at 6000 RPM. Peek torque of 190 ftlb was at 7000 RPM (255
> Hp). A 13b should be 8% better. If you could tune for that 190 ftlb at 6000 then a
> 13b at 205 ftlb and 6000 RPM will make 234 Hp. The 4 rotor Le Mans engine made
> 448.6 ftlb at 6000 (556 Hp) or 224.3 ftlb (278 Hp) for a 2 rotor.
> I want a turbo normalized 26b motor in my Lancair IV-P. Hmmmmmm....
> Brent
> The following facts are based on empirical knowledge, direct observation and
> published data.
> After the intake port opens, a low pressure pulse is produced. This pulse
> propagates along the intake runner until it reaches the end (the end being the
> point where the diameter of the runner increases significantly) where it inverts
> and returns as a high pressure pulse. It has been demonstrated that the
> characteristics of this pulse (amplitude, duration, slope) are proportional to the
> air requirements of the engine at that throttle setting and RPM. The runner length
> should be set so that the returning pressure pulse coincides with the closing of
> the intake port. For proper wave reflection the runner must terminate in a full
> radius bell mouth (Radius >25% ID for >90 degrees). The absence of the bell mouth
> will result in a vena contracta significantly smaller than the runner ID and
> attendant flow losses.
I specify a one inch radius bell mouth on the latest design but that is
easily changed.
> The intake tube ID should be selected so that the mean air velocity during the
> intake period is 100 meters per second (3937 inches per second). For a 40 cuin
> rotary at 6000 RPM and a Ve of 1.0 the intake runner diameter should be 1.313 (1.50
> tube with a 0.065 wall). For a Ve of 1.3 you want an ID of 1.497 inches.
Is 1.5 close enough? :-)
> At 6000 the port open duration is 0.0075 seconds. Sea Level speed of sound is 1100
> ft/sec so the propagation distance for the port open period is 99 inches. The peek
> amplitude of the of the induction pulse occurs between 25% and 30% of the initial
> port opening, therefore the optimal propagation length should be between 40% and
> 50% of the total. The runner length is 1/2 the propagation length or, in this case,
> between 19.8 and 24.75 inches. Actual length must be determined empirically.
> Variable length induction is pointless on an aircraft engine.
I suggest slightly longer so torque peak occurs closer to cruise RPM for
BSFC improvement reasons.
> Exhaust lengths always seem to end up between 26 and 31 inches (regardless of RPM)
> and their diameters are proportional to the amount of horsepower they are flowing
> (0.025 square inches per horsepower seems about right).
> Paul's pig tail induction, while cleaver, suffers two drawbacks. It has no bell
> mouth on the end of the induction runner and the large angle the flow is turned
> through will cause the wave front to skew, reducing it's peek amplitude. This is
> because the path around the ID is shorter than the OD. This is the same effect that
> requires track and field runners to start in a stagger, so they all run the same
> distance, and finish in a line.
I added the bell mouth in the last design. What can I do to adjust for
the skew or is it something one must live with? What do you estimate
this wrap up is going to cost in the way of HP?
> Get whatever turning you need to do done as close to the port as possible and then
> run a straight, parallel wall pipe for the remainder.
> In 1984, the peripheral port 12As we were building for Daytona were making 200
> horsepower and 175 ftlb at 6000 RPM. Peek torque of 190 ftlb was at 7000 RPM (255
> Hp). A 13b should be 8% better. If you could tune for that 190 ftlb at 6000 then a
> 13b at 205 ftlb and 6000 RPM will make 234 Hp. The 4 rotor Le Mans engine made
> 448.6 ftlb at 6000 (556 Hp) or 224.3 ftlb (278 Hp) for a 2 rotor.
> I want a turbo normalized 26b motor in my Lancair IV-P. Hmmmmmm....
> Brent
03-28-2004, 11:57 AM
#58
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by Drago86' date='Mar 27 2004, 11:45 PM
The stock manifold is great for stock ports. the X-section area isnt a problem untill you port the motor, in which case you can make the runners in the plates bigger aswell. MS7 is right in that it is a big problem, the ports im looking at now have 2.5 square inches, where as the stock secondary LIM runners are about 1.3 square inches. Ive though about bandsawing the whoile manifold and hogging it out, but the casting is only so thick.
no porting. we have to use a stock intake manifold, unported. this is limiting our power a bunch, the stock intake doesnt flow enough, for an engine with headers on it. the s5 ecu sucks too, for any kinda power.
adam; get an ecu already you need it!
03-28-2004, 12:20 PM
#59
Super Moderator
Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Originally Posted by j9fd3s' date='Mar 28 2004, 01:57 PM
adam; get an ecu already you need it!
I still need to finish the harness, Im waiting for the rest of the wire to come in. Im going to finish the case today, and I need to load in the dual-table code. It wont be long, Ive been working a lot in the past couple of weeks, and havent had much time to work on in.