Random, which filter are you using on the random special? I saw the pics, is that just ABS piping (3") and 90 degree PVC bends?

Also, you mentioned in a much earlier thread (see, I searched smile.gif ) about the cooling lines that route through the throttle body. Have we figured out why they're there? I can't see how it would cool the throttle body. Also, I'm wondering if they use the TB as some sort of radiator.

For those who don't know what I'm talking about, there are two tubes attached the bottom of the TB. Supposedly, they route coolant around the TB, but it must be post-engine, because it seems to make it hotter.

Anyway, I'm thinking of removing the lines and was wondering your all's thoughts about it.

later,
a

Tunez, could you repost pics of your intake? The old posts don't link right.

 

The engine "coolant" runs through your throttle body to keep it from freezing during the winter. Remember that your engine coolant is "cooler" than the engine itself, so it serves to cool ... well, the engine That nice hot water is pushed through your throttle body so that in the winter, if moisture condenses inside your throttlebody, your throttle plate doesn't become frozen to the TB wall.

However, if you live in an environment that almost never sees freezing temperatures, or is really dry (welcome to New Mexico ) then you can reroute those lines so they feed into eachother. No need for the extra heat in your throttlebody / intake manifold.

And I think Random's special CAI is built with 2.5" flexible metal tubing, not 3" ABS. At least, that's what I remember wink.gif

-Red-

 

The 3" abs was a "second generation" prototype I made. I never performed as good as my original, so I scrapped it.

The original is made of 2.5" flexable exhaust tubing, heat wrapped (not tape...wrap).

 

Doesn't the ribbing of the bendable-ness of the pipe make the air turbulent?

 

Random, is that just the flexible exhaust pipe you can get at Trak or Pep boys? I thought of trying that, but wasn't sure.

Also, which filter are you using? My Ractive is a bit smaller than a K&N, so I may try to get it in the fenderwell next weekend (after I take it off for a cleaning).

And yes, the ribbing will cause turbulence, however, at the speeds we are talking about, the pipe will be turbulent (or transitioning to turbulent) above 2000 rpm, even in a straight, smooth pipe. You would have to go to great lengths to keep the flow laminar (smooth) everywhere in the pipe. In some cases (which this may be), a turbulent flow actually looses less pressure in a bending pipe because of the randomness of turbulence. If the turbulence stays in the boundary layer (near the pipe walls) it keeps smoother flow in the core, which would be the same as a really smooth pipe of smaller diameter. Airplane wings and engines do this all the time.

If this is what is happening, it could explain why he got such good gains, while companies that have smoother, wider pipes have not seen the same results.

Random, do you have any more pics of your setup? I'd like to give this a run as well.

Thanks,
a

 

Yeah, just been scratching the surface of fluid dynamics lately at my new job... Not to turn this into a big theory discussion, but if this were the case in the Random Turbulence Special ™, then would a larger (3") pipe do better than a smaller (2.5") one, because you have a larger smooth core? I'm not pulling these numbers from the failed Random prototype with the 3" ABS. I'm strictly comparing 3" to 2.5" ribbed exhaust pipe.

I've been mulling the fabrication of an Iago MaddPower ™ CAI out of the same stuff, but I didn't because I thought the ribs would create so much turbulence that they'd impede airflow.

 

Wider is better to a point. After that, the fluid slows down and then must be sped up right at the throttle body (or MAFS). This causes a pressure loss, which is not recoverable (same as 90 degree bends in the pipe). Slower air also sits longer and allows for heat soak (which can be minimized by the thermal wrap).

Also, slower air will not develop as much turbulence and will have a smaller boundary layer. This could negate the effects by having the roughness still affecting the core flow. However, we are talking small differences. You definitely don't want to go much bigger than the MAFS, in fact, that size is ideal.

You want the flow to be balanced all around, not speeding up and slowing down for changes in pipe area (which a 3" pipe would have to do at the MAFS). You want minimal slow-down(at idle) and a little bit of resistance for shifts (the throttle plate closes for a second and flow may want to revert back down the pipe). Overall, I think Random's design does this. 2.5 to 2.75" should be fine for this application. If you get larger than 3", I think the problems start to outweight the benefits.

Oh, this effect can also be seen in nature with Shark skin (appropriate enough smile.gif ).

Shark skin has very small triangle ribs running around the body. These create tiny little vorticies of turbulence right at the skin level. The turbulence stays right at the skin and water is free to move around the shark with much less resistance. This accounts for much of a sharks acceration ability and overall speed.

a

 

From what I can tell, the "advantage" of the Random special is one of two things.

#1. the turbulent air. all other CAI's have smooth bores between 2.5" and 3" and show moderate gains.

#2 For some reason the smooth bending of the flex pipe rather than several 90 bends somehow allows better airflow. The random special has no straigh sections. It is one big curve vaugely similar to an "S" shape.

The Gen2 Random special with 2 90 Degree bends and 3" tubing flowed LESS air according to my MAF than the normal random Special. (Tested on the same day, so no temp variation.)

Just so you guys know..when I test. I hook the CAI up, then I turn the OBD-II computer to measure MAF and TPS and RPM. Then I run it to redline in each gear(1-2-3-4 only). I then record the top values in each gear. I then do a freeway cruise, and floor the accelerator in 5th for as long as is safe (in Los Angeles...there aren't to many straight roads...and the ones that are...are busy as hell/unsafe!). and record the Top RPM and Top MAF value. It then compare RPM vs MAF readings in 200 RPM increments to determine which CAI has the best flow.

For true HIGH SPEED FLOW, I head to the desert between LA and Phoenix at night, there I can do top speed runs in 5th gear to get "JESUS AIR" readings.