Tree Monkey MS462 - PART 2

[CJ Brown]

On a race engine at wide open throttle, as long as the intake tract flow is optimized for the engine, there should be close to zero vacuum in the intake manifold. ideally the intake tract and carb will offer zero restriction at WOT. The pressure differential that causes air to flow into the engine is actually inside the cylinder eg: that's where the vacuum is - not in the intake. Also, many race engines have close to zero vacuum at idle as well, due to overlap on the camshaft.

 

[tree monkey]

idle and full throttle please, I bet the needle barely moves at full throttle. but I could be wrong

no I need to correct myself, I don't think it will show any vacuum

 

[tree monkey]

I bet it can’t react fast enough but that’s only speaking of the gauge.

very posable

 

[Redfin]

Maybe ... why? Lol

You have this connected to impulse?

 

[huskihl]

I don't think the needle can bounce back and forth 50 times per second and give us a number we can read. I bet it vibrates right above zero

 

[Stump Shot]

idle and full throttle please, I bet the needle barely moves at full throttle. but I could be wrong

I'm going to predict it shows just a small amount of pressure. We shall see...saw.

 

[Stump Shot]

You have this connected to impulse?

Yes

 

[XP_Slinger]

no I need to correct myself, I don't think it will show any vacuum

There has to be enough to keep the fuel pump diaphragm twitching. Wonder if it will show up on the gauge

 

[Stump Shot]

We can't really compare vacuum of a bottom loaded two stroke to that of a top loaded four strokes manifold vacuum which happens from the other end of the piston with no ports to bleed anything off.
A four stroke engine has a small amount of crankcase pressure, mostly from blow-by, which has to be bled off.

 

[tree monkey]

There has to be enough to keep the full pump diaphragm twitching.

I don't believe the pump needs to work at fuel throttle. I believe there is enough vacuum caused by the vinturi to draw fuel from the tank

 

[huskihl]

I don't believe the pump needs to work at fuel throttle. I believe there is enough vacuum caused by the vinturi to draw fuel from the tank

Didn't someone take off one side of the carb at full throttle and it kept running?

 

[tree monkey]

Didn't someone take off one side of the carb at full throttle and it kept running?

I don't see that working

 

[tree monkey]

could test it by removing the pump side diaphragm, priming the engine to start it, and running it at full throttle. open the gas cap to insure there is no pressure in the tank

 

[Stump Shot]

Uploading...

 

[tree monkey]

Uploading...

will this take 2 days?

 

[Stump Shot]

will this take 2 days?

...err, ten more minutes, or two days, could go either way. LOL

 

[p61 western]

I bet it can’t react fast enough but that’s only speaking of the gauge.

I bet your right.

 

[Stump Shot]

no I need to correct myself, I don't think it will show any vacuum

Wrong

I don't think the needle can bounce back and forth 50 times per second and give us a number we can read. I bet it vibrates right above zero

Wrong

I'm going to predict it shows just a small amount of pressure. We shall see...saw.

Wrong

Wasn't like I pictured it in my pea brain at all.

Four minutes...

 

[huskihl]

Wrong



Wrong



Wrong

Wasn't like I pictured it in my pea brain at all.

Four minutes...

Sounds like a typical tree monkey breadcrumb trail

 

[Stump Shot]

Sounds like a typical tree monkey breadcrumb trail

...well it is his thread. LOL