Here I am, up at work (at my new job) I gotta work till ten tonight and me and another sales rep are the only ones in the office. I normally am not able to get on honda-tech anymore during the day, since the new call center that I work in has a low service level we are "banned" from the internet. But.....today is Saturday, and there are no bosses here as well as no calls coming in. And anyone who has seen my Deep Thoughts posts before know what this means.........

I've been hearing several people tlaking about intake manifolds lately, espicially on turbo cars. For the reason that they are proven to increase flow and effect volumetric efficency. The JG Victor X comes up in conversation quite often. I've taken several looks at the manifold, and it seems to be a well designed piece. I've also looked at the STR and Jun manifolds for instance. And anyone who caught that issue of SCC or Turbo (can't remember which one) a few months back where they were talking about the all motor drag cars formulas for success. There was a pic of the AEBS designed intake manifold for b-series motors. I'm not sure if it is avaliable to the public, but this was a very nice looking piece. It had two large velocity stacks for two different throttle bodies (I'm not sure of the diameter) that were on top of the plenum. And the injectors, if I remember it right, were on the under side of the runners.

For anyone that has seen the Jun piece first hand and had a chance to look inside the plenum, at the junction point of the plenum to each runner there is a velocity stack on the inside of the plenum for each runner, I thought that was pretty wicked, but then I started thinking about it. Although it first seems as a good idea to increase intake charge velocity in such the manner that the ventrulli plate does so, but this seems like it would be more effective since it is not decreasing the size or volume of the runners on the way to the ports. But, when thinking about the extra violence that this could present in the plenum, I'm not sure if it is worth it. The way that I see it is that considering that the velocity stack protrudes approximately 3/4 of an inch into the plenum, the air that finds its way to the back sode of the velocity stack could distturb the incoming intake charge into the runner by the motion of the air that is behind the stack trying to become part of the incoming intake charge. (Damn, I wish I had access to a flow bench ) Cause I'm sure that the disturbance is there, just not sure how prevalant the voilence is to the incoming intake charge.

And about the AEBS manifold for the all-motor varienty, like I said earlier, I believe that the injectors are placed on the underside of the runners, we all know that this aids in atomization since the intake charge's direction of flow is corralative to the direction of the injectors and with the injectors being placed on the underside of the runners there is less chance of the incoming air that is traveling at an impressive rate of speed through the runner "destroying" so-to-speak the injectors pulse direction. Pictore two injectors in a runner, one on bottom and one on the top of the runner, and now take into consideration the intake charges speed at lets say...seven thousand RPM and keeping the flow rate and discharge speed of the injector the same, it would logically seem as if the injector on the top side of the runner could atomize more efficently due to the way that it is obstructing the intake charge air more and following the same designated path as the air from the injection point. The fuel admitted from the injector on top could easily be "deflected" on to another path in the port, this is prevalant in that problem we all have heard about at on time or another, which is "fuel puddling" in the intake tract. Thus the focus on proper atomization that has overwhelmed the racing industries design primciples over the past 10-15 years.

As far as atomization goes with injector placement, it can only be taken so far, discharge angle and velocity are just as prevalant to the issue I would think. I'm sure that everyone has heard of "upstream" injectors at some point in time. Of course, the discharge angle of the upstream injector "fights" against the intake charge, as it is shot against the charge's direction in the runner. Now, as far as hampering flow goes with an upstream injector, I believe it is there, but I have no way of commenting on that as I have no resources avalible to me for research on that topic. But, the upstream injector's placement can severly aid in atomizationif angled right, if angled too far below "X degrees" (for sake of argument we will assume 45 degress to be the middle "perfect" angle numerically), then the fuel can easily be puddled since the intake charge simply "knocked it over" on its way into the port. On the other hand (and this one I'm not as sure about) with the injector placed upstream at say, ninty degrees, then the fuel would be in a lateral movement, I would think that this could hamper atomization since the injectors pulses are relatively short in duration (at least opposed to the airflow rate) that the fuel could be "picked up" by the intake charge and carried in all directions, some areas being more atomized than others.

But back to the AEBS manifold for a minute......

The throttle body positioning is amazing to me on this manifold, keeping in mind direction of flow, short of having an individual throttle body set-up such as the Toda piece, this seems as if it would provide the best chance at a direct path to the ports from the throttle plate, seeing as every other manifold on the market uses the typical honda throttle body positioning.

With that in mind, I have heard several reports that Larry (ENDYN) is developing an intake manifold with equal length runners from the throttle body as well as upstream injectors placed on the under side of the runners. Now, aside from what you may think about ENDYN or Larry, this is a good idea at first glance, the thought of an equal mix of air and fuel in each cylinder during every engine cycle is great, but, a few things that I wonder about in this instance is the runner entry angle to the ports and how manifold absolute pressure will be monitored. If the runners, for inctance start at or very near to the single throttle body, than there is no place to effectively measure the MAP. There will have to be a plenum of some sort, or at least thats what I would think. Also, the runner's angle at the port. I'm not sure if the fact of each runner having equal length from the throttle body could effect this, but, I'm assuming that the runners will be longer in length than OEM Honda, that means that they will have to take up more room and runner angle might have to be comprimised. Runner angle at the port has to be one of the most indecisive parts of intake manifold design, seeing as a sharper angle (without taking the angle to the extreme) could aid in intake charge direction, but it could also hamper atomization, seeing as the intake charge could easily overpower the intectors fuel pulse into the runner and combining that with the fact that fuel is heavier than air, there could easily be the case where more fuel is backing up against the intake valves in between openings. On the flip side, assuming it is not taken to the extreme a flatter runner angle could hamper flow some but also aid in atomization seeing there us more room and time for that matter, for the air and fuel to mix.

On to the JG Victor X for a brief moment, the Victor X looks to be a well put together manifold aside from the welds in the runners, they are not matched from cylinder to cylinder, thus providing different airfolw rates, velocities, and atomization characteristics from cylinder to cylinder. And seeing as the injectors are placed in the stock location the fact that the welds cover the entire circumfrence of the runner (including the area below and just before the injector) it would seem to me as this could hamper atomization by abundately disturbing air that has not met with the fuel yet, alowing the air at the top of the port to theoretically "consume" more of the fuel. I'll have to hear some responses and think about that one some more before I can form an opinion. The JG plenum is very gracious and well designed though, I will say that is one thing I noticed immediately was the quality of the transition between the plenum and the runners.

Now, I know that this may not be "real world" or "daily driven" type of stuff, but I just killed almost an hour at work by typing this, plus I like to see what others think about the more complex forms of engine design, development, and preperation.

Have fun non-VTEC, I know you'll be back for this one.

One more thing I'd like to add, is about velocity and its relevance to the issue, intake manifolds on a stock Honda were not designed for boost, but they were designed thoughtfully, I don't think that the runner angle on the B18C5 came to be by accident. But when positive manifold pressure is entered into the equation, there is many more variables and much more room to play around with intake manifold design on a "street car".

 

there's so much stuff there to read i dont know where to start.......

you mention the JG manifold which i have only seen pictures of........it does look like a nice manifold. pretty large plenium and short runners......makes good for high RPM power......i'm sure it will work good for turbo as well.......i'm kinda skeptical that it would be a well chosen peice to use on a daily driven N/A street car if it will rob you of pretty much most of you low-mid rang power.......i would have to hate having to rev the **** out of my car everytime i come so a stop sign just to get it moving again.........same thing goes for thos big STR or Venom turbo manifolds.........they drag-race only manifolds........

i have never seen or heard of the AEBS manifold you are talking about.....it sounds like a interesting design...one thing i will comment on is the injector placment..............maybe AEBS found that it will automize the fuel better by placing the injectors on the underside the runners but they will not be pointing directly into the cylinders like the stock honda manifolds or the skunk2, JG vector X or al the other manifolds out there........

i'm sure if honda found out that the injector placment was that much better on the underside of the runners they probably would have done it a long time ago........i guess AEBS found it works well for a stricly "race only" type of application but maybe for a street driven car that has to pass smog and remain streetable it probably wont be a good idea? that's just my thought on that.......

and what about the cost of this unit that AEBS is selling? will all their time in reasearch and development be a affordable choice for us consumers. this new design better blow the competion out of the water by 30hp or more for it to be worht it........assuming that this thing is gonna be ridiculously high in price like many other import parts are......

how much better can they get from the simple skunk2/ITR design that will make it streetable and provide excelent power all over the rev range?

i dunno........i like my ITR manifold...i dont think there is anything in the world i would change it for.........

later

 

Definately, all motor on the street, the stock piece is the best compilatio of comprimises out there. Without a doubt, but you did touch on one thing that I haven't thught about in quite some time, and that is the effect that the length of the runners has on power production throughout the rev band. I'll get back on that one....

As far as the ability to utilize more advanced methods of fuel dispersment on the street as opposed to those that Honda has utilized from the factory, they are full of comprimises. One large factor in this is whether or not the manifold is in vaccum or not, as velocity increases in the intake tract, so does the ability ot play with the injection characteristics.

Hmmm......

 

You guys all know the GSR maniflld 0wnz But seriously, this is a good thread with some very good info!

 

The performance that ive seen with individual runners is that you'll get a lot of area under the power curve in the highend. Torque drops dramatically after the 5250.

You will have some tuning problems to suit street driving. I would play around with individual runners if I were building a track car. But for street/track, gotta stick with the best of compromises: ITR manifold from mild to wild camshafts

 

Now to throw a wrench into the mix.

Ericks Racing uses a modified GSR manifold on thier record breaking all motor car.
I am very curious as to the mods they performed on this manifold. I wonder if they still use the dual runner effect? (Buterflies operational) I wonder how there GSR manifold would work on a healthy street 2.0 liter B18C1....

 

if u wanna read some good **** on custom intake manifold design check these links
http://www.sdsefi.com/techinta.htm
http://www.sdsefi.com/air12.html
"Velocity stacks to go on the end of the runners were shown to improve airflow by 19% on the flow bench over straight tubes. These were formed over a machined steel die in a hydraulic press by greasing the die and the short piece of tubing."
hmm.

there are no good manifolds available for the sohc, if they r they r oversized turbo monstrousities. i was thinking of creating a sheetmetal intake manifold but my issue is with sensor mounting locations like iat and iacv sensors...vaccuum lines would be simple..but the sensor mounting locations trouble my brain.





[Modified by JaeOne3345, 10:57 AM 6/23/2002]

 

I liked that design on the manifold for the RX7, that was nice, but once again, I notice the quality of the welds, every manufacturer has their own ways of welding the runners, but I figure that this could be done with a little more attention to detail. I only wonder if it is possible to cast a manifold from a mold, the complete piece, thus there would be no welds in the runners at all. I strongly believe in the velocity stack, I think that it is one of the best engineering principles around. I would love to see the flow bench results for that manifold if you have access to them.

Also, one thing I can't get past is how evey manifold on the market has different runner angles, how are these calculated from manufacturer to manufacturer? Or are they simply a shot in the dark and happen completely by chance? Hmmm... I dunno on that one and can't get past the thought of somthing happening by accident on a cruical part of the engine that dictates mixture preperation and delivery. The two things that dictate the quality of the burn.

Runner length and its effect on velocity is the main factor with the abilty for the manifold to create more/less power at a certain RPM. It all boils down to comprimises. Some that are not worth it. Personally, on a street car, as silly as it amy sound to some, I will always aim for top end power of low end, simply because with low end, then there is the battle with traction, thats no fun.

But back to runner entry angle for a moment, noticing on the stock pieces, be it a ITR, B16, or GSR, all of the Honda OEM manifolds that I have ever seen are radiused for the entire length of the runner, but on the other hand, every aftermarket manifold that I have seen has straight runners feeding directly into the ports, I can only wonder what effect that this has on low/top end power. But, I would figure that the radiused runners would benefit entry angle in several ways, one of which being dictating the airflow's reaction to sudden changes in direction.
With the arched runners as opposed to the flat (straight) runners, the air, or at least I would think the air would enjoy a steeper, but more gradual transition into the ports such as that seen in the stock OEM pieces. Picture this... we have two identical engines side by side, one with your favorite brand of intake manifold on it, and the other with the stock ITR piece, now picture air (in vaccum, not boost) moving through the runners at "X" amount of CFM. one manifold's air will benefit from the slow transition, the other will benefit from decreased restriction. Which one
is relevant to your application? Hmm, whats more important at the time, a slightly higher quality burn and not a severe increase in horsepower, or a severe increase in flow resulting in more power made, simply because the engines volumetric efficency is increased, couple that with tuning and there is a substansial increase in power. In boosted applications, of course, this all changes, since the intake charge is much more violent compared to a vaccum one, the attention is more abundant in the area of efficency. Not as much as in the sense that it would be focused on a normally aspirated engine,
but more along the lines of reducing the violence in the intake plenum and runners. For more than one reason, the main reason being that there is increased air flow, and the need to correctly handle this airflow. Furthermore, there is reversion, the more room that is in the intake runners going into the ports means that there is more incoming unburnt air and fuel for the reversion to charge against when trying to enter the intake tract. Hmmm..... But I would be interested to see the effects of a ITR style manifold such as the skunk piece but with a much larger plenum and runners, but following the same
delivery path to the ports......hmmmm.....


[Modified by riceboy, 10:19 PM 6/24/2002]

 

Now I've gotten to thinking about runner length, and its effect on the incoming intake charge, I'm sorry if I post to my own posts, butI just like to throw ideas out there and see what others think about what it is that I'm thinking about at the time.

Anyways......on runner length, we all know that shorter runners aid in higher RPM power, duh, but why? With the longer runners there is more airflow direction and dictation, this aids in the mixture preperation, providing a cleaner burn and more low end torque since more of the fuel is burned and on top of that, with the longer runners, velocity is increased, once agian aiding in mixture preperation. But bring either forced inducton or higher RPM with increased airflow into the mox, then you have the componets avaliable to toss aside the need for the velocity incrases of the longer runner since airflow is taking over now, resulting in the same effect on the intake charge. Furthermore, thinking about how with increased veolcity and the ability to run the shorter runners with less restriction to the intake charge but, the runner entry angle is comprimised with the shorter runner, giving less room to play with as far as entry angle goes. Now, I know that the entry angle is not near as important as the velocity increases or efficency increases but why not dedicate a little more time and have it all?

Anyone who is firmilar with the Apexi Dunk exhaust system, knows that the diameter of the piping increases as the distance from the exhaust to the manifold increases. This is to prevent reversion of the exhaust gasses, but, reverse this theory for a second, picture the intake charge moving its way thorugh the runners, if the diameter of the runners gradually increased on its way to the entry to the ports, there is more room for expansion of the intake charge, resulting in better delivery to the ports and less impact on delivery angle is present. On the other hand, velocity will slightly decrease at the point of injection, and combined with the fact that there are differences in intake velocitiesat different points in the runner, combine this with the increasing diameter of the intake runners and it will take a well placed injector to take advantage of this.

Now I'm starting to think about the inplications of running twin injectors on each runner, one upstream from underneath and une downstream from the top side of the runner.

Hmmmm.......


[Modified by riceboy, 4:49 AM 6/25/2002]

 

do u think they should design intake manifolds for NA cars and boosted cars seperatly?

do u think there are intake manifold designs where a boosted car would see a huge benifit while an NA motor would be hurting and vise versa?

 

I have a JG Victor manifold with 8 injector bosses. I took another look at it. I'm not sure if we are talking about the same manifold as I can find no obvious welds in it. There is a very light casting scar that runs equally thru all the runners as well as the plenum. If this is a weld, it's the best I have ever seen but it certainly wouldn't cause un equal flow.
Earl

 

good call on my improper use of grammer earl, you are right, those are not welds, but I'm trying to find a word to refer to the difference in the "notch" where the angle changes where the runners meets with the ports, granted the angle is not big, thus the reason this is the intake manifold of my choice, but if you get to looking at the angles they are different from runner to runner, or maybe my eyes are just decieving me I havent measured them yet, if some one would measure the angles I would appreciate it.

EDIT-I was looking at the SP intake manifold and the STR intake manifold the other day as well, and what I noticed about the SP piece is that is had the worst welds I have ever seen on something ment to promote airflow,

Also, the STR piece has a rather large "dip" in the runners where the runner meets with the port, this could definatley promote fuel puddeling and hamper performance.

Although one might argue that with the extreme velocity that is present in the intake runners on a boosted application where the intake manifolds are more readily used could over come fuel puddeling, but any amount of excess fuel that is in the intake tract can hamper flow, atomization and back up against the valves and promote excess carbon deposit. One more thing about the angle of delivery, the steeper the angle of delivery the less chance for fuel puddeling in the runners, but, too steep of a delivery can hamper flow, anyone ever think that this could be why OEM Honda manifolds use radiused runners?


[Modified by riceboy, 4:16 AM 7/3/2002]

 

Yes. The manifolds should be designed for each particular engine if possible. The best thng to do is port the head and flow it to find out how much cfm it moves and what cam profile would make power where you want it. Then grind a cam, then build a manifold all designed to move the same cfm on a flow bench. When complete you should be able to flow the same cfm throught he complete assembly.

For an N/A car the manifold has to be able to flow a given amount of CFM and if its too small or too big it can hinder power. Where as a boosted manifold can be designed with different intentions, the runners may not need to be so long or wide. You can make a runner that creates more velocity without caring about the diameter suffering because its not fed with vaccum.

I only skimmed through most of the posts but, I didnt see runner diameter mentioned. It also effects velocity so now you need to know what length, diameter, and injector location is good for your application.

 

great thread. This is why i love H-T

 

I took a grinder and evened out the areas you mentioned. With a turbo, I'm not sure it makes a big diff. N/A is completely different story.