Why Do Bigger Ports / Runners Make More Power?

Since 99.99% of porting is making things bigger, why does this make power? Ported head, ported IM, bigger shorter runners on VictorX/BBK style IM.

Cosworth Engineering

 

Because they can!

Bigger ports move the powerband up; shorter, fatter runners move the powerband up. Too big and you lose air velocity and kill power everywhere. It is an art to know how much to remove and where. Sometimes material is added to a port to get the best flow. I pay other people to do this stuff for me and then test it to see how good they are, because I don't know **** about it.

 

B19Coupe Racing

 

Bigger helps in certain spots providing the build needs it. I think every head benefits from a perf. 3 angle VJ, and blending it into the throat of the port. And right is here is where the decision needs to be made, do i stop the port work here? Does the rest of the build really necessitate a complete rework of the ports? A built 2 liter might really like it, an otherwise stock B16 might not.

 

bigger is better...right?

 

i hope a bunch of kids dont read this thread and come to the realization that bigger ports are better. thats all the sport compact community needs is more mis-information. there is a lot more to cylinder heads than making things larger.
you rocket, along with a lot of other members realize this, but many do not.

what if a car with a smaller port mades less peak but has a broader powerband and out accelerates the big port car. whos weiner is bigger??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">Bigger helps in certain spots providing the build needs it. I think every head benefits from a perf. 3 angle VJ, and blending it into the throat of the port. And right is here is where the decision needs to be made, do i stop the port work here? Does the rest of the build really necessitate a complete rework of the ports? A built 2 liter might really like it, an otherwise stock B16 might not.</TD></TR></TABLE>

bingo..
contraption engineering

 

I am very curious about IM porting and how my personal motor would be affected. I'm sure you got my email Rob?

 

Is there any basic principles to go by when reshaping (as opposed to just enlarging) a port for best flow? I know about line of sight porting and deshrouding stuff, but this is sometimes easier said than done. Does anyone port their own heads or have detailed pictures? One of my friend's just had his done and I was unimpressed, nothing I couldn't myself with some carbide bits. So now I want to give it a try.

And for the OP, the simple answer is that bigger things flow more air. But as everyone else said, it isn't always about peak flow.

 

People don't like to be choked, neither do engines.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AWDstylez &raquo;</TD></TR><TR><TD CLASS="quote">Is there any basic principles to go by when reshaping (as opposed to just enlarging) a port for best flow? I know about line of sight porting and deshrouding stuff, but this is sometimes easier said than done. Does anyone port their own heads or have detailed pictures? One of my friend's just had his done and I was unimpressed, nothing I couldn't myself with some carbide bits. So now I want to give it a try.

And for the OP, the simple answer is that bigger things flow more air. But as everyone else said, it isn't always about peak flow.</TD></TR></TABLE>

there are certain areas of the port you can work that pick up flow, certain areas where you can pick up some volume if needed without harming velocity, and certain areas you can try to slow the air down a little.
getting someone that knows what works to share their findings with you will be the hard task. but like steve said, everyone can benefit from a good valve job. luckily honda wasnt WAY off with most of their ports, and unless you are putting the head on a larger engine than it was designed for, the stock port size isnt too far off.

 

Ha, can't fool some of you guys.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Aquafina &raquo;</TD></TR><TR><TD CLASS="quote">People don't like to be choked, neither do engines.</TD></TR></TABLE>

Not true, i knew a girl once who....

 

 

Sweet, so bigger ports really do make more power!? imma go make my ports bigger in my head now and see how much it flows...ill post the results later.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Professor15 &raquo;</TD></TR><TR><TD CLASS="quote">Sweet, so bigger ports really do make more power!? imma go make my ports bigger in my head now and see how much it flows...ill post the results later.</TD></TR></TABLE>


did you read anything on this thread? it is not all about making things bigger in every case for example

read this, this is good info right here

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lohatch &raquo;</TD></TR><TR><TD CLASS="quote">
luckily honda wasnt WAY off with most of their ports, and unless you are putting the head on a larger engine than it was designed for, the stock port size isnt too far off.</TD></TR></TABLE>

PUT YOUR DEMEL AWAY LOL

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lohatch &raquo;</TD></TR><TR><TD CLASS="quote">i hope a bunch of kids dont read this thread and come to the realization that bigger ports are better. thats all the sport compact community needs is more mis-information. there is a lot more to cylinder heads than making things larger.
</TD></TR></TABLE>

seems people already are

 

the more air the engine can go inside the motor and the more exhaust can get out of the motor..makes more power....that why turbos make more power...force induction.. am I right or am I right??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b16nonoy &raquo;</TD></TR><TR><TD CLASS="quote">the more air the engine can go inside the motor and the more exhaust can get out of the motor..makes more power....that why turbos make more power...force induction.. am I right or am I right?? </TD></TR></TABLE>

Flow velocity and flow capacity are two different things. Yes, you're right, the more air you get in the more power you can make. Kids seem to think that 70mm throttle bodys on stock B16's is a good idea for some reason.

 

also mainly depends on the short block
some cases it not about removing meterial but adding it to straighten out the flow
also bigger intake valves may help. exhaust fows well enough is some cases

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by richard7968 &raquo;</TD></TR><TR><TD CLASS="quote">
did you read anything on this thread? it is not all about making things bigger in every case for example
</TD></TR></TABLE>

Professor15 was being sarcastic, you idiot.

Get off my playground.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Combustion Contraption &raquo;</TD></TR><TR><TD CLASS="quote">

Not true, i knew a girl once who....</TD></TR></TABLE>

Baaaaaahahahaha! I knew something like that was coming from SOMEONE. I knew it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gibsanez &raquo;</TD></TR><TR><TD CLASS="quote"> Kids seem to think that 70mm throttle bodys on stock B16's is a good idea for some reason.</TD></TR></TABLE>

They do that because it's an automotive myth that has been passed down by those old-timers, that a bigger opening to the engine results in m@d horsepoweR.

Idiocy perpetuates through time, and that is a prime example of such.

- Derek

 

Perhaps this discussion should be precluded by explaining how the difference of cam timing affects how efficiently an engine can "pump air"?

If the ports are too big intake air velocity decreases.
At high RPM most of the air ingested into the cylinders happens as the piston is rising on the compression stroke. If the air is not carrying the momentum to continue filling the cylinder you have less air/fuel to burn.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gibsanez &raquo;</TD></TR><TR><TD CLASS="quote"> Kids seem to think that 70mm throttle bodys on stock B16's is a good idea for some reason.</TD></TR></TABLE>
Becuase that is what they read in the advertisements in magazines...makes me sick that the people who can make a difference in the industry by teaching the basic fundamentals of how an engine works would rather keep their market dumb and make a buck, than use their millions for R&D and make a product that is more ideal for average enthusiast...guess it costs too much to educate people, no money in that huh...
Rant over

 

Then why does the VictorX gain horsepower? [Generic statement: you can fill in with your own details on when you've seen where this was the case]

At least from the posts I see who has a clue and who doesn't. The real test is if you can actually come up with a good combo given what you know.

 

more air more power
bigger whole alot more air comes in small hole comes in slow basic phsyics

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cltitus &raquo;</TD></TR><TR><TD CLASS="quote">more air more power
bigger whole alot more air comes in small hole comes in slow basic phsyics</TD></TR></TABLE>

Couldn't have said any better myself....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cltitus &raquo;</TD></TR><TR><TD CLASS="quote">more air more power
bigger whole alot more air comes in small hole comes in slow basic phsyics</TD></TR></TABLE>

Im confused. Use some punctuation to clear that statement up. Bigger hole more air, but with the same pressure drop at the other end of the hole, the velocity is slower than a hole of smaller size with the same pressure drop.