DIY Intake

Bulletz4break

I could see some young kid driving a civic doing something like this but come on guys don't do this to a 370z... Not to mention that the tubing isn't even smooth inside and is going to cause turbulence. If you can't afford an intake just leave it stock.

SuperDave

Thanks for the bump, it's not that we couldn't afford a brand name intake, it's that some people get a bigger feeling of accomplishment and sense of pride making something themselves, equivalent to something brand name, for a fraction of the cost. You never built a dog house from old pallets?

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SuperDave

I'm sorry, I've got to comment again. That so many people are under the misunderstanding that any intake pipe which is not smooth must create air turbulence, which must be bad for your engine...


Without getting into aerodynamics, venturi effect, and optimal velocity equations, is a golf ball perfectly smooth? Are an airplane's wings perfectly straight? Do the factory rippled intake tubes on billions of cars create turbulence which would reduce the efficiency of said car? Is some / any air turbulence always bad? Think about why...

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wanker

Sorry can't agree. Surface drag has many factors including the air temperature (i.e., density), velocity, compressibility etc. Hence, given the relatively low velocity of the air in an CAI, and the many turns of an engines CAI system, I'd still say that smooth is better.

SuperDave

Correct, and if it's reduced surface drag and a smoother air flow you are trying to accomplish then congratulations. However, if it's horsepower you are trying to accomplish (as with an intake), then you want more air as opposed to smooth air, as well as some turbulence (see: volumetric efficiency) to aid in mixing with fuel, which is heavier than air.

What do you think a turbo does? Makes the air really smooth going into the engine, or crams a crap ton of air into it without worrying about how "turbulent" it is.

This is where most people go wrong. Yes, usually when trying to reduce drag, smoother = better. But you're not trying to reduce drag here, you're trying to increase volume. More air = more power, smoother air !=(necessarily) more power.

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Bulletz4break

Why is intercooler piping smooth then? So your saying it would be better if it was ribbed? Your logic is way off. You don't want turbulence.

Jordo!

The problem is the overly sensitive MAF's on this car -- they are VERY sensitive to turbulence.

If the home made intakes are sufficiently secured, should work okay (heat soak being the only issue if unshielded). If they are moving around, i can pretty much guarantee you you will see evidence of losses on a dyno due to random misreads of air flow...

EDIT: I wouldn't have painted the inside... that is almost definitely going to flake off and make its way into your engine...

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Masterbeatty

A for effort! But... this car is an icon, not a Honda Civic you had in high school. Ghetto air intakes like this should not be on any Z car, including a CRZ!

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Nick M

I showed this to a friend who worked at K&N for a long time, and he cringed.

He said he's never seen a flowbench or anything other instrument in testing produce better flow results from corrugation vs. smooth internal piping. Which is probably why almost every single intake kit every produced has smooth piping.

He also said there may actually be a small increase in power due to increased velocity due to the tube length (which is the benefit to longer tubes, not temperature) but an ebay short ram would likely net the same power gains.

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Cbtech

Both pipes are secured with the MAF tube as well as at the bend and the filter by the bumper brace, there is no movement. Also heatsoak would be an issue for a G3 as its chrome pipe and completely unprotected

As far as spraying inside, the paint is enamel not typical wicker basket rattle can spray so there is not going to be any kind of flaking unless there is something scraping it off on the inside which also would need to be pretty sharp to do so.


the piping is not "corrugated" which stays corrugated even when bent. Example below:



The piping is "flex pipe" which has a the same smoothness shown below internally when bent. there is minimal undulations in the piping



I would be on the same page as all of haters if it was truly corrugated piping as that would not be conducive to fairly smooth air flow.

I never owned a Honda so i wouldnt know. Again as Dave said, this is for the love of DIY and not the person that wants to spend the most money over others. By looking at the finished product you would never, ever suspect that it was a DIY unless i pointed it out to you. Most look at it and ask me if its the Stillen G3 set up. I have done several DIY's on this car that work very well and are less than 1/3 the cost of your high priced retail MODS.

This DIY modded Z will keep up/beat any other similar high priced modded Z.

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SuperDave

Doesn't Nate have G3's, a tune, FI exhaust, all that suspension work, etc...? Wasn't he the fastest of all of us for a while, until you figured out that map 1 vs map 2... Who's the fastest now? Yea... That's all I need to know.

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Read T

...Yeah, but I'd still rather have a CRX (like a high school kid) than a CRZ.....

It's a damn air intake. You guys are all arguing over 1hp.

Also, if this car was carbbed or not warmed up, turbulent air could help atomize the fuel.

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Bulletz4break

This reminds me of when my buddy tried using PVC as intercooler piping on his Eclipse GSX

Jordo!

That all sounds reasonable to me

I for one have nothing against DIY bang-for-buck projects. There's plenty of commercial products where you pay for crap or overpay for something that could be assembled/obtained for far less. If you've put thought into it and it works, you are set.

Bought or home made, tho', you might think about swapping back in stock airboxes, getting a baseline dyno, and then dyno testing yours to ensure it is working as desired.

If you do, and can get hold of some K&N filters, you could have a three way shoot out.

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Jordo!

It depends on where and how much tho'. Many OEM MAF's have airflow sraighteners to reduce tumble effects and thus take more stable readings as air passes over the hotwire. Ours doesn't and is thus very sensitive to misreads when pre-MAF turbulence is introduced.

Also, we're talking air ingestion into a system ("suck") not the mixing and compression of air and fuel ("squish"). At that point, turbulence is not really an issue again until we get to its expulsion ("blow") to facilitate optimally timed post combustion (bang) events to re-create vacuum inside the cylinders (ready to "suck" again). However, internal turbulence can work against effective mixing, its just less of an issue as the aim is compression at a fixed point (timed spark event).

VE is another issue entirely -- effective cylinder filling, usage of the mixture, and ultimate emptying of post-combustion gasses. With a turbo, some of that is re-routed, to be used to spin the turbine, but, yes, restrictions or poor flow characteristics matter there too.

On the intake side of things, its a balance between smooth flow and speed vs. volume (faster in a narrower tube, slower in a wider tube, all things being equal), provided the engine can optimally accommodate the volume of air being drawn in.

As to the flex-tubing on the Z, that's strictly convenience (and maybe a bit of extra outer cooling) for Nissan -- "smooth tubes" definitely make a bit more power than the OEM ones as verified on several before and after dynos -- same diameter, smoother transitions, less flex, less internal turbulence, more airspeed, improved flow, better power.

Straitened vs greater turbulence is also a factor even in filtering incoming air. Straightened air simply flows faster, all else being held equal.

On a somewhat related note, you will have greater filling with hot over cold air, as the gasses expand, but you have less oxygen (reduced efficiency) taking up the same volume, thus, less power to be made during combustion events... same is true at higher altitudes as well.

BTW, compressors work by functionally improving VE by cramming more oxygen into the same space (available volume of each cylinder), not by simply creating a greater volume of gas. It's the number of oxygen molecules (and, well, a concordant volume of fuel) that matters.

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