AFR, VE for turbo calcs

[Greg_S]

Ive been doing a bit of investigation into different turbos and playing around with the turbo calculator posted on the forum.

What AFR is recommended across the rev range on the I5? what sort of Volumetric Efficiency can I expect on my engine for the estimations? And does anyone have any figures for pressure drop & efficiency on the RS2 intercooler.

Quite a big ask I know

[Jeffer]

VE is IIRC 85 or 90%
I believe S2central made some readings on the RS2 ic. Don't know for sure tough...

[Greg_S]

Cheers Jeffer. Also I am trying to understand a couple of bits on the garret diagrams.

What is the difference between Corrected Gas turbine flow and corrected air flow?

[Jeffer]

It happend to be that I read Corkey Bells, Maximum boost this weekend. Espescially the compressor map chapter . I haven't read anything about those corrections though?
Do you have a pic of the map?

[Greg_S]

yeah will dig it out in a bit. been up in loft to get book out too. map is for gt30r in thevpdf cat mark h posted.

[Jeffer]

Found an intresting sheet Greg! I've already put some of our specs in there

[Greg_S]

Cheers jeffer, will take a look at that one.

As for maps i was refering to I have included a screen shot of the pdf.

Was trying to work out the differences between the two maps

[Greg_S]

http://www.turbobygarrett.com/turbob...o_tech102.html

Interesting reading

[Jeffer]

Cheers Jeffer. Also I am trying to understand a couple of bits on the garret diagrams.

What is the difference between Corrected Gas turbine flow and corrected air flow?

Can it be that airflow refers to the compressor flow. The corrected gas turbine flow is the amount of gas at wich the turbo will spool, if I have read it correct....
The 1.06 AR requires 4 LBS more gas @ Pressure ratio 2. Likely there's an equation that shows the math for backpressure between exhaust flow #'s and the gas turbine flow.... Maybe some turbo experts have a more experienced awnser to this

[Greg_S]

That would make sense. I had a read on the garrett site but didnt manage to work it out yet

[Greg_S]

Looks like the GT30R is a good match with that spreadsheet you posted. will see if I can work some calcs out later in the week

[Jeffer]

Looks like the GT30R is a good match with that spreadsheet you posted. will see if I can work some calcs out later in the week

Greg what sort of power are you looking for?

[S2central.net]

Greg - what version of the spreadsheet are you using ?

I've spent ages on this stuff... Concentrating on the compressor side though - not the turbine side of things which has always hurt my head with respect to selection of the right turbine for a desired performance level.


Paul

[S2central.net]

Meant to say that the default figures I have used for the RS2 intercooler *seem* to work out reasonably well, in respect to power & torque estimates but I've never actually had the time to collect lots of logged data.


Paul

[Greg_S]

Jeffer, looking for about 400-420hp, with as little lag as possible. Not bothered about all top end power, want an all rounder.

Paul, im using the vauxhall spreadsheet originally posted. what is the Tr rankin bit on the sheet?