[455-4+1]

Hi all

Just put together a spreadsheet to check a few numbers and got some conflicting results from a Turbo supplier over here

If you could please shed some light on this would be much appreciated
I have used the following parameters and formulas from SA Design book by Jay K Miler.

433.89 CID
100% VE at 6500 (I tried at 90 and 95 but turbo guy came back at 100% so used this to correlate with his numbers)

NA cfm at 100 % VE = 816.1
10 lb boost Pressure Ratio is 1.68
I used the after cooled/non after cooled graphs to determine density ratio
With 74% comp efficiency I got 1.46 PR with aftercool and 1.39 PR without

This gave me corrected boosted cfm of 1191.5/1134.4 cfm with and without aftercool

Converted this to 82.2/78.3 lb/min
converted to 0.622/0.592 kg/sec for their maps

For a twin turbo I would just divide these 2 numbers ?

This way I get 41.1/39.15 lb/min or
0.311/0.296 kg/s for 6500 rpm at 10lb per turbo

Am i doing something wrong here ?

Any help would be much appreciated
Turbo guy came up with allot higher kg/sec numbers (30-35% higher)

Maybe he isn't allowing for compressor efficiency (I went with 74% line which is definitely not linear as boost climbs for non after cooled )

Many thanks in advance