DaveO;
Thanx for the advice. I'm guessing you would recommend TechnoSquare? and should I wait if I am considering the Plenum upgrade?

03 Sedan, White on Black. Clear Corners, Blinker Mirrors, Stillen: High-Flow Air box, Grounding Kit, Exhaust, Z-Tube, Eibach Pro Kit, 18'' XS Style 420.

 

jasijay,

I've been very happy with TechnoSquare's ECM program upgrade. The improvement in my AT Sedan's "driveability" was well worth the cost... and the accross the board power increase was a bonus.

If you're sure you going to add a plenum in the near future then you may want to wait. It'll save you $150.00 for the reflash.

DaveO

2003 G35 AT Sedan / DP / Willow / Premium / Sport
350Z T-Stat & Air Duct / Stillen CAI / Crawford Plenum
GrdGear 7-Wire Kit / TS ECM / E-Fans
Street Edge TC / B&M Cooler / Stillen Exhaust

 

I think the airflow is better in the bumper slot than up high in the compartment where direct air is harder to come by. Tempurature changes can't be that significant can they in the
.0x time it takes to get from the intake opening to the throttle body? Wonder what temps of the incoming air are in those two places - i bet there's not much diff.

2003.5 DP 5AT Sedan (E-thing but Nav)
14.2 @ 97.18
Injen CAI
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Polk ex-3500 Tweeter Upgrade/Shock Sensor/H-Liner Under Hood

 

SixFive,

"I think the airflow is better in the bumper slot than up high in the compartment where direct air is harder to come by. Tempurature changes can't be that significant can they in the
.0x time it takes to get from the intake opening to the throttle body? Wonder what temps of the incoming air are in those two places - i bet there's not much diff."


Our opinions certainly differ.

Consider external areodynamics. Gs manage to get 0.26 to 0.28 Cds. The front end low pressure zones that help the car "stick" to the road at high speeds are located where?

Think about underhood temp profiles, low pressure areas and potential dead air spaces. Measure temperatures at various points. Think "heat soak" at idle and low speeds.

Think external temperatures. Measure ambient air temp, pavement temp, air temp 12" above the pavement and air temp 29" above the pavement.

I bet you'll be surprised. I certainly was!

DaveO

2003 G35 AT Sedan / DP / Willow / Premium / Sport
350Z T-Stat & Air Duct / Stillen CAI / Crawford Plenum
GrdGear 7-Wire Kit / TS ECM / E-Fans
Street Edge TC / B&M Cooler / Stillen Exhaust

 

"Some people think that the resonator in the intake is just to quiet things down, but it actually does much more. It absorbs the standing waves that accumulate in the tube from the negative pressure differential between throttle body and MAF. Intakes are tuned throughout RPM range for specific velocity just like exhausts. When that is altered, most ECU's dont like it and clamp down on fuel and timing to be "safe"."

I wonder how many 350Z's there are running around in safe mode?

2004 G35C 6MT Black. What Honey? I don't know where they came from. I came home and it was like that...

 

Any opening in the front of a G35 is a high pressure zone, what is in the way of that flow, that's what matters, weather it's just off the lower lip to the tip of the grill, pressure will be the same. The front of these car's are designed to get air in for the radiator, the grill is designed for look's, not air flow. Oem intake air channeling has to work past the grill, hood lip and the radiator shroud. But it does the job of course, if someone wanted maximum air pressure, it would not come from behind the radiator grill however.

The only worthwhile air temp data comes from reading the air temp at the MAF, logged from a Digimoto ODBII reader after the car has been driven. As a example.
AEM CAI 350Z
Outside Air Temperature (according to the 350Z multi function gauge) = 57F
Coolant Temperature = 203F
Inlet air temperature = 90F

Injen CAI 350Z
OAT measured 80
Coolant temperature 192
Speed 60
Gear 3rd
RPM's 4500
Intake Temperature 86

Another AEM CAI (polished)
Temp = 74F
Coolant Temp = 212F
Air Inlet Temp = 106F

Oem 350Z intake system
Ambiant Air - 93
Intake temp - 99
Coolant - 190-192

polished injen/pop charger full cai hybrid*
outside temp = 90F
Air Inlet Temp = 95F
Speed = 60 MPH
RPM around 4400-4500 in 3rd gear.
This setup run's piping to place the filter in a high pressure area right behind the front bumper grill.


What we need is a Intake dyno shoot out. Make it closed hood. Use one blower to for the radiator and one for the intake. Then drive each car and log the MAF temp data and see which one show's the lowest actual intake temp readings.



"All that's necessary for the forces of evil to win in the world is for enough good men to do nothing.”
Edmund Burke

G35 6mt

 

Another good idea Jim.

I'd like to include also air temperatures at the throttle body in the test. I've been using a thermister to measure the external TB area temperature under various operating conditions. Wish I had a better way.

DaveO

2003 G35 AT Sedan / DP / Willow / Premium / Sport
350Z T-Stat & Air Duct / Stillen CAI / Crawford Plenum
GrdGear 7-Wire Kit / TS ECM / E-Fans
Street Edge TC / B&M Cooler / Stillen Exhaust

 

So you're saying the temp down low is warmer - on any warma nd sunny day thats probably for sure - didn't you post some stats on the temp diffs a long time ago?.

Some days I am getting warmer air from down under, sure but I'm still going on my notion that airflow is better with the intake opening stuck in the open air down in the bumper. That's a wide open direct shot of air and at 65 the pull is there that was not stock. I haven't driven a shorter intake modded car like mine so my theory is just theory. If I get bored one day I will put my stock tube back on and see how the plenum and other mods react...

2003.5 DP 5AT Sedan (E-thing but Nav)
14.2 @ 97.18
Injen CAI
10 Wire Hyper-Ground
Crawford Plenum (V4)
UR Crank Pulley
Polk ex-3500 Tweeter Upgrade/Shock Sensor/H-Liner Under Hood

 

4 valve per cylinder engines have 20% more valve area to enable the engine to act like it is 20% larger at high rpms.

At low and cruise rpms the downside is very low air speed [velocity] to fill the cylinders........why many 4 V turn higher rpms [10-20%] at cruise to get enough air to make enough power to pull the car.

Factory engineers have to use extraordinary measures to tune the intakes to squeeze efficiency out at 55 mph to optimize EPA highway mileage test.

Changing the usually long piping from TB thru MAF and out to air inlet horn or filter box usually decreases efficiency at low rpms.......under what ever rpm 60 mph cruise is.

Low rpm top gear lugging with AC on is a critical point, every single HP counts to avoid a downshift which cost fuel on MPG test.

Without variable cam lift to compensate for low rpm stagnation and reversion........you learn to live with the minimal low rpm power in exchange for the extra 20% at high rpms. Many engines now have variable plenum volume and dual or diameter control runners and runner lengths but these don't help much at cruise or low rpm starts as they are tuned higher.

Compare the torque curve of a 3.8 liter GM 2V to a 3.5 4V

 

Q45tech:

Thanks for the enlightenment - never knew why 4 valve engines seemed to have less low end torque (the high-end power due to increased capacity and airflow being a given), but my "Butt Dyno" told me so as well.

I own both engines you mentioned at the end of your post - the VQ in my '04 G35, and the 3.8 in my '91 Pontiac SSE. Although the SSE is a heavier car and FWD, it still leaves harder than my G (neither car modified from stock), and would take it from 0-30 MPH (after which, SEE YA!).

Thanks for the schoolin'........

Sport Sedan Fan
2004 6MT Sedan/Sport/Navigation/Premium/Aero