küsimus turbiinikoja mõõtude kohta

[kala]

leidsin netist kolades sellise teisenduse,aga nii palju kui veel ringi kolasin siis sain aru et t3 ja t4 flantsiga need arvud muutuvad.
ehk oskab keegi öelda mis vastab sellele kui turbo on T4 63/68 0.88A/R mis selle A/R cm võiks olla?
6 cm2 = 0.41 A/R
7 cm2 = 0.49 A/R
8 cm2 = 0.57 A/R
9 cm2 = 0.65 A/R
10 cm2 = 0.73 A/R
11 cm2 = 0.81 A/R
12 cm2 = 0.89 A/R
14 cm2 = 0.97 A/R
15 cm2 = 1.05 A/R
16 cm2 = 1.13 A/R
17 cm2 = 1.29 A/R
19 cm2 = 1.37 A/R
sry kui teema juba siit läbi käinud ja lolli küsimusena tundub,aga otsinuga ei leidnud või ei oska õigesti otsida.

[Mihkel]

0.88 A/R on ju tabeli järgi jämedalt 12cm2.

Aga IMO, kui Holsetiga siin kõrvuti võrrelda, siis need A/R vs. cm2 ei tundu küll reaalselt kattuvat.
16cm2 kojaga HX40 Super nüüd 1.13 A/R turbiinikoda välimuselt küll ei meenuta.

[kala]

pildi järgi on see 88ar suurem kui 12cm.
sellepärast see täbel ei tundugi nagu õige

[KaroK]

http://www.turbobygarrett.com/turbobyga ... 102.html#b" onclick="window.open(this.href);return false;

Understanding housing sizing: A/R


A/R (Area/Radius) describes a geometric characteristic of all compressor and turbine housings. Technically, it is defined as:

the inlet (or, for compressor housings, the discharge) cross-sectional area divided by the radius from the turbo centerline to the centroid of that area (see Figure 2.).
compressor housing showing A/R characteristic
Figure 2. Illustration of compressor housing showing A/R characteristic

The A/R parameter has different effects on the compressor and turbine performance, as outlined below.

Compressor A/R - Compressor performance is comparatively insensitive to changes in A/R. Larger A/R housings are sometimes used to optimize performance of low boost applications, and smaller A/R are used for high boost applications. However, as this influence of A/R on compressor performance is minor, there are not A/R options available for compressor housings.

Turbine A/R - Turbine performance is greatly affected by changing the A/R of the housing, as it is used to adjust the flow capacity of the turbine. Using a smaller A/R will increase the exhaust gas velocity into the turbine wheel. This provides increased turbine power at lower engine speeds, resulting in a quicker boost rise. However, a small A/R also causes the flow to enter the wheel more tangentially, which reduces the ultimate flow capacity of the turbine wheel. This will tend to increase exhaust backpressure and hence reduce the engine's ability to "breathe" effectively at high RPM, adversely affecting peak engine power.

Conversely, using a larger A/R will lower exhaust gas velocity, and delay boost rise. The flow in a larger A/R housing enters the wheel in a more radial fashion, increasing the wheel's effective flow capacity, resulting in lower backpressure and better power at higher engine speeds.

When deciding between A/R options, be realistic with the intended vehicle use and use the A/R to bias the performance toward the desired powerband characteristic.

Here's a simplistic look at comparing turbine housing geometry with different applications. By comparing different turbine housing A/R, it is often possible to determine the intended use of the system.

Imagine two 3.5L engines both using GT30R turbochargers. The only difference between the two engines is a different turbine housing A/R; otherwise the two engines are identical:
1. Engine #1 has turbine housing with an A/R of 0.63
2. Engine #2 has a turbine housing with an A/R of 1.06.

What can we infer about the intended use and the turbocharger matching for each engine?

Engine#1: This engine is using a smaller A/R turbine housing (0.63) thus biased more towards low-end torque and optimal boost response. Many would describe this as being more "fun" to drive on the street, as normal daily driving habits tend to favor transient response. However, at higher engine speeds, this smaller A/R housing will result in high backpressure, which can result in a loss of top end power. This type of engine performance is desirable for street applications where the low speed boost response and transient conditions are more important than top end power.

Engine #2: This engine is using a larger A/R turbine housing (1.06) and is biased towards peak horsepower, while sacrificing transient response and torque at very low engine speeds. The larger A/R turbine housing will continue to minimize backpressure at high rpm, to the benefit of engine peak power. On the other hand, this will also raise the engine speed at which the turbo can provide boost, increasing time to boost. The performance of Engine #2 is more desirable for racing applications than Engine #1 since Engine #2 will be operating at high engine speeds most of the time.

[Raceboy]

Need numbrid ei ole põhimõtteliselt võrreldavad, kuna A/R on suhtarv ja cm2 on absoluutarv. Seda, kui suure pindala (area) ja raadiuse suhe see 0.63 vms on, pole ju öeldud Seetõttu võibki 16 cm2 Holseti turbiin paista sama suur kui mõni .63 A/R Garretti koda.