Well i was just pondering this today for some reason..I think it would really not be that difficult to do. Now my goal is to make more HP for the turbo setup, maybe N/A gains would result, who knows. The hardest part would be getting a flange that fits/bolts to the head. Really, prob not that diff to either find or have one made. Next, the flange for the TB, once again, not too big of issue to make. Now, my ideas: From the flange on the head, i can use some mandrel bent piping, ie from JC Whitney, ect..for the intake runners. They can bend upward at like a 90 degree bend. Maybe make them 2.5" runners? Then find a pipe, like anywhere from 3"-5" in diameter, and make that the main upper section that everything like the TB and sensors connect to. Weld on some injectors bungs, and fit the stock fuel rail..no biggie.. Now for all you intake guys out there, what would be the *best* size for the runner diameter's, and also the top main tube section? Remeber, this is for a turbo application, so high CFM flows must be utilized. I dont know crap about intake design science and the theroies behind it, but i really think i can make one of these..and gain some really good HP. I know a 1g guy that gained 50 HP alone from an aftermarket intake! Discuss :)

Sounds like a great idea dude. Not sure on the sizes that would best suit your purpose. But I where to take an educated guess I would say go apx. 50% bigger then stock.

Now if you need any help fabricating this I would love to help...I love poo like this. And I work for a machine shop so I could get your flanges made up for a little bit of nothing and possibility the welding. I'm a designer with CAD at home so I can make some decent prints and have that shit made up pretty easy and very professionally done so it looks good....Theses guys are good here. Look us up on the web www.altoprecision.com. If I can help let me know...I would be happy to!

I've personally got a quad TB setup on the back burner right now that I hope to get working sometime by next summer.:thumbsup

mm... fun stuff..

turbo manifolds allow you to do wild stuff.. mainly because, well.. you don't need an air reserve as the intake is pressurized :)

personally i'd use a variety of sizes of piping with a very small inlet into the head..

Because your dealing with expanding gasses and pressure differerntials, you want the most air to flow at the greatest velocity.. big pipes give you flow, but not velocity.. you have only fractions of a second to fill the cylinder at 5000rpm.. so velocity is where you should focus your attention.. CFM will take care of itself

i'd design it like a reverse 4-1 header.. except instead of a sharp + at the end of the collecter i'd use velocity stacks..

also a rectangular cross section will flow better than an oval in most cases..

the NA box i made for schoeby didn't work too well off idle.. it'd bog easily as the flow ramps up VERY quick.. but once it started to flow it screams..

-- WheatKing

If it's for a turbo application, and you are going to run some serious boost through it, I doubt you would have to be very careful with the size and shape of the design. For a naturally aspirated car, defenitely, but when you are force feeding air into the engine, you don't have to worry so much. That's why those sheet metal intakes work so well for turbo DSMs.

But, what I would do for this paticular application (and I don't have the intake manifold calcualtions in front of me right now, so this is just off the top of my head) I'd make the intake runner diameters about 20% bigger, and the runner length would be no more than 12 inches long or so. The plenum VOLUME shouldn't be too much bigger than it is now. I don't know what the volume of our current plenum is, but I wouldn't make it more than 15% more volume, maybe 10%. Too big of a plenum can cause some serious problems (poor gas mileage, absolutely no bottom end too).

I don't remember what the volume size should be, as I don't have the proper reference material in front of me right now. But I seem to remember something like this (for NA cars, anyway): the intake plenum should have no more volume than the engine displacement for a 4 cyl, or something like that. don't quote me on it, all I remember specifically is big plenums can cause problems.

sheetmetal intakes on DSM work because people like magnus spent a ton of time on a dyno making sure it worked..

just welding something together and hoping it works doesn't mean it's gonna be better..

the plenum should be approx 1/2 the size of the engines total displacement for a NA application.. on a turbo application there are 2 ways of doing it..

either no plenum.. so a high rate of velocity can be maintained.. or a very large plenum.. so you have a large slow velocity highpressure area that flows through smaller pipes which increase velocity.. into the cylinder (low pressure area)

going bigger doesn't always mean it's better..

for instance.. the ports on the PT cruiser head are smaller than our ports.. yet outflow ours due to shape and profile..

The whole trick is to move as much as you can, as fast as you can.. and just because it's pressurized doesn't mean you can ignore how it flows.. getting to a design that works.. isn't easy..

perhaps you may want to try the magnus approach.. make a flange.. then make a plenum.. and use silicone couplers to tune the lentgh of the runner till an optimum length is reached..

It 1/4" could be the difference between an engine that screams to redline and one that totally bogs or dies ..

-- WheatKing

>the plenum should be approx 1/2 the size of the engines total
>displacement for a NA application.. on a turbo application
>there are 2 ways of doing it..

THAT'S IT! thanks :)

Whatever you do, I suggest you make several prototypes. Maybe make the prototypes out of steel for affordability and ease of welding. Make a couple different plenum sizes and runner sizes. The idea of using couplers to adjust runner length sounds good too. When you decide on a winner, do the whole thing in aluminum. Then sell them to us for cheap.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

Yea, I can understand how it's easy to get confused with intake manifold design. There is a lot of wave frequency theory when you get down into the nitty gritty of it - but that's where the best manufacturers can get an extra 10 hp by just making the intake runners a perfect length and sectional area.

a good site is http://www.eng.ed.ac.uk/~jchick/Y5/thesis/FormulaStudent/public_html/pt7.htm

they have an equation you can plug into excel to get an idea of what dimensions to use to get a helmholtz resonating effect.


good luck and keep us posted! :thumbsup

Yeah, its def a tricky science, but doing the testing and building is the fun part! at least for me it is haha.. And Kent, i may take you up on that offer man! Since you live right by me, and all that, give me a shout sometime, we can go over all of it or whatever..So what do you guys think would be a good starting point?? Runner size and plenum size? I really want to look at the 4g3 intake to see what was done to it, over the stock design..since their manifold is quite similar to ours..Dyno tuning wont be that big of deal either..i can get the hookup and dyno time for that..

Here is something to get you started it was posted on another board. It is just copied and pasted because there is no way in hell I could explain it any better. It is very genral but hope it helps some.

Swordfish aka jeff
"In order to provide correct answers, the rpm range from bottom to top is a necessity as is the throttle body diameter, and space limitations. The plenum volume is critical on N/A engines, but not as much on turbo cars, and a basic rule of thumb is: The smaller the plenum, the lower the rpm range, and bigger means higher rpm. The throttle body size and flow rate also affect the plenum size: Bigger TB, smaller plenum, small TB, larger plenum.The runners work very much the same way. This is why you see so many sheet metal manifolds today in racing.

On the inside, you dont want anything that will break off and fall into the back of the intake valves. You can build it with or without velocity stacks on the inside. Make sure the transition from plemun to runner is smooth if you are not using velocity stacks. A fairly large plenum with longer runners is going to make for the best street setup with a wide power band. A huge plenum with short runners will make more peak power.

A 2300 cubic centemiter plenum volume has shown to be successful on 2.0L engines for a good all around plenum volume. Couple it with a 15cm and you would have a good larger turbo/cams combo. I dont know if you will have the space for a 15 cm runner but probably a 10cm runner would work in your given space. Optimal runner length to the back of the valve is 20 cm to 23 cm. Runner diameter would need to be about 5.8-6.0 cm

jeff "


I should be getting a TIG welder later this year and hope to start to play around with some designs. I will probably focus more on an NA design for the 420a though.

EDIT I was looking at sheets of 6061 Alum and was wondering how thick would it need to be? would .190" work or would you want to get .25" thick? Also would you need to treat it after it was all welded? Any other coments about material to use would be nice.

Nathan

Thanks Nathan, thats some great stuff right there :thumbsup haha damn i'm gonna print that shit out

>EDIT I was looking at sheets of 6061 Alum and was wondering
>how thick would it need to be? would .190" work or would you
>want to get .25" thick? Also would you need to treat it after
>it was all welded? Any other coments about material to use
>would be nice.
>
>Nathan

I personally think that .25" would be a little over kill. Not sure on the "treating" either..do you mean heat treat or like a finish so it stays pretty. I'm not experience at all with alum. so I don't know if it warps when it's welded or anything. I think it comes from the mill pretty stiff though and you have to aneal it if you want to bend it and work with it much. That's according to Jesse James though when he make his gas tanks. :wary I'm not sure how to bring it back to is "stiff"...hehe..state either. It's been too long since my metalurgy/heat treat class:rolleyes

I think 1/8" sheet would be fine for the plenum. 1/2" would probably work for the flanges. What about using large aluminum tube for the plenum. I've seen some aluminum tube in 5-6" diameters. I wouldn't bother with any sort of heat treatment. I suppose you could anneal to relieve the stress around the weld, but I doubt it is necessary.

Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire