designing and building manifolds.

[mrmadmax]

Originally posted by autronicDSM
correct me if i'm wrong but it shouldn't matter that flow is constant or pulsed since we would like to see if there's difference in flow to each runner? just my $0.02

also somebody said earlier that air entering TB flows less to #4 because it's so close. what if we make the plenum longer and offset it so TB is placed farther away from #4?

That's exactly the point... It does matter whether the flow is pulsed or continuous IMO. On a 'constant flow' flow bench, I think the air will always go towards 2 & 3 (or wherever it inlet is pointing) simply because the four outlets all flowing at the same time will easily out-flow the inlet, but in a pulsed flow condition with only one (or at max two) cylinders flowing at one time, the inlet will flow enough to maintain the entire plenum at a more positive pressure than the outlets, thus the flow will be pretty even. The entire purpose of the plenum is to even out the flow to each cylinder as well as provide an air "reservior" from which the runners are fed.

 

[autronicDSM]

That's what I thought too for awhile until everybody started to say how #1 and #2 run leaner and how manifold flows uneven and how Magnus manifold could make things even worse and such. I haven't looked at my fuel rail but people say it narrows down in the middle...leaving #1 & 2 with less fuel. Is that really true?

 

[JET]

I have never heard anything about the fuel rail narrowing. I find it hard to believe that it is not a constant bore the whole way down, just from a machining perspective. You don't want to have to try to drill with the flutes, and you would need a tapered drill to make a hole like that.

 

[DSMu4ia]

Stock fuel rails are known to warp and not maintain a consistent diameter.

Hence drilling them out has became popular.

 

[autronicDSM]

I think your car would start on fire before you warp the rail.

 

[DSMu4ia]

That's one of the problems with the new DSM'ers, they think before they listen.

 

[autronicDSM]

HAHAHA good one. I never heard anybody warp the fuel rail on DSM and drill them out. Too bad talon digest archive search is down.

There's a reason why there are plastic spacers on there...so heat from the head doesn't transfer to the rail.

 

[DSMu4ia]

Oh ya, I must be lying.

I've never done it myself, but if you take the rail from a 1g, and try to slide the appropriate sized drill bit through it, it will get bound up if not get stuck.

Do you really think those plastic spacers stop all the heat? What about im-proper torquing?

I've got about 3-4 fuel rails outside, I'll check them for warpage this weekend and if they are warped, I'll post pics so you can STFU.

 

[autronicDSM]

Sir, you're an idiot. There's a difference between over torquing and warping from heat. You over torqued yours too many times and I don't need to see pics of it. Get a torque wrench...

 

[JET]

Another reason why he is an idiot: If the fuel rail warps, tell me how the hole magically changed in size? Yes, it may not be straight but it will be the same size. Now stop intruding on good threads and ripping on people that know way more about DSM's than you ever will.

 

[Ikestaa]

If you had a pyramid shaped intake manifold, similar to the ones pictured above. Could you use three pieces of sheet metal in the intake plenum to direct air to the correct runner, or would this defeat the purpose of a plenum?

 

[autronicDSM]

Like this?

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I think plenum would be too small for pyramid shape and those dividers would just obstruct the flow because of constraints on the plenum size. After re-reading some posts on here and talking with a guy who works at lab at school I think the best design would be like one marshall did with plenum big enough so there's no air starvation after 1 cyl. draws air in and using velocity stacks to help accelerate air in-take. If you look at stock intake #1 and #4 runners are pretty close to corners giving it limited space to draw air from. Making planum longer would help.


I was also thinking about velocity stacks. I know in NA cars air flows over the edge of them and that accelerates air. But in turbo application air is under pressure...does that change flow characteristics? I think to make effective use of velocity stack it would have to be made like this so the air horn sticks out into the plenum.

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[mrmadmax]

Originally posted by autronicDSM
....

I was also thinking about velocity stacks. I know in NA cars air flows over the edge of them and that accelerates air. But in turbo application air is under pressure...does that change flow characteristics? I think to make effective use of velocity stack it would have to be made like this so the air horn sticks out into the plenum.

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Yeah, the radiused entry is certainly a plus. According to my fluid dynamics texts, the square edge entry influences the pressure drop in the manifold by 0.5 x Velocity squared / a constant (part of Bernoulli eqn.). Using a proper radius changes the 0.5 to 0.05, which is a 10 fold decrease! If you leave it out, you get a contraction of air inside the runner. Of course, this factor changes with the square of velocity, so it may not have much effect at lower RPM's. I don't see the advantage of having it sit inside the plenum however. What was your reasoning for that?

 

[autronicDSM]

I just seen some designs for NA cars using these with air box and stacks were siting like that. I just wanted somebody who knows more then me to tell me if it would make a difference or not.

 

[tanner261]

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Like this one from a Turbotrix cutomer?

 

[autronicDSM]

Son of a .... somebody beat me to it.

So how well does this manifold work? I assume it's on your motor? Since you're from MI maybe I can check it out sometimes?

I was looking at their website and I couldn't find how much they want for one. Turbotrix making these or was it on their customer car?

 

[Blizz92tsi]

Ooohhh MY GOD!! That is really awesome. Sign me up for one of those! That looks like it was very very expensive. I'd still love to have one.

 

[GalantVR41062]

velocity stacks, is said to increase flow by 25%, thats a big difference, and the intake man I would make will look like the Turbo Trix with the volocity stack inside the plenium. Which will be 5"dia and 16" long.

 

[tanner261]

No, it's not my car. You can see pics of this car at Turbotrix's website under customer cars.

 

[awd4bangr]

You ladies in the Twin Cities area can buy all of the tubing, bends, and velocity stacks from Cremco in Litchfield, MN. It's about 1 hour west of the metro. They have all of the same crap as Burns but the pricing is about half.

 

[autronicDSM]

Do you have phone number or website for them?

 

[RabidDonkeyBoy]

http://www.turbotrix.com/

 

[autronicDSM]

...for Cremco not turbotrix.

 

[awd4bangr]

Cremco doesnt have a web site. Dont know the phone number any more. Try Quest Dex or something similar.

Not to piss on anyones parade but I've not seen or heard any original ideas in this thread. At some point in the past 10 years or so all of this stuff has been designed, built, and didn't make the final cut for one reason or another.

I don't know how long some of you have been around DSM's but some of the shops that are sometimes forgotten have spent lot's of time and money designing, building, and dyno / track testing so many different intake manifolds and exhaust manifolds it's hard to keep count.

Keep this in mind when you try to reinvent the wheel.

 

[GalantVR41062]

I did not intend to reinvent the wheel I was just posting what I will make for my car, which is not 100% original, but its hard to come up with that original stuff now days. Also I was just talking about what I would change a little here a little there do I have a flow bench, no, do I have the time/money to dyno test each unit, no. But doing some minor calculations and based on what I have read with differences in flow threw the head with different manifolds/port work, I can make a good intake and exaust manifold. Also haveing about 1" of plenium befor the #4 runner and after the #1 runner will equal flow a lot, and the stock mani just sucks. then for exaust manifold tubing diameter I came up with about 1.75"ID would match a nicely ported exaust port and not be to big, help keep exaust velocity up for good spool and power. But thanks for the shop in MN that sells that stuff. Good info