Turbo selection

With all the posts appearing asking "which turbo?" I thought it might be an idea to create a thread that helps to prescriptively give people an answer.

Rather than a "you should use a GT35R/T61/T67" type thread, I thought it would be an idea to give people the tools to decide for themselves.

Basically, a large part of turbo selection is choosing one that is neither too large or too small for your application. You need one that is at it's most efficient in the RPM region between max torque and max boost. This is calculated by knowing three values. The pressure ratio, the airflow requirements at max torque and the airflow requirement at max power. (Don't worry too much about what these values actually represent at the moment)

From this you can plot the points on a turbo's compressor map, and see if that particular turbo is suitable for your application. If the points are too far to the left or right of the "map" then you need a smaller or larger turbo. Simple as that! (Well OK not quite as simple as that, but good enough for starters! )

I created this spreadsheet a year or so ago, when I was trying to spec a turbo for myself. The 2nd sheet is an example of the Garrett GT4202R turbo. Notice that the red line is nicely on the "efficiency island"? That's how it should be. If you want to have a play around and look at various turbo's and see if they would suit a particular application, I suggest looking at the garrett website:- http://www.turbobygarrett.com (Which appears to be down at the moment )

Right, that's enough to get started.... If anyone else wants to contribute then feel free, I'll try to add more when I get chance....

Cheers!

turbo-spec sheet.zip

Good stuff Tony. Thanks

If someone is a whizz with Excel then you can have questions that when answered give you an ideal turbo

Good man Tony - hope these might be useful addition

Could someone please have a check over this sizings list sent to me to see if there are any glaring mistakes - I will then edit)

Cheers

Turbo Sizes.xls

Just some other pics highlighting difference between T4 and T3 for info (sorry of not totally relevant to air flow - just in case people ask...)

Good man Tony - hope these might be useful addition

 

Could someone please have a check over this sizings list sent to me to see if there are any glaring mistakes - I will then edit)

 

Cheers

There weren't any errors in Terry's spreadsheet when he first wrote it and mercifully, there still aren't now

-Ian

Cheers guys.

It would take a little time to sort out a single spreadsheet that would generate a "you need this turbo" answer. It's not just a case of saying I want 500HP and then using somekind of look-up to see what turbo can supply 500HP. You need to have the compressor maps (in excel format) for each and every turbo and then from that you would want to write a macro that would say the turbo that spends most time in the highest efficiency zone for the horsepower and rpm values you've entered is X.

The reason why I created the spreadsheet in the format I did was so that people can make a more informed judgement on turbo choice, rather than prescriptively saying this is the turbo you want. If you see what I mean.....

Really what we need to produce is a turbo selection guide, but to be honest it would probably be a lot easier to just put a link to the garrett site and let people read through the "turbo tech 101/102/103 guides.....

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech101.html

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech102.html

http://www.turbobygarrett.com/turbobygarrett/tech_center/turbo_tech103.html

and then put a link to their page with all the turbo's on:-

http://www.turbobygarrett.com/turbobygarrett/products/turbochargers.html

Where you can choose a particular turbo (for example GT3582R) which would show you the details of the turbo with a compressor map you can click on:-

http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/GT35/GT3582R_714568_2.htm

And then using the spreadsheet above (to save you the maths) you can look at the map and see if the "red line" that you would get if you plotted the pressure ratio and airflow numbers onto that map would take it through a sensible efficiency region.

(Don't think I can make it any simpler than that )

With all the posts appearing asking "which turbo?" I thought it might be an idea to create a thread that helps to prescriptively give people an answer.

 

Rather than a "you should use a GT35R/T61/T67" type thread, I thought it would be an idea to give people the tools to decide for themselves.

 

Basically, a large part of turbo selection is choosing one that is neither too large or too small for your application. You need one that is at it's most efficient in the RPM region between max torque and max boost. This is calculated by knowing three values. The pressure ratio, the airflow requirements at max torque and the airflow requirement at max power. (Don't worry too much about what these values actually represent at the moment)

From this you can plot the points on a turbo's compressor map, and see if that particular turbo is suitable for your application. If the points are too far to the left or right of the "map" then you need a smaller or larger turbo. Simple as that! (Well OK not quite as simple as that, but good enough for starters! )

 

I created this spreadsheet a year or so ago, when I was trying to spec a turbo for myself. The 2nd sheet is an example of the Garrett GT4202R turbo. Notice that the red line is nicely on the "efficiency island"? That's how it should be. If you want to have a play around and look at various turbo's and see if they would suit a particular application, I suggest looking at the garrett website:- http://www.turbobygarrett.com (Which appears to be down at the moment )

 

Right, that's enough to get started.... If anyone else wants to contribute then feel free, I'll try to add more when I get chance....

 

Cheers!

Excellent write up, why it isn't a sticky?