well, that, and round runners make it so that the air in the middle is farther away from any edge, reducing velocity. unless you are making mega huge amounts of power, a sqaure design is mo bettah.

OK think about this.

A big inch V8 motor with a custom tuned sheetmetal intake. Now these motors may have a ton of displacement, but they will only net 2-2.5 horsepower per cubic inch. Even a large inch blower motor on gas (not Nitro) has a hard time making 4 horsepower per inch.

Now take a Mitsu. Motor for example. 122 cubic inch motor that can very easily make 4 horsepower per cubic inch. Some of the big boys are making in the neighborhood of 6.5-7.25 per inch on leaded race fuel.

The reason for the square runners is the factory head has square ports on the entry.

that makes sense. do u include any of the resonance effects when designing the plenum and runners? as for software used in modeling the intake, has anyone used or have experience with ADINA? they have it on campus, how user friendly is it?

i duno bout you guys but if you work the math right on that mani unless the nissan manifold looks totaly diffrent thoes manifolds are only going to be good for low end power they will flow out in the upper rpm range.. the runners arent nearley long enough this would be a good drag headder but what about the auto x guys who dont always run low rpm

Don and Danny are currently working their magic building my BB DET shortblock with Custom JE pistons and Eagle rods, Race porting and polishing the head w/ .5mm oversized stainless valves. I have seen their quality work first hand. I spent a week at the shop hangin out and lending a hand. I was astonished by the quality of work that was produced ( I have previous experience tinkering in a fabrication/speedshop). Don is meticulous in his porting work and everything is flowbenched for optimum results. Danny is quite skilled w/ fabrication. I don't know why I never considered it before, even seeing the DSM manifolds they were building there. I guess I'm gonna step up and lay the scratch down for the prototype. You guys keep on the look out for flow numbers of the manifold and the head work. I guarantee there is a much better alternative @ Polk Performance, than some of the other head porting and manifold designs that are/were available. The SR20 is movin on up!

John

Originally posted by javierb14
as for software used in modeling the intake, has anyone used or have experience with ADINA? they have it on campus, how user friendly is it?

Well, a lot of the big aerospace and auto companies use Catia(sp?). Suppose to be the best out there for design. Pro/E is also very popular. For more basic stuff, SolidWorks is real easy to use. IDEAS is more powerful than SolidWorks but it's behind Pro/E and Catia.

My friends used Soildworks to make the model, put that into FlowWorks to see the flow patterns and pressure distributions. Then they took those numbers and plugged it into ADAMS to see how it affected the performance on the motor.

Here is probably a stupid idea. Why not make an IM with the specs as the IM on a B18C5? I'm sure someone has runner length + diameter plus the area of the plenum. I know that if I wanted to say design an IM that made more high end torque for a VG30 I'd use a low port IM to base it off of. I figure it would just be easier LOL :cool:.

I will also back up Don and Danny on their ability. I recently had a chance to meet Don and see some of the stuff they build at the shop. His attention to detail is incredible and it shows in his work. Definately will be a great year for these guys and the SR20.
Travis

Damn thats a mad nice manifold and def. worth the money but I gotta get my turbo motor situated first but I give Danny and Don props for makin such a master piece.

Originally posted by 200sx se-r-t
this would be a good drag headder but what about the auto x guys who dont always run low rpm
Uh...right... drag racing is all about low end power. Suuuuure.

Originally posted by Nismo87SE
Here is probably a stupid idea. Why not make an IM with the specs as the IM on a B18C5?

My guess is that it wouldn't work the same... reasons: different displacements, different ports sizes(which leads to different air velocities), different cam/valve timing, and you'll want to tune your manifold for either low, mid, or high range power.

Don makes an intake manifold on a head.. on a flow bench.. Everything is hand ported and flowed to get it all perfect. That's the only way to truly make a nice flowing and performing manifold. There's more that goes into it besides flow.. Danny gave me a little schooling in valve lift and runner sizing to increase velocity or flow and how they affect each other at different RPM on different engine designs. Pretty interesting stuff!
Travis

Actual loss of low end and felt loss of low end are two different things. It goes back to an argument I have had with someon before about turbo lag.

Many people look feel the lag of a turbo and says the car makes less low end power. When actually on a dyno chart there was a gain in low end HP. What they were mistaking for lag was the fact that the gain on the top end was much more than the gain on the bottom end. The bottom end had a gain none the less. His response well if it feels like lag it is lag in my book. The way I look at it is that I have more HP at every RPM point, so my car is going to be faster from A-B, which is the whole point of racing (not taking into account a linear powerband for powering out of a corner)..

A properly designed sheetmetal intake will sacrafice VERY little if any low end power. The gains in the mid to upper end will more than make up for the little if any loss on the bottom end. Sure the car might "Feel" like it lost bottom end power, but a before and after dyno chart will tell the tale.

I am working with two customers right now on SR20 Sheetmetal intakes. One is Nismodriver on the board (DET powered B12) and the other is SR20SER (stock NX2000) I am waiting on a low port Cylinder head to get some flow numbers so we can start designing a sheetmetal intake for you guys. We will also be using my 240 to design the RWD app.

Feel Free to call me at the shop with any questions.

Danny

This is not an insult or anything, just an observation.. That manifold's plenum is not that great - it is a square box - resonant shape.

andris

Any idea on a time frame for the high port manifold? I think that it will be a good seller if it is properly designed manifold. What type of testing are you doing?

This is not an insult or anything, just an observation.. That manifold's plenum is not that great - it is a square box - resonant shape.

The entry to the runners have a full 1/2" radius on them. A lot like a bell-horn. This is to help make for a smooth transition into the runner.

Oh, I know - I'm talking about the plenum, not the runners. The plenum is a long straight rectangle with a straight throttlebody entry and a straight endcap. As I understand it, you're better off with a slight angle on the endcap and a non-direct throttlebody entry.

something like /_____/

instread of |_______|

paralell plenum walls, perpendicular endcaps, and straight throttlebody entry are all things that contribute to resonance. This can end up harming flow. You'll notice that the really high-end rediculous motors (I think there is a toda motor pic somewhere, also a mugen one; BTCC level stuff) have teardrop/bullet shaped intake manifold plenums. They are a very non-resonant shape. This Greddy Silvia manifold is a decent example:
http://www.sr20parts.com/images/forsale/greddy_intake_2.jpg

andris

I should add that perfecting that type of thing takes serious time with a CFD system and a lot of testing/research - certainly beyond the scope of a normal fab shop. I'm sure the Polk manifold makes some power as it is.

andris

Tell them about the Green car.. Danny... :)

Man it is unfortunate one couldn't just cut the runners off the IM and just flip it vertically so the TB is on the other side. Actually if I could get my hands on one I'd probably try to do it anyway :p. However I know nothing of welding and I'd assume it would be very difficult to reweld the runners back on?

Originally posted by andris

paralell plenum walls, perpendicular endcaps, and straight throttlebody entry are all things that contribute to resonance. This can end up harming flow. You'll notice that the really high-end rediculous motors (I think there is a toda motor pic somewhere, also a mugen one; BTCC level stuff) have teardrop/bullet shaped intake manifold plenums. They are a very non-resonant shape. andris

When my friends designed their manifolds, they used a cylinder as their basic plenum shape; except, that the radius of the ends were different. So actually, it was more like half a cone with the pointy side at the farthest runner from the TB. If you look at the Greddy manifold, it's similar; the plenum kinda tapers down at the farthest runner. When my friends were doing CFD work, they found that if they used a straight up cylinder, then they'd have these recirc regions at the last runner and it would see less pressure and flow than the other runners. So they tapered it and it got rid of the recirc region, and got the pressure distribution and flowrates even. Also, on the entrance to the runners, you should put a trumpet on it. It smooths out the flow into the runners.