You dont say what fuel you use and what nitro content

I don't know how heavy or light is a ZOAR make of props that you use

often changing from heavy weight APC to lighter weight zinger can solve these issues as a example

A low nitro content fuel will bog more easily as nitro adds grunt at low end power to get past the bogging point
if you do use high nitro a 2.5 turn sounds very low for high nitro but more correct for low nitro like 5%
i would expect 3 to 5 turns for 20% nitro fuels nearly the double compared to zero nitro fuels


If you are budget consious and want to stay in low nitro other solutions can exist

Changing exhasts with four strokes is less likely to give any useful extra grunt at low end and will often give more power at top end but in marginal cases might make the difference

Changing props to lower pitch helps reduce bogging issues so maybe a 16*6

however diamater 16 inch is close to max for a 150 and 17 might be too much certianly my 180 is maxed at APC 18 *6 W a heavy prop slow to spool up and lots of 180 are using 16*8

three bladed props can solve some of these issues

possibly going to a 14* 8 in three blades might work or even a 15*8
( best to look to drop pitch to 6 if your plane can handle the drop in speeds and extra fuel consumption so three bladed 14*8 or drop to bigger 15*6 )

roughly a three bladed 15* 8 is equal to two bladed 16*8

in two bladed version the APC WIDE blades can be interesting
problem is the APC 14*4 W and APC 18*6 W are the only sizes I know of

If there is a 15*6W then that might do the job or even a 16*4 W or 16*6 W might also work if such an animal exists

Most modelers just throw nitro at the problem going from 10% to 20% will often cure these problems

If 80% of your flying is done at 1/3 gas you wont notice the extra consumption so much possibly by 10% to less than 20% so a ten minute tank might drop to ~8 minutes running

If most flying is at full gas then expect the run time for the same tank to drop by a whopping to 1/3rd so from 10 minutes to more like ~6 minutes

However staying with low nitro and going to bigger diameter prop with less pitch will bump up fuel used by ~10% plus but it will be cheaper low nitro fuel

Most good hover type props are very low pitch reliitve to diamater
examples are 14*4 or 18*6 which are less than the 1/2 square types such as 14*7 or 18*9
deep pitch often cuases bogging from the air swirl around prop slipping of the deep pitch props and creating huge drag even though engine is working perfectly the sudden massive extra load from stalled blades or semi stalled can bog the engine
..........if its a very heavy prop
......or too deep a pitch prop
.......or low nitro fuel
....... or very heavy airframe
..... or hot engine from lack of cooling in hover mode
.......or fuel starved or semi fuel starved
........or underpowered for the job
......or working at very high altidudes
.... or bad fuels


Hope some solution works for you

I myself prefer to throw low end grunt tractor power BHP and low nitro at the problem so a 90 to120 class plane will get a Saito 180 and and a 120 to 180 class plane will get a Saito 220 all running on zero or 5% nitro fuels
I generaly reach for the biggest diamater prop with the smallest pitch and fly around mostly on 1/3 gas and fuel cost and consumption isn't to bad for example less than 1 onz per minute with the 180 saito

Ralf