Blower boost without load???

[ghittner]

Does a blower make boost in neutral or does it need a load to produce boost like turbos?? Mine doesn't seem to boost until it has a load on it, so I guess I have to test pulley changes on the water? Ron?

[repo man]

mine does.

[DMOORE]

My motors do not produce any boost at idle. In fact, My boat cruises at 3000rpm's @ 55mph and isn't producing boost at that time. It is still in vacume. It isn't until I get some load on it that it starts to make some boost.
Darrell.

[Warp Factor]

On a positive displacement blower, boost will depend on throttle position versus rpm. In neutral, you won't see boost unless you "wing" the throttle.
If you're trying to change maximum boost, there's no way to know what change you made without going full throttle under load, so yes, you need to test changes on the water.
You might be able to get a rough number by mashing the throttle mometarily in neutral.

[BOOGEYMAN]

I personally have never seen any boost at idle....eithor blower or turbo! I guess if you are running that small of a turrbo(with an extreamly small turbine housing) or run your blower that fast(LOTS of overdrive!!!!) you MAY see boost at idle.
Travis.

[ghittner]

When I mash it from idle in neutral I may get a pound or so, I was running 4 pds before on the water under load and I made a pulley change looking for 8 pds. I was looking for a difference while still on the trailer and saw none so I'll check it out in Havi this weekend. Thanks for the info.

[svt2224]

My boat makes about 15psi with a quick whack of the throttle.

[MikeF]

Boost only happens when air is available to the blower/turbo. Throttle blades closed.......no boost, throttle blades open....now air is available for consumption....now valves are the restriction, depending on how far blades are open = boost.

[ghittner]

My boat makes about 15psi with a quick whack of the throttle.
What size blower/ engine combo? How much boost are you running on the water?

[Trouble Maker]

I never see any boost pressure until I start to go past 4K rpms. Set your top end boost to what you want, then anything below that is just what it is. Remember the engine is an air pump and boost doesn't begin to build until the efficiency of your air pump begins to decrease...so not building boost pressure at lower rpms isn't a bad thing, it just means you have an efficient engine/air pump..