Wassup Vance man! :smile:
BTW one of the strokers was planning to do ITB's.....but the person could not source the itb's to him......itb's are doable with the right tuner's such as Fastraxturbo or Mitch formerly from AEM.
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ITB and tuning the engine
- Thread starter midNight Sun Xpress
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Wassup Vance man! :smile:
BTW one of the strokers was planning to do ITB's.....but the person could not source the itb's to him......itb's are doable with the right tuner's such as Fastraxturbo or Mitch formerly from AEM.
Yes Mitch was one of the name that came up. TODA told me to work with HKS if I decide to go with their package. The tuners does exist, you just have to know where to find them.
I am also talking about the NSX. If you were capable of understanding simple concepts, you would have understood that. The other references were a rebuttal to your comment about tuners here. I know you think the nsx is unique, but motors are motors.
The nsx does have some challenging differences, but nothing compared to some other cars I have worked on. For example, I have done ITB installs on V8s and on a V12. So, using your vast knowledge of everything automotive, what -specifically - would make installing them on an nsx more difficult?
Also, please give me some examples of cars that you personally have built and tuned so that I can put your comments in their - um, proper - context. I'll go first: my 2nd try at building an nsx was the first high-powered turbo nsx in this country and was very likely, at the time, the highest whp street legal nsx in the world. Your background?
Thank you so much for your permission; I feel so much better now.
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Re: not even close. . . .
I concur. Though US tuners don't normally have as heavy a price tag as Japanese tuners do. I know a couple of tuners, here in the US, that have had great success in tuning and fab'ing ITBs for Honda (hayward (sos), kinsler, king motorsports). Bisimoto has an awesome setup on a F22:
If the guy can make the above work, I'm sure he can tune an ITB system developed for the NSX.
Hogan in Cali made this manifold that was good enough for a high hp drag racer. I'm sure it flows well enough.:wink:
However, there's something about ITBs that is undeniably attractive from an engineering perspective. Not that I'm an engineer - far from it.
I concur. Though US tuners don't normally have as heavy a price tag as Japanese tuners do. I know a couple of tuners, here in the US, that have had great success in tuning and fab'ing ITBs for Honda (hayward (sos), kinsler, king motorsports). Bisimoto has an awesome setup on a F22:
If the guy can make the above work, I'm sure he can tune an ITB system developed for the NSX.
Hogan in Cali made this manifold that was good enough for a high hp drag racer. I'm sure it flows well enough.:wink:
However, there's something about ITBs that is undeniably attractive from an engineering perspective. Not that I'm an engineer - far from it.
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Re: not even close. . . .
Actually, sometimes power under the curve with ITBs may be less. There are alot of variables affecting tuning with ITBs. Diameter and total length of the throttle bodies (including air horn), along with cam, head and exhaust modifications all have an affect on the power and torque band. ITBs are more sensitive to air density, and barometric changes as far as fuel tuning. Thats why some people are always screwing with their jets and metering rods with individual carbs. Fuel injection makes tuning easier in that aspect, but you have alot more compensation tables to adjust, and if not set right, may not run optimally at different temps and altitudes.
I really doubt that a stock 3.0 or 3.2 will gain much with ITBs as they are not going to "force" additional air into the cylinders. Nature only gave us about 14.5 psi that our engines can injest.
On a 3.8 motor, the stock manifold may possibly be too restrictive, and ITBs will shows larger gains. On a side note, I have recorded vacuum picking up in the stock manifold at high rpm which can be anything from poor pickup placement port for the map sensor to excessive turbulence in the runners.
True, there is something about seeing, and hearing ITBs on an engine, but for the horsepower to cost ratio, it doesnt make much sense.
I'd do it, but I dont have 5-6 grand in my pocket.
Actually, sometimes power under the curve with ITBs may be less. There are alot of variables affecting tuning with ITBs. Diameter and total length of the throttle bodies (including air horn), along with cam, head and exhaust modifications all have an affect on the power and torque band. ITBs are more sensitive to air density, and barometric changes as far as fuel tuning. Thats why some people are always screwing with their jets and metering rods with individual carbs. Fuel injection makes tuning easier in that aspect, but you have alot more compensation tables to adjust, and if not set right, may not run optimally at different temps and altitudes.
I really doubt that a stock 3.0 or 3.2 will gain much with ITBs as they are not going to "force" additional air into the cylinders. Nature only gave us about 14.5 psi that our engines can injest.
On a 3.8 motor, the stock manifold may possibly be too restrictive, and ITBs will shows larger gains. On a side note, I have recorded vacuum picking up in the stock manifold at high rpm which can be anything from poor pickup placement port for the map sensor to excessive turbulence in the runners.
True, there is something about seeing, and hearing ITBs on an engine, but for the horsepower to cost ratio, it doesnt make much sense.
I'd do it, but I dont have 5-6 grand in my pocket.
yes,
it is almost guaranteed to loose some bottom end power wit itb's as you decrease the tuned intake length significantly- all the gains will be in the upper rev range so street- driveability will suffer for sure.
'david' is right, nsx is not different than anything else, this is not a 'holy grail' either and like i said before, any qualified bike mechanic can synchronise the itb's and the overall tuning is easily achieved with a dyno and ems.
itb's are nothing new- i have a 1972 alfa with mechanical fuel injection and factory itb's- no big deal here.
it is almost guaranteed to loose some bottom end power wit itb's as you decrease the tuned intake length significantly- all the gains will be in the upper rev range so street- driveability will suffer for sure.
'david' is right, nsx is not different than anything else, this is not a 'holy grail' either and like i said before, any qualified bike mechanic can synchronise the itb's and the overall tuning is easily achieved with a dyno and ems.
itb's are nothing new- i have a 1972 alfa with mechanical fuel injection and factory itb's- no big deal here.
I would think the vtec on the nsx plus the emisions/ecu constraints would make this more complicated than your old alfa or a bike,,no
Not really. Ferrar/BMW all have similar Variable Valve Timing System and they use ITB. That alone tells the world that ITB is a good application for performance production car.
Not necessarily. Any induction system can be tuned for optimal performance at a certain RPM range. In general terms: you want low rpm power, use a longer and narrower runner. Want high rpm power, use a shorter and wider runner.
For my 3.6, there's really no other options besides a custom manifold or the ITBs to let the engine breath at the level it should. The stock manifold, though it flows extremely well, is still too restrictive. Like a sprinter with a breathing condition.
For a stock 3.0 or .2, I think ITBs are a hard value proposition. But I wouldn't mock someone for trying. It'd be an extremely interesting project.
Agreed. The stock TB is very efficient for the 3.0 and 3.2. All of the ITB I have seen from Japan are disclosed with the 3.5 stroker kit, which uses stronger pistons/Con Rods with raised RPM to achieve additional HP. Just by putting ITB into a car with stock internal will probably not see any significant improvement.
The truth is, it will be a very expensive project and may not achieve proper result if you enter the project blindly.
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Hehe, don't worry David. Sometimes you're better off to just leave it alone........ :wink:
It is kind of frustrating though, isn't it? :frown:
One of the starting points is the decision of what size bodies to use. This would vary with the displacement and will affect the shape of the power curve. If this works just like carbs, and I'm sure it doesn, small diameter moves the curve back giving better response, large moves the curve up netting higher peak HP. This is something where only experience will net favorable results. And considering the cost, verifying the cred of the source of what size to use is imperative. Ideally the entire intake system should be flow-bench designed. But in our case, using what has been used already in the out-of US racing venues seems to make sense. (?)
One of my biggest issues with most Japanese ITB setups is based on the throttle bodies they use. Without getting into bashing any particular brand, they almost always use either an off-the-shelf Toyota throttle body or modify a set intended for something else. A couple of the nsx kits are throttle body sets designed for Porsche flat six motors fitted to an intake manifold for nsx heads. Of course, the spacing on the TBs is less than optimal.
None of the sets I saw in Japan used Jenvey throttle bodies, which are widely considered the best available for ITB applications. None were tapered, which is a nice feature on ITBs and improves the flow characteristics of them. They do, however, make up for the lazy engineering by charging way too much money for them.
None of the sets I saw in Japan used Jenvey throttle bodies, which are widely considered the best available for ITB applications. None were tapered, which is a nice feature on ITBs and improves the flow characteristics of them. They do, however, make up for the lazy engineering by charging way too much money for them.
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I also expect that the diameter of the throttle bodies impacts the area under the power curve, as Tanto2 mentioned. Having the throttle bodies closer to the cylinders will improve throttle response in any case. How large the throttle bodies are will impact where peak power is produced.
If my measurements are correct, the runners in a stock NSX intake manifold have a cross section of about 1801 mm2, which is equivalent to a 48mm port. Since the intake manifold is port-matched to the cylinder heads, that's the size of the stock entrance to the cylinder heads as well.
Increasing the size of the port will reduce the velocity of the flow and may increase peak power at the expense of low and mid-range power. Whether that's good or bad is a matter of personal preference.
Science of Speed mentions that their ITB setup includes "lightweight aluminum individual throttle bodies (48mm)". As far as I can tell, that's the same port size as stock. They also state their ITBs are a "3-dimensional port matched manifold", further indicating that they have the same size as the stock entrance to the cylinder heads. Moving the throttle bodies closer to the cylinder heads will improve throttle response, but keeping the stock port diameter will limit top-end horsepower gains. Since the intake runners are shorter, some top-end power should still be freed up, however.
I don't know what internal diameter Toda uses for their NSX ITBs.
If my measurements are correct, the runners in a stock NSX intake manifold have a cross section of about 1801 mm2, which is equivalent to a 48mm port. Since the intake manifold is port-matched to the cylinder heads, that's the size of the stock entrance to the cylinder heads as well.
Increasing the size of the port will reduce the velocity of the flow and may increase peak power at the expense of low and mid-range power. Whether that's good or bad is a matter of personal preference.
Science of Speed mentions that their ITB setup includes "lightweight aluminum individual throttle bodies (48mm)". As far as I can tell, that's the same port size as stock. They also state their ITBs are a "3-dimensional port matched manifold", further indicating that they have the same size as the stock entrance to the cylinder heads. Moving the throttle bodies closer to the cylinder heads will improve throttle response, but keeping the stock port diameter will limit top-end horsepower gains. Since the intake runners are shorter, some top-end power should still be freed up, however.
I don't know what internal diameter Toda uses for their NSX ITBs.
Design theory, in general terms:
Intake Port to Torque Peak
*Long Port Length: Improve low RPM range
*Short Port Length: Improve high RPM range
*Large Cross Section: Works better on larger CID and higher RPM
*Too large of a cross section can cause reversion and less power
*Small Cross Section: Works better on smaller CID and lower RPM
*Smallest cross section without losing HP is the best size
Good ITB discussion here and an ITB designer even added his own .2 cents.
For me, I couldn't care less about low end. Just give me excellent mid-range and good high rpm performance.
Intake Port to Torque Peak
*Long Port Length: Improve low RPM range
*Short Port Length: Improve high RPM range
*Large Cross Section: Works better on larger CID and higher RPM
*Too large of a cross section can cause reversion and less power
*Small Cross Section: Works better on smaller CID and lower RPM
*Smallest cross section without losing HP is the best size
Good ITB discussion here and an ITB designer even added his own .2 cents.
For me, I couldn't care less about low end. Just give me excellent mid-range and good high rpm performance.
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Did you take into account the fact that the flange is at an angle to the port?
Yes, I tried to. But if someone with an intake manifold lying around could double-check my results that would be great.
