A&Q about 350Z
Q:
I want you guys' ideas on what are the economic ways of getting out the max hp without getting a supercharger or turbo ? I already have an Air intake and I'm waiting on an Injen TD exhaust ? I thought I read something about a plenum but I'm not sure what it is and how it works. Any ideas are greatly appreciated.
the Juiceman
- '05 Redline Enth.
- AEM Air Intake
- Injen SES TD Titanium Tips
A:
One word of caution too: high-flow everything isn't always going to help a naturally aspirated engine. The valve train produces pressure, and that pressure is regulated by devices such as resonator tubes and exhaust tuning. When you open those up, you can kill torque at the expensive of a bit more peak HP.
Now if you go forced induction, then you don't care about the loss of resonation nearly as much, because it is a game of stuffing air into the intake. But if you are using regular atmospheric pressure, then tuning for air changes is very important.
A:
Most race cars are open header, n/a or not. You do have to take some care into balancing exhaust flow, but no aftermarket system for n/a applications is going to be 'too' high flow.
19[TT]91
My TT beauty is gone.
2[00]2 Honda 954RR
Suzuki 1200 S; sportscar eater
19[I4]94 Integra GSR Sedan
Long live the Z...
aka SAHTT
A:
At some point you may also need to do some tuning such as an ECU reflash. Generally you want to wait to do this until you get all your NA mods.
03 Daytona Blue MT
Injen CAI
Borla TD Exhaust
Crawford Plenum, Cats, Headers and Strut Bar
Nismo Suspension, LMGT4 wheels, clutch and flywheel and cams
StopTech BBK, 332mm front and 328mm rear
Technosquare ECU Reflash
3.9 FD
Emerald City Z Club
A:
>applications is going to be 'too' high flow.
It's not that it's too high. It's that you want to obtain backpressure in the exhaust, and resonance in the intake. Car manufacturers tune for it, it actually increases your flow.
"Production cars have specific length air intakes to cause the air to vibrate and buffett at a specific frequency to assist air flow in to the combustion chamber. Aftermarket companies for cars have introduced larger throttle bodies and air filters to decrease restriction of flow at the cost of changing the harmonics of the air intake for a small net increase in power or torque."
A:
that back pressure is pure bull! it seems like an old wife's tale that would not die!
it may be some truth but more nonsense than anything
A:
No, it's not bull.
I have witnessed a Supra being tuned where the intake length was varied and there was a positive power change when it hit the resonance. When the intake is opened wide, the torque curve falls. Turbo folks know this well; you sacrifice the backpressure in the exhaust, for example, to give you lower non-boost power, but increase your boost flow.
When the valves close, there is a pressure wave pushed back against the air going into the intake. If you use the pressure wave to pull the air into the intake, you can actually do better than a constant flow.
This is why many people actually lose power when they install open intakes on pre-tuned cars. There are several 350z intake reviews that show just that...
A:
BTW, here is more reading on the subject. Nissan apparently tunes for it as well (according to this site):
People don't want to accept that there is more to "tuning" than just slapping on the biggest exhaust and intake you can find, but it's true. You can hurt performance with these mods.
A:
Zoom,
When a engine manufacturer tunes an engine for performance, it is normally done with all of the OEM equipment in place. When this is done, the sensors are "calibrated" (or fudged) to account for the intake and exhaust systems quirks. In other words if the temp sensor reads 105F, the actual air temperature might be 98F. If the airflow accross the sensor is changed, ie smoother flow from a laminar flow filter, the sensor might read higher or lower and the engine in turn may run rich or lean. This is a simple example, but a MAF sensor is much more sensitive to changes in flow dynamics and the fudge factors are actually complex equations. This is why when you do engine modifications, you really need to re calibrate the ecu to get maximum performance.
The pop charger did increase airflow, but most likely the engine compensated by running richer than it normally would. So in effect you gain HP from the airflow but loose HP from running richer than ideal and in the end you only get a net gain of X%. The other effect is that the smoothed air path from the filter eliminates some of the turbulent eddies in the intake, in effect reducing torque. You get torque from turbulence, long intake runners, and warm intake air. You get HP from high laminar flow at high RPMs. Torque is real, HP is calculated. If you run near redline all the time, get the nice filter, high flow exhaust, etc. If you like gas mileage and daily roasting of the tires, stick with the OEM setup.
Ok sorry for the long post, but I live in the middle of nowhere and Im bored. One more thing, Laminar flow filters (K&N, etc.) are great for performance, but cant filter the fine silicates when clean. (out of the box). So if you drive on dusty roads, you should use a paper filter for best engine life.
06 Lemanz Sunset Track Z
Best car I ever bought.
IHI Turbos comming soon.
A:
350TTZ..thanks for the great info, you reinforced my thoughts on how the MAF sensor would change the calibrations due to the increased air flow. Adding your comments to Z32's, it is starting to make sense to me now. I do only street and highway driving, so now I am not sure about installing the 'pop charger' in the '06.
'06 Silver Alloy 350Z Touring