heres one for you engine gurus

[trx400EXtreme]

heres a question...... is it possible to make a NATURALLY ASPIRATED engine more than or equal to 100% volumetricly efficient? Im saying no, but a have friends that say otherwise....... lets here what you guys think.

[Pipeless416]

4 valve/ cylinder engines.. i say yes.

[Tommy 17]

Yes its is possible. What you have to do is you have to increase ur pressure to above ambient pressure in the intake maifold. This will throw in more air to the combustion chamber. Typically its done by a turbo or super charger but it can be done on a NA motor by doing something as simple as adding valves or increasing ur valve size... I've heard numbers as high as 120 or 150% for an NA motor but personally I don't think thats possible. I could see 110% thou.


Incase some people are wondering what your talking about the volumetric efficiencey is the measure of air into the cylinder under induction vs. when it is at a static condition.

[trx400EXtreme]

interesting........ seems like that would only be possible at a very high RPM though.

[416exfreak]

I remeber reading in either 5.0 Mustang and Super Ford magazing or Muscle Mustangs and Fast Fords a while back about a 1'080HP NA small block.

I beleive it was a windsor based engine... I dont remember, im trying to find some info on it... I cant seem to find the book among my mountain of magazines...:o

[trick450r]

Originally posted by 416exfreak
I remeber reading in either 5.0 Mustang and Super Ford magazing or Muscle Mustangs and Fast Fords a while back about a 1'080HP NA small block.

I beleive it was a windsor based engine... I dont remember, im trying to find some info on it... I cant seem to find the book among my mountain of magazines...:o

if not seeing the connection to the topic...and yes you can have 100% volumetric efficiency, with some good head work.

[416exfreak]

Originally posted by trick450r
if not seeing the connection to the topic...and yes you can have 100% volumetric efficiency, with some good head work.

I got confused as to what Volumetric Efficientcy meant!:blah:

Its all good though. Im still looking for that damn book... lol.:chinese:

[wilkin250r]

Originally posted by trx400EXtreme
interesting........ seems like that would only be possible at a very high RPM though.

Not necessarily, it could be done at fairly low RPMs (less than half the redline max), so it's possible. However, such a design would be silly, because it would severly restrict the upper RPM power of the engine, so you are half right. It would only make sense to design it for the upper RPM range.


Basically, in order to stuff more air into the cylinder than would normally fit, you need that air moving very fast. Once the exhaust valve closes, the inrushing air will have it's own inertia, it's own force behind it. It doesn't want to stop, so it will continue to rush into the cylinder and pressurize it above normal atmopheric pressure. If the intake valve is timed correctly, you can trap that pressure and use it. You can even use sound and pressure wave with a header tuned to a precise frequency for even greater effect.

It's all very precise, the header, ports, and camshaft all have to be designed to work together, and often will only work over a fairly narrow powerband. But yes, it is possible.

[dbc112]

Disclaimer.. I know nothing about the original thread... but started thinking.

Wouldnt colder air be better? More dense? When it is heated it would utlimatley expand etc? Am I stupid for asking?

[907Rider]

Originally posted by dbc112
Disclaimer.. I know nothing about the original thread... but started thinking.

Wouldnt colder air be better? More dense? When it is heated it would utlimatley expand etc? Am I stupid for asking?
yes thats why cold air intakes add more power. Thats why when you buy a turbo you get an intercooler, to chill the hot air from the exhaust.

You can get kits that use co2 to chill the intake(and intercooler) but I have never use them so I have no idea how good they work.

[dbc112]

Hmmm.. What about a bottle of highly compressed air rather than a turbo? Like a shot of NOS but much less of course. Routed to the intake? Like a gheto intercooler.

[907Rider]

Originally posted by dbc112
Hmmm.. What about a bottle of highly compressed air rather than a turbo? Like a shot of NOS but much less of course. Routed to the intake? Like a gheto intercooler.

Hmmm I dont know, I think a co2 kit would work.
http://www.jcwhitney.com/DEI-CRYO%3Csub%3E2%3C-sub%3E-AIR-INTAKE-CHAMBERS/GP_2010342_N_111+10201+600013959_10101.jcw
http://www.jcwhitney.com/DEI-CRYO%3Csub%3E2%3C-sub%3E-TANK-AND-INSTALLATION-KITS/GP_2009884_N_111+10201+600013959_10101.jcw

[dbc112]

Pricey!!! Go to a paintball store and get an old tank etc for much less. Here you go, hook it up to a trigger system! Pull the trigger, for a "shot" of air! Ok, this is getting stupid..

[KXRida]

Originally posted by 416exfreak
I remeber reading in either 5.0 Mustang and Super Ford magazing or Muscle Mustangs and Fast Fords a while back about a 1'080HP NA small block.

I beleive it was a windsor based engine... I dont remember, im trying to find some info on it... I cant seem to find the book among my mountain of magazines...:o


I too have that magazine somewhere. I was amazed! lol