This deserves it's own thread..

Intake manifold parts..





Kinetix 'aint got nothing on this stuff..

Team this up with a 4" throttle body, 4" CAI, and ram air ducting in the bumper.. and we'll have one of the most badass intake setups out there for a FWD VQ. I have to sit down with Clark at JWT, to figure out what kind of runner length the new cams will want, but, I expect this thing to make some serious power, all over the place.

Travis

 

how much coin did that run you

 

Tell us where you got the billet parts? That whole setup looks great...

 

Velocity stacks that have their inlet located in the center of the plenum flow much better than with the opening at the bottom of the plenum, I can't really tell for sure where you're going with this design so I'm just guessing that those inlets are leading to runners. Are you planning to make a top half that's symmetrical to the top?

 

I want!

 

Very nice!!!!!!!!!!!!!

 

Are you willing to make the head flanges? Not the middle piece in the pictures

 

Sure.. I can have whatever made..

 

How much would the head flanges be?

 

sweet work, let us know how it turns out.

 

Typically, when you have a completely flat plenum floor, you can run into problems with trying to draw air from the boundary layer, or, where the velocity is very low. However, since the floor of the plenum has a decent taper to it, running towards the radiused port entry, this effect is negated. The flow velocity along the floor will be moderate enough, so that it functions adequately. While I agreee that for a N/A motor, raising the velocity stacks off of the base of the plenum would result in better flow.. I can say (from testing on other engines), that the difference between flush mounting the velocity stack with the base of a curved plenum, and raising them is negligable.. We're talking about a few horsepower at best, at out power level. This design will work fine, and we have plenty enough room for the runner length that I wish to achieve.

Here's a rough sketch on what I plan on doing..



This is obviously a rough idea, and the shape will most likely change, to get the runner length where I want, and plenum volume where it needs to be. I'm probably going to try a 10" runner. Combined with the 2" or so from the head's port entry, to the combustion chamber, I'll have a total length of about 12". This should make peak torque at around 6000-6500rpm, and nice power out to around 8500rpm. I plan on going to about 8200, give or take.. as that's where these cams will make power out to.

To calculate optimal runner length, I go off of desired peak TQ. The general rule of thumb that I use, is that peak TQ @ 10,000rpm, requires 7" of runner length. For every 1000rpm that you want to decrease, or increase the peak TQ, you add or subtract 1.7" of runner length.

The plenum volume will be around 5.5 liters, or, 135% of the engine displacement. This is what I usually start with on any N/A engine that's going to rev this high.

Travis

 

you have any idea what the stock plenum volume is? I know that its best (peak HP only) to have the largest plenum possible, but its all relative since you will of course lose power and especially torque with an oversize volume. Ive been designing honda cbr600 plenums and we usually start at 2.4L and only go up from there, since its making peak power at like 10k. It would be good to know what the stock plenum volume is because then you would have a good idea of what the minimum would be and go up in volume from there since you want a higher peak RPM.

Is the cost for having the velocity stacks in the bottom lower? I would think that those extra few HP might be worth it since youre already making the plenum from scratch, not like it would be a lot harder. I can understand if its a price thing though. From testing on those honda 600's, theres quite a bit of difference in flow velocity between inlets in the bottom of the plenum and inlets at the center.

This is from a pretty simple plenum design, but the proof of concept is there




Obviously, with the engine speed at 10k any flow difference is more pronounced than at 8k, but I would think since youre starting from scratch you would do it the best you can

 

The higher the RPM, then, the bigger the plenum you would want.. I can see a 600cc street bike engine needs a large plenum, as you're revving it out past 10K.

Your test show a flat plenum floor.. have you ever tested with a curved floor? It makes a difference.. The parts are already made, so, cost is an issue.. Our design will sacrifice a few HP, but, it will make a TON of power over the stock manifold, and will be worth it for the price.

Travis

 

that plenum is actually 110mm diameter tube, maybe i misunderstood and you mean curved front to back? Ive never tested that

 

Maybe I can try a large tube and just place the TB in the center. Raise the stacks to the center of the tube, and call it a day.

 

when I was thinking about building my own manifold with a tube, the diameter I found was HUGE, like 8" or something. I also was going to look into an oval design, but its hard to find what you need in that type. One of these days ill model a manifold for my manifold and see if I can find the optimal type. If that ever happens, ill definitely post my findings

 

Using a tube with a ID of 5.75", 13.5" long, will give me a plenum volume of about 5.7 liters, or, around 140% larger than the displacement of the engine. I can put the velocity stacks in the center of the tube, and maintain a 12" total runner length, with adequate hood clearance. What do you think? I would probably use 2" runners, slightly tapered up to 2.25" velocity stacks.

Travis

 

I see no fault in that so long as there's enough space inside the tube to keep the stacks off the wall. Would be cook to see some people start doing some really custom manifolds on maxs. In many cases they are cheaper than any aftermarket manifold and can be a lot better

 

Well if you need injector bungs , please give us a ring for your project,

Click on the link in my sig

 

Are you going to use a drive by wire throttle body or an electronic one from another car?