Multiple TB questions
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Multiple TB questions
I plan on fabbing up either an adaptation of an existing intake with a segmented plenum and 4 TBs or building a sheetmetal with 4 from scratch. If I didnt go that route, I already decided to use a single 105mm accufab with a single plane intake. My thoughts are to use 4 30mm tbs in place of the 105, but it that logical? Please dont try and diswade my thoughts on the initial sizing, it works and that is my starting point. Is there anyway to use the stock pcm to control multiple throttle bodies? How about adapting a TPS to work with the smaller ITBs? The electrical system on LSX setups is my weakest subject, so just playing around with ideas. What are the guys doing to run the accufab 105mm ford, I mean from the TPS aspect? Iam sure many of you guys have had the same ideas as I am having.
Brandon
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Interesting you just brought that up. I infact was just thinking of something similar. As I was going about the mechanics of it in my head, I started to wonder how you would get a IAC valve somewhere in the mix for idle/driveability. But I have no idea how to solve that, but I haven't really thought about it too much.
As far as controlling the multiple throttlebodies, I don't see that as being a problem. You'll just have to setup one of the throttlebodies with the TPS, and use some sort of adapted mechanics to run all the throttlebodies together, so that they all open at the same time. Therefore when the TPS reads WOT on one throttlebody, all of the throttleplates will be open as well.
As far as controlling the multiple throttlebodies, I don't see that as being a problem. You'll just have to setup one of the throttlebodies with the TPS, and use some sort of adapted mechanics to run all the throttlebodies together, so that they all open at the same time. Therefore when the TPS reads WOT on one throttlebody, all of the throttleplates will be open as well.
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Originally Posted by Haans249
Interesting you just brought that up. I infact was just thinking of something similar. As I was going about the mechanics of it in my head, I started to wonder how you would get a IAC valve somewhere in the mix for idle/driveability. But I have no idea how to solve that, but I haven't really thought about it too much.
As far as controlling the multiple throttlebodies, I don't see that as being a problem. You'll just have to setup one of the throttlebodies with the TPS, and use some sort of adapted mechanics to run all the throttlebodies together, so that they all open at the same time. Therefore when the TPS reads WOT on one throttlebody, all of the throttleplates will be open as well.
As far as controlling the multiple throttlebodies, I don't see that as being a problem. You'll just have to setup one of the throttlebodies with the TPS, and use some sort of adapted mechanics to run all the throttlebodies together, so that they all open at the same time. Therefore when the TPS reads WOT on one throttlebody, all of the throttleplates will be open as well.
Brandon
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I haven't really thought about what throttlebodies to run, but it also just dawned on me that the LS2 based, fly by wire, tb's use automatic throttleplate adjustments to act as the IAC valve. Maybe there is an answer to the Iac valve issue with flyby wire throttlebodies, but that maybe too complicated.
As far as the Harrop intake, i have no clue how they run the IAC aspect, thats a good thought.
As far as the Harrop intake, i have no clue how they run the IAC aspect, thats a good thought.
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If there's one thing I know about, it's the Harrop. The throttle linkage is controlled from one opening point, just like the LSX type intake. It then has linkage that attaches all the other TB's. The TPS is controlled just like the normal LSX intake and even uses the stock sensor on the bottom of the throttle cam. The Harrop has a single tube that runs down the center of the intake that the stock IAC sensor bolts to. This tube ties into all the runners thus giving you normal IAC control. It's hard to explain in words, so I'll see if I can find the pics that had all these things covered. Not trying to disweigh your TB sizing, but just wondering why you would choose 4 30mm's? Total surface area of the 4 would be less than a 90mm intake. If you think about it, the Harrop for stock cubes uses 8 52mm TB's, and big cubes use 8 55mm TB's. You can't simply multiply 30mm times 4 and get 120mm worth the surface area. Something to do with radius times pie(3.14) blah blah geometry stuff. I'm sure somone will post the formula.
Here's the pics, hopefully Drewman won't mind me posting his pictures:
Go to the last pic in the first set of links and you can see the IAC/TPS stuff. https://ls1tech.com/forums/showpost....8&postcount=42
Here's the top.
Here's the pics, hopefully Drewman won't mind me posting his pictures:
Go to the last pic in the first set of links and you can see the IAC/TPS stuff. https://ls1tech.com/forums/showpost....8&postcount=42
Here's the top.
Last edited by Beast96Z; 05-29-2006 at 02:40 PM.
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That is very true, rough surface area calculations puts the Harrop intake at 16,981 square mm's with the 52mm plates, while the 4 30mm throttlebodies entails a surface area of only 2,826 square mm's, which is not even half of just one 90mm throttlebody, which is at 6358 square mm's. Something along the lines of being closer to the harrop would be to use only two 90mm throttlebodies which will yield an effective area of 12717 square mm's. Much closer to that of the harrop. If you really wanted to get crazy, you could use two holley, or accufab 105mm's and get you 17,309 square mm's, which is right inbetween the small and large version of the Harrop.
My original thoughts were to use two 90mm's mounted facing frontward on the engine, using a simple modified throttlecable to run them both, and then using custom tubing to connect the outside parts of where the IAC valve plugs into, connecting both the thorttlebodies IAC passages from the outside, and then putting the IAC valve into one throttlebodies....is that really mad any sense haha.
My original thoughts were to use two 90mm's mounted facing frontward on the engine, using a simple modified throttlecable to run them both, and then using custom tubing to connect the outside parts of where the IAC valve plugs into, connecting both the thorttlebodies IAC passages from the outside, and then putting the IAC valve into one throttlebodies....is that really mad any sense haha.
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Originally Posted by Beast96Z
If there's one thing I know about, it's the Harrop. The throttle linkage is controlled from one opening point, just like the LSX type intake. It then has linkage that attaches all the other TB's. The TPS is controlled just like the normal LSX intake and even uses the stock sensor on the bottom of the throttle cam. The Harrop has a single tube that runs down the center of the intake that the stock IAC sensor bolts to. This tube ties into all the runners thus giving you normal IAC control. It's hard to explain in words, so I'll see if I can find the pics that had all these things covered. Not trying to disweigh your TB sizing, but just wondering why you would choose 4 30mm's? Total surface area of the 4 would be less than a 90mm intake. If you think about it, the Harrop for stock cubes uses 8 52mm TB's, and big cubes use 8 55mm TB's. You can't simply multiply 30mm times 4 and get 120mm worth the surface area. Something to do with radius times pie(3.14) blah blah geometry stuff. I'm sure somone will post the formula.
Here's the pics, hopefully Drewman won't mind me posting his pictures:
Go to the last pic in the first set of links and you can see the IAC/TPS stuff. https://ls1tech.com/forums/showpost....8&postcount=42
Here's the top.
Here's the pics, hopefully Drewman won't mind me posting his pictures:
Go to the last pic in the first set of links and you can see the IAC/TPS stuff. https://ls1tech.com/forums/showpost....8&postcount=42
Here's the top.
Brandon
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Originally Posted by Haans249
That is very true, rough surface area calculations puts the Harrop intake at 16,981 square mm's with the 52mm plates, while the 4 30mm throttlebodies entails a surface area of only 2,826 square mm's, which is not even half of just one 90mm throttlebody, which is at 6358 square mm's. Something along the lines of being closer to the harrop would be to use only two 90mm throttlebodies which will yield an effective area of 12717 square mm's. Much closer to that of the harrop. If you really wanted to get crazy, you could use two holley, or accufab 105mm's and get you 17,309 square mm's, which is right inbetween the small and large version of the Harrop.
My original thoughts were to use two 90mm's mounted facing frontward on the engine, using a simple modified throttlecable to run them both, and then using custom tubing to connect the outside parts of where the IAC valve plugs into, connecting both the thorttlebodies IAC passages from the outside, and then putting the IAC valve into one throttlebodies....is that really mad any sense haha.
My original thoughts were to use two 90mm's mounted facing frontward on the engine, using a simple modified throttlecable to run them both, and then using custom tubing to connect the outside parts of where the IAC valve plugs into, connecting both the thorttlebodies IAC passages from the outside, and then putting the IAC valve into one throttlebodies....is that really mad any sense haha.
Brandon
#9
id go for eight bodies on a V8!
but then ilove the sound and looks, as well as the performance, that indavidual TBs give you! also i was brought up on 4 pot running bodies and the noice they make is fantastic at high rpm! also you see much better topend than what you can ever get on a plenum. but with VERY big cams you do loose a little idle quality on bodies.
thanks Chris.
PS. anyone got the Harrop website link????
but then ilove the sound and looks, as well as the performance, that indavidual TBs give you! also i was brought up on 4 pot running bodies and the noice they make is fantastic at high rpm! also you see much better topend than what you can ever get on a plenum. but with VERY big cams you do loose a little idle quality on bodies.
thanks Chris.
PS. anyone got the Harrop website link????
#10
http://www.harrop.com.au/
Two things.
First, only one or two cylinders are breathing at a time. So with a plennum, the TB has to handle that. With ITBs, each ITB has to be able to handle the full volume from a single cylinder. With paired cylinders what was required would depend on the firing order and the pairing.
Second, is there an instance of two cylinder intake pairing used in a high performance or race application? All multiple carb setups I know go into a single plenum.
Two things.
First, only one or two cylinders are breathing at a time. So with a plennum, the TB has to handle that. With ITBs, each ITB has to be able to handle the full volume from a single cylinder. With paired cylinders what was required would depend on the firing order and the pairing.
Second, is there an instance of two cylinder intake pairing used in a high performance or race application? All multiple carb setups I know go into a single plenum.
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Originally Posted by DavidNJ
http://www.harrop.com.au/
Two things.
First, only one or two cylinders are breathing at a time. So with a plennum, the TB has to handle that. With ITBs, each ITB has to be able to handle the full volume from a single cylinder. With paired cylinders what was required would depend on the firing order and the pairing.
Second, is there an instance of two cylinder intake pairing used in a high performance or race application? All multiple carb setups I know go into a single plenum.
Two things.
First, only one or two cylinders are breathing at a time. So with a plennum, the TB has to handle that. With ITBs, each ITB has to be able to handle the full volume from a single cylinder. With paired cylinders what was required would depend on the firing order and the pairing.
Second, is there an instance of two cylinder intake pairing used in a high performance or race application? All multiple carb setups I know go into a single plenum.
Brandon
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One aspect you would loose is the single atmosphere for each cylinder. With 2 runners sharing one TB, that still leaves room for contamination of the incoming air charge. Seems like you would loose some of the "driveability" factor that is so great with the ITB set-up. However it may still be better than a single inlet manifold. If it is economically feasable, it would be interesting to see the results.
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Originally Posted by Beast96Z
One aspect you would loose is the single atmosphere for each cylinder. With 2 runners sharing one TB, that still leaves room for contamination of the incoming air charge. Seems like you would loose some of the "driveability" factor that is so great with the ITB set-up. However it may still be better than a single inlet manifold. If it is economically feasable, it would be interesting to see the results.
Last edited by xfactor_pitbulls; 05-30-2006 at 11:31 PM.
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Also, just by using the harrop as a guide line, (4) 50 mm would be the ticket. If that is the smaller of the two setups, then it would suffice for what I am doing. Basically it would only feed one cylinder at a time per TB, so therefore would only require about the same amount of air as an equally sized ITB. Pretty sure there is more to it than that though. The added plenum volume would have some effect on the air efficientcy I would think. It just hard to even guess at how much. The smart thing to do in this situation would be to start where the harrop is or just a tad above and go from there. Make the TB mounting plates just big enough to allow for an additional growth of maybe 10mm. That should cover any needed additional capacity.
Brandon
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I think this has already been figured out, but if not, hope this helps.
Most ITB setups have a vacuum line from each throttle bore, after the throttle plate. Then you would run each line to a common vacuum accumulator, just a box that sits near the throttle bodies. From here, you can plug in your brake booster line, MAP sensor, PCV, and any other vacuum source. If you have access to the machining tools neccesary, this is where you want/need your IAC. You'd plug it into the vacuum accumulator on the post-IAC passage, and get it's feed/inlet from after the air filter and before the throttle plate. It's hard to explain. One other way to do it is run a pipe from after the air filter, but before the throttle blade, to the accumulator. Inline somewhere in this tube you'd place the IAC. But you'd need to machine the pipe at this point so that it not only accepts the IAC, bolted on with no leaks, but that the spindle/plunger seals onto a recieiving conical piece. Hard to fab...I've been looking EXTENSIVELY for some remote mount IAC valves, that you just plug in a rubber 5/8" line or whatnot on both sides, but havn't found crap. I did find one that has an internal plunger, and it can mount flat, but making the flanges and dividers would be just as much of a pain in the a$$. Let me know if you find one...
Another option is to not use an IAC, and just use the blades as idle adjusters. They should have an idle screw on them. And if you bought ITBs in the first place, idle quality is a secondary concern. But I understand, if you have EFI, one of the major advantages is great idle, even with ITBs.
As for the TPS. This has a lot to do with tuning, but generally, you just use a standard GM 3-pin TPS on a single throttle body. Most aftermarket ITBs have a mating surface for a GM TPS. Mine do, pics below, courtesy of my checking account and TWM Induction. Let it be known, your factory EFI will probably not be very accepting. The LS1 EFI uses a MAF input for airflow. MAF + ITBs = bad. The alternating "gulps" from the ITBs will play fun games as your MAF tries to figure out wtf is going on. Generally speaking, a AlphaN or MAP based EFI system is preferred. AplhaN is out of the equation on the street. Thus a MAP based system is preferred, one that can be tuned. This sucks, because most MAP based ECUs, both stock and aftermarket, are also MPFI and not SFI. The LS1 SFI is more efficient and smoother, better tq and MPG, at lower RPM. But past ~3000rpm it goes to batch fire anyways. So your Camshaft Position Sensor is useless, as is your extra Crank Position Sensor.
Done rambling, here are some pics of the 48mm TWM throttle bodies that will go on my 3.4l DOHC V6 Fiero if I ever get off my a** and do it.
Most ITB setups have a vacuum line from each throttle bore, after the throttle plate. Then you would run each line to a common vacuum accumulator, just a box that sits near the throttle bodies. From here, you can plug in your brake booster line, MAP sensor, PCV, and any other vacuum source. If you have access to the machining tools neccesary, this is where you want/need your IAC. You'd plug it into the vacuum accumulator on the post-IAC passage, and get it's feed/inlet from after the air filter and before the throttle plate. It's hard to explain. One other way to do it is run a pipe from after the air filter, but before the throttle blade, to the accumulator. Inline somewhere in this tube you'd place the IAC. But you'd need to machine the pipe at this point so that it not only accepts the IAC, bolted on with no leaks, but that the spindle/plunger seals onto a recieiving conical piece. Hard to fab...I've been looking EXTENSIVELY for some remote mount IAC valves, that you just plug in a rubber 5/8" line or whatnot on both sides, but havn't found crap. I did find one that has an internal plunger, and it can mount flat, but making the flanges and dividers would be just as much of a pain in the a$$. Let me know if you find one...
Another option is to not use an IAC, and just use the blades as idle adjusters. They should have an idle screw on them. And if you bought ITBs in the first place, idle quality is a secondary concern. But I understand, if you have EFI, one of the major advantages is great idle, even with ITBs.
As for the TPS. This has a lot to do with tuning, but generally, you just use a standard GM 3-pin TPS on a single throttle body. Most aftermarket ITBs have a mating surface for a GM TPS. Mine do, pics below, courtesy of my checking account and TWM Induction. Let it be known, your factory EFI will probably not be very accepting. The LS1 EFI uses a MAF input for airflow. MAF + ITBs = bad. The alternating "gulps" from the ITBs will play fun games as your MAF tries to figure out wtf is going on. Generally speaking, a AlphaN or MAP based EFI system is preferred. AplhaN is out of the equation on the street. Thus a MAP based system is preferred, one that can be tuned. This sucks, because most MAP based ECUs, both stock and aftermarket, are also MPFI and not SFI. The LS1 SFI is more efficient and smoother, better tq and MPG, at lower RPM. But past ~3000rpm it goes to batch fire anyways. So your Camshaft Position Sensor is useless, as is your extra Crank Position Sensor.
Done rambling, here are some pics of the 48mm TWM throttle bodies that will go on my 3.4l DOHC V6 Fiero if I ever get off my a** and do it.
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Very good post and I am about to go to bed, but real quick. The system will not use a MAF (speed density setup). It will maintain a stock MAP sensor though, I dont figure it to be a problem with my simple design and a double wall that goes front to back. You can also use the back side of the intake to handle all vaccum related accessories since it would have limited common airspace through out the plenum. I guess this kinda dances back and forth between a single plane and ITB. I think I will make two manifolds, one traditional forward mount with a single TB and the one we have been speaking of. It would be alot easier to build two at once, rather that at different times.
Brandon
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I forgot where I stole this from but here ya go:
I had been thinking about building a itb system using motorcycle itbs. After quite a bit of digging, I found out that the Suzuki GSXR 1300 aka Hayabusa, and Kawasaki ZX12R have the biggest that are available for an inline 4, both measuring 46mm. They are on a smaller bore center of course. On ebay they usually go for close to $200, and we'd need two of em + a lot of creativity.
Basic references for BHP per cylinder, assuming ca.(ca.= approximately) 120mm from butterfly to valve head and a max of 9,000 rpm are:
Up to 30 BHP/CYLINDER - 30mm
up to 33 BHP/CYLINDER - 32mm
up to 39 BHP/CYLINDER - 35mm
up to 46 BHP/CYLINDER - 38mm
up to 51 BHP/CYLINDER - 40mm
up to 56 BHP/CYLINDER - 42mm *8 CYL = 448 + 10% = 493 HP
Up to 65 BHP/CYLINDER - 45mm *8 CYL = 520 + 10% = 572 HP
up to 74 BHP/CYLINDER - 48mm *8 CYL = 592 + 10% = 651 HP
up to 80 BHP/CYLINDER - 50mm
up to 87 BHP/CYLINDER - 52mm
up to 93 BHP/CYLINDER - 54mm.
These power figures may be increased by up to 10% in a purpose - designed, well proportioned system.
As butterfly to valve distance increases, butterfly size will need to increase in proportion to system taper and vice versa.
And here's my motorcycle research:
Motorcycle ITBs:
Kawasaki
Z750S 34
’06 Vulcan 2000’s twin 46
’02 ZX12R 46 bore spacing 85.4 mm/2=42.7, (111.76/2=55.88)
’06 ZX-14 44
’04-‘06 ZX10R 43
Yamaha
’04 R6 38
’05 R6 40
’03 R1 40
’04-‘06 R1 45
HONDA
CBR954RR ’02-’03 up to 42 from 41
CBR1000RR ’04-‘06 44
CBR1100XX 42
Suzuki
’03 GSXR 1000 (42) 50mm@ airbox side to 42mm @intake-manifold side.
’99-‘06 Hayabusa 46 81mm bore =3.2”
94-99 neons had 49mm
Jdm Toyota AE111 Levin 20v MAP 44mm ITB's funky shape at outlet though.
I had been thinking about building a itb system using motorcycle itbs. After quite a bit of digging, I found out that the Suzuki GSXR 1300 aka Hayabusa, and Kawasaki ZX12R have the biggest that are available for an inline 4, both measuring 46mm. They are on a smaller bore center of course. On ebay they usually go for close to $200, and we'd need two of em + a lot of creativity.
Basic references for BHP per cylinder, assuming ca.(ca.= approximately) 120mm from butterfly to valve head and a max of 9,000 rpm are:
Up to 30 BHP/CYLINDER - 30mm
up to 33 BHP/CYLINDER - 32mm
up to 39 BHP/CYLINDER - 35mm
up to 46 BHP/CYLINDER - 38mm
up to 51 BHP/CYLINDER - 40mm
up to 56 BHP/CYLINDER - 42mm *8 CYL = 448 + 10% = 493 HP
Up to 65 BHP/CYLINDER - 45mm *8 CYL = 520 + 10% = 572 HP
up to 74 BHP/CYLINDER - 48mm *8 CYL = 592 + 10% = 651 HP
up to 80 BHP/CYLINDER - 50mm
up to 87 BHP/CYLINDER - 52mm
up to 93 BHP/CYLINDER - 54mm.
These power figures may be increased by up to 10% in a purpose - designed, well proportioned system.
As butterfly to valve distance increases, butterfly size will need to increase in proportion to system taper and vice versa.
And here's my motorcycle research:
Motorcycle ITBs:
Kawasaki
Z750S 34
’06 Vulcan 2000’s twin 46
’02 ZX12R 46 bore spacing 85.4 mm/2=42.7, (111.76/2=55.88)
’06 ZX-14 44
’04-‘06 ZX10R 43
Yamaha
’04 R6 38
’05 R6 40
’03 R1 40
’04-‘06 R1 45
HONDA
CBR954RR ’02-’03 up to 42 from 41
CBR1000RR ’04-‘06 44
CBR1100XX 42
Suzuki
’03 GSXR 1000 (42) 50mm@ airbox side to 42mm @intake-manifold side.
’99-‘06 Hayabusa 46 81mm bore =3.2”
94-99 neons had 49mm
Jdm Toyota AE111 Levin 20v MAP 44mm ITB's funky shape at outlet though.
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The obvious thing here is that you'll have to pair the cylinders that fire oppisite of each other so 2 cylinders aren't feeding from the same TB at the same time. Once you figure the order, you'll have to find a way to pair these runners and still have room to fit it under the hood. You still face the problem of incoming air contamination with the cylinders paired, but I doubt it would be as bad as the single inlet.
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Originally Posted by Beast96Z
The obvious thing here is that you'll have to pair the cylinders that fire oppisite of each other so 2 cylinders aren't feeding from the same TB at the same time. Once you figure the order, you'll have to find a way to pair these runners and still have room to fit it under the hood. You still face the problem of incoming air contamination with the cylinders paired, but I doubt it would be as bad as the single inlet.