All of these new threads with intakes being a hot topic and burning #7 has sparked my interest once again

I have never been able to explain my thoughts very well as to airflow distribution and what not

So I drew up a visual in paint to show what my mind is thinking
I may be all wet and have it all wrong but figured I’d post up for the hell of it
And get some other minds thinking along with me


Heres my thoughts written out in words LOL
There is a lot going on inside the intake manifold at extreme speeds
Ex. at 6000 rpm the crankshaft makes 100 revolutions every second
And since it’s a 4 stroke
There is 2 revolutions / event
Event being Spark, IVO, IVC, EVO, EVC



My thoughts lie heavily in the point where the intake valve opens and starts pulling in air


This is happening on 2 cylinders at a time ...50 times per second

heres the drawings
the red lines on the right 4 are used to indicate the air flowing to the cylinder
the other 2 examples on the left is firing order and cylinder numbering

there are 2 drawings total one being a car style intake and the other being a truck intake

first the truck

--------------------------------------

looking at this I can see # 8 getting the air's momentum heading toward the back of the intake and 7 getting slammed full of air on the next stroke

this could be the reason #7 burns

I see a very unbalanced setup with the air having a hard time getting to those front cylinders also

how accurate is it if the cylinders are taking in different amounts of air
and corrections to the fueling is done across 8 injectors based on avg from 1 WB?

Im not just singleing out no.7 here
I think they are all off and it leaves alot on the table

I also see where there could be some issues with the car style intakes but not near as bad with the larger fully open plenum
I run a LS6 intk and Im not bitching ...just thinking
I also wander if the speed of the air coming by the front cyl's
while heading to 7 or 8 would create a vacume on them

Kinda like the same principle as venting your crankcase to the exhaust
if that made sense


heres the car intk



I didnt do one of the vic jr because i dont see this as being an issue
only problem I have there is the short runners
But who knows, that may be a good thing...
Im real interested in seeing some of the results of this with the WCCH adapter or 4bbl TB

Hit me back with some input
Im interested in what others are thinking

Id love to see more options and results...
Hopefully this will stir the pot and get more people thinking

 

those are some good visuals right there. I would definitely like to know how this pans out with the Vic Jr... I'll be its much better than any one of the stock intakes... great illustrations!!

 

good illustrations man, Ive wondered about the same thing. Its funny on the truck intake how the problematic cylinder is closer to where the air enters to go to each cylinder. Why dont we hear about #8 going lean instead of 7, I guess the answer is runners arent identical?
Sometimes I wonder what GM engineers are thinking and why things are the way they are, with all the testing they do you would think this wouldnt be a problem.

Let me know when your hooking up the F1 race car intake and the 8 widebands I want to be there to see this

 

its not a problem until we start jacking around with it

 

how much is being left on the table?

well there was a thread over on tech. going from the truck intake(i think) to a vick jr style they were able to tune in an extra 105hp with the same fuel. this was a boosted vehicle tuned to the edge of knock on pump gas. the guy that did the test said they tested the intake presure at each port and there was as much as 2psi diference between 7 and the lowest other port. number 7 wont break if you are carefull with the tune but we are tuning till we hit knock and that has to be overfueling the other cylinders.

 

Thats a good point.

Itd be nice to be able to control each injector individually and see which cylinder is knocking.

 

An extra 105 HP with an open plenum Vic Jr. !!!!....Jebus, that's insane !!!

Anyboy ever seen a 4.6 PI intake ??...I can see why the Mustang crowd raves about this intake vs. the new one with the front-mount TB...with the large lower plenum, equal length runners and the center mounted TB it'll pretty much flow anything you want it to....and it delivers equally to all cylinders as well !! Too bad GM had to front-mount the TB and throw in the wierd plenum system we have.....

4.6 intake:

 

does the victor jr intake require special fuel rails??

 

yes but it comes with them for $390.

somethings to keep in mind... the distrabution problem isn't a show stoper. i ran low 10's and made over 1000rwhp on a stock truck intake. the vic jr intake most likely kills some low end and that wouldnt' be ideal for many truck guys. i haven't noticed any loss of low end though. with the intake, fuel rails, tb, 90, fuel line fittings i am into this intake for around $1000. unless you have the turbo to push the extra 100hp thru the motor you wont see those kinds of gains. most na guys will probably see more in the 20rwhp gains area with a loss of low end to match. this intake is rated something like 3500rpm to 7000rpm.

i hope to be going to the dyno in a couple of weeks and will be able to report on a few things.

i do have one interesting observation. before with the stock intake my truck would start to cut out if the wideband ever went under 10.9-1. last night while tuning i saw it go as low as 10.4-1 and it wasn't cutting out. this sugests to me that before i had an average of 10.9-1 but some of the cylinders were probably much richer. rich enough to kill the spark. now with even flow it will take a much richer reading to cause the spark to cut out.

 

there are stand alones that allow you individual cylinder fuel trim. i remember talking to kurt from w2w and he said something about always adding a little fuel to the back cylinders with bs3.