Air Intake Mods

Anonymous · February 9, 2005, 20:53

This one's a bit backwards as far as mods go but have a look at these:

Basically I made the above mods to the intake system using 3" diameter air intake tubing (spiral wound wire reinforced). I removed the stock fabric tube and replaced it with the blue tube you see in the photos. The difference was that I extended the blue tube into the side vent for a better cold air feed. In the last picture you can see the bellmouth that I fitted to clean up the end of the tube and reduce any turbulence.

Results: Unfortunately not good, after numerous PMD runs, I couldn't get anywhere near my previous times recorder with stock intake systems and H&S inlet pipe. All I can conclude is that the increased length of the new pipe had buggered up the tuning between the helmholtz resonator and the intake pulses. Looking at the overall length of piping from side intake to airbox I think there was simply too long a run - probably about 4'. I ran this setup for about 3 months.

I have since returned to the stock fabric pipe and noticed a big improvement in performance. The engine feels more responsive throughout the rev range but particularly at the low - mid range. All I can say is that it gives me confidence in the stock setup, all be it with a slight mod in the form of the H&S pipe. When I get all the mods done and the Unichip tuned I'll be interested to what power I can get retaining the system as it is now.

MRMike · February 9, 2005, 21:04

Thanks for posting that Rusty..really interesting! Nice to know you tried somethign different! Nice design and implementation also! I'm just experimenting with an intake on teh 350! Hopefully it will net me some power!

Anonymous · February 9, 2005, 23:09

I know this is off topic but Mike what do you think of the 350Z - I'm strongly considering getting one next. Performance & looks / £, it's an absoulte bargain - look good with TE37s.

MRMike · February 10, 2005, 14:13

I really like the 350Z Rusty, I'm more than happy to meet up with you so you can have a good look at it.

I won't go into too much detail here as your intake deserves more replies! I'll PM you about the 350Z

By the way do you think the results of the intake would have been better if you had used a plastic pipe-airbox tube as opposed to a metal one? Also I remember Mike Cough?? stating that a similar intake had improved his performance, how was his different?

The reason I'm interested is i'm doing something similar, and am debating which type of pipe to use. The ventilation pipe that yourself and Mike used might agitate air and improve the effectiveness, alternatively it could hamper the airflow. Did you consider smooth piping? As that's what I currently have in my garage..

roger · February 10, 2005, 14:16

Rusty,

You say you have the H&S inlet - is it a new one or an older one?

Mine didn't come with the bracket to hold to the body, so just "floats" between the 2 ends.

Thanks for info

Roger

Anonymous · February 10, 2005, 14:26

That's the older one (the same as I've got): the newer ones are a tighter fit and don't have that bracket on. As long as it stays in place I wouldn't worry about it: I don't even use that bracket on my one!

SteveJ · February 10, 2005, 14:29

The main problem is that you have extended the pipe into what is a low pressure area, hence reducing the manifold intake pressure.

The chances of it being anything to do with resonance are pretty slim given that the changes you have made are prior to the air filter which effectively damps the resonance pulses anyway.

dreambackup · February 10, 2005, 14:34

Quote from: "SteveJ"The main problem is that you have extended the pipe into what is a low pressure area, hence reducing the manifold intake pressure.

compared to what kind of place?

Anonymous · February 10, 2005, 16:58

Quote from: "dreambackup"
Quote from: "SteveJ"The main problem is that you have extended the pipe into what is a low pressure area, hence reducing the manifold intake pressure.
compared to what kind of place?

I guess that the area behind the battery (the area that the stock inlet draws from) must be a higher pressure area since it wouldn't have been hard for Toyota to design the intake like my prototype. There must have been a positive reason for them to route the intake from inside the rear wing back into the engine compartment behind the battery.

If I think about it logically, the main improvement I could hope for is colder intake temps but if that is acheived by drawing vfrom a lower pressure area then obvioulsy I haven't acheived much. I must also question if the intake temp really needs lowering - it may already be pretty cool as I'm sure the battery does a pretty good job of sheilding the intake.

Anyway, nothing ventured, nothing gained. I just wanted to share my experience in case anyone else was thinking of doing something similar and hopefully save the hassle.

Anonymous · February 10, 2005, 17:25

Quote from: "MRMike"I really like the 350Z Rusty, I'm more than happy to meet up with you so you can have a good look at it.

I won't go into too much detail here as your intake deserves more replies! I'll PM you about the 350Z

By the way do you think the results of the intake would have been better if you had used a plastic pipe-airbox tube as opposed to a metal one? Also I remember Mike Cough?? stating that a similar intake had improved his performance, how was his different?

The reason I'm interested is i'm doing something similar, and am debating which type of pipe to use. The ventilation pipe that yourself and Mike used might agitate air and improve the effectiveness, alternatively it could hamper the airflow. Did you consider smooth piping? As that's what I currently have in my garage..

Might have to take you up on your offer to see the 350Z - I'll wait for your PM!

I used that pipe because it is sold in Demon Tweeks as intake piping and was the right diameter at 76mm. It's flexible with spiral wire reinforcemnt to stop it collapsing under suction.

I think that what Mike did was to put in a cold air feed pipe from the side vent to the stock intake pipe hole in the wall of the engine bay (behind the battery) This is in effect similar to my system. I know that Mike said that replacing the venturi tube (behind the rear light) with clothes dryer hose made a performance difference but I'm not sure if he measured the difference that the side vent hose made on its own so its hard to seperate the two. I know that my measurements with the H&S inlet pipe were better than stock but the measurements with H&S inlet pipe and blue hose were worse than with just H&S pipe - if that makes sense. And when doing my testing with the blue pipe I really went for it but no matter how hard i tried it was simply slower. After looking at the side vent, any air entering the vent should find its way to the stock pipe location anyway - I'm guessing that more air from under the car finds its way to the intake than from the sidevent though.

Overall I think that the sidevent, in it's current form, is not a good place to draw air from. Wheter this would change if you added a C One vent or something I don't know. I don't think that the type of pipe has a massive bearing on the matter. As long as its not hideously rough or obstructive it should be OK.

Anonymous · February 10, 2005, 19:01

C-One side vent covers should increase the pressure there.

Anonymous · February 11, 2005, 18:24

After driving the 2 today, i'm not sure I agree with the low pressure theory. My reasoning is that even at low speed the engine feels noticably crisper and more responsive. At these low speeds I can't see how there would be enough airflow over the vent to cause a low enough pressure area inside it for there to be a noticable difference in engine performance. I still think that it must be the length or something else that we don't know about.