Building a fast car? Get $400 OFF the all inclusive VIP package deal: hpcdmy.co/vipy34 Kickstart your EFI Tuning knowledge. Get 50% OFF the EFI Fundamentals course: hpcdmy.co/offery34 TIME STAMPS: 0:00 - Introduction 1:05 - Tuning with ITB's 8:30 - Setting Up Throttle Plates 15:21 - Vacuum balance bar/MAP signal 18:44 - Idle speed control 21:54 - Trumpet length 25:06 - Questions 44:00 - BUILD.TUNE.DRIVE!
I run an eight ITB system on a 452 cu. in. Ford FE engine. The computer is a Megasquirt 2 running the ITB program which is a blend between alpha-N and speed density. The fuel map is modulated by the AFR sensor. There is a small common plenum in the intake manifold. I run the vacuum signal to the Megasquirt. I have attached a Ford PWM idle air valve to this plenum. Most of the air at idle comes through this valve. As a consequence, cylinder to cylinder air/fuel balance at idle is less sensitive to the throttle blade position. The ITBs are all balanced. The cam is 248/254 at 0.05" on a 110 LCA. Lift is 0.640/0.645. The engine will idle smoothly at 550 rpm, but I set it at 700 with the computer. The compression ratio is 10.8:1 and it runs 93 octane pump gas. The engine made 550 hp and 570 lb.ft. torque at 5900 rpm. It propels my stock interior 1968 fastback to 7.1 sec in the 1/8 mile. The car has a roll bar, CalTracs, subframe connecters, A/C, electric power steering and a stock water pump.. There is another 60 hp to be had if I changed from the Edelbrock heads to the newer TFS heads, but as a show/street car, it's fast enough. I recommend an ITB setup for any vehicle in which you have a large cam that you want to calm down for drivability. The engine originally had a Edelbrock Victor intake and an 850 cfm Mighty Demon carb. It would not idle below 850 and the idle was rich to compensate for the exhaust gas dilution. The ITB setup made the same horsepower as the 4 barrel setup, but it made a lot more torque, and improved part throttle operation immensely.
People will argue black and blue about being able to thoroughly tune ITBs on speed density alone. I guess the argument would be if the shared vaccuum manifold is large enough, you would be able to get a consistent enough MAP signal to work. In that case however, youre essentially now creating a plenum after the throttles, thus directly negating the benefits of using ITBs in the first place.
You don’t need a large volume. All you need is a tuned resistor in the vacuum lines. This will filter the pulses out and still provide better response than a single large plenum.
All you need is sufficient signal to establish a baseline. The rest can be handled with delta tuning. Tuning ITB's is a pain... but the payoffs are worth it. There's a huge difference between enough volume to balance a reasonable vacuum signal, and the combined volume of a single throttlebody intake.
By using large MAP balancing tube you definetly will cut fluctuations depending on pipe size connecting runner and balance tube. But one of the consequenses of smoothing MAP signal that way is increase in MAP signal delay, as pressure in balance tube would lag, causing inadequate AFR
My factory fuel injection is Alpha-N. True story! Bosch Mono-Motronic from the late 80's. I'm surprised how well the car drives with how little goes into the system, but it's also very obvious when something is not happy because it'll run like crap instantly. It's only got a few sensors; RPM pulse from ignition module, throttle angle, lambda for fuel trim, intake temp and coolant temp, and that's it. The coolant temp sensor is also somewhat notorious, it has a large sway over the injected fuel amount, and if it's broken, garages will blindly throw lambda sensors and catalytic converters at the car to get it to attempt to get it to pass emissions when all it is is a cheap temperature sensor. And given the expense of those parts, and the age of the car, many ended up scrapped because of it instead.
I used to have a 4 zylinder ninja 600 bike (with itbs of course) The workshop manual explained that speed density is used below a certain rpm and low throttle opening. 3k rpm (so 1/5 of the reline if I recall correctly) Above that alpha n is used.
From the motorcycle world, Healtech makes a throttle body syncing tool that has 4 individual map sensors to tie to each throttle body. Small form factor , usb to computer and Their software gives live data and is real nice for a speedy sync Awesome video
Wonderful clear instruction. Thank you. If you are familiar with motorcycle engines most of this will be familiar but if you aren’t this is an eye opener.
I converted my three cylinder, one litre car engine to use BMW K75 motorbike ITBs, which don’t have integral injectors. I drilled the inlet ports to take them. They work really well using a variable TPS but the trickiest part is getting a steady idle, as mentioned here. Once done, the throttle response is very good indeed and the torque and power are up 20% on the standard engine.
The last car we did was a 1800cc bmw, it runs 45mm bmw motorcycle itbs and car made 129rwkw and reved to 7600rpm and we have it running so good you would not know it has itbs, i ran 2 vacuum logs, one right near the engine for fpr and map, the second runs out near throttle blades and runs brake and idle stepper, this has proven to be very good, also running injector in throttle body further away from head seems to be better in our experience, all our cars run itbs or webers,
I'm Running alpha-n with map multiplication on turbocharged cbr1100xx, air/water ic and flex fuel, works very well and wasn't particularly hard to tune or setup, don't be afraid of the itb's👌
You can use map on a itb set up. It’s all about execution. The way to do it is to create a common plenum with a small volume. If the vacuum signal fluctuates too much for a good signal put restrictors in the vacuum lines. Almost like carburetor jets. If the signal is not responsive increase the flow in the vacuum lines. You can almost think of it like a resistor capacitor electrical circuit. Then you can calculate the natural frequency as well as other values.
Great Video as usual from HPA! My question, you suggest that the main advantage of ITB’s is tuning, however traditional Mercedes go for long intake runs with single throttle body and BMW give there drives the sensation of motor sport with Tappet shims and ITB’s! Why is that? It’s not turning?
Got my Toda 33mm trumpets to use Toda CF Powersurge tank to my Garrett GTX2867R Gen dos. Now I just need an really nice condition with a low price NB2. Yes I know, GLWT 😂. All the while still buying parts before the car. Kinda like placing the horse to push the carriage (A$$ Backwards) 😂. Always nice YT Team HPA. Stay blessed, y'all ❤
Peter on Andersson Turbo systems , take bikes out of the box and do them at 5,10,15,20 , 25 and 30 % throttle, gives vastly both better driveability AND more importantly better laptimes !! Far more critical on two wheels....life saving when riding on the very limit...turbo or no turbo...Aplha/N..... ofcourse...On the bikes we use "clocks" as this sync is a very iterative process
Depending on the application, a simpler solution / strategy for varying trumpet lengths for testing, would be incremental series of spacers, between the trumpet / throttle body, rather than manufacturing entire trumpet assemblies, and the spacer selection varied for future tuning options, such as track differences and conditions. Would it be realistic to utilize a MAF in combination with ITBs, by placing the MAF at the entry of a common air box feeding the ITBs?
I learned a lot from this video. I currently run twin DCOE Webers, and have always dreamed of ITB’s. At 25:00, regarding the brake booster, definitely go for an electric vacuum pump. Holes in the inlet runners has a detrimental affect on air flow/speed, especially on a well sorted flow-benched NA engine. 🇦🇺🤜🏼🤛🏼🍀☮️😎
A lot of them use map under idle/low load/light throttle conditions and tps/alpha-n above a certain threshold. Some are tps/alpha-n only. Depends on the manufacturer.
On a silvertop 4age ITB that has no dedicated map sensor vacuum port, would you recommend me drilling one coming from all 4 thottles rather than tapping from the main vacuum rail being shared with ISCV, brake booster, idle up and power steering vacuum? Would sharing vacuum really result to some sort of inaccurate map sensor reading? Thanks heaps!❤
At 36:00, regarding Mass air flow sensor on ITB’s. Are you saying, if I put ITB’s on my Kent 1700, I could build a plenum incapsulating the trumpets, and run a MAFS at the inlet, on a NA engine to get better tuning through the rev range??? Great video!!! 🇦🇺🤜🏼🤛🏼😎☮️🍀
I was thinking about the nonlinear relationship to throttle plate position and airflow. I wondered if anyone had tried an iris style shutter in a carb or ITB. I didn’t find much online about irises, but I did come across roller barrel throttle body designs. Very interesting. Seems that would make tuning due to airflow easier?
It makes sense on a boosted motor that the throttle response wouldn’t be as noticeable. That being said, a rally driver who’s got the wheels spinning most of the time, could tell the difference. I’d love to know if all rally cars still run ITB’s????
Used ignition timing for idle with ITBs on my old Fiat. Set base idle with the throttle adjustment screw and then used ignition tuming to make it stable. It works pretty good if you don't have any other way of doing it. My last build uses DBW and gives a lot better control
@@ArneChristianRosenfeldtsaying only inline 4-cylinders are ITB is false. Some BMW 6-cylinders and 8-cylinders are ITB. Nissan RB (6-cylinders) are ITB.
If you have a capable ecu, use dbw. Makes tuning much easier as you can limit the dbw opening percentage regardles of pedal position. So you can easily limit the dbw opening to 10% rev it out on the dyno or even on the road. Correct the maps accordingly. Increase opening by 10%. Repeat
A: how are roller throttle bodys on the air flow compaired to the non liner standard butterfly valves? and B: With an electric throttle actuator and wireless throttle pedal can a linear flow opening be programed to give a linear feel?
Roller barrel throttle bodies ought to give higher flow than an equivalent diameter butterfly when fully open, but at low openings just off idle, the air flow has to take a tortuous path through the barrel and they’re often thought of as “difficult” when it comes to tuning for drivability.
What about using a combination of TPS and Map? Certain ecu's will allow this, takes a long time to tune, but surely the end result should be a smoother and more responsive part throttle. My 2 cents, some think the biggest diameter itbs are the best, smaller diameter itbs are easier to tune.
i got thinking... what if engine with itb has commin plenum like e46 m3, but use map sensor, but in plenum, before throttle plates shouldnt that work? or am in the wrong?
Why can't we simply run a much larger plenum to hold the air signal to the MAP sensor? I have an LS3 ITB kit run on a MAP (def. not saying its setup correctly!) But the valley cover on my kit has been converted into a large vac storage tank. 14" long and 2" high. this receives the signals from each V8 trumpet/runner. Then one opening on the rear is used to feed the map. I'm all for changing over to alpha-N. Was just curious about your Thoughts on this setup.
Does a V8 even need a plenum? In the past V8 with cold Vee used these two plane intakes. 8:2:1 distributor, all tight tubes all the way to the single throttle body. With low stroke intake should almost be sine shaped. Do we need two intake valves to shorten the path from valves to throttle body in the center and MAP sensor.
Great video with a lot of info. After going over all the different options available, I’d like to see how YOU set up the V8 with ITBs. Mechanically, in regards to the balance bar, idle bypass or not, etc.
The trumpets on a BBC ITBs is >3x more voluminous (360mm) than a single trumpet FI (102mm). Too much air! I wonder if each trumpet of the ITBs had a disk installed with a 12.75mm orifice, would it run?
I have a Porsche 968, and it has a TPS, and a MAF, as well as closed loop Lambda. Can I put ITBs and an Airbox on it and run the stock ECU? I don't really know if it has a MAP Sensor, just starting to disassemble it.
You are going to need a standalone ecu for sure. So many different ways to make your itbs and your worst mistake will be having a limp home mode before the ecu starts to feel like it wants to add and subtract fuel at the same time
No you can not use the stock ecu and you will struggle to get long runners and plenum with out hitting the brake booster. I run ITBs on a 944 4v engine in my 944 turbo
I'm actually surprised no one makes a small maf to either mount in the trumpet close to the throttle blade or plug into the hole you use for summing atmospheric pressure. Not sure how that might work there as fuel would probably skew the mafs function. I guess repositioning the fuel boss and tap plug would be the best arrangement...I'd either average them all together or for high horsepower/need for data race applications, use a breakout can-bus board that plugs all the mafs in and feeds the individual cylinders into the ecu. This would allow the ecu to adjust each cylinder individually on the fly
With ITBs you can get a lot of back flow from the opening and closing of the valve, so individual mafs may not work well. Can see this on itb videos, especially with stand off Injectors.
We're not carb tuners sorry so can't help you with that one. If you don't plan to tune the project yourself this is a conversation you should have with the company/tuner you plan to do that work for you. We do hope to cover carb tuning in the future if we find the right team member with the relevant knowledge, but for now our experience is with EFI. Sorry I couldn't help - Taz.
@@hpa101 I have like 10 sets of Webers and Dellortos from old Alfas so keeping the cost down is the biggest reason, also have a fuel injected twin spark engine from a 1988 Alfa 75 (Milano). Was thinking of putting this in a Alfa 105 stepnose im building. So the thought is to keep the stock injector position on the Twin Spark and fabricate carb mounts fitting the intake runners, they are just round with a rubber hose on the end so looks easy to do. Put a TPS on the carbs, a balance tube for the MAP and run it like that...
The problem then comes as heat. Especially if turbocharged. Because you are assuming ideal gas pressure alone does not equal density. PV=nrT. This is why modern cars use MAF sensors. So you can have high boost numbers with high heat and have the same amount of air entering the engine as NA. Thus requiring the same fueling. This is why speed density will be inconsistent based on air temp and pressure. Alpha N will also fall flat on its face in a turbocharged application.
This is a old xchool problem from using twin webers on a 4 cylinder, it you want a vac signal for a distributor a single runner tap does not work. the sigmal is very low and pulses.
I got em from the same company Andre is showing. Comes with a ton of different ways to configure your system and 2 different types of electronic throttle actuators
As adonay944 says, particularly with regard to the cam; with my engine, it’s typically limited to about 270° cams if you want to keep a plenum. Jenvey envy is a thing!
If memory serves me well the 1991 Overall LM Winner Mazda 787B engine code: R26B uses a 4 rotor, 3 spark plugs per rotor, now get this, with telescopic ITB setup. The Mazda engineers says it's just a simple pulley cable system... yeah... maybe for a Mazda engineer 🤔 engine made 700 hp weighing at almost 400 lbs. Talk about power density 😮 th-cam.com/video/3qdgKYFiuIc/w-d-xo.html HPA, please delete if not allowed.
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TIME STAMPS:
0:00 - Introduction
1:05 - Tuning with ITB's
8:30 - Setting Up Throttle Plates
15:21 - Vacuum balance bar/MAP signal
18:44 - Idle speed control
21:54 - Trumpet length
25:06 - Questions
44:00 - BUILD.TUNE.DRIVE!
I run an eight ITB system on a 452 cu. in. Ford FE engine. The computer is a Megasquirt 2 running the ITB program which is a blend between alpha-N and speed density. The fuel map is modulated by the AFR sensor. There is a small common plenum in the intake manifold. I run the vacuum signal to the Megasquirt. I have attached a Ford PWM idle air valve to this plenum. Most of the air at idle comes through this valve. As a consequence, cylinder to cylinder air/fuel balance at idle is less sensitive to the throttle blade position. The ITBs are all balanced. The cam is 248/254 at 0.05" on a 110 LCA. Lift is 0.640/0.645. The engine will idle smoothly at 550 rpm, but I set it at 700 with the computer. The compression ratio is 10.8:1 and it runs 93 octane pump gas. The engine made 550 hp and 570 lb.ft. torque at 5900 rpm. It propels my stock interior 1968 fastback to 7.1 sec in the 1/8 mile. The car has a roll bar, CalTracs, subframe connecters, A/C, electric power steering and a stock water pump.. There is another 60 hp to be had if I changed from the Edelbrock heads to the newer TFS heads, but as a show/street car, it's fast enough.
I recommend an ITB setup for any vehicle in which you have a large cam that you want to calm down for drivability. The engine originally had a Edelbrock Victor intake and an 850 cfm Mighty Demon carb. It would not idle below 850 and the idle was rich to compensate for the exhaust gas dilution. The ITB setup made the same horsepower as the 4 barrel setup, but it made a lot more torque, and improved part throttle operation immensely.
Awesome info, I appreciate your sharing, Boss. Cheers.
Damn, 60 hp is a lot. I'd change the heads if there was no drivability penalty to it.
People will argue black and blue about being able to thoroughly tune ITBs on speed density alone. I guess the argument would be if the shared vaccuum manifold is large enough, you would be able to get a consistent enough MAP signal to work. In that case however, youre essentially now creating a plenum after the throttles, thus directly negating the benefits of using ITBs in the first place.
The would then not be Individual Throttle Bodies , they would be shared.
@@krusher74 exactly
You don’t need a large volume. All you need is a tuned resistor in the vacuum lines. This will filter the pulses out and still provide better response than a single large plenum.
All you need is sufficient signal to establish a baseline. The rest can be handled with delta tuning. Tuning ITB's is a pain... but the payoffs are worth it. There's a huge difference between enough volume to balance a reasonable vacuum signal, and the combined volume of a single throttlebody intake.
By using large MAP balancing tube you definetly will cut fluctuations depending on pipe size connecting runner and balance tube. But one of the consequenses of smoothing MAP signal that way is increase in MAP signal delay, as pressure in balance tube would lag, causing inadequate AFR
My factory fuel injection is Alpha-N. True story! Bosch Mono-Motronic from the late 80's. I'm surprised how well the car drives with how little goes into the system, but it's also very obvious when something is not happy because it'll run like crap instantly. It's only got a few sensors; RPM pulse from ignition module, throttle angle, lambda for fuel trim, intake temp and coolant temp, and that's it.
The coolant temp sensor is also somewhat notorious, it has a large sway over the injected fuel amount, and if it's broken, garages will blindly throw lambda sensors and catalytic converters at the car to get it to attempt to get it to pass emissions when all it is is a cheap temperature sensor. And given the expense of those parts, and the age of the car, many ended up scrapped because of it instead.
I used to have a 4 zylinder ninja 600 bike (with itbs of course)
The workshop manual explained that speed density is used below a certain rpm and low throttle opening. 3k rpm (so 1/5 of the reline if I recall correctly)
Above that alpha n is used.
From the motorcycle world, Healtech makes a throttle body syncing tool that has 4 individual map sensors to tie to each throttle body. Small form factor , usb to computer and Their software gives live data and is real nice for a speedy sync
Awesome video
Wonderful clear instruction.
Thank you.
If you are familiar with motorcycle engines most of this will be familiar but if you aren’t this is an eye opener.
I converted my three cylinder, one litre car engine to use BMW K75 motorbike ITBs, which don’t have integral injectors. I drilled the inlet ports to take them. They work really well using a variable TPS but the trickiest part is getting a steady idle, as mentioned here. Once done, the throttle response is very good indeed and the torque and power are up 20% on the standard engine.
The last car we did was a 1800cc bmw, it runs 45mm bmw motorcycle itbs and car made 129rwkw and reved to 7600rpm and we have it running so good you would not know it has itbs, i ran 2 vacuum logs, one right near the engine for fpr and map, the second runs out near throttle blades and runs brake and idle stepper, this has proven to be very good, also running injector in throttle body further away from head seems to be better in our experience, all our cars run itbs or webers,
I'm Running alpha-n with map multiplication on turbocharged cbr1100xx, air/water ic and flex fuel, works very well and wasn't particularly hard to tune or setup, don't be afraid of the itb's👌
You can use map on a itb set up. It’s all about execution. The way to do it is to create a common plenum with a small volume. If the vacuum signal fluctuates too much for a good signal put restrictors in the vacuum lines. Almost like carburetor jets. If the signal is not responsive increase the flow in the vacuum lines. You can almost think of it like a resistor capacitor electrical circuit. Then you can calculate the natural frequency as well as other values.
Fantastic setup synopsis. I'm amazed this is free.
Great Video as usual from HPA! My question, you suggest that the main advantage of ITB’s is tuning, however traditional Mercedes go for long intake runs with single throttle body and BMW give there drives the sensation of motor sport with Tappet shims and ITB’s! Why is that? It’s not turning?
Got my Toda 33mm trumpets to use Toda CF Powersurge tank to my Garrett GTX2867R Gen dos. Now I just need an really nice condition with a low price NB2. Yes I know, GLWT 😂. All the while still buying parts before the car. Kinda like placing the horse to push the carriage (A$$ Backwards) 😂. Always nice YT Team HPA. Stay blessed, y'all ❤
Love videos like this, highly considering paying to get the more detailed classes and discussions.
Peter on Andersson Turbo systems , take bikes out of the box and do them at 5,10,15,20 , 25 and 30 % throttle, gives vastly both better driveability AND more importantly better laptimes !! Far more critical on two wheels....life saving when riding on the very limit...turbo or no turbo...Aplha/N..... ofcourse...On the bikes we use "clocks" as this sync is a very iterative process
Depending on the application, a simpler solution / strategy for varying trumpet lengths for testing, would be incremental series of spacers, between the trumpet / throttle body, rather than manufacturing entire trumpet assemblies, and the spacer selection varied for future tuning options, such as track differences and conditions.
Would it be realistic to utilize a MAF in combination with ITBs, by placing the MAF at the entry of a common air box feeding the ITBs?
Genuine solid knowledge expressed here.
I learned a lot from this video. I currently run twin DCOE Webers, and have always dreamed of ITB’s.
At 25:00, regarding the brake booster, definitely go for an electric vacuum pump. Holes in the inlet runners has a detrimental affect on air flow/speed, especially on a well sorted flow-benched NA engine.
🇦🇺🤜🏼🤛🏼🍀☮️😎
You have a brake booster ?
Also, will be using harbor freight (hazard freight) tools: ICON Diagnostic Smoke Machine. Just to vacuum leaks if any are accounted and rectified for.
What do motorcycles use to measure air intake? They have ITB's I wonder if they use alpha N?
A lot of them use map under idle/low load/light throttle conditions and tps/alpha-n above a certain threshold. Some are tps/alpha-n only.
Depends on the manufacturer.
On a silvertop 4age ITB that has no dedicated map sensor vacuum port, would you recommend me drilling one coming from all 4 thottles rather than tapping from the main vacuum rail being shared with ISCV, brake booster, idle up and power steering vacuum? Would sharing vacuum really result to some sort of inaccurate map sensor reading? Thanks heaps!❤
Dreaming of ITBs on my gen 2 coyote
I would like to see a back to back comparison
At 36:00, regarding Mass air flow sensor on ITB’s. Are you saying, if I put ITB’s on my Kent 1700, I could build a plenum incapsulating the trumpets, and run a MAFS at the inlet, on a NA engine to get better tuning through the rev range???
Great video!!!
🇦🇺🤜🏼🤛🏼😎☮️🍀
Yes
My bmw s54 engine has this from factory
I wonder how the Toyota 4A-GE blacktop does it, afaik it uses a MAP sensor with ITBs, and in factory setup it works fine and smooth.
I was thinking about the nonlinear relationship to throttle plate position and airflow. I wondered if anyone had tried an iris style shutter in a carb or ITB. I didn’t find much online about irises, but I did come across roller barrel throttle body designs. Very interesting. Seems that would make tuning due to airflow easier?
It makes sense on a boosted motor that the throttle response wouldn’t be as noticeable.
That being said, a rally driver who’s got the wheels spinning most of the time, could tell the difference.
I’d love to know if all rally cars still run ITB’s????
Brilliant video!
How important is the length of the inletmanifold + itb? So from engine to the valve?
With the RB26 running an Emtron… Can you run Throttle Mass Flow? With a pressure/temp sensor on the balance bar and plenum? Thanks!
What do you think of using ignition timing to control idle speed in alpha-N ITB setups?
Used ignition timing for idle with ITBs on my old Fiat. Set base idle with the throttle adjustment screw and then used ignition tuming to make it stable. It works pretty good if you don't have any other way of doing it. My last build uses DBW and gives a lot better control
Curious, are the issues with MAP/ITBs made worse / better / same with more cylinders? Eg, going from 4 cylinders to 12?
Why does Bugatti not use ITB on their V16 or W16? Ferrari has one throttle per bank. Porsche has one throttle per bank.
Only inline-4 have ITB.
@@ArneChristianRosenfeldtsaying only inline 4-cylinders are ITB is false. Some BMW 6-cylinders and 8-cylinders are ITB. Nissan RB (6-cylinders) are ITB.
Hello. Please recommend budget ecu for easy setup of itbs? i read some ecu has special map just for itbs
Ever run a jet and canister before the map sensor?
So, why can't we use the MAF sensor? I feel I didn't really understand that part.
Perfect, i wanna build a itb BP4w for my NA miata next year
If you have a capable ecu, use dbw. Makes tuning much easier as you can limit the dbw opening percentage regardles of pedal position.
So you can easily limit the dbw opening to 10% rev it out on the dyno or even on the road. Correct the maps accordingly. Increase opening by 10%. Repeat
That motor was ment for a turbo
Can I used ITB for mazda RX-8 hybrid engine
A: how are roller throttle bodys on the air flow compaired to the non liner standard butterfly valves? and B: With an electric throttle actuator and wireless throttle pedal can a linear flow opening be programed to give a linear feel?
Jenvey has two versions of the ETA and yes it is an automatic lunge back in my seat with the eta2 but I do have crossovers due to hood clearance
Roller barrel throttle bodies ought to give higher flow than an equivalent diameter butterfly when fully open, but at low openings just off idle, the air flow has to take a tortuous path through the barrel and they’re often thought of as “difficult” when it comes to tuning for drivability.
What about using a combination of TPS and Map? Certain ecu's will allow this, takes a long time to tune, but surely the end result should be a smoother and more responsive part throttle.
My 2 cents, some think the biggest diameter itbs are the best, smaller diameter itbs are easier to tune.
i got thinking... what if engine with itb has commin plenum like e46 m3, but use map sensor, but in plenum, before throttle plates shouldnt that work? or am in the wrong?
Why can't we simply run a much larger plenum to hold the air signal to the MAP sensor? I have an LS3 ITB kit run on a MAP (def. not saying its setup correctly!) But the valley cover on my kit has been converted into a large vac storage tank. 14" long and 2" high. this receives the signals from each V8 trumpet/runner. Then one opening on the rear is used to feed the map. I'm all for changing over to alpha-N. Was just curious about your Thoughts on this setup.
Does a V8 even need a plenum? In the past V8 with cold Vee used these two plane intakes. 8:2:1 distributor, all tight tubes all the way to the single throttle body. With low stroke intake should almost be sine shaped. Do we need two intake valves to shorten the path from valves to throttle body in the center and MAP sensor.
Great video with a lot of info. After going over all the different options available, I’d like to see how YOU set up the V8 with ITBs. Mechanically, in regards to the balance bar, idle bypass or not, etc.
But what about variable length intakes? Where the trumpets are serving controlled. I know some motorcycles are that way...
The trumpets on a BBC ITBs is >3x more voluminous (360mm) than a single trumpet FI (102mm). Too much air! I wonder if each trumpet of the ITBs had a disk installed with a 12.75mm orifice, would it run?
why not using maf + map ?
Would it be worthwhile to vacuum - balance each port at set up?
Yes. It's in the video starting at 15.23
@@rugwalle I see it now, thanks!
I have a Porsche 968, and it has a TPS, and a MAF, as well as closed loop Lambda. Can I put ITBs and an Airbox on it and run the stock ECU? I don't really know if it has a MAP Sensor, just starting to disassemble it.
You are going to need a standalone ecu for sure. So many different ways to make your itbs and your worst mistake will be having a limp home mode before the ecu starts to feel like it wants to add and subtract fuel at the same time
No you can not use the stock ecu and you will struggle to get long runners and plenum with out hitting the brake booster. I run ITBs on a 944 4v engine in my 944 turbo
Thank you
It would be nice to have Alpha-N by gear tables.
I'm actually surprised no one makes a small maf to either mount in the trumpet close to the throttle blade or plug into the hole you use for summing atmospheric pressure. Not sure how that might work there as fuel would probably skew the mafs function. I guess repositioning the fuel boss and tap plug would be the best arrangement...I'd either average them all together or for high horsepower/need for data race applications, use a breakout can-bus board that plugs all the mafs in and feeds the individual cylinders into the ecu. This would allow the ecu to adjust each cylinder individually on the fly
With ITBs you can get a lot of back flow from the opening and closing of the valve, so individual mafs may not work well. Can see this on itb videos, especially with stand off Injectors.
I was thinking of running two side draft Weber 40 DCOE as ITBs , on Alfa 2.0 Twinspark engine.. Is there any obvious problem with this?
We're not carb tuners sorry so can't help you with that one. If you don't plan to tune the project yourself this is a conversation you should have with the company/tuner you plan to do that work for you.
We do hope to cover carb tuning in the future if we find the right team member with the relevant knowledge, but for now our experience is with EFI. Sorry I couldn't help - Taz.
@@hpa101 Im going to use them as throttle bodies :) so.. leave the injectors in original place and put a pair of Weber 40s as throttles.
@@theservant752 ahh I missed that, tapped out at Weber 😂 What advantage are you going for with this over other proven options? - Taz?
@@hpa101 I have like 10 sets of Webers and Dellortos from old Alfas so keeping the cost down is the biggest reason, also have a fuel injected twin spark engine from a 1988 Alfa 75 (Milano). Was thinking of putting this in a Alfa 105 stepnose im building.
So the thought is to keep the stock injector position on the Twin Spark and fabricate carb mounts fitting the intake runners, they are just round with a rubber hose on the end so looks easy to do.
Put a TPS on the carbs, a balance tube for the MAP and run it like that...
The problem then comes as heat. Especially if turbocharged. Because you are assuming ideal gas pressure alone does not equal density. PV=nrT. This is why modern cars use MAF sensors. So you can have high boost numbers with high heat and have the same amount of air entering the engine as NA. Thus requiring the same fueling. This is why speed density will be inconsistent based on air temp and pressure. Alpha N will also fall flat on its face in a turbocharged application.
Let me play devils advocate. What if you have a setup with 4 map sensors and individual cylinder tuning?
i think the signal would be too unstable to work with
The map sensor readings will be very choppy from single cylinder intake valve opening/closing
Time and money spent vs just using alpha-N which is more straightforward than 4 map signals (imagine all the inputs you'd use on the ecu!)
This is a old xchool problem from using twin webers on a 4 cylinder, it you want a vac signal for a distributor a single runner tap does not work. the sigmal is very low and pulses.
When the throttle plate opens, the vacuum signal drops to almost nothing very quickly. That's a big part of the reason for Alpha-N tuning with ITBs.
How about electronic throttle bodies ?
I got em from the same company Andre is showing. Comes with a ton of different ways to configure your system and 2 different types of electronic throttle actuators
The answer is, it shouldn’t be that hard but it takes consideration
I think the most important question is: do you really need itb? 🙂
Dont need them but depending on engine and cam setup you want them
As adonay944 says, particularly with regard to the cam; with my engine, it’s typically limited to about 270° cams if you want to keep a plenum.
Jenvey envy is a thing!
If memory serves me well the 1991 Overall LM Winner Mazda 787B engine code: R26B uses a 4 rotor, 3 spark plugs per rotor, now get this, with telescopic ITB setup. The Mazda engineers says it's just a simple pulley cable system... yeah... maybe for a Mazda engineer 🤔 engine made 700 hp weighing at almost 400 lbs. Talk about power density 😮
th-cam.com/video/3qdgKYFiuIc/w-d-xo.html
HPA, please delete if not allowed.
That is relative to your ability. Worth it relative to your goal. Missing context, but I'm not your target.
lol, now imagine doing this on a flat 4 with dual ITB weber CARBS! and just a book and ZERO experience!! prepare to spend some time!!! =)
Where there's a will, there's a way, especially if you have the time - Taz.