Anyone done a tuned runner intake?

[ChromeRhino]

Hi was wondering if anyone has ever tried a tuned pipe between the block and carb before and if you noticed any seat of the pants gains and if there were any unforseen problems you you ran into?

 

[landuse]

Hi was wondering if anyone has ever tried a tuned pipe between the block and carb before and if you noticed any seat of the pants gains and if there were any unforseen problems you you ran into?

Is this for a 4 stroke engine?

 

[ChromeRhino]

It takes advantage of the inherent properties any conventional internal combustion engine, 2 stroke and 4 stroke. The tuning is a little different and the exhaust can play a bigger role with 2 strokes but it is still effective.

---------- Post added at 11:38 AM ---------- Previous post was at 11:33 AM ----------

I have done it and have gotten good results but I don't see anyone else doing it and was wondering if I just hsvent come across the people who are, if they have and had problems with it or if its just that nobody has ever thought about it before.

 

[mckutzy]

What does such a thing look like?...

 

[landuse]

I don't think I have seen one before either. I would be interested in seeing what it would look like

 

[Jrgunn5150]

Looks like this lol,

There is an Australian company selling carb elbows, but I don't think that is their intended purpose.

 

[ChromeRhino]

Lol yeah, just like that

I will build another one with my old briggs if I have some time. Will propably build a matching tuned exhaust and intake too. It looks pretty basic and kinda goofy but works well if done right. Maybe I will design and build a kit for the predator motor for a living lol

I will write a post about how it works and maybe do some drawings to illustrate what I'm talking about.

---------- Post added at 05:01 PM ---------- Previous post was at 05:00 PM ----------

Its definitely less compact than stock though.

 

[Desertduler]

Tuned intake runner length is only effective at certain RPM levels, the correct length can be adjusted as shown above for this big block Chevrolet fuel injection set up. The correct length goes along with the maximum peak hp which is determined by the camshaft profile, valve diameter, etc, along with primary exhaust tube length and tubing size. The longer the intake runner length the more effective the intake reversion is at high RPM. Notice the different lengths in the injection system velocity stacks, why is that? because a big block Chevy has different lengths of intake ports in the cylinder head, the long velocity stacks feed the short ports in the cylinder head and the short ones feed the long ports in the cylinder head so that all the intake runner lengths will be the same for this engine. When everything comes together like it should be figured out in an engine only then can the maximum power level be achieved at a certain rpm so if our camshaft profile is supposed to make peak hp say at 6800 rpm then the intake and exhaust should be most effective at that rpm level. You don't adjust the length of the intake or the exhaust just because. There is a science behind the reason why.

 

[chancer]

But I thought the original question was "a tuned pipe between the block and carb"

Now these pics and descriptions are talking about intake.

What does the original question Thing Look like?

 

[ChromeRhino]

Maybe I will try to find a shop with a little dyno to do before and after comparisons. Gunna leave the governor on and keep everything bone stock.

 

[mckutzy]

Thats cool.. and appreciate the thinking aloud...... BUT... still begs the question.....what does it look like?

 

[ChromeRhino]

I'm working on getting time to sketch one out. There are none available for these engines. Heck, the only ones for cars are either made from the factory or custom made.

 

[Poboy kartman]

Thats cool.. and appreciate the thinking aloud...... BUT... still begs the question.....what does it look like?

It's a pipe between the carb and the block...(see post #1).

Automotive wise, there are basically 4 main kinds: the stock manifolds, a dual plane , a single plane, a semi- both: ie: (Edelbrock Performer RPM for example) , and then the boxy tall fabricated ones for ultra high RPMS.

Interesting thing for me is going to be how to accomplish this in a small engine. See...the really main difference in these manifolds on cars is height...now, that may be because there are 8 cylinders to tie together, but I wonder if gravity doesn't play a part in what makes them tick as well as runner length?

At any rate, what it boils down to is velocity. Longer runners deliver the fuel charge into the combustion chamber at a higher velocity than short ones...which is good for high rpms when charges are being exchanged very quickly, but not so good for off idle power.

So...even discounting gravity as a force in velocity, there is fuel suspension to consider....a fuel charge traveling horizontally is going to have a tendency to allow the fuel to settle to the bottom of the runner while one going nearly straight down isn't.

Now, on a car....the carb is already above the intake valves and positioned so that all you have to do is go up.

On a small engine...it's typically in a parallel line
...so how do you raise it without an S curve or a plenum box?

This should be interesting!

 

[chancer]

This would be like (similar to) the Idea of putting a 1" riser between the Holley and the Manifold on a V8?
But tuned? HMMM cool.

[EDIT] To answer Poboy.
You get a vertical shaft engine,

 

[ChromeRhino]

Ok. So a tuned intake runner is a piece of pipe/tube that carries the air/fuel mixture from the carberator to the engine block, where it then follows the path inside the head to the intake valve and finally into the combustion chamber. So it looks basic and kinda funky. Here is a sketch I made up to show one version of what it could look like: http://s53.photobucket.com/user/chromerhino10/media/20160410_145654_zpsipxaetlf.jpg.html




Now, as a piston moves down it creates a low pressure wave in it's wake. The low pressure that the piston causes is less then the atmospheric pressure (normal pressure outside of the engine, i.e. 14.7 psig at sea level) so the higher pressure (atmospheric pressure) pushes air through the air filter, intake, carb, intake runner, past the intake valve and into the combustion chamber.To understand the thinking behind a tuned intake runner you have to understand that air has mass. If you have ever stood in a 30mph wind gust you get that concept. So imagine the intake valve opens and the piston is moving down, there is a high pressure wave that has moved through the air filter, through the carb and picked up some fuel and is heading towards the cylinder. Since the air/fuel mixture has a mass, it has a measure of energy in the form of inertia, so when the intake valve closes the air slams into the valve and is compressed. The molecules being compressed transfers the energy back up the way it came in by slamming into the other molecules, which causes a sonic compression wave that will travel near the speed of sound until it hits something else to bounce off from or escape to the atmosphere. This is one of the reasons people say it's important to keep your air box on with a proper air filter in it. So now there is a compression wave bouncing back and forth in the intake system.

So, If the wave is traveling back towards the intake valve when it opens, the air will create a force of pressure into the combustion chamber greater than the force that the atmospheric pressure alone would cause. Any amount of air forced into the combustion chamber is considered to be "forced induction" or have a "charged" effect. This is the basic idea to a tuned intake runner and intake system design. Will it act like you have a super charger or turbo on it? No, not even close. But you can improve efficiency (increase power) at different rpms in narrow bands. To do this, you take the average temps of your intake in normal operating conditions, use the calculation to determine the rate of speed a compression wave travels at that tempature (speed of sound), and then find a length of pipe that would provide the a harmonic travel length starting and ending at the intake valve. The rate of speed between the valve closing and opening depends on the specs of the cam and rpm. If you put it all in to a revelant equation you can determine at what rpm you would get a "charged" effect. So, if you wanted more torque taking off you could tune for a lower band of rpm's but if you want more power mid or at high rpm you can tune for those rpm's as well.

You will likely find that you can get a "charged" effect throughout the rpm range in spots anywhere the compressions wave is heading back towards the combustion chamber. There are other advantages to using a tuned runner intake. For instance, the pipe will allow distance from the hot engine allowing a cooler charge of air, allows more time for the air/fuel mixture to atomize (break the fuel particles up into smaller droplets and mix into a more fine and mixed charge so it explodes more efficient and quicker), and moves the carb further from the engine heat. There are drawbacks from this idea also. You have to have more room to add the additional tunned intake runner pipe, you have to secure the carb so that it doesn't shake too much and cause too much stress on the mounting points, it looks goofy, you get a slight reduction in efficiency in the rpm range where the compression wave is moving away from the intake valve and a few other things you could argue if you wanted to be picky. To further cover the fuel/air mixture I think it's important to understand why a longer path from the carb to the combustion chamber, if properly designed and executed, would improve power. All fluids have a certain amount of surface tension that prevents it from breaking apart. A longer runner will allow the tumbling of the faster air hitting the fuel particles to overcome the surface tension of the fuel and break them in to a more desirable finer mist of air and fuel. Also, the air flow passing the butterfly in the carb is tumbling and slow. A longer runner will allow the air to straighten out and be more organized, increasing velocity and efficiency. This allows more of a charge of air to enter the combustion chamber, breaks the fuel apart more, mixes the air with the fuel more and allows you to design the length and diameter to tune it to certain ranges of rpm's.

An important part of this system is to have a well tuned intake system. It works best if you have a plenum to hold a reserve of charged air to act as a spring to bounce against and make the wave move back towards the intake valve (like an air box or length of pipe with an air filter seperating the atmospheric pressure and intake pressure and compression waves) and a proper air filter. Yes, a proper air filter IS essential to a proper tuned engine. Sure, it's there to stop dirt and debris from getting into the intake system and engine but one of the secretes of a proper air filter is to easily allow air to enter into the intake system but not back out. It is designed to allow the air in but have enough resistance of air moving back out to keep in a charged (more pressure than the atmospheric pressure) back out, along with allowing the compression wave to hit it and be able to bounce back instead of escaping into the atmosphere. Grab a K&N filter, put it up to your mouth and blow a forceful amount of air in the direction that it's supposed to go, then try it the other way and you will quickly get what I'm talking about. It should be much harder to force air backwards out of the air filter and very easy to blow it the direction that it was designed to flow.



While this is generally designed and better suited for 4 strokes you can use the same principles and thinking to have a simular effect on a 2 stroke. The difference is that normally this is done with a tuned exhaust pipe because of the inherient properties of how a 2 stroke makes power. You can use this information to design an entire tuned system from air filter to tip of the tuned exhaust pipe.

I will try to add illistrations later but I hope this helps explains what I'm talking about, why it would help and maybe learn a little more about the inherient properties of an internal combustion engine and how it works. This is certainly not a comprehensive explaination of how an engine works or a perfect way to describe what a tuned runner intake and intake system does, but I hope it has helped.

Let me know what you think. I have no pictures since I have had two phones destroyed that had all my pictures on. I will design and build another system with all the steps. Hopefully I can get a dyno pull of before and after to show peak hp/tq and rpm graphs to show how it works and how much it effects the output of the engine.

 

[ChromeRhino]

It's a pipe between the carb and the block...(see post #1).

Automotive wise, there are basically 4 main kinds: the stock manifolds, a dual plane , a single plane, a semi- both: ie: (Edelbrock Performer RPM for example) , and then the boxy tall fabricated ones for ultra high RPMS.

Interesting thing for me is going to be how to accomplish this in a small engine. See...the really main difference in these manifolds on cars is height...now, that may be because there are 8 cylinders to tie together, but I wonder if gravity doesn't play a part in what makes them tick as well as runner length?

At any rate, what it boils down to is velocity. Longer runners deliver the fuel charge into the combustion chamber at a higher velocity than short ones...which is good for high rpms when charges are being exchanged very quickly, but not so good for off idle power.

So...even discounting gravity as a force in velocity, there is fuel suspension to consider....a fuel charge traveling horizontally is going to have a tendency to allow the fuel to settle to the bottom of the runner while one going nearly straight down isn't.

Now, on a car....the carb is already above the intake valves and positioned so that all you have to do is go up.

On a small engine...it's typically in a parallel line
...so how do you raise it without an S curve or a plenum box?

This should be interesting!

Wow, it took so long to write it all out, sketch the picture, load the picture and everything that I didn't know there were more comments.

You can mount the carb at a slightly elevated level, make a curve to the side, curve it up, curve it up to the side or have it straight out... and more. While it might effect the performance depending on location, the difference is surprisingly not that significant. As far as the fuel settling, it really isn't that big of a deal if it's designed correctly. Besides, the some of the fuel sticks to the walls of the intake. The air moving in the intake near the wall will encounter these droplets and cause the air at the outer perimeter of the pipe to slow down and stall, which creates a vortex in the center of the pipe for the rest of the air/fuel mixture to follow. It's kind of the same fluid dynamic principles they use to design the size, shape and surface properties of the ports inside the head.

If you take a look at the old cross ram MOPAR's with the dual offset 4 bbl carbs you will see that the carb position and runners aren't what you would think would be ideal... but it worked just fine. Sure, they did it for hood clearance purposes but it shows that it will work just fine in a un-idealistic configuration.

 

[ChromeRhino]

I think you would be surprised on how much off idle performance you can gain from a properly tuned intake runner and intake system.

---------- Post added at 01:58 PM ---------- Previous post was at 01:46 PM ----------

This would be like (similar to) the Idea of putting a 1" riser between the Holley and the Manifold on a V8?
But tuned? HMMM cool.

[EDIT] To answer Poboy.
You get a vertical shaft engine,

Its kinda simuilar but much more exaggerated. And you don't need a vert shaft engibe. The vacuum and charged air is more forgiving to position and configuration than you would think. Take a look at the attached picture below of a 413 cross ram engine. Hardly what you would think of an ideal pathway for the air/fuel mixture to travel, but it worked well.

---------- Post added at 02:09 PM ---------- Previous post was at 01:58 PM ----------

The above attached image of the 413 cross ram incorporates tuned runners like I'm talking about. They are what runs from one carb up over the tappet covers, across into the other head's intake ports. Its a cross ram "ibtank" but it stretches out the intake runners in the head to create a tuned resonance chamber. You can look at modern EFI intake systems to get further ideas of tuned intake runners as well as plenums, and well designed intake systems. All new vehicles take advantage of tuned intake runners. One of the first modern examples was the 2.2L Chrysler engine. I had one of these engines in a turbo II configuration when I was 18, and which started me curiosity about the tuned intake runner and how it worked. Below are a few examples. There's examples of the 1986 2.2L/2.4L (which is just a stroked 2.2L), Integra, Chrysler intake for trucks they refer to as the "Keg intake", and a few more examples. The design they use for the Dodge trucks is designed for low and mid rpm tq and actually limits the truck from breathing very well at higher rpms.

There are manufactures that have developed variable intake runner designs to help make engines more efficient throughout the rpm range. This idea is not new... but you don't see it on any of the small engines.

 

[ChromeRhino]

What I did is get a pipe of appropriate size, put a couple bends in it, added custom flanges, mounted the carb, added an intake pipe (before the carb intake pipe) and topped it off with a good air filter. The pipe lengths, diameters and positioning (bends) were all calculated for the specific applications. The intake pipe worked as a plenum and the air filter was placed where nice cold air could get in. The "seat of the pants" comparison to the stock setup proved to a few of us to have a noticeable gain. There was no other modifications other than the runner pipe, and extended intake pipe. There was already an adapter and air filter on two of the engines we tried this on. The other was on a really big leaf blower/vac mounted on a trailer. We tuned it to optimize the normal working range of 3500 rpm. It worked great on that application also.

After we were satisfied that we were going to keep the new intake system on we adjusted the carb settings to fine tune for each application. One engine had mods added to it after a while and the intake system seemed to amplify the mods. The person who owned the engine asked me to make a new intake system for him to adjust the rpm range and tweak it better to suite what he wanted after the mods but I didn't have time to monkey with it.

I must say that I had my reservations about whether it would be effective or not but when my buddy asked what he could do to get a more power without spending very much money this was my off the wall idea that I came up with. He was more confident in my thinking then I was in my own thinking and he asked me if I would come up with the figures of what he needed and it went on from there. We think it gave definitive results and worked well. I just didn't know if anyone else here had ever tried it either since I have not seen any threads talking about it and have never seen any pics of anything like what we had done.

 

[Poboy kartman]

Ahhhh....but keep in mind...when you start comparing those intakes to a small engine, the parameters ARE different!!!!

While theory may be the same....mechanics aren't. In the case of intake runners: well, you wouldn't think that air / fuel separation could occur in such a short distance....and that what you posted up has as little relevance as it does....

Now, I know. you're a fart smeller...lol...but you have to consider this: SCALE!

Those big block engines are moving HUGE amounts of air...(and 6" of extra runner there = maybe 1" on a small engine. (if that...!)

So the volume and velocity are going to negate some of the air/fuel separation...

Now.....the other shoe! Those engines can deal with a variance in A/F much better than a small engine. The A/F change is going to be more critical in the small engine.

Soooo...here's the thing: that separated fuel is going to find it's way into the combustion chamber with catastrophic results....(I'm not talking about damage or anything....but TUNING! )

I'm just throwing something out there for you to think about as you design this thing.

Not trying to be negative...just pointing out a couple of obstacles to keep in mind

 

[chancer]

This whole thing reminds me of the "Bronda" That Kartfab and lick Nick each made.
Just a or three inch "Runner" to adapt the Honda carb to a Briggs Flatt head.