guess i'll try my hand at playing with the numbers from the other thread in here:
Mercedes-Benz Unimog S404 series - Mercedes Unimog S404.3 - (M180) - Enginerebuilding.eu
Engine type: M180.928
Construction Year: 1960-1975
Number of cylinders: 6
Bore ø: 80 mm
Engine content: 2195 CC
Compression ratio: 7 : 1
HP: 80
psi boost for horsepower target calculator - racingcalcs
134 cubic inch, guessing 3500 RPM peak 80 HP for 80% VE, and then dropping off from there (if we pretend the curve is flat at 80 hp up to 5k rpm, we'd be at a dismal 56% VE, i'm confident peak is somewhere between 3500 and 5k
) let's compromise and say max 4k rpm for a 70% VE
134 * 0.5 * 4,000 / 1,728 = 155 CFM of air that it "could" pump
155*0.70=108 CFM of air that we are actually pumping, with our 70% VE
8 psi will net us 10.8:1 compression ratio, so let's shoot for that
(8+14.7)/14.7 = 1.54 pressure ratio
108 * 1.54 = 166 CFM that we will want to pump
[(0.5 * 134 * 4,000) / 1,728 ] * 0.70 * 1.54 * 0.069 = 11.5 pounds of air (mass air flow)
with apparently a 1:10 ratio between pounds and HP, should result in about 115 hp
slightly better than a 22re
with a 1.5 pressure ratio and 11.5 lbs of air, the below
GARRETT® GT2554R at the link
PT Turbo | PT Turbo
seems to have a map that has the most potential to be functional across the range you might see. Somebody, anybody, else please please double check me on this and let me know why i'm out to lunch
they claim:
Horsepower: 170 - 270
Displacement: 1.4L - 2.2L
but i think they are working with better base engines
ORIGINAL GT SERIES AERODYNAMICS
INTERNALLY WASTEGATED TURBINE HOUSING
SOLD AS A COMPLETE TURBO (INCLUDES TURBINE KIT & ACTUATOR)
SMALLEST BALL BEARING CONFIGURATION AVAILABLE
WATER COOLED CHRA
internal wastegate makes this $800 turbo pretty nicely priced for a brand new unit, that you could probably call and get setup closer to what you want from them and have support
and then the next question would be: can you flow enough fuel to support 115 hp? should be pretty easy with the propane, i'd imagine any setup that could support 80 hp could support 115
set the base timing back, i dunno, 5? 10? degrees, start and WOT a full pull on a flat spot, check for knock. no ping? add some timing, try again. do a good loaded pull until it starts to have a problem, back it off, i dunno, 2 or 3* for safety and call it a day
double edit: that final 115 HP would be with the 80 HP gas as a base reference, max tuned, probably 100-105 ish HP on the 'pane?