here is more information for other people who want to read good information:

http://www.dragzine.com/tech-stories...ake-manifolds/

"
Berry mentions that with custom intakes, the volume of an intake plenum generally matches the displacement of an engine. This means if an engine displaces 500 cubic inches, then the volume inside the plenum is typically going to also have a volume of around 500 cubic inches. Under this type of design, ideally no cylinder is starved for air because the volume inside the plenum is enough to fill all the cylinders simultaneously.
If the volume of the intake plenum is not properly matched and is too small for the application, an engine could develop a stall or sluggish response from an engine at the starting line or after each shift, as combustion events literally draw all the available air from the manifold faster than it can be filled by incoming air. Engines with too small of a plenum may perform well at lower RPM but suffer as RPM increases.

A plenum that is too large for the application could also cause too great a loss of velocity as the incoming air is slowed too much when it enters the plenum. This again results in a lack of power as the intake ports and cylinders won’t fill as fast as possible. A lack of velocity can also result in sluggish engine response – especially in the lower RPM range – and an improper air/fuel ratio.
According to Berry, the overall shape of the plenum lends some flexibility to design needs. This goes back to the issues of clearances and aerodynamics. Whether the plenum is wide or tall, Berry says they’ve seen no differences in how an engine performed. In many forced induction designs, Wilson manifolds incorporates what they refer to as the humpback. This shape helps better manage air as it comes into the plenum, slowing it down and allowing the cylinders to fill evenly. Better air management will often translate into better performance and engine life."

I completely agree with you that concentration to the runners is more important, however, there are limits on both ends (large and small) to the plenum as you can see in the article pending the application the manifold is intended to be used in.

And no, I am not a teacher or even trying to act like an engineer. Just someone who has done research and product testing for a long time. Having tuned nearly 100 engines along with R&D on the dyno tends to force you to learn things and look beyond the scope of what you are actually looking at.

 

I think u guys scared the op away.

 

Its ok, his uncle will read it.

 

What exactly have I assumed? I take it you're done with the intake manifold discussion so we can move on? I have not mentioned anything about Tony. Tony in fact assumed A LOT about me with the whole drag racer thing. He's either extremely arrogant or not too smart to make those assumptions. Read it again. That's what derailed the whole thread.


Good job on avoiding any meaningful debate.You're pretty good and picking one sentence and twisting it around without looking at the context of the whole post.

In the early days I learned that throttle response begins to suck when volume between the throttlebody and intake valves is too large by spending a month trying to tune the tip-in resonse not knowing why the car studdered so badly and hunted for idle until I figured out it was the intake tract that Spearco designed.

I also got rid of distribution problems on some stock manifolds by adding a 1" spacer between the runners and plenum to increase volume and when possible widening the plenum. This was with no changes to the runners. I've datalogged with pyrometers on every header to see the changes. I've flowed said intakes on the bench with various plenum sizes. All of this was learned from experience and first hand from people much smarter than me. So google it if you have to, try to be picky in what information you choose to believe because I've seen some very poorly put together websites with lots of misinformation linked in this forum as a credible source of information. Don't just find the first poorly written article that agrees with your opinion, keep digging and you will find what I've said is true.

Why don't you tell us about your experiences where you tried a large plenum with bad results such as uneven distribution or poor resonse, or whatever your experience was. I would like to learn about the intake manifolds you've designed and your successes and failures. I can't be the only one who has actually built manifolds (well, had them built).

I'm actually in the middle of having a one off manifold made for my Indy engine that's going in my car. It's been dyno'd in stock form as it was built in the '80s from intake to dry sump. I'll be the first to admit if it loses power from the custom intake manifold it requires to clear the hood.

 

Wrong. You don't need velocity in the plenum, it only matters in the ports. Lower velocity in the plenum can be a benefit.
Exactly as I've been saying from the beginning.
Wait, is higher plenum velocity or lower plenum velocity better, you're contradicting yourself. You just said higher velocity is better, now you're saying lower is better. Which is it? It states that slowing the velocity down is the goal and that it helps to evenly fill the cylinders.....this could also be called "even distribution" lol. Guess what a larger plenum is designed to do?

Again, exactly as I've been saying. Too small you lose power and end up with uneven distribution. Too large and you hurt throttle response but not power.
You're not who I was referring to in the teacher posing as an engineer comment. You've done research and product testing? Does this consist of more than google and CAIs? I don't care how many engines you supposedly dyno'd, you don't have a good grasp on intake manifold design and you're hanging on to this crazy notion that's dead wrong in a desperate attempt not to be proved wrong. The difference in me and you is I've made the mistakes, admitted to them, learned from them, and moved on. Most of my knowledge comes from my failures. Regardless of who has "dyno'd the most engines" you need to do more research on this subject.

For those that want the simple way that works more than 90% of the time, a higher plenum volume gives more even distribution and more power up until it gets so large it hurts throttle response and there's not likely enough space under the TL's hood to build one that hurts throttle resonse noticeably.

 

Well, he only has 3 engineers. It requires a team of at least 15 engineers and a 7 figure budget just to design the plenum. He probably realized he was in over his head.

 

i have no need or drive to battle with anyone as I have done it for 12 years on other message forums and yet bad information still gets posted and people to this day still do not listen. I'm not avoiding anything. I agree with a lot of what you have said other than what has been discussed about plenums.

I've given you a few articles which back what I have said, yet all you have is "your word" which means shit to me considering I am new here, yet not new at all to talking to people who think they know everything about anything I've done some research on you and I can appreciate many of your posts as they appear to be very informative with backing to them as far as different transmission fluids you have tried and various entertainment/audio posts. But I do not, and will not agree with you about plenums and I'm sure there will be more that I wont agree with. Doesnt bother me but I'm not the kind of person who just lets people post contradictory information to my own research, readings without giving a different view. again, the only information I am "arguing" against is your statement that you can run as large a plenum as you want and not hurt velocity, flow...etc. I simply do not take information for granted unless you are people like in the last article who build custom intake manifolds for a living and obviously know a thing or two. Pretty obvious to me you neglected to even read it.

but thats cool.

 

You contadicted youself with the same article in the same post. Why don't you address that instead of the other crap.

Can you get it out of your F-ing head that I said you can run as big as you want.

For the last time 1.YOU CAN RUN AS LARGE OF A PLENUM AS YOU WANT..........UNTIL IT HURTS THROTTLE RESPONSE.....

2. VELOCITY DOES NOT MATTER IN THE PLENUM, ONLY IN THE RUNNERS. Your own article contradicted itself about velocity in the plenum. 50% of the article agrees with me.

Let me rephrase that........ Velocity will never matter in the plenum as long as throttle response is good. Can you understand that? #1 and #2 are related if you didn't put it together.

 

 

Haha experience > on paper theory

 

What happened ??? Was the OP " dreaming " ?

 

Tony aint here and the concept of an infinite plenum is simple. Whats the problem?

 

i know nothing

 

The thread is in the 3g tl section, that is the problemm

 

^^^^^^^^

 

I was just at sema and the size of the intake plenums on the N/A j35 race motor and the tt j35 is HUGE! Both of them are about the same size as well. Now I couldn't see down in them to see the shape of the inlet ports and runner size and shape, so I'm sure there is a lot going on there. These were made by engineers though, which this forum has declared war on, so please ignore everything they do.

 

Lol says the guy with a custom intake mani

 

And you didn't take any pics?

 

I will get a link tonight. I only took pics of the two twin turbo motors. It was just interesting that the N/A motors manifold was just as big. Honestly I don't think this maters much, its the guts inside I need to see and take a picture of. I would be the manifold runners shape,size, volute, and even angle are all different compared to the two. Its hard to take much away from this without seeing whats inside. I will bring my allen screw driver with me next time and take the top off the manifold to take a picture. :-) (kidding)