Inliners International Forums General Discussion Blown and Injected Custom made fuel injection intake

Hey every one me again tried searching to no good end

Going to start building my own multi port injection intake out of alluminum

Its going on a turbo charged 292 and was curious as to runner length and intake volume and shape. I have a D shaped extrusion with oval runner and very noce velocity stacks

Does length hinder performance and the volume of the plennum is there a rule of thumb for any of this?

Thank and happy inlining

One thing, you do not want to have the end of the plenum close to the velocity stack.

There is a rule of thumb. Can't remember the formula off hand.

MBHD

Here's a recent test session with one of the original Ramcharger engineers using their formula from back in the day to create the optimum runner length.
Ramchargers

Here's a Slant 6 EFI intake....effective runner length will be between 15-1/2" to 16" long.
[img][/img]

How do you get around room in the engine bay being an issue. How much volume should the plennum have?

And how stable are intakes when they're hanging out 16 " away from the block?

Every engine depending on compression, cam and desired rpm point will want a different length ram tube.

Using pipemax for my OHC Pontiac six with my cam and compression spec's say the ideal length for the 3rd harmonic is 14.942", including the port length in the head which is between 3 and 4 inches. So a 10" intake tube. Metal, especially light weight aluminum, shouldn't have any issues supporting it's own weight as long as it's not paper thin.

The bigger question I had was if you were using a 12 port head or if your intake ports are combined? If still open then that is another whole set of crazy air flow dynamics I don't know what software/calculation would model that well.

From PipeMax.
- Induction System Tuned Lengths - ( Cylinder Head Port + Manifold Runner )
1st Harmonic= 37.709 (usually this Length is never used)
2nd Harmonic= 21.402 (some Sprint Engines and Factory OEM's w/Injectors)
3rd Harmonic= 14.942 (ProStock or Comp SheetMetal Intake)
4th Harmonic= 11.760 (Single-plane Intakes , less Torque)
5th Harmonic= 9.542 (Torque is reduced, even though Tuned Length)
6th Harmonic= 8.028 (Torque is reduced, even though Tuned Length)
7th Harmonic= 6.928 (Torque is greatly reduced, even though Tuned Length)
8th Harmonic= 6.094 (Torque is greatly reduced, even though Tuned Length)
Note> 2nd and 3rd Harmonics typically create the most Peak Torque
4th Harmonic is used to package Induction System underneath Hood

Plenum Runner Minimum Recommended Entry Area = 2.032 to 2.286 Sq.Inch
Plenum Runner Average Recommended Entry Area = 2.337 Sq.Inch
Plenum Runner Maximum Recommended Entry Area = 2.387 to 2.825 Sq.Inch

Minimum Plenum Volume CC = 525.3 [typically for Single-Plane Intakes]
Minimum Plenum Volume CID= 32.1 [typically for Single-Plane Intakes]
Maximum Plenum Volume CC = 4093.2 [typically for Tunnel Ram Intakes]
Maximum Plenum Volume CID= 249.8 [typically for Tunnel Ram Intakes]

The actual runner length also includes the length inside the intake ports, so you are likely to not have the entire length as an external dimension. But for tight engine compartments, automakers like Ford and others sometimes have a 2 pc. intake with the plenum being removable and often the runners come outward from the head by a certain amount and bend back over the engine in a U shape. You still can get the desired runner length in a tighter more compact space. Engines that rev much higher and need a higher RPM peak manifold need a much shorter runner, so they usually don't have clearance issues under the hood. I have one Slant 6 race EFI intake i've made have adjustable Ram Tubes so it can be fine tuned a little more precisely.
Look for a Ford 300 EFI upper intake on ebay and you can size your plenum around that as a baseline, since they are close to the same cubes as the 292.

This example:

[img][/img]

Is exactly what you do not want, the last intake runner too close to the end of the plenum.

MBHD

What does it do to the intakerunner being close?

Mine will have to be very close to the end as i have limited space under the hood now that te engine is raised an the body dropped

Here os the 16 inch runner with 3" in the hole the other 13" out not including the 4 " for the D shaped plennum extrusion

also why does a custom intake have to be 16 inches out when clifford and offy and such have short runners? is it because it is a turboed application? so many questions because i am just not understanding my apologies i get there are flow harmonics hmmm as homer would say... doh!!

That isn't an actual representation of the final product, its just a teaser for the Slant guys for port spacing and to show runner dimensioning for those purposes only. The real deal won't be shown publicly until after its finalized and tested. And then probably not even on here. It doesn't even have port flanges on it or even the TB flange, its just generic, nothing more.
You've been on forums long enough to know you don't throw ideas out there or somebody else will take them.

The # 6 port would not get equal flow of air to that port, it would get less air & be more turbulent.

The #6 intake port on the picture is too close to the end of the plenum.

You would want a couple of inches past the last intake port, then you can put a plate on the end of your plenum.

MBHD

If you want to make the most amount of HP, you would make your intake port runners short.

The Clifford & Offy are short runners just so they will fit on almost any car or truck.

I do not know how well or how bad this will work.



MBHD

Looks like a manifold from Mr. Hotrod6? NICE!!!!

MBHD

First, and EFI intake and a carb intake have two entirely different needs. Trying to create an EFI intake using carb thinking usually doesn't equal a good intake. And EFI intake only has dry air to pass thru it, and is called a "dry" intake, while a carb intake has fuel/air mixed together and is much heavier than just the dry air in an EFI intake, and is considered a "wet" intake. The runner length tunes the intake to make its peak torque based on that determination. Read through the link of the article I posted early on to get an understanding of how it works. For a turbo 292, you will want the peak power to be around 4500 or 5000 RPM for a street engine probably, and a runner length of 15" to 16" will provide that. If you want peak power to be at 8000 or so, then a 10" to 11" runner will be what you want.
In a nutshell, the Ramchargers formula for calculating the optimum runner length for a particular RPM is as follows:

84,000/N=L, where N is the desired RPM to tune for, L is the length in inches from the valve head to the opening of the ram tube, and 84,000 is a constant. Example below:

84,000/7000 RPM= 12" runner length

Yes its an spa turbo manifold from mrhotrod6 its really well crafted! Just needs a good ceramic coating

Okay read the like and your last post scott its making more sense but danv i'm really going to have to pull some magic to get it all under the hood:0

The picture looks like paired intake ports to me, I'd be shocked if someone can calculate a runner size for that will give harmonic benefits anymore accurately than me randomly saying 4". 8" 12.324", 53". If anything I'd expect the harmonic length to either need to halved or doubled, but the port shape can't be great for harmonic tuning.

Its a turbo engine, don't over think it as the harmonic benefit will really only have a very tight range of rpm for noticeable benefit, assuming you can even figure out what the common ports want. That all said, I'm going to be building an intake for my turbo engine using the same logic and data I posted above, but if I find fitment issues, I'll shrug my shoulders and shorten the tubes as needed, writing it off as a nice idea.

**IF someone has ran real world testing (not calc's or models) of various lengths of the common port intake with similar cam spec's, THAT is the data you'd like to see and use.

Not sure how this idea will work based on a siamese intake port, but for a IR cylinder head design, it is very accurate. Many top Chrysler engineers used the Ramchargers results when they designed and developed the Hyper Pack intake manifold that has runners that are 18"+ or longer back in 1961.

Josh, the factory Ford 300 EFI intake has runner lengths that are close to 16" or 17" in length. The only reason the Slant 6 can have runners that extend straight outward is because the center of the engine is practically inline with the glovebox and not the center of the engine compartment.LOL Think of extending the runners outward about 6"-8" and then do a 90° bend upward and maybe back toward the valve cover to get the rest of the length. The Atlas 4200 engine and many others engines use this design very successfully, and have since EFI became the norm 20 or so years ago.

Well the head will be divided ad i am going to divide the runners all the way down i'll have to take pictures of the dividers i have in the head maybe i'll look at looping it around and see what i can make fit as i am limited like i said an ou can see from the pictures

Since your dividing the ports you should be in good shape then. Just check out ebay or google images for the Ford 300 EFI intake and you'll get the idea of how they get long runners to fit in a small engine compartment.

100% agree!

Since the runners are in fact divided, carry on!

so what i have learned in some of my own searches is that the air moving down a runner (depending on runner volume) gains velocity and somewhere around 300 mph is top speed before it gets restrictive to flow? correct me on that if i am wrong

so when the piston is at bdc and all the air is in the air gains inertia and crams just a little more air into the cylinder before the valve closes and when is does is send a sound wave up the runner and if it is tuned ( which is the reason for the mathematical equations above stated) because if it is tuned right is will come back at the exact time the valve is opening again.

which this seems all honky dory to me but if it is a turbo application ( obviously off idle for arguments sake) does all of that just go out the window since the turbo is forcing air into the cylinder instead of tuning the runner to have all its ducks in a row for optimum flow?

This is an manifold designed for naturally aspirated, the best inline design IMO. It's a 4 cyl, but just add a couple more velocity stacks & its for a 6 cyl.

http://www.bing.com/images/search?q=turb...electedIndex=11

Try & make something similar, but your velocity do not need to be offset side to side, they can be all in a row & the velocity stacks should be raised up from the plenum floor for best flow.

Also note is has a tapered plenum, larger in the front & gets smaller towards the back cylinders.

Note the short runners. Something you should go with.

Something of what your "D" plenum should look like w/raised velocity stacks.
http://www.bing.com/images/search?q=turb...lectedIndex=240

Does the tappered plennum gain velocity to the rear stacks? And why does a rais velocity stack and better flow then flush? I would think it would cause trbulance down the plennum am i backwards on that?

Great pictures thanks hank

Mine is made this way.


I made it this way, just because it was easier to fab.
I believe it will work just fine, but have read having the velocity stacks raised up from the plenum floor is ideal. Better/more equal airflow to all stacks.

Having a tapered plenum is supposed to create equal flow & have equal temperatures to all velocity stacks IIRC.

MBHD

How much tapper should the plennum have is there a rule of thumb per foot or somethjng of the sorts?

Not sure about the taper rule of thumb, but here is a good shaped plenum to get you an idea. http://www.ebay.com/itm/2JZGTE-intake-ma...45107da&vxp=mtr

Since you have a "D" shaped plenum, I would only cut a small chamfer like this one.
http://www.ebay.com/itm/2JZ-GE-FFIM-SUPR...686cd19&vxp=mtr


Worrying too much about all these dimensions, plenum taper, velocity stacks even with the plenum floor is really not too much of a concern unless you are really going to try & set a new record.
Same for the turbo exhaust manifold, having individual exhaust header tubes will give you the most amount of power over your SPA manifold, but how much more?

You can have a very, very ugly log type exhaust manifold, that can look like it cannot flow well at all & still make a lot of power.

I had told Douglas to have his fuel injectors installed right in the center of the velocity stacks about 1-2" above the stacks.
He did do part of the idea, but his injectors were a bit further away from the velocity stacks than what I wanted.
If you look at the video, you can see one set of 6 injectors directly over his velocity stacks, IIRC, his other six were placed in the intake runners.

He still made great power & ran w/a blown up engine before the end of the 1/4 mile, & ran a 8.6 @ 165 MPH.

Here is his old car .The yellow Chevy Opala w/a 250 inline Chevy 6.
https://www.youtube.com/watch?v=R825adfxyq8&index=53&list=FLC47WILAMLZIhl7pE8DUelg

MBHD

A lot of unnecessary worrying. More importantly, the runners should have taper in them instead of just being straight. The plenum being tapered isn't a deal breaker, there are many that are and aren't, and the runners being tapered are of more importance than the plenum being tapered. The radius' increases airflow and is necessary to help the air make the transition when changing directions and going around corners.

I think i will do a gradual tapper in the plennum runn the velocity stacks flush

But how sever does the tapper have to be on the runners?

Have you guys heard of air boundry on none tapered runners?

The taper doesn't have to be extreme, it just helps keep air velocity from stalling. Again, look at any factory EFI intake design. Many that you see are the result of millions of dollars of R&D testing, and will provide an excellent comparison. This will eliminate having to try and go off in a tangent to create one for yourself. The Ford 300 EFI intake is an excellent comparison because it is near identical cubic inch, and they did what Chevy never did do, and that is they actually made one from the factory.
Starting from scratch for a new design though, its helpful to have a 3D modeling software package that can do stress analysis and air flow analysis like I have, it will save hundreds of hours in chasing dead ends and will help get you on track the first time out.

I think for your intended use of wanting good upper RPM power your intake will work real good for that.

I'll have to trade aome pieces woth ross machine racin but i will be able to get the taper into the runners

That is what I am looking for. Cross my fingers.

MBHD

I don't think you have to worry, it looks well thought out.

So today i cut and tappered the plennum send back my velocity stacks for round ones ordered some u bends so i can make the turn around to gety runners to length now i jist need to find some sheet alluminum to make the dividers out of

Well have pictures of the plennum here soon

So how does manifold runner length vary from the formula if you are using a carb?