Air intake question.

[Fred D.]

Why does the air ducting from the MAF run to the side of the front light in a sealed area. It seems to not collect much air from the boxed in area its attached to, I'm sure it gets enuf air for average operation. But it looks like I can cut the air induct 6-7inchs back, and it would allow direct air flow through the grill into the air duct. Any thought on my idea would greatly be apreciated.

[Q45tech]

The entire Earth's atmospheric pressure is pushing in to fill the engine. All engines are already supercharged by this 14.7 psi pressure [at sea level] a fact many over look. In order to optimize mpg and cruising power at 55 mph [1800 rpm] a long tuned tube is necessary.

Nothing you can do to make it better without losing the tuning effect...........Some people use a cone filter to gain a few HP at the top end while significantly affecting the lower rpm low load conditions.

Changing anything in the induction system won't change your zero to 60 or quarter mile time by even 0.1 seconds...........assuming a clean to moderately clean air filter.

[Jeff Williams]

The ultimate intake:

Cut a round hole in your hood, then turn the plastic intale hose vertical. Mount the MAF on the end, and stretch a piece of screen door across the end with a tywrap.

This may net you 200 to 300 rear wheel HP, easily!

No really, I ran the Stillen POP charger on Layla for about 150,000 miles. I didn't see much difference, but I did not box it in, insulate it, or modify the ducting you are talking about.

I believe my mileage increased some, due to warmer intake temps, and it really sounded mean when I got on it.

The issues were the K&N oil drove the MAF nuts and I had to clean it often.

If you think there is a restriction, then just remove the lower portion of the filter box, and use tywraps to hold the filter to the MAF. I believe Dennis stated it right, ther isn't much gain to be had.

INFINITI designed the intake for quietness, which was WAY more important to the company than HP at the time. They already had the fastest sedan in the market.

If you want to add some fractional HP, then insulate the existing pipe between the MAF and the plenum. That pipe gets hot, and the plastic doesn't do much for heat transfer.

I believe the intake was designed when the Q had no grille, and nobody changed it when they added the grille. The area around the light is a very high pressure area, and not much face area is needed, for adequate air volume to the intake. A lot of cars use this area. The bumper also protects this area from most water splashing.

[Q45tech]

As I've pointed out for years buy a Dwyer manometer on ebay and do some testing to measure the pressure drop before the MAF [I have a tapped hole in the top center of the filter cover to quickly rig up a rubber hose from there inside cabin to manometer to see the restriction in real time

[Q45tech]

What most haven't bother to test is that the oem system actually has less restriction as the speed increases [above say 80 mph] PROVING that all the possibile pressure from speed velocity has been considered in the oem design.

All the from speed pressure backs up infront of condenser [where the horn intake is].

Measure the pressure build up in front of MAF at high speed.

Note the manometer pictured below has a full scale reading of 1.0 inches of water that is 1/28 x 6.8 or 1/4 of a PSI of air pressure.

Unfortunately real testing with real test equipment has a way of debunking all those theories out in the car driving public.

I have 13 different [range] manometers in my test equipment stable and at least another 24 pieces of expensive test equipment that are unknown [unowned] by the typical shop or dealer.........things that are routinely used by automotive engineers.

I need a real flow bench if anyone wants to contribute.

[Q45tech]

Measure the under hood in engine compartment negative pressure at 80 mph [compared to the pressure in front of condenser] to understand why in compartment cone filters are less desirable.

The condenser and radiator drop the pressure as the speed increases. The underbody velocity is higher and thus sucks the air out of engine compartment assumming the required plastic belly pan is in place to help cool the transmission.

Take the Q to a wind tunnel and see for yourself.

[sijoko]

This is what I have done.

Remove the snorkel that goes from behind the drivers side headlight to the area behind the grill. Now the air box will be picking up from underneath the headlight.

Then, get yourself a hole saw and drill a 2" hole through the bottom of the air box and the sheet metal. This will bring in high pressure air from the area underneath the headlights. You could also install a PVC elbow on to the hole to get a bit of ram air. I didn't.

I did this after having the Stillen PopCharger for about 2 years. This modification is better in my eyes.

You do not lose the bottom end like you would with the Stillen/Jim Wolf setup and you will still have awesome top end power.

[mcrews]

The intake from on 05 G35 sedan loaner, my q was in the dealer shop.It still had the long slit across the radiator.

fyi

[Q45tech]

Measure the pressure and report!

[sijoko]

You measure it and report!

[Louis Cyphier]

If you want to add some fractional HP, then insulate the existing pipe between the MAF and the plenum. That pipe gets hot, and the plastic doesn't do much for heat transfer.

quite the contrary, plastic is used because of its excellent qualities. thats why I laugh when I see, shiny metal tubing all over the engine bay (aside from IC piping)

[Q45tech]

Measure the inlet air temperature and the air temperature inside plenum [or runner above injector] at WOT and high rpm................at the speed the air is forced into the plenum not much time for radiation to heat air.

Now at idle or cruise rpm the situation is different as the air flow speed is 1/30 to 1/15 slower than at high rpm.

Velocity[feet per minute] = 1096.7 times the SQRT of pressure drop in "H2O divide by 0.075 [at standard SAE temp and barometric pressure.

D = D0 x (T0/T) x (P/P0), where

T0 = 545.69ºR (86ºF) or 303.15ºK (30ºC),P0 = 14.7 psi (= 1 atm = 760 mm Hg = 29.92" Hg = 1.033 kg/cm2 = 1.013 bar = 33.9 ft H2O), andD0 = 1.1649 g/L = 32.986 g/CF = 0.072751 lb/CF.Note that T, P, T0, and P0 must be in absolute temperature and pressure. For ºF add 459.69 to get ºRankine and for ºC add 273.15 to get ºKelvin.

The air speed in the duct between the MAF and TB is ~~ 125 feet per second at 70F and 29.92 Hg.

The flow/speed is a series of near sine waves that overlap. Approximating the intake cam shape with a flat top.

[qsiguy]

Heard all this a million times. I personnally love the sound with the aftermarket setup, just want to make the aftermarket setup perform the best it can so I can keep the throaty roar. I don't really care if the stock setup is better, just like I wouldn't care if the stock wheels (pie pans) were the best performing wheel in the world. I'd still hate them because they are ugly IMO. If the stock suspension height was the perfect setup for handling I'd still like it better lowered an inch or 2 because it looks better.

I also am considering modifying the intake plumbing at the grill to get ram air. IMO, and I'm not gonna check the numbers on this (hehe), seems logical that you would get better ram air flow through the intake plumbing whether using stock or aftermarket airbox/filter, if the intake tube is capturing clean, less turbulent air direct through the grill than from behind the headlight. Only drawback I see is heavy water splashing up into the grill would increase chances for flooding intake on the stock system. Even so, the water would have quite a job making it's way through all that plumbing into your engine.

Some argue that the 90-93 Q's perform better and they do have the intake opening directly behind the grill.

My $.02

[heywier427]

well said!

[Q45tech]

Why not build a function generator to make and track rpm/load to create any sound you want and amplify thru under hood speakers. Throaty sound why not a Ferrari or BMW V10 or NASCAR.

[maxnix]

Why not build a function generator to make and track rpm/load to create any sound you want and amplify thru under hood speakers. Throaty sound why not a Ferrari or BMW V10 or NASCAR.

That would be so kewl for the perception over reality crowd!

Either you want to think it is fast or you really want it to be fast, with some reliability. No one can drive a dead car.

[Jeff Williams]

My Q gets 2 MPG better fuel economy with the STILLEN POP Charger, over the stock intake.

[Fred D.]

Q45tech thanks for the data. The mass air flow sensor and all of the Q45 computer sensors should adjust to diffrent air pressures. Cold air is more condensed & has more oxygen this helps the fuel burn better and more complete. I believe the boxed in OEM design for the 94 Q was for sound reduction, and stoped water entering. A open/& closed air induction, 1/4 mile test needs to be done.

[Q45tech]

The problem with quarter mile runs is 10 HP will only be 0.1 second different and 0.5-1 MPH..........you need around 20 runs at the same ambient temperature to be statistically valid.

Easier and faster to just read/graph the inside plenum temperature or just the peak MAF voltage. The higher the voltage the denser total amount of the air flowing. Even 0.01 volts higher is significant

The Consult makes this easy to do.

[Fred D.]

Cold Air Intake Systems let your engine breathe in large amounts of cooler air, resulting in increased power at the wheels. Cold air intakes enhance the combustion process of your engine, which uses both oxygen and fuel. Cold air intake systems pull in more cold air, more cold air means more oxygen resulting in more usable power and torque throughout the engine's RPM range. Most Cold Air Intake systems relocate the air filter outside of the engine compartment or away from the heat of the engine for a cooler intake charge. Cold air is denser and heavier than warm air, which means that there is more oxygen in a cold cubic foot of air delivering a higher volume of air into the engine. Replacing your vehicle's stock air box with a cold air induction system removes one of the biggest restrictions on your engine.