original air scoop

[bighorn]

Do You Leave The Original Air Scoop On Under The Bonnet When You Put On A Hks Mushroom Filter.

[Nutter_John]

yep reduces some of the hot air around that area

[pitslayer]

ive found without them on, the car sucks hot air in, instead of cold air, and subsequently looses abit of performance. however previous owner of my new galant, took it off and put a crappy airfilter on which does nushink but rust, the guy had no clue when it came to cars

[bradc]

stick with the stock cold air box and filter if possible. Consider upgrading to a high performance k&n or ralliart panel filter.

[ANTHONY]

wot he said above is the way to go

[bighorn]

I dont wanna b a pain, but where would i get 1 of these filters from

[DefeXion]

Not exactly related to the Q in this topic, but I didn't think this deserved it's own thread. Would changing the design of the air intake help airflow? I have often thought about this because of the dynamics of airflow through a tube.

e.g. when you blow air into the small end of a funnel, it comes out a lot slower and less dense on the big end of the funnel. But if you blow air into the big end of a funnel, it comes out the small end alot faster and more dense. I know playing with density will screw the airflow sensor over, but that might be where you get rid of the airflow sensor and get a tuned map. N/a for lyfe.

eg
\
-\__

-> airflow
--__
-/
/

rather than
---/
__/

-> airflow
__
---\
----\

[Kenneth]

Not exactly related to the Q in this topic, but I didn't think this deserved it's own thread. Would changing the design of the air intake help airflow? I have often thought about this because of the dynamics of airflow through a tube.

Yes, changing the intake design could very well aid air flow... if you do it right.

Slow moving air is more dense than fast moving air, so ideally you want to be drawing the air from a area of stagnant or high pressure air. be careful with what you do though, because if you are using the standard air flow meter any possible performance gain could be offset by screwing up the airflow measurement. I would be interested to see how a decent cold air feed attached to the standard air box works.




e.g. when you blow air into the small end of a funnel, it comes out a lot slower and less dense on the big end of the funnel. But if you blow air into the big end of a funnel, it comes out the small end alot faster and more dense. I know playing with density will screw the airflow sensor over, but that might be where you get rid of the airflow sensor and get a tuned map. N/a for lyfe.


IIRC, an increase in speed lowers the pressure, which I think lowers the density rather than increases it.
The standard air flow meter isn't that bad, you just have to think carefully about where you place it.

Tuning for MAP has its uses, but don't forget that it has its downsides and dangers also. MAP relies on the breathing of the engine to stay constant, if something changes (exhaust etc) then the breathing of the engine changes too. If it is something that makes the engine breathe more freely, then you will lean out on the fuel. This means that when you make mods, you need to re-tune.

An air flow meter doesn't have this issue as it is able to still calculate the correct volume of fuel for the amount of air..


Basic idea of how MAP and MAF work differently... (note, i don't claim this is 100% accurate, only approximately how they work)

MAP: reads the pressure in the plenum, reads RPM, reads the TPS, reads the temp sensor.
Then looks up a table which tells it what injector duty cycle to apply to this combination of sensor readings. This is a "hard coded" setting that is set by the tuner. The AFR produced is a result of this setting and the mass air flow. More air and you get a leaner mixture.
However I do believe that some of the more advanced standalone systems are able to make compensations using wide band sensor input. (think expensive though)

Air Flow meter: Reads Air Flow Meter signal, reads RPM, reads TPS, reads temp sensor.
Looks up air flow map (usually air flow in grams per second), calculates load index based on air flow, RPM, TPS and temp.
Looks up Load vs RPM fuel map and finds appropriate AFR.
Works out how long to open injectors to add fuel in the appropriate AFR
Resultant AFR is pretty close to the one chosen on the RPM vs Load map.

As you can see, there is an important difference between MAP and MAF based calculations:

MAP uses a fixed setting (injector duty cycle) to provide a variable result (the AFR)

MAF on the other hand uses a variable (the air flow) to generate the Injector duty cycle, which provides a fixed result (The AFR)

[DefeXion]

I see... I figured you could use the movement of the car to your advantage in this situation. While stationary, the car will be sucking the amount of air it needs to run. In this situation, no extra airflow is generated because the flow is being generated by the engine.

Once the car starts moving, the idea is to catch a larger volume of air than the engine can suck in by itself to let the movement of the car become the majopr source of airflow, creating a sort of n/a'ish turbo :). However, there is another problem. If it is only phsically possible to suck as much air into the engine as the induction stroke allows, any extra air that the intake would pickup might be blocked by pressurised air trapped in the intake, and therefore be diverted away and into the airflow of the body.

Darn... I was getting excited there. Was starting to think "You just wait and see you silly turbo cars... you just wait and see". ^_^

Still, it would be an interesting test to put a hole in my bonnet to create a custom air intake. Might start by taking a light out first.

[Kenneth]

I see... I figured you could use the movement of the car to your advantage in this situation. While stationary, the car will be sucking the amount of air it needs to run. In this situation, no extra airflow is generated because the flow is being generated by the engine.

Once the car starts moving, the idea is to catch a larger volume of air than the engine can suck in by itself to let the movement of the car become the majopr source of airflow, creating a sort of n/a'ish turbo :). However, there is another problem. If it is only phsically possible to suck as much air into the engine as the induction stroke allows, any extra air that the intake would pickup might be blocked by pressurised air trapped in the intake, and therefore be diverted away and into the airflow of the body.

Darn... I was getting excited there. Was starting to think "You just wait and see you silly turbo cars... you just wait and see". ^_^

Still, it would be an interesting test to put a hole in my bonnet to create a custom air intake.

Air scoops do work. If the air coming through the scoop is enough to overcome any pressure drop in the intake, then you will get a positive pressure in the intake manifold.

Air speed in the intake IS important though, and is a toss up between speed and restriction (much like the exhaust actually)

If the intake runners are narrow, the air speed increases. If it increases enough it will continue forcing itself into the cylinder even after the cylinder has finished the induction stroke. In this manner the cylinder can actually fill greater than its displacement. Most road vehicles are designed to have this happen at a fairly low RPM so that you get good torque for driving.

Just as important, or perhaps more important is getting the exhaust correct, check out this link (it will take a fair bit of your time, but its damn good :) )
http://www.superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/

Awesome link for N/A exhaust tuning.

[DefeXion]

You Legend :D that links is great. My current exhaust tip is worse for wear, so I mayaswell to an entire exhaust retune at some point when I replace the tip. Got a mate who is getting a 3 inch for 600-900 dollars which is pretty damn good imo. madrel bent.

btw... do you still have that legnum engine? I did more reading on the forum and found that the oil galleries don't match up between my eng and your heads so that was a no no right there. Interested in a whole vr4 engine now.

[Kenneth]

You Legend :D that links is great. My current exhaust tip is worse for wear, so I mayaswell to an entire exhaust retune at some point when I replace the tip. Got a mate who is getting a 3 inch for 600-900 dollars which is pretty damn good imo. madrel bent.

btw... do you still have that legnum engine? I did more reading on the forum and found that the oil galleries don't match up between my eng and your heads so that was a no no right there. Interested in a whole vr4 engine now.

Yep, still got it. its in parts though, so you would need a gasket set and put it back together :P Still, if you want to build a N/A monster (I would do this if I didn't already have turbos... lol) then it does mean you would have to pull it to bits to do some head work anyway (not to mention upping the compression)

3" would probably be a bit on the large side unless you wanted all out top end performance.

[DefeXion]

I am a compromiser, so was thinking maybe 2.75inch or a well bent 2.5 inch. Like that article says, size doesn't matter as much as flow. If I did 3 inch, I might be able to fit a test pipe up near the manifold to increase resistance when it needs it and remove it for race. Getting into alot of variables there, so will read that article properly and have another think about it.

When are you free. I can come round and take a look and discuss the possible changing hands of green pieces of paper.

[DefeXion]

maybe tonight?

[Kenneth]

maybe tonight?

Yep, tonight will be good. Any time after 5:30pm should be good. Do you know my address? (may have mailed or PM'd it to you...)

[DefeXion]

Yeah, still got it and your home number. don't have your cell though.

[bighorn]

This is the HKS Filter that i put on my Legnum, can ne 1 tell me if ne good
http://img522.imageshack.us/img522/5083/dscf0001nk5.jpg

[jpnvr4]

I dont wanna b a pain, but where would i get 1 of these filters from

U can get a ralliart 1 from here:
https://www.rhdjapan.com/home/products/products.php?int_category_relation_id=1411&int_catalogue_id=628&page=6&nextpage=5

[DefeXion]

well it looks pretty