Naturally aspirated manifold positive pressure

[CapnBoost]

Found a website claiming a lot of things from more power to better mileage, etc. It reminded me of something I read about some particularly well designed intake manifolds that actually developed positive pressure. I can't remember the racing series, but it seems to me it was on the order of ~10psi.

Can anyone else recall where i may have seen this?

[Bob]

That's equivalent to achieving a volumetric efficiency greater than 1... as far as I know it's not possible without forced induction

[coolieman1220]

i always wondered what would happen if you put a little electric motor in your intake to help force air into the manifold. it might have to be kinda powerful since the pressure it would create would have to be greater then the engines intake pressure sucking to make a difference but what if it just helped suck air thru the filter faster?

[Quiggs]

i always wondered what would happen if you put a little electric motor in your intake to help force air into the manifold. it might have to be kinda powerful since the pressure it would create would have to be greater then the engines intake pressure sucking to make a difference but what if it just helped suck air thru the filter faster?

They sell them on eBay. Useless.

[johnnynumfiv]

They sell them on eBay. Useless.

Leaf blowers. They add 11hpz.
Leaf Blower Bolt on Dyno pull- Video

[Matra et Alpine]

The laws of physics, for fans to work they require larger energy input than they can return. Nothing is 100% efficient. SO losses screw all the BS

[Quiggs]

Thermodynamics ftmfw.

[coolieman1220]

that goes to show how much psi you actually need to get more power from FI. pretty crazy.

[ruim20]

Did thoose manifolds used ram air?

[CapnBoost]

Did thoose manifolds used ram air?

I don't think so. Maybe velocity stacks... I'm wracking my brain to figure this out.

I'm pretty sure it was in one of the power adder books. I checked Maximum Boost by Corky Bell, it's not in there. Maybe street turbocharging. All of my books are packed up. :/

[Alastor]

I don't think so. Maybe velocity stacks... I'm wracking my brain to figure this out.

I'm pretty sure it was in one of the power adder books. I checked Maximum Boost by Corky Bell, it's not in there. Maybe street turbocharging. All of my books are packed up. :/

I would guess some kind of inertial method of supercharging.

Regardless of how it is done, if there is really no FI, the positive pressure is either momentary and/or in a small localized area of the manifold. Otherwise there would be no way to get new (lower pressure) ambient air into the manifold.

[digitalcraft]

i always wondered what would happen if you put a little electric motor in your intake to help force air into the manifold. it might have to be kinda powerful since the pressure it would create would have to be greater then the engines intake pressure sucking to make a difference but what if it just helped suck air thru the filter faster?

They could call it something like a 'turbo', maybe run it off exhaust pressure for even more power.

[MrPete]

Random thoughts on the topic.
Use a plenum air inlet feeding from a place of high pressure on the car (base od windshield is a good place), this will provide the engine with a pressurized souce from which to draw the air it needs. This is not always a ram effect, just a higher than atmospheric source. At the Atlanta Motor Speedway in July of 1973, the car I was crew member on gained .5 second a lap with just a change of air inlet box. Also, an engine builder for NASCAR Cup cars told me they routinely see a volumetric efficiency of 120%.

[CapnBoost]

I would guess some kind of inertial method of supercharging.

Regardless of how it is done, if there is really no FI, the positive pressure is either momentary and/or in a small localized area of the manifold. Otherwise there would be no way to get new (lower pressure) ambient air into the manifold.

That makes a great deal of sense. I don't suppose you're familiar with the tuning for resonation?

Random thoughts on the topic.
Use a plenum air inlet feeding from a place of high pressure on the car (base od windshield is a good place), this will provide the engine with a pressurized souce from which to draw the air it needs. This is not always a ram effect, just a higher than atmospheric source. At the Atlanta Motor Speedway in July of 1973, the car I was crew member on gained .5 second a lap with just a change of air inlet box. Also, an engine builder for NASCAR Cup cars told me they routinely see a volumetric efficiency of 120%.

This is interesting, however, the internet being what it is is there any way you could provide some sort of outside evidence? I really mean no offense but, it's hard to believe that even with the pressure generated at the windshield that 120% volumetric efficiency can be achieved.

EDIT: I found it! Motorbooks Workshop, How to Tune and Modify Engine Management Systems, Chap 12 "Clever designs have taken advantage of high air-flow characteristics, inertial effects, and pressure-wave tuning to achieve air density in cylinders that substantially exceeds atmospheric pressure with as much a 10 psi positive pressure at the intake valve."

No emphasis added, word for word. Now, how is this possible?

[P4g4nite]

That's equivalent to achieving a volumetric efficiency greater than 1... as far as I know it's not possible without forced induction

Volumetric efficiency - Wikipedia, the free encyclopedia

No emphasis added, word for word. Now, how is this possible?

Because air is squishy..