please port your manifold to match the engine

look at this, its a huge difference

I ported one runner to the engine, the other is stock

 

have fun with that hornets nest.

 

it may be a huge difference in size BUT is it a huge difference in performance/drivability

 

This modification could backfire in a major way.
Years ago, I noticed the intake runners were MUCH smaller than the block ports. Drawing on my knowledge of pistons engines (port matching is a common upgrade on V8's), I posted the subject on this very forum. Someone directed me to an engine builder's website that conclusively stated the intake ports sizes were undersized to promote velocity: under no circumstances should you port them to match the irons on a stock engine! If you do, the slower moving intake charge will kill your midrange powerband, giving you poor acceleration.
Let us know what your results are once it's back together.

 

A little something called reversion. Something to avoid.

 

Would this be a good idea if you're running a blowthrough turbo set-up though?

Or just a bad idea all together

 

Of all the people that say this is a bad idea, have any of you ever compared a ported manifold to a non ported one?

The reason I say this is because everyone always says "well I heard this...", or "statistics show blah blah blah". I have NEVER EVER heard of anyone actually trying this and saying whether it works better than stock or not. It's just like all the stupid bastard arm chair mechanics on VWvortex that cringe at the thought of 2.5" exhaust and headers, thinking that they're going to lose all their precious low end torque.

I have a port matched (and grooved) manifold on my car, and I have plenty of low end, but I was never able to compare it to a stock manifold because I did a bunch of crap at the same time as the manifold, and I don't know whether the manifold is helping or not, but my car ran really good and got 24 miles to the gallon taking it easy, and 20 running hard.

 

IMO, kinda dizzy but will try to convey.
Starting basic understanding of airflow, density, mass, velocity, temperature.

Taking the intake above for consideration, instead of calling the primary runner small will call that normal. The air flows through the runner and hits the larger opening of the blocks intake, the air will lose velocity as it expands to fill the void, in my consideration the air is cooled slightly, dispersed in itself, basically lowering the density of the air, but stretching its mass more broadly. It seems the air does not initially lose any velocity but its area is streched thinner, so its amount of travel is less in velocity while maintaining the initial amount of area traveled as equal.

What that seems to mean is, once flow rate is met with the max efficiency, the smaller runner dumping into the larger runner will cause a vacuum void leading from the recessed flat area on the intake ontoward the intake into the housing causing all kinds of distorted flow under different loads?

 

Low rpm small runner intake into large intake port on block = distorted airflow/spirally, ideal for idle consistancy/best mixture.

High rpm small runner intake into large intake port on block = works as well as the intake will allow at that rpm, because of the velocity of the airflow little or no distortion.

Matched runner intake into the intake port on block = no distortion or very little at low rpm through its max flow rate; might affect idle stability.

Large runner intake into small intake port on block = bottleneck

Port matching only a little into the intake runner might not mess up the low rpm effects. Matching the port all the way to the top of the intake might. A lot of if's.

I asked a certified experienced overschooled mechanic, and re-iderated as best I could.

 

Relax a little, buddy. Are you saying I was foolish to check with an engine builder before taking a power tool to my intake?
I'm all for trying out new ideas, but I'm also for knowing what I'm doing. If you NEVER heard of anybody comparing this mod to a stock intake, why didn't YOU compare to stock instead of ruining the result by doing "a bunch of crap at the same time as the manifold"? Maybe you should be ranting at yourself?

It's beneficial for all of us to share opinions & experience, but tempering your words with respect for you fellow forum members (most of whom build their own cars) would definitely win you a wider audience.

 

I will let you guys know.

Those following my huge mega thread, know my engine is street ported using racing beat templates.

I will go EFI, but to start the car and break in the engine I will use the stock nikki with this manifold.

I´ve also read about reversion in this forum... does not make much sense to me. You always "move" the curve. If you have to loose some low end power for hi end power so be it.

One of the rotary problems, is to suck more air. On carburated models, the intake runners are filled with air+fuel. Fuel takes space. If you switch to 2 injector in the middle iron, you will instantly see improvement because your intake will simply flow more volume of air.

The intake and the irons show a very crappy finish by factory. Even if you dont enlarge them, theres plenty of room for improvement

 

this looks like an interesting project, at first glance seems like the way to go, but then i thought about it and read some of the responses, and my thoughts on it (simple language) matched ports is the highest you can go, because of reversion (from manifold mods) right?. my own thought is why not live it just a millimeter, or two smaller than the engine port, that way you still have a bigger port but you don't have to worry about reversion. now, another problem i was thinking about (not sure if this would be true) is lag. it's not gonna be a huge difference like with a turbo of course lol. but, i think once again, that when you try to step on the gas, it's gonna take it just that much more for the fuel/air to stabilize itself due to port differences, now with that said, once it's stabilized and the small lag is gone, the only other thing that can happen is a bit of a stronger pull than with a stock manifold thus giving you a bit of a "boost"......(these are just observations on my part, please correct me if i'm wrong).

 

Read This:

http://www.yawpower.com/Flow%20Testing.html


and for those who are too lazy:

 

I'm not questioning Yaw Power, but i think someone needs to put this to the test(Dyno) to put an end do this. Because alot of people in the race section to port match, while most people in this section always refer back to Yaw's site. I'm honestly undecided about this.

 

I don't think yaw would put unsubstantiated statements on his website. But maybe carl and sterling would care to pipe in. I'm sure there is room for improvement in everything, but absolute port matching as in the above pictured mani, and that which v8 people try to achieve, lowers the velocity inside the the air horn and therefore reduces the flow.

 

I think sterling has something up his sleeve since he has an option not quite available for the intake manifold on his website.

 

I´ve read that article a long time ago, I remember that trochoid was doing his first porting when I read it!

I was unable to find a WHY in that article. I mean, "it flows less" just doesnt cut it for me.

I do respect Paul Yaw as a very experienced person, but I think testing it this way most likely wont show the same results when other variables change.

Example:

On a stock Nikki, maybe

On a sterling Nikki?

On a ported engine with a stock Nikki?

On a ported engine with a sterling Nikki?

On a stock engine that manifold might run better unmatched... but when you port the engine.... you need more volume of air and gas.

Im a lawyer, I know **** about about a lot of stuff. I try to aply common sense.

Common sense a lot of times can be wrong.

This thread rocks

 

He's got a flowbench, tested it, figured it out
Carl has a flowbench, tested it, confirmed it

If you want to apply common sense, then look at his flow vs. velocity argument and what Jeff is saying about reversion. Those are common sense principals that point to a stance where even if it *does* flow more, it doesn't necessarily increase power.

I'll tell you what, when you can show me back-to-back dyno graphs with a stock manifold and a port-matched one, I'll throw my empirical proof and common sense out the window and take you for your word that it's better

Jon

 

Just a suggestion but maybe you should check the air flow with a flow bench like Yaw did, then it won't be such a big mystery, although you'd probably need a few manifolds to test different porting sizes and shapes with.

 

LOL



I´ll try. I do have an extra manifold

 

I'm confused as to why being a lawyer would have anything to do with this thread, this topic, airflow dynamics or anything really.

I'm a computer technician. I know "****" about "stuff" too. I'm not trying to discredit your knowledge or firsthand experience but that statement just comes off as being really arrogant. If you had said "I have a degree in engineering with a specialization in airflow dynamics" or "I make my living flow testing things for x company" then maybe it would be relevant, but I don't see how being a lawyer in this context would be any more relevant than being a nurse, fireman, or aircraft flight attendant. They know "****" about "stuff" too.

Jon

 

There ya go!

I'm actually VERY interested in any manifold porting ideas that get backed up by empirical evidence since I'm looking to port another manifold for my car. We have some questions about whether the one I have was ported in the most efficient way possible or not, but we would need many manifolds and lots of dyno time to test the different ideas we have.

Jon

 

Threads like this are fun as long as everybody plays well with others.

Even if Im wrong, a lot of people can learn from it.

Just remember that when you flowbench test a part, you remove the rest of the engine from the equation. I would really like to try to dyno both.

Things go to the shithole when people starts throwing rocks at you :p

Lets try to keep this thread healthy

 

I hope you don't mind, I put your quote in my signature because I find it amusing.

You're right about one thing, there needs to be some sort of evidence or proof to back up any flow-related mod you do (or any mod for that matter).

It's just that your initial post was very confident-sounding in how beneficial this "free" mod would be, there was no doubt or maybe there. It's the kind of post that can make someone blindly try it, or believe it and have them trying to counter someone else's argument because "they saw it on the forum"

Jon

 

Im gonna have to start every post like the norwegian guy "Excuse my english, Im argentinian"

I meant that Im a lawyer, not an engine builder or even a mechanic. Meaning I know NOTHING (****) about a lot of stuff.

No worries Vipernicus, I say a lot of expressions incorrectly Like the time I sayd "not my cup of coffee" insted of "not my cup of tea"