I hate to throw parts at trucks hoping the problem is what you think it is. I have found lately that sometimes little things can seem like something else. I can site several examples of things here, but wont bore you with them. I can tell ya for me it always turns out to be the simple little things that go wrong and throw me for a loop.
I hope your troubles are solved with a pump.
I could not get enough info for the B-1 turbo to make a decision on it.
I know the HX-40's work well and if set-up right will last a good long time. Big wheels and shafts add to more lag. Small housings add to restrictive exhaust flow. The HX-40 does not have a big shaft to slow the spool up down nor a real large exhaust wheel. Both of these help to spool the turbo faster and make less work for the engine. Of course this adds to the overall power output.
OTOH, the smaller shafts are not as stong... I have not tried the 16 housing on my truck yet. Piers has modified the housing to make it spool faster. Im running the 18 housing and the lag is there, but not too bad.
Your auto truck would prolly work well with a HX-40/16 modified by Piers and your top HP level would increase.
Finally, big turbos that pack in more air at higher boost levels need larger exhaust housings to get the extra air you just packed in back out. You can fill your cylinders with all the cool air you want, but to make the engine the most overall power you have to scavenge and remove the combustion gases as well. Small housings wont cut it. Low end power may be increased with small housings, but your top end power goes down. The 12cm 40 housing has the tiny little 1. 5 cross sectional area. To borrow a line, most people would laugh at trying to get 500HP with an exhaust pipe of that diameter.
You may have lowered your 1/4 miles times with the smaller 12cm housing because most of the race is won or lost on the first part of the 1/4 mile. Acceleration in the low end helped your 60 foot time and hurt your top end at the end.
Don~
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