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[patsmx5]

You're wrong. The pressure in the cylinder right when the intake valve opens is higher than the intake charge. The residual exhaust gasses push into the intake contaminating the charge untill the piston decends and expands the chage in the cylinder enough that it's of lower pressure than the intake, at which point the charge flows in.

I said bigger valves will be shrouded more. There is nothing wrong with that statement. I also said bigger valves will be heavier, which is also true. You can talk combustion chamber design all day long, but my points still stand.

Pressure and flow are two different things. If you have high backpressure from an incorrectly sized turbine, then you need to select a correctly sized turbine, not change the exhaust valve size.

The chamber is always contaminated with exhaust gasses. Welcome to <100% VE.

Look up Scavenging,  your off as usual, how do you think N/A motors can achieve VE's above 100%?
Scavenging and intake pulse tuning.

I said nothing about valve weight, easily overcome with spring pressure.

You really have no clue...

I see you're not arguing pressure anymore...
I'm talking about a turbocharged engine obviously. Even with a "100%" VE N/A engine, you still have a combustion chamber's worth of exhaust gasses. Over 100% and you begin to flush the chamber, but you'll never get all the exhaust gasses out.  I don't know. I understand.

[Joseph Davis]

Eh, I'm siding more with Pat on this.  There are a lot of variables at play and some give-take taking place, but for the most part Pat is correct.

While exhaust pressure is elevated, so is intake pressure.  For the majority of turbocharged vehicles on this planet the ratio of inlet to outlet pressure is roughly the same as a NA vehicle.  The highest discrepancy with respect to exhaust is always before spool occurs... who cares, you don't make any power there anyway.

Also, pent roof yadda yadda.  4G63 are shrouded from the factory and flow like crap regardless of impressive static flowbench numbers.  They outflow Honda B-series yet make mediochre power.   There are other examples.

Using the piston as an expander on the inlet stroke is all well and good for a blower car, but when you are dealing with a Cup motor or a short RS high rpm NA setup or some turbo setups the piston very much sucks the intake charge past the intake valve restriction - lessening this restriction makes it easier to fit more air mass.  With respect to the exhaust, the gasses compress and if they take a little longer to escape the chamber well tuning the ignition timing to place the bulk of that exhaust pressure at a good rod angle simply means more of it is spent moving the engine down the road.

[Conceptz-X]

This discussion specified Mr. Davis was considering N/A. 
if you read the opening thread you would not be talking...

Is there any significant problem with running intake valves in place of exhaust valves, and vice versa?  This would be for a NA application, IIRC the exhaust valves on a turbo car are a different variant of stainless and of course all exhaust valves have more guide clearance. 

I'm sitting here fapping to a catalog of OEM valve dimension and my hamster wheel is spinning.

Also still with proper tuning there will be a pressure pulse arriving at the tintake valve at the time it opens overriding any residual pressure in the chamber.   (runner length tuning)

[Conceptz-X]

 the piston very much sucks the intake charge past the intake valve restriction

Mr. Davis Im dissappointed.  Air in regards to Absolute pressure can never be sucked or pulled.  it is simply pushed from a higher pressure to a lower pressure.  when static, the air may have any pressure but no differential.

[Joseph Davis]

This discussion specified Mr. Davis was considering N/A. 
if you read the opening thread you would not be talking...

Is there any significant problem with running intake valves in place of exhaust valves, and vice versa?  This would be for a NA application, IIRC the exhaust valves on a turbo car are a different variant of stainless and of course all exhaust valves have more guide clearance. 

I'm sitting here fapping to a catalog of OEM valve dimension and my hamster wheel is spinning.

Also still with proper tuning there will be a pressure pulse arriving at the tintake valve at the time it opens overriding any residual pressure in the chamber.   (runner length tuning)

I'm not a big fan of intake harmonics.  For every harmonic there is an anti-harmonic, it all averages out meaning if you mathematically masturbate to pipe organs have you accomplished anything other than wasting your time?  Exhaust harmonics are somehat important, depending on the application.

 the piston very much sucks the intake charge past the intake valve restriction

Mr. Davis Im dissappointed.  Air in regards to Absolute pressure can never be sucked or pulled.  it is simply pushed from a higher pressure to a lower pressure.  when static, the air may have any pressure but no differential.

Cool, let's kill the discussion off for the laymen: the near-atmospheric crankcase pressure on the bottom of the piston is one hell of a cockblocker that fights engine acceleration and a bigger intake valve helps.

[Conceptz-X]

edit: You may also wish to consider crank case pressure, as it is reduced, your effective pressure above the piston rises in proportion.
I have a 5 stage dry sump setup for when I finally get my shit right.  (probably overkill)

[patsmx5]

edit: You may also wish to consider crank case pressure, as it is reduced, your effective pressure above the piston rises in proportion.

What? That makes no sense.

[Joseph Davis]

It made sense, read it again.

[patsmx5]

It made sense, read it again.

I don't understand it, please explain. And he or someone crossed it out too.

[Conceptz-X]

I was saying the exact thing JD started off into, as I composed mine, JD posted

[Conceptz-X]

then he called me a Nigger on Myspace

[patsmx5]

I was saying the exact thing JD started off into, as I composed mine, JD posted

What he said makes sense. What you said does not. You're saying that by reducing the pressure on the bottom of the piston, the "effective" pressure above it will somehow change. This makes no sense.

[Conceptz-X]

the differential of pressure is what moves the piston, reduce it on the bottom and it moves down easier.

that whole air getting pushed not pulled thing...

[patsmx5]

the differential of pressure is what moves the piston, reduce it on the bottom and it moves down easier.

that whole air getting pushed not pulled thing...

So you're saying that reducing the pressure of the air below the piston  means the piston does less work compressing the air below it as it travels up and down the cylinder. Yeap. But this does nothing to the pressure above the piston. Just means the piston does less work on the air in the crankcase.

[Conceptz-X]

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

[patsmx5]

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

Oh I know it works, and so do you. You just explained it the wrong way. You wouldn't oil a rusty bearing and tell me it spins better because you reduce the effective pressure. It's because you reduce the coefficient of dynamic friction by oiling it. Similarly, vac pumps remove some of the mass of air out of the engine, so the pistons do less work moving it around. And the vacuum also helps seal the rings up too.

[Conceptz-X]

and Dry Sump helps remove the Oil Windage further reducing drag

[Joseph Davis]

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

Oh I know it works, and so do you. You just explained it the wrong way.

First he hops on me for speaking layman, and now you hop on him.  Let's just get over that shit because it impedes the exchange of ideas.

[DmC]

Guys who use big words to impress have small ideas.

[widebody93]

Lol true story Dennis.

[patsmx5]

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

Oh I know it works, and so do you. You just explained it the wrong way.

First he hops on me for speaking layman, and now you hop on him.  Let's just get over that shit because it impedes the exchange of ideas.

I didn't realize what he was saying because he said it wrong. He'd already posted some other shit about pressure that was wrong, so I was thinking WTF. We don't need any more misinformation out there. Big words or not.

[Joseph Davis]

Guys who use big words to impress have small ideas.

My small ideas are power, and traction.

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

Oh I know it works, and so do you. You just explained it the wrong way.

First he hops on me for speaking layman, and now you hop on him.  Let's just get over that shit because it impedes the exchange of ideas.

I didn't realize what he was saying because he said it wrong. He'd already posted some other shit about pressure that was wrong, so I was thinking WTF. We don't need any more misinformation out there. Big words or not.

Pot, kettle, black.

[patsmx5]

Guys who use big words to impress have small ideas.

My small ideas are power, and traction.

you look at ambient too much, you have to look at absolute.  there is a reason race cars run vacuum pumps and dry sump...  Dyno Proven Powa

Oh I know it works, and so do you. You just explained it the wrong way.

First he hops on me for speaking layman, and now you hop on him.  Let's just get over that shit because it impedes the exchange of ideas.

I didn't realize what he was saying because he said it wrong. He'd already posted some other shit about pressure that was wrong, so I was thinking WTF. We don't need any more misinformation out there. Big words or not.

Pot, kettle, black.

ok

[Robb]

You guys are Aaron Caking up this thread. 


Reported.

























Jd, I remember reading in that faggot Taylor's 1st book about how he believed a I to E valve ratio closer to 1:1 would make more midrange torque, then proceeded to do nothing to verify the claim other than reference some dated materials others wrote.  What is your take on this?  Also, what does Sir Harry Ricardo think about it?

[Joseph Davis]

Taylor didn't do anything, not even write his own book.  He left that for undergraduates to do.  Try to verify his referrences, a good third of them have nothing to do with what he's saying and another third don't quite mean what he's saying.   Still a good primer.

As for Good Sir Harry, http://s256.photobucket.com/albums/hh166/joeymisanthropy/Literature/Ricardo/

[Robb]

Those fucking rotary coils in your fotofuket crashed my work computer.  Goddamnd rotaries. 

[Joseph Davis]

The burned out Ignition #1, #3, #4, and Aux Out drivers in this Haltech, courtesy of Vlad the impaler, crashed my paycheck for today.

[Robb]

The burned out Ignition #1, #3, #4, and Aux Out drivers in this Haltech, courtesy of Vlad the impaler, crashed my paycheck for today.

Really?  Aaron Cake would tell you that they are more reliable than the Sun, and make rotaries produce no harmful gases, and emit only flowers and kittens from the tailpipe.

[Joseph Davis]

I thought only Microtech was Cakeboy approved?  Not that I paid enough attention to remember.

[Robb]

I thought only Microtech was Cakeboy approved?  Not that I paid enough attention to remember.

No he was all about some fucking haltech.  Piss poor shielding my biggest complaint, Ign. interference and other junk.  Supposedly the new stuff is better, but somehow I doubt it.