It depends on where you are in the efficiency range for each combo. Down in the 10~12 psi range the smaller turbos should make as much or better power, but 15+ psi the 98 will stomp it.

 

not true, all things the same at the same boost level you are moving the same volume of air through the engine. But you may make more power with the bigger turbo cause you generate less heat

 

Maybe with 2 of them.. lol

 

I picked up 10mph in the quarter going from a TC76 to a s400sx3-75 with 2# less boost. Exhaust side and compressor cover plays a big role obviously.

 

I have very little testing done so far on low boost. Both turbos at 12-13psi.

-Specs on Engine - 408, 9.5-1, 235/235-610/610-116+2 cam HUC lobes, TEA Trick Flow 235 heads, Vic Jr, 90mm TB, KB T-6 3" Id turbo log, 4" DP, 4l80E, 3.42 gears

-On the 2 step at 3500 rpm, still able to build the same boost.
-The 98mm does spool a lil slower, but comes in at a lower ramp rate, helps maintain traction
- I also can get on the brakes at 70mph and start building boost = 70mph smoke show... lol

-Waiting on better weather to turn it up and see what it does.

 

Unless the turbo itself is causing excessive back pressure

 

On my previous 370 engine...
Going from a TC78 on a CM motorsports kit, to the GT91mm on the KB kit, I gained right at 100rwhp, same boost level.

 

Ever heard of Volumetric Efficiency? So your telling me a 66mm impeller at 15#'s of boost will move the same amount of air as a 91mm large frame turbo at 15#'s of boost?

 

Booo.... I want a big engine and big turbo...

Look forward to the results, thanks for sharing!

 

Haha, the way your truck is running, makes me think... why didnt I push a 4.8 first with tons of boost...