Some naturally aspirated engines can achieve more than 100% VE. One exception might be to tweak VE to "tune" the calculator to a naturally aspirated base HP figure. WRC cars make good use of this by making 300HP pretty much continuously ! Leave VE and BSFC alone. However you could used it to work out how much power you can make at much lower RPM if you are limited to a peak HP figure. This calculator is designed to size a compressor based on Air consumption in lbs a minute at Wide Open Throttle at peak RPM. Most Turbo engines run higher pressure ratios at lower RPM. Then enter the boost figure that will occur at that peak RPM figure. This GT2871R map indicates that a pressure ratio of 3 will deliver 400HP.Įnter the capacity in CC, together with the RPM that peak power will occur at. Select what to solve for and enter values for the other fields. Looking at the GT2871 - sure you can get more. Look at the Air mass figure, multiply that by 10 and you have a clear idea of the power capability of the turbo at maximum efficiency. Or look at it another way, find the compressor map figure, in the middle of the island, where the turbo is at its most efficient. For example, you will notice that air mass in lb/min is roughly equal to peak HP divided by 10. Imperial measurements with regard to engine tuning can be very helpful and easy to understand. If you look at other manufacturers you may need to convert from other units of measurement. One assumes you will be looking at Garrett Compressor maps in lb/min. A win-win.This calculator will help you choose the right Turbo Charger in conjunction with a Compressor Map. Displacement (Liters) (122.04 CID) Ambient Air Temp (deg F) Altitude (ft above sea level) (14.502 psi barometric pressure) Fuel Type. By fitting a larger turbo we will lose some low down torque but we will get it back at higher RPM, which give us more power, without necessarily increasing stress on the engine. On a test drive they may feel fast but when you get used to the low down torque, exploring the upper reaches of the rpm range will reveal there is nothing less to give, the engine is being choked due to the small turbo. Generally turbos supplied by the car manufacturer are hopelessly undersized. Some common expamples are: 4B11T121.9 4G63121.8 EJ20121.6 EJ25149.9. Garrett has an excellent resource on their website detailing the technical aspects of a modern turbocharger OE Turbos Video can’t be loaded because JavaScript is disabled: Turbo Size Calculator – How It Works () Too big an AR ratio will feel sluggish, too small engine can be difficult to drive smoothly. This is usually a trial and error process. This line absolutely lie to the right of the surge line on the compressor map.Ī steep surge line on a compressor map shows that a turbo will produce high boost pressure at low CFM flow rates.Ī shallow surge line on a compressor maps shows that a turbo will not produce high boost at low CFM flow rates. The following two calculators can be used to estimate the engine horsepower of a vehicle based on the weight of the vehicle. Then draw a line from this point down to Pressure Ratio of 1 and a CFM of 20% of the maximum. To do another, click the Clear Values button and then. Plot the CFM number onto the compressor map graph. The value will be returned in estimated horsepower, based on blown pressure increase. Surge LineĬhoose the RPM where you want to achieve full boost. Generally speaking erring on the larger size of turbo is better than smaller. We are looking for the line to be in the highest efficiency areas of the map for as long as possible. Plot multiple points to see where the turbo performs versus your requirements. Compressor Chartsīolt the pressure ratio number and the CFM (or lbs/min) number into a compressor map graph for various RPMs. Boost Required for 'X' Horsepower Calculator. When we obtain the pressure ratio and CFM and lbs/min numbers we can now look at turbo compressor maps to see which turbo will be most suitable for our application and goals. RB Racing Turbo Boost and Airflow Calculator. check out our boost temperature calculator or our quarter mile calculator. Great when planning a new turbo kit or intercooler to see if it can achieve your goals. Turbo Size Calculator – Using the numbers This calculates the boost (psi) to achieve a nominated horsepower target based on your engines specifications and maximum rpm.
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