I have a feeling once COBB finalizes the VVEL tuning aspect of the accessport, an intake will definitely be a worthwhile modification, since the motor in theory should be able to take in more air at the top end (assuming Nissan does not already have the cams at maximum lift).

Taken from another thread, see link below.

G37Sam drives a G37 and has Stillen G3 Intakes, FI Test Pipes & Catback and UR Crank Pulley.

He did an UpRev Tune and got 34HP and 32TQ gains.

http://www.the370z.com/tuning/13882-...ned-uprev.html

This is amazinggggggggggg.

My understanding is that the issue really has the potential to show when headers and HFCs are used together. Add in CBE & CAIs and then you run the risk of knock and/or engine damage...

what is running lean? I probably know it in other terms but does it mean that the engine isn't pumping enough fuel and air in the cilinders?

Very good counter response m4a1mustang....

I don't have a CAI...I was initially planning to get one, but after reading all of the posts here and dyno results, I totally changed my mind about it...In one thread, I recalled seeing similar results in reference to the CAI gains...Tony was right, most of the gains are seen at 7k and above....and like "Matt" said in another thread, I don't think any of us are planning to run our Z's at 7K plus majority of the time....

I just don't feel that the minimal gain of horsepower up top, is worth the loss of torque and power in the midrange....

Ideal Air/Fuel ratios for a N/A car are in the 12.5 to 12.8:1 range. Too lean would be in the mid 13:1 range.

Turbo cars like to run richer in the mid 11's as more fuel is used to cool the combustion and keep detonation under boost controlled.

damnit so if I get HFC + exhaust I would have to find somebody that can tune the ECU up.

horray for more money to spend

In simple terms -- too much air, not enough fuel. Running rich would be the opposite.

Self admittedly, I know jack squat about A/F ratios, but i'm curious... my AP says that i'm running an avg. of 14.2-14.4 at idle, is that a normal idle ratio? is it only considered running lean at a specific RPM?

To a point, like most ECU's.

You are fine! Optimum A/F ratio at idol is 14:7! Now WOT (Wide Open Throttle) You reallly want to be in the high to mid 12 range once you get above 4-5000 RPM. At the lower RPM's the A/F being leaner will not be catastrophic to the engine. However if you run it the high 13's low 14's in the upper RPM range you can cause serious damage to the engine. Detonation will occur inside of the engine and you can actually hear it if it is real bad. Bottom line, it is not enough fuel.

Thanks, Tony

I totally agree. On my TT mustang @ 25PSI we are at 1000 RWH! My A/F throughout the entire curve is 11:4-11:7. Keep in mind, I am also running unleaded 109 octance VP race fuel in order to achieve this.

Tony

There are 2 fuel control systems. The first, when at idle or partial throttle, is controlled by the MAF and 02 sensors who are constantly sending readings back to the ECU to maintain ideal Stociometric ratios (14.7:1). This is called closed loop. An A/F gauge will bounce around a lot as the mix is read and constant corrections are sent to the ECU. When you go wide open throttle (open loop), the fueling defaults to some pre-built fuel maps in the ECU. These are usually slightly modified by the Long term fuel trims (correction factors) that are determined over time by the adjustments the 02 sensor Has been making. Typically the Z corrects from a slightly rich tune.
As Parts are added (Exhaust, Intake, HFC's), the rich correction is reduced as the Fuel trims approach Zero. Add Zero to the pre-built map and you'll have a bit more power due to the leaner mix.. (richer is slower). To truly see how closely you are to optimum, read the A/F ratio at WOT as is the case with all dyno plots.

In this picture, Additive is the short term fuel trims, Multiplicative is the long term trims:
http://images51.fotki.com/v747/photo...ueltrim-vi.jpg

Tis why I love this forum, lots more people smarter than I, learn somethin new every day, thanks, +1 rep to you sir.

No you do not. If you run the HFC's and CBE your car will not become too lean. The ECU will correct and do it's job. Here is why the intakes change the A/F ratio's so much more than the exhaust system.

Inside your stock intake tube is a MAF (Mass Air Meter) As the air rushes by it, it samples that air. It works directly with the ECU and is calibrated specifically for the car. If you change altitude your cars A/F ratio will change. Meaning being at sea level opposed to driving in the mountains. In the higher altitude your car will actually be richer. Here is why, the air is thinner up there, your car naturally will take in less air. It naturally wants to lean out due to this and in most cases the ECU will compensate by dumping too much fuel and make the car rich. The MAF and ECU are designed from the factory to do this. However, they only work to a certain extent being that the elements from one place to the next are too different. If it worked perfectly your A/F would be optimum wherever you drove.

Now if you put an aftermarket CAI on the car that changes the location of the MAF or the tubing diameter it will change everything. The car is not calibrated for it. In the case of the Stillen Gen III intakes with exhaust & headers the intakes are causing the car to run way too lean. This is why you need a re tune so at the least amount you can bring the A/F ratios back to where they need to be. I know this how you may ask, over the past two days I dynoed a car that had Stillen Gen III intakes with our exhaust components and the car was borderline unsafe in terms of A/F. We re tuned the car, picked up alot of mid range power and low end torque just be getting the A/F back in the 12's. To be continued I am sure...

Thanks, Tony