Throttle Body, What is it?

Friends,

“Seharusnya, walau pun kita meng-inject-kan water injection melalui throttle body yang ada di ujung, pada prinsipnya, aliran butiran air akan tersedot/terhisap sesuai dengan urutan vacuum yang terjadi pada masing-masing silinder, jadi butiran air itu akhirnya akan merata pendistribusianya, mungkin anda harus lebih dahulu memahami apa dan bagaimana cara kerja throttle body ini, coba nde lihat cuplikan di bawah ini.”

#*# Tapi apa yang mas kemukakan juga tidak salah, kekhawatiran tersebut ada”, oleh karena itu, beberapa orang praktisi water injection, membuat system water injection yang bertekanan (10 psi) dengan pemasangan injection needle pada port nya. Saya kalau tidak salah ingat pernah punya documentnya, kalau ketemu akan saya kirim via email🙂 bagaimana ? #*#

“Itu Jawaban Dari Saya Dari Pertanyaan Berikut Ini”

====

Kebetulan ada sedikit pertanyaan seperti ini di mailing list yang biasa aku monitor, berikut cuplikan nya :

####

From: “Muzakir” <muzakir@bobcpp.co.id> Add to Address Book
To: “‘Alamsyah Real'” <ke2alam@yahoo.com.sg>
Subject: RE: FW: [ditechinjection] One way valve,
Date: Tue, 22 Jul 2008 10:43:37 +0700

Makasih share nya mas Alam.
Udah saya buka di wordpress, tp gak ada gambar internal
compartemen engine.
Saya udah pernah coba dgn mat. spt yg di Ditech, air ngalir saya
batasi kira2 1 liter utk jarak tempuh 50km. Cuma kalo saya
bayangkan air itu hanya masuk ke cyld no 1 dan sedikit ke cyld
no.2 saja.
Karena intake water di TB (escudo 2.0) dipangkalnya, maka kecil
kemungkinan bisa sampai cyld 4.
Ada solusi lain gak ya Mas Alam.
Oya mas, saya merasa mas Alam ini ilmuwan lah, benarkan?
Mari kita pikirkan cara agar air bisa masuk ke seluruh cyld dgn
rata.

Satu lagi, saya lupa ntah dimana liat, mereka aplikasi dgn steam,
jadi jelas mix di TB nya akan bagus dan akan rata ke seluruh
cyld. Steamnya adalah water line dgn cooper tubing dibelitkan pd
exh manifold sepanjang 3 feet. Kira2 gimana Mas, ada pendapat ttg
itu?
Trims mas atas merepotkannya.

—–Original Message—–
From: Alamsyah Real [mailto:ke2alam@yahoo.com.sg]
Sent: Monday, July 21, 2008 19:09
To: Muzakir
Subject: Re: FW: [ditechinjection] One way valve,

kalau power, saya tidak bisa merasakan (tidak terlalu
significant) mungkin karena mobil saya menggunakan transmisi
automatic.

kalau irit atau tidak, tergantung dari bukaan valve (kran
aquarium) sebelum masuk ke intake manifold, semakin boros airnya
semakin irit pemakaian bensin-nya (saya juga tidak tahu kenapa di
mobil saya, walau saya pasang boros *kran saya lepas* mobil saya
tidak mberebet, tetap nyala dengan baik). hasil setelah pasang
wa-i, dulu saat bensin masih 4500/l perjalanan serang – kotabumi
butuh rp. 200.000 sekarang setelah bensin naik jadi 6000/l
perjalanan serang – kotabumi butuh cuman rp. 150.000. iritnya
terasa banget.

kalau mau lihat fotonya ada di
https://go2alam.wordpress.com

geto mas,….
🙂

— Muzakir <muzakir@bobcpp.co.id> wrote:

> Mr. Alamsyah,
> Maaf, saya nyambung aja dari milist, mau tanya2 dikit ya..
> Berasa apa sih sejak pake Wa-i ?
> Jika hemat kira2 dari berapa ke berapa km/liter?
> Jika tambah power, signifikan gak?
> Mas, jika boleh share foto bagian inject ke TB / carbu nya
dong..
> Trims mas Alam, pengen juga sih, cuma saya di Medan, terpaksa
harus
> mandiri masangnya.

####

What is a throttle body?

The throttle body is to modern engines what carburettors were to engines of 30 years ago. They are devices that regulate the quanity of air being allowed to enter the engine, and thus, indirectly, alter the fueling. The throttle is modulated by, you guessed it, the throttle pedal – the further you depress the throttle pedal, the wider open the throttle butterfly, the more air that enters the engine, the more fuel that is burnt, and the more power the engine produces. More power, more acceleration.

Where can the throttle body be found? This is shown in the picture, right: if you open the boot of your MGF/TF, and peer into the engine through the inspection grille, you’ll see the inlet plenum. To the left of this, you see the throttle body itself (the silver item in the centre of the picture), which is also attached to the air filter.

There are three types of standard throttle bodies available for the MGF/TF. The first is a black plastic item, with an internal choke measuring 48mm. The second (fitted on MY2000 onward MGFs) is an alloy throttle body with the same 48mm internal choke. The final variety of throttle body is the 52mm internal diameter choke alloy item found fitted as standard to the MGF Trophy 160 SE, the MGTF 135 and MGTF 160.

How do throttle bodies work?

Throttle bodies are essentially very simple devices, yet manufactured to within extremely tight tolerances.

As mentioned above, the throttle body is, in some respects, similar to a carburettor, in that it basically consists of a length of pipe in which a flap, hinged through its centre, acts as a ‘butterfly’ valve to regulate the quantity of air passing though it. Unlike a carburretor, however, the throttle body does not regulate any fuel flow – this function being performed by the fuel injectors in the plenum. The more the butterfly valve is rotated, the larger the opening of the throttle (illustrated opposite, right). The narrowest point in this pipe is the choke – to which the butterfly valve’s diameter is matched.


On a standard throttle body, the diameter of the butterfly valve is 48mm. On the “Trophy” throttle body (so-called, because it was first found fitted to the MGF Trophy 160 SE), the butterfly diameter is 52mm. A 4mm increase in diameter may not sound like much, but because the cross sectional area of the choke is calculated by the equation, pr2 (where p is Pi = 3.142, and r is the radius of the circular butterfly valve), the increase in diameter of the choke from 48 to 52mm results in a 17% increase in area. Result: much more air can flow into the engine (because the resistance to flow is inversely proportional to r4).

The throttle butterfly is operated by the throttle cable, whose linear motion is converted into the necessary rotary action by the throttle cam on the side of the throttle body (shown in the pictures near the top of the page). On the other end of the butterfly axle is a throttle position sensor (TPS). A TPS is a small potentiometer (pictured opposite, right, removed from the throttlebody) performs an essential function, as it provides the engine management system information regarding the position of the throttle, and therefore engine load – vital for the fuelling and ignition mapping for optimum performance and efficiency. TPS sensors are normally used on performance engines where airflow sensors may be confused by pressure pulses in the inlet tract. Airflow is not measured, but calculated based upon engine speed and throttle position. If the engine is significantly modified, the airflow characteristics may change beyond the limits of the MEMS fuelling/ignition map necessitating re-mapping (which usually means replacement of MEMS with an aftermarket programmable ECU).

Other throttle body functions…

You may have noticed that there are two other pipes leading into the throttle body, that appear to have little to do with the basic breathing functions of the throttle. The lower of these two pipes is for the oil breather system, that allows fumes from the engine to be recirculated and burnt in the combustion chambers. The upper pipe is the idle control air inlet from the idle air control valve (IACV).

2 thoughts on “Throttle Body, What is it?

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