designing and building manifolds.

[99 gst 420a dsm]

I have a cutom built turbo header on my 97 eclipse RS, im not cool with the rediculous price of the hahn and star turbo kits, my kit was made a little different than what i have ever seen, i have a machinest friend who machined me an exhaust manifold flange from my exhaust manifold-cylinder head gasket, honed out the exhaust ports a little, then i had him make me a flang from the turbo-manifold gasket from a garrett t3/t04e i aquired, i then chopped a stock header from a 91 grand am with a 2.3liter quad 4 4cylinder DOHC 16v. it all worked out perfect and i now have the header as well as the 3 inch downpipe coated in a fiberglass header wrap..... as for the intake everything has just been port and polished, im not sure if i want to make a new intak manifold yet... maybe for when i get to the nitrous stage

 

[earz_93]

i just kind of skimmed over this thread, but this may be of interest to some of you. http://www.sdsefi.com/tech.html
there are some interesting articles on here.

 

[Big Woo]

Here is a pic of an intake I built for my DSM. Some of the manifold specs are 160 cid plenum, 5.5" tapered runners, with built in 1" radius trumpets in the plenum.

 

[Big Woo]

Here is another pic looking inside the plenum, showing the runner trumpets. I will try to get some better pics posted soon.

 

[Big Woo]

Here is another pic of the intake showing thr inlet trumpets, before the plenum cover was attached. Also the trumpet radius is 3/4" not 1" as I mentioned above. This pic shows that the runner trumpets protrude above the plenum floor.

As others on this forum have found very few 4G63 intakes use a trumpet or bell at the runner/plenum intersection. Most just weld some tubes together at ninty degree angles.

Currently I am working on a similar intake with variable length trumpets/runners. The length will very based on RPM, and will be controled by a stepper motor, and a AEM EMS.

 

[autronicDSM]

Looks good, did you notice any gains in lower RPM? How's top end?

 

[122andy]

Originally posted by Big Woo
Here is another pic of the intake showing thr inlet trumpets, before the plenum cover was attached. Also the trumpet radius is 3/4" not 1" as I mentioned above. This pic shows that the runner trumpets protrude above the plenum floor.

As others on this forum have found very few 4G63 intakes use a trumpet or bell at the runner/plenum intersection. Most just weld some tubes together at ninty degree angles.

Currently I am working on a similar intake with variable length trumpets/runners. The length will very based on RPM, and will be controled by a stepper motor, and a AEM EMS.

Those velocity stacks look identical to the ones I did. In fact, alot of the measurements are similar, such as runner length and plenum volume. I dont think the velocity stacks did anything special over a nice tapered entrance to each runner, but it obviously didnt hurt it either. I just made another one for my brothers car that just has tapered inlets to each runner, it will be interesting to see how it performs. Overall you should be happy with your intake as long as you are using the car at high rpms(6800+) alot.

 

[JET]

Where did you guys get the runners from? That manifold looks very nice!

 

[122andy]

www.runnersforDSMsheetmetalintakes.com

I made mine out of 2 1/4" tubing. Basic metal working tools will get the job done, especially if you are using aluminum.

 

[Big Woo]

The runners were made using 2 1/4" O.D. .250 wall 6061 aluminum tubing. First I cut the runners to length, then bored a two degree taper through the tube, and took the inside diameter of the trumpet end to 2.050 diameter (if I remember correctly might have to check that one). It would have been nice to start with slightly less wall thickness tubing, but I used what I had available.

Then I made some vice jaws for a "KURT" vice that would form one end of the tube into a rectangle. A little heat and some turing of the vice, and the tube goes from round to rectangle end to end. After forming the ends I had to go back to the other end and squeeze a little to take about the .045-.055 egg shape out.

The trumpets were made seperatly on a CNC lathe also out of 6061 aluminum. They were bored with a 2.050 I.D. ( I think) and have a 2 1/4" diameter step on the runner end .125 deep to keep trumpet, runner concentricity perfect.

I hope this helps some.

 

[GalantVR41062]

That manifold looks real nice, I would assume if performed well.

 

[draculia]

Originally posted by autronicDSM

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here's sketch of my idea, any feedback appreciated.

i just wanted to say that a sort of example of this type of manifold on a production car would be the vw 2.0 crossflow manifold. granted the vw one has extremely long runners, but its based on the same idea.

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[GalantVR41062]

Well due to a little money left over and some time on my hands I started making my intake manifold yesterday. A few specs are the 5"X16"long plenium that I crushed down to a rectangle(tb to small for 5" pipe) Then I am using 2.5" od tappered runners, with volocity stacks. The plenium is 250ci with about 1" befor the #4 runner and 1" after the #1 runner. the TB will be more twards the top of the plenium and runners are in the middle. To make my Vstacks I took a brocken 3bolt axel and hammered off the end that goes into the diff, cleaned up the grease welded the joint so it does not flex (press point were the axel shaft went into) then with a grinder took off the lip so it just fit inside the 2.5" tube(it is tappered up towards the axel shaft going away from the diff) and pressed away, instant Vstack.(pics this week). I dont like how the welds came out or the shapping of the plenium but for my first try I think it will work dam good. I plan on a aluminum revision as soon as I get my dads tig welder hooked up. I figured I started this thread so I might as well make my own manifold as well. Good luck.

~John

 

[greyforestgst]

this is all extremely cool, but why cant we somehow adapt a 4 -> 1 exhaust mani collector and use it backwards, then use some mandrel bent runners to zip into the head? this would keep low torque high, and using big runners and a giant collector would put up the numbers that the box intake manis can make up high.

 

[JET]

You have to have a plenum to equalize the pressure between the cylinders.

 

[marshall]

The area between the TB and runners would be the plenum, just a different looking one than we're used to. I think the backwards collector is a good idea, it just comes down to packaging constraints.

Marshall

 

[JET]

Taking all of your air from one spot in the plenum is going to cause a serious pressure differential inside the plenum. That is probably why they are normally spread out.

 

[autronicDSM]

Toyota uses 1 into 4 intake manifold on the Corolla. I'll take a picture of it for you guys. I think it's not even equal length runner but I don't remember off top of my head.

 

[autronicDSM]

Originally posted by JET
Taking all of your air from one spot in the plenum is going to cause a serious pressure differential inside the plenum. That is probably why they are normally spread out.

But having runners close (2 & 3) doesn't do any good either. I would think those 2 cylinders "fighting for air" (I can't think of technical way of saying this). I will make my plenum longer and spread the runners further apart.

By the way, here's some pics of 1 into 4 intake manifold in case anybody who thought of this wonders how we could fit that on a DSM. I'm curious, what effect this would have if we had 3" throttle body and IC piping? Under boost it shouldn't matter but I wonder how low end TQ will suffer. Here's Toyota's manifold

 

[greyforestgst]

Originally posted by autronicDSM


But having runners close (2 & 3) doesn't do any good either. I would think those 2 cylinders "fighting for air" (I can't think of technical way of saying this). I will make my plenum longer and spread the runners further apart.

By the way, here's some pics of 1 into 4 intake manifold in case anybody who thought of this wonders how we could fit that on a DSM. I'm curious, what effect this would have if we had 3" throttle body and IC piping? Under boost it shouldn't matter but I wonder how low end TQ will suffer. Here's Toyota's manifold

thats what im talkin about
id think low end torque would be higher than stock, seeing as how air velocity isnt brutally killed by going in to a giant box and having to find an exit

 

[RED_AWD_BLUR]

Why would low end tourqe suffer? I think the runner length is what decided where the intake tunning peak would show itself. As far as I can tell those runners don't look that much shorter if at all than the stock dsm runner length.

 

[RED_AWD_BLUR]

what toyota did the pic you have come off of?

 

[autronicDSM]

Corolla

 

[autronicDSM]

Reason I asked if low TQ would suffer is pressure waves comeback off plenum's wall, that's why you can tune runner length. With this design it will bounce around from the first bend...at least that's what I think. I'm no expert.

 

[BoostinAWD]

Don't know why this thread died so early.

In the process of building one myself also, out of stainless though, only drawback is the flange right now. Nobody makes them out of stainless, so I may have to fabricate one.
GalantVR41062 I am very interested in how you made those velocity stacks. I have a spare 3bolt rear also and would like to know how you did that.

This is by far one of the most helpful threads I've came across.