turbotoaster

Assuming the spec of engine, manifold and boost were the same, how could these 2 turbo specs effect the power and boost threshold

Compressor
70.3mm inducer, 94mm exd with a 56 trim and 0.60A/R
turbine
82mm wheel dia with a 84 trim and a 1.01A/R



Compressor
76.5mm inducer, 103.5mm exd with a 58 trim and 0.72A/R
Turbine
67mm exd, 74mm ind with a 82 trim and a 1.00 A/R


Now from what i can see the first turbo has a smaller front end but a larger rear end.

Now i know engines are effected by the turbine housing so would dropping the wheel size on the back and increasing the comp wheel cause it to surge and then not produce the big numbers at the top end due to small wheel, or because the rear end are both about 1A/R it wouldnt make a difference.

Can any of your turbo guys give me an idea on how this effects rotarys, i can an idea for piston engines but thought id ask to gain some better knowledge.

the reason i ask is compare the gt4294 to the gt4202, the only difference i can see is a small increase in comp wheel size, i know the gt4202 will produce more power but does the bigger comp wheel increase the boost threshold over a gt4294?

Thanks

Maybe Mr Rainbird can help me with this as he seems pretty good with turbo specs

Lee

turbotoaster

anyone got an idea

Rick

Larger comp wheel will increase boost threshold, yes. The smaller turbine wheel will also come in lower, but doesn't have the potential for as much boost and sugre becomes more likely.

Rick.

turbotoaster

so then by saying that its better to go with a smaller comp wheel and larger turbine wheel for the same power as they balance each other out in terms of boost threshold but you get no surging?

turbotoaster

bump for more help if possible