Originally posted by scarecrowX on May/14/03
the lines are the airflow demand lines for a B18B engine. add one line to the right for an idea of where the B18C would sit at 8K. the far left line represents 3000rpm, each line increasing in 1000rpm increments. to calculate boost pressure from the pressure ratio, take the (pressure ratio x 14.7) - 14.7.

we'll start with the SMALLEST of the T4 compressors and work our way bigger:
T04B's




T04E's












as you can see, about 50% of the engine's demand lies not only outside the compressor map, but beyond the surge limit for pretty much every single T04.

Originally posted by scarecrowX on May/14/03
now we'll look at the T3 turbos, starting with the smallest, the 40 trim:










the demand lines are covered far better by the T3 series turbos than the T4's. compressor efficiency may be lower in some areas, but an efficient intercooler will more than compensate for slight variations in efficiency between them. anything bigger than a 50 trim looks to be good enough, even for the higher pressure ratios.

Originally posted by scarecrowX on May/14/03
last, but certainly not least, the mistubishi turbos.
surprisingly, the Mitsubishi turbos look to be an ideal fit for the B18B engine.

the TD04H-13G is the turbo found on most 1g dsm cars with automatic transmissions.

the coverage of demand lines is surprisingly good. the only downfall of this turbo is the undersized turbine which would tend to strangle the higher rpms.. porting could help, as could switching to a TD05 turbine.

the TD04H-15G as found on some higher end volvo turbo cars

again, only the turbine housing is a drawback.

the TD05H-14B turbo found on all 1st gen turbo dsm's with manual transmissions:


these turbos may be less suited to the GSR/type R engines as they rev higher. like i said in the first post, add another demand line to the right of 7000rpm to get an idea where 8000 rpm would fall on the map.