Thread: SR Individual Throttle Body Design and Theory (ITB)

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Well, there are limited amounts of information out there, regarding SR ITB technology and the bits and pieces of info that actually do exist, are hard to come by. This thread will be a compilation of everything I can find, relating to Individual Throttle Body Systems (with a focus on the Nissan SR20 platform).

In this thread I will include:

- ITB Theory (Complete with articles and other technical information)
- Images/Videos of different setups (Off the shelf and custom)
- Information on specific off the shelf manufactured kits (with prices and specs)
- ITB dyno results (vs regular plenum or other ITB setups)

* Hopefully all of the ITB experts of the world will feel compelled to contribute their knowledge to this thread. I would like to make this a one stop resource for everything SR20 ITB!!!

Feel free to contribute!!!

Let's Begin!


ITB = Individual Throttle Body (Also known as Independent Throttle Body)



SR specific and General ITB technical/theory (Articles):

Jenvey - ITB Theory (Link)

Individual Throttle Body Selection

Butterflies, Barrels or Slide Throttles

Why not just use a big single throttle body?

Miscellaneous

ITB The Way It Should Be - Import Tuner Magazine Circa 2008

Individual Throttle Bodies - Wrenchin' Circa 2009




ITB Related Discussion (Threads) From Various Forums:

http://www.sr20-forum.com/vvl/52225-2-0-ve-itb-dyno.html

http://www.sr20-forum.com/all-motor/11152-sr20-itbs-found.html

http://www.sr20-forum.com/vvl/61637-2-0-ve-dyno-testing.html




Available SR ITB setups


SR20VE

Hayward Performance (Link)
(British Columbia, Canada)

Application: SR16/20VE head (NEO VVL) (suitable for 2.0 L - 2.2 L)

Cost: $3300.00 USD

Manufacturer Description:

THIS SYSTEM IS ONLY AVAILABLE AS A COMPLETE UNIT, IF YOU NEED IT FOR AN INLINE DRIVE APPLICATION THEN STRAIGHT AIRHORNS CAN BE SUPPLIED. THE CARBON AIRHORNS ARE NEEDED TO FIT INTO THE FRONT WHEEL DRIVE ENGINE COMPARTMENT.

Custom Nissan SR20VE 30 HP increase over best previous intake system on a 2000 cc engine. Custom Carbon airhorns just for this Nissan system.







SR20DE/SR20DET

Hayward Performance (Link)
(British Columbia, Canada)

Application: SR20DE

Cost: $1800.00 USD

Additional Options: TPS / $80.00 USD

Manufacturer Description:

Package Includes

- Manifold
- 48mm straight bore throttles
- 90mm long airhorns
- Fuel rail and mounts
- Linkage
- Cable pull
- TPS (Optional for extra charge)







Extrudabody (Link)
(Florida, USA)

Application: SR20DE/SR20DET

Cost: $1499.00

Manufacturer Description:

The SR20DE/SR20DET kit is a bolt-on kit, it includes the manifold, 4 ITB's in either 45mm or 45mm Tapered to 50mm, 2 Base plates, Balancing Kit, Throttle Cam/Stop, Fuel Rail and mounting hardware, TPS and Mini Harness. our Standard Filters are also included, see them in the Air Delivery section. Note: the Manifold is 48mm and has a 1.5mm step from the ITB to the Manifold can be run as is or Porting the base like shown in the Pictures will increase flow and HP! Injectors are not included!





Jenvey (Link)
(England, UK)

Application: SR20DE

Cost: $1113 GBP (appx. $1710 USD)

Optional items:

Linkage Kit - $148.22, Linkage Brackets and Rod - $19.33, Hall Sensor/contactless TPS - $154.66, Air Filter - $122.44

Manufacturer Description:

Nissan SR20DE throttle body kit from Jenvey Dynamics includes four SF48/4.5/1 taper throttle bodies ( ITB's), a Jenvey Dynamics EFI inlet manifold, fuel rail and four 90mm long airhorns. Jenvey throttle bodies and all Jenvey throttle body accessories are engineered for Motorsport, offering excellent performance, reliability, lightness and value. This kit is ideal for road, track or rally use.This kit is for the SR20DE high port engine as used in the GTiR.Made to order - up to 2 weeks to dispatch.





Tomei "4 Throttle System" (Link)


Application: SR20DE

Cost: $2640.00 USD (MSRP)

Manufacturer Description:

SR20 "4 Throttle System". Not just for looks! Enjoy the pleasures of quad open throttle bodies and the harmony they produce. The response and feel of the NA driveability and enjoyment.

- 45mm







EFI Hardware (Link)
(Victoria, Australia)

Application: S13/S14 SR20 (and other)

Cost: $1400 AUD (appx. $1400 USD)

Manufacturer Description:

Tapered Bore Throttles have a clear advantage over Parallel Bore Throttles at increasing power and torque. By accelerating the air through a venturi (in this case a tapered bore) the air speed through the throttle body is increased. This enhances the engine cycle's scavenging effect to provide more air and fuel in the combustion chamber and therefore more power and torque.

The Tapered Bore has 3 sections:

Inlet from ram tube - 52mm
This then tapers down to a short parallel section for the throttle plate - 50mm
There is a second taper down to the outlet flange of the throttle body - 48mm

Kit includes:

- 2 x direct fit tapered bore throttle bodies 52/50/48
- fuel rail and mountings
- linkage
- 4 x ram tubes and bases
* note - injectors, fuel rail fittings and tps not included in kit price but can be supplied on request





IKEYA FORMULA (ITB Kit Link) (Main site Link)
(Tochigi, Japan)

Application: S13, S14, S15 RWD SR20DET

Cost: 278,000 - 283,000 Yen (appx. $2730-2780 USD)

Manufacturer Description:

Increased air mass flow by turbo tuning will become resistance if normal throttle and surge tank are used. From these reasons behind:

- Review on the capacity and structure of surge tank to deliver the increased air mass flow to each combustion chamber effectively.
- to stabilize the even air suction system to each combustion chamber by having quadruplet throttle.

By solving these issues, it's made possible to produce smooth/ powerful force and torque in addition to clear engine responsiveness at high/middle revolution range.

Kit Includes:

-Surge tank x1 (3,000cc inlet diameter phi80)
-Throttle x2 (phi 45)
-Throttle linkages
-Delivery pipe x(50cc)
-AAC tank x1(200cc)
-Negative pressure hose
-Hose band
-Gasket
-Bolts and Nuts









Additional manufacturers will be added soon....




Dyno Proven SR ITB setups (Horsepower numbers)


Info to come...



_______________________________________________


I am by no means an expert on this subject; I am learning along with everyone else.

This thread will be a work in progress and I will add information as I come across it. Feel free to add links to articles or set-ups that you have on you SR powered car. All information on this subject will help to advance our aging SR engines.

Feel free to post up dyno graphs (before and after results) of your ITB setup, along with the relevant engine/build specs. I will do my best to keep the first post(s) accurate and current.

Thanks.

In this section, I will do my best to outline how one might go about tuning an ITB set-up, as well as what tuning options are available for ITB kits.

Running an ITB intake set-up on your engine is not a common practice. It is not common because it is cost prohibitive (ITB's are not cheap), not to mention the added difficulty in tuning the ITB's. Tuning a single-throttle plenum style manifold with a MAF/AFM setup is generally regarded as being much easier. A good tuner can tune both, with the proper hardware/software.

More often then not, a full stand-alone engine management system is needed to properly tune an ITB setup. Options are the usual suspects, such as: AEM, Mega Squirt, etc. There have also been recent advancements in OEM ECM tuning that will now allow for MAF to alpha-N or speed density (MAP) conversion via daughterboard/firmware upgrades. The NismotronicSA tuning package is the latest step in Nissan OEM ECU tuning. It eliminates the need for a MAF setup and allows tuning via engine speed (RPM via the crank sensor) and throttle position (via the TPS sensor). This type of tuning is known as alpha-N. I will let some experts explain the difference between MAF/AFM (mass air flow/air flow meter) sensor tuning vs alpha-N tuning.

Alpha-N Tuning (Can be used for ITB tuning)

Both of the below descriptions are somewhat specific to BMW applications but the general tone of the description is applicable to all car manufacturer platforms that wish to tune via this method.

Here is an explanation on this type of tuning: (from here - Authored by Gustave Stroes)

An engine management computer, regardless of how sophisticated or crude, really only controls two parameters. The ignition timing and the fuel delivery. The computer (DME or some aftermarket brand) uses an array of input sensors to try and determine what state the engine is in at any point in time. Is it loafing along on the freeway at low rpm, or at max throttle climbing a hill at high rpm? Is it hot outside so that the air is thin? Or is it butt cold and the air is real dense?

The list goes on, but the goal of the computer at all times is to sample its input sensors and then determine the appropriate output signals for ignition timing and fuel delivery (usually this determines how long the fuel injectors fire, which is called the pulse width, but it can also entail "when" to fire the injectors if the injection is sequential).

The two most important things that the computer wants to know in order to determine spark and fuel are: 1) engine load, and 2) engine rpm. Engine rpm is easily determined from a crank sensor. But engine load is a little more tricky. The best parameter to use in determining engine load is the MASS of air entering the engine at any time. If you can measure the mass of air directly then you are well off. Current BMW's do just this with what is called a MAF sensor, or mass air flow sensor. This is usually some type of heated wire or film, which is cooled by the air flowing over it. In order to keep the wire at the same temperature additional electrical current must be provided, and the measure of this extra current gives a fairly direct indication of the mass air flow.

Our E30 M3's used a similar system, although it measures the VOLUME of air flowing into the engine. The sensor is called an AFM, which stands for air flow meter. The volumetric flow is determined by how far a flapper (or barn door) is pushed aside by the incoming air. The flapper is connected to a potentiometer (variable resistor, POT, wiper, there are many names). But for the computer to know how much fuel to mix with the air it needs to know how many molecules of air are coming in, and that can only be determined by knowing the MASS of the air, not just the volume. So, we need to combine the AFM air volume signal with an air TEMPERATURE measurement Then the air mass can be determined. So we are ok.

Note that in both cases the computer has some hard data on how much air is entering the engine, so if you improve engine breathing (header cams etc...), the basic code will still sort of work as the computer is aware of the additional air. It's not perfect, but it works ok most of the time for changes that are not too drastically different than the baseline.

Alpha-N is different. Here there is no direct measurement of either the mass of air, nor the volume of air entering the engine. That way any possible obstruction from either a MAF sensor or AFM sensor in the intake path is removed. The air can flow right into the engine unobstructed. So how does the computer know what to do? It still has rpm info from the crank, but it can't measure the mass of air coming into the engine for fuel mixture determination?

The answer, in a crude sense, is that you "train" the computer what to do in a given situation (on the dyno). For every possible combination of throttle position and rpm, the tuner determines the appropriate ignition timing and fuel delivery to yield max power but not incur detonation. The computer just remembers all this (in the form of maps which are stored on a chip), and when it sees a certain combination of rpm and throttle position in the field, it just says "what did they tell me to do in this situation?" and does that.

So now throttle position and RPM are the two dominant input parameters to the engine computer. This is where the Alpha-N name derives from. Alpha for the angle of the throttle plates and N for RPM.

Now if you have an Alpha-N system, and add a hotter set of cams that allow more air into the engine, but you do not reprogram the Alpha-N computer, then the computer has no knowledge of the extra air now entering the engine and it just gives the fuel and spark that it was told was appropriate for the milder set of cams. One can see how this could be a problem. Your mixture especially, but also your ignition timing will be way off. If your mixture goes lean you can potentially damage the engine. That is why folks say that an Alpha-N system needs to be retuned everytime you make a change to the engine. The computer is "flying blind" to some extent, although it does at least have an air temp sensor and a barro sensor to try to compensate for density changes in the air due to temperature and elevation.

I have oversimplified some subjects to make it easier to understand, and as usual there is probably more that I did not say than that I did say about Alpha-N, but hopefully that gets some folks a little closer to understanding it.


Here is another explanation: (from here - Authored by nik@vf-engineering)

What is Alpha N?

Alpha N is the term used by the DME manufacturers to describe a mode of operation. Most German vechicles are designed with an Air Flow Sensor (aka MAF) to provide optimal driveability and clean emmissions control. Removing the MAF on most BMWs forces the DME to operate in Alpha N mode. Alpha N mode is not something that an aftermarket tuner has created. Alpha N mode is often regarded as a built-in safety mode for the engine should the MAF fail.

How does Alpha N work?

Most German vehicles DMEs use inputs from 1)Coolant temp sensor 2)Crank sensor 3) MAF and 4) O2 sensors to control the clean and efficient operation of the motor. Should the DME loose one or more of these 4 critical sensors, the car will likely run poorly. If the MAF (a very critical input) were to fail, the Siemens MSS54 DME for the S54 M3 drops into Alpha N mode and uses the throttle position sensor to calculate the Mass of the air entering the combustion chamber. This is also know as "Speed Density Mode" ie get-you-home mode and the Check Engine Light will usually light up. The car may run well for the time being, but the S54 was designed to be run with an MAF for emmission and driveability reasons.

So what is the big deal if I want to pull out my MAF and just let the car run in Alpha N?

There are some consequences such as a check engine light, not as accurate fuel trimming and MAF calculations and increased emissions. Fuel Trimming is a major function of the DMEs fuel management system. It represents the actual addition or subtraction from the actual fuel mixture being setup by the DME.

Removing accurate fuel trimming and allowing fuel trimming to be calculated off the throttle position sensor instead of the MAF can have side effects on driveability characteristics such as throttle response, smooth part throttle and tip-in onto acceleration. In order to achieve factory-like driveability, fuel trimming based off MAF data is essential - which is why BMW use a MAF. Adding forced induction does not make it a neccessity to remove the MAF - just look at all the thousands of non-S54 BMW supercharger kits currently in use that all keep their MAFs and the dozens (close to 50 sold in 3 months) of VF-S54 supercharger owners.

The code in the DME can be deleted so that the check engine light does not come on. The code in the DME can also be changed so that the DME does not use its fuel trimming features etc. However all of the forementioned requires altering emmissions and OBD2 programming characteristics of the DME and this is not taken too well by the authorities if you plan to drive your car on public roads. Additionally and possibly more importantly to the performance enthusiast, the functionality and intelligence of the DME is reduced and limited if sections of code are deleted from the DME.


ITB Tuning Options:

Stand-alone ECM/ECU (Engine Control Module/Engine Control Unit)


Stand alone tuning options can be found in the Engine Management System Comparison thread (Authored by @BenFenner)

True stand-alone engine management systems will allow you full functionality to tune your ITB's as you see fit. They will also allow you to eliminate some components such as the MAF, without causing an issue within the on-board diagnostic system (OBD).


OEM ECU tuning options

Real Time Daughterboard Solutions:




NismotronicSA (Link)

Application: OBD1 ECU's (Please consult the Nismotronic web-site for compatile ECU's)

Cost: $550 USD

Description: (John/Dave: Feel free to have me adjust this section if you see fit)

John Kerr @JKTUNING and Dave Dunn @OnTheChip have teamed up to bring you the latest option for tuning the OEM Nissan ECU, NismoTronicSA. If you have an OBD1 ECU, you can now add a the NismotronicSA tuning package (NEMU RT daughterboard and TunercodeSA firmware) to your stock ECU. This will make it much easier to tune an open air ITB setup via the TPS. As mentioned up above (in the last section), you can eliminate your MAF sensor and tune directly via the TPS (along with the CAS). You will have to make changes to your fuel and timing maps on a dyno but this is what will give you the precise tuning you are after with an ITB intake set-up.

JKTUNING explains the feature here.








Standard ECU/board Tuning

In theory, you should be able to use an ITB intake setup on your stock ECU, and tune via the MAF. You would have to incorporate a plenum to cover the ITB's as the MAF would need to be used in a typical maf tube intake system. Basically, you would build a plenum around your ITB's and have it attached/mounted with some sort of plate. You could then run a standrad-type intake tube out of the plenum and have the MAF sensor situated in the intake tube (exactly like it is in a single-throttle plenum-based intake setup). You would have to use the MAF sensor for tuning air flow or volume because an unmodified ECU will be searching for readings from the MAF (along with the TPS, o2, CAS and ECT sensors) to deliver the correct the Air/fuel mixture.

Here is a picture showing what I mean. (not SR20 or Nissan specific)



If you were to run ITB's on a stock untouched ECU, you must realize that the tuning would be somewhat crude. The ECU would adjust to the air flow changes brought about by the ITB's but it would be nowhere near as precise as tuning via Alpha-N/TPS. You would be at the mercy of the ECU's open-loop correction capabilities.

You could add to the tuning with a piggyback controller which would allow you to make some fuel and timing adjustments. This would allow you to get the tune more on point but it would still be somewhat crude when compared to tuning the ITB's directly via Alpha-N (CAS/TPS/direct fueling/timing map adjustments). Two well-known piggy-back controllera are, the A'PEXi SAFC or the Greddy E-Manage Ultimate (or Blue). Both of these controllers have been discountinued (you would have to find a used unit) but there are newer versions of them as well as many other types of piggyback controllers that would work.


Notes:

Nissan used an ITB/Plenum setup for the SR20DET on the RNN14 Pulsar GTi-R.

(More info on the GTi-R setup will be posted soon!)



(For the members I mentioned in this post, feel free to PM me (or post up) if you feel I need to adjust any of the information I have posted or if I have misrepresented anything product related.)


Stay tuned for more ITB goodness SOON!

Space.

i love itbs

in australia,a few guys have these...
SR20

Thanks for posting that link! I will add it to the list.

Do you have any links to build threads, where some folks from down under are using them? Have people been happy with them?

There should be a company that produce a more affordable ITB kit for VE than Hayward!!! Spending $3000+ on a ITB kit its way too much when Honda's can get a very nice set for half of that!!
Just my oppinion..

^I agree but I have friends with big bore/stroked K series cars and they spent around 3,000 on their ITB setups. It sucks but the power we can make with them is excellent. We should have a couple of 300whp pump gas cars in our camp soon.

The Honda ITB's that are $1500 and under are all Chinese knock offs. The obx K series ITB's are direct knock off's of the Hayward's.

$3500 is fair considering Kinsler units are $5000+.

When you are only going to sell 5-10 units to an entire community, why would they short change themselves.

@Payu Please PLEase PLEASe PLEASE read this, it will only take a couple of minutes
Revenge of the Nerd- Boycott Fakes!