Selecting a manifold for AFR 265's - single versus dual plane - thoughts anyone?
02-25-2014, 01:57 PM
#31
Registered
iTrader: (3)
I generally like propping for peak power, or close to it. If you build an engine, wanting to spin it around 5500, you want peak hp to occur near or around 5500. If the HP peaks at 6500, well then you chose incorrect parts, like camshaft for example. Most marine builds will make peak torque 1000-1200 rpm below peak hp, but not always.
The reason to NOT prop at peak torque, are torque loading the drives , and detonation can be more likely at wot because your cylinder pressure is very high.
I've seen many guys build a high performance marine engine, aftermarket heads, cams, etc, and then prop the boat at 5000rpm max , because they want to take it easy on the engine. If 5000 wot tickles your sack, build a 5000rpm engine. But don't build a 6000rpm engine and prop it to 5000.
The reason to NOT prop at peak torque, are torque loading the drives , and detonation can be more likely at wot because your cylinder pressure is very high.
I've seen many guys build a high performance marine engine, aftermarket heads, cams, etc, and then prop the boat at 5000rpm max , because they want to take it easy on the engine. If 5000 wot tickles your sack, build a 5000rpm engine. But don't build a 6000rpm engine and prop it to 5000.
02-25-2014, 02:08 PM
#32
Registered
I generally like propping for peak power, or close to it. If you build an engine, wanting to spin it around 5500, you want peak hp to occur near or around 5500. If the HP peaks at 6500, well then you chose incorrect parts, like camshaft for example. Most marine builds will make peak torque 1000-1200 rpm below peak hp, but not always.
The reason to NOT prop at peak torque, are torque loading the drives , and detonation can be more likely at wot because your cylinder pressure is very high.
I've seen many guys build a high performance marine engine, aftermarket heads, cams, etc, and then prop the boat at 5000rpm max , because they want to take it easy on the engine. If 5000 wot tickles your sack, build a 5000rpm engine. But don't build a 6000rpm engine and prop it to 5000.
The reason to NOT prop at peak torque, are torque loading the drives , and detonation can be more likely at wot because your cylinder pressure is very high.
I've seen many guys build a high performance marine engine, aftermarket heads, cams, etc, and then prop the boat at 5000rpm max , because they want to take it easy on the engine. If 5000 wot tickles your sack, build a 5000rpm engine. But don't build a 6000rpm engine and prop it to 5000.
02-25-2014, 02:15 PM
#33
Registered
iTrader: (1)
Usually propping for around 200-300rpm under peak hp in normal conditions gives best results and a little wiggle room for changing load weights, weather, water conditions, and etc.
Going past peak hp is for 4 wheeled vehicles or very short distance acceleration racing.
02-25-2014, 02:54 PM
#35
Registered
iTrader: (1)
02-25-2014, 03:03 PM
#37
Registered
iTrader: (1)
Sure. Here you go.
02-25-2014, 03:07 PM
#38
Registered
iTrader: (3)
if you really want to be a bad azz, let Pslonaker build you an engine. Youll see the HP and TQ cross at 5252rpm on the dyno sheet. Amazing stuff.
