Last night, I installed my 5/16" MD plenum spacer, a K&N air filter, and performed the clutch pedal adjustment mod. All I have to say is: wow! It really is like driving a whole new car now. The gains from the plenum spacer are really noticeable. Also, with the clutch engagement point moved closer to the floor, the car is much easier, and fun, to drive now.

I'm taking my car in to Dyno Authority on Thursday to get my car baselined. I had intended to do it before installing these mods, but due to the snow we had here recently I was unable to make my earlier scheduled appointment. I'll post my results when I get them. Had it not been for this forum, I would have never known about the plenum spacer or the clutch adjustment mod (since the dealer told me you couldn't adjust the clutch pedal). I'm very happy!

Next step is either a new exhaust system or new wheels and tires. I'm now researching cat-back exhaust systems to determine what the best (greatest torque and high-end power gains with the lowest loss in low-end power) exhaust is for an NA set-up. I'm also looking at Axis Hiro wheels with the anthracite finish (should look good on a silverstone Z), and some better all-weather rubber. I'm open to suggestions if anyone has them.

 

I keep tellin people --there is no better Mod for the Dollar than the MD 5/16. No --I dont get a kick back from MD. Congratulations

On the exhaust, remember, NAs like a little back pressure.

 

That's a myth. Read up; about 1/4 of the way down. http://www.sportcompactcarweb.com/te...haust_systems/

 

Congrats! What's this clutch engagement adjustment you are talking about?

 

Yes more info please

congrats on your new mods

 

The clutch mod can be found here: https://my350z.com/forum/engine-and-drivetrain/128253-high-clutch-want-to-lower-your-clutch-engagement-point.html Tantrum has put together a pretty nice pictoral guide on how to perform this mod, and I highly recommend that anyone who doesn't like the position of clutch engagement on their car try this simple procedure.

Regarding the backpressure of an exhaust system, the article that Undrgrnd posted a link to does a pretty good job of explaining why its not true that backpressure is actually harmful to any engine, including an NA motor (The article was 'mostly' accurate; I did catch a few errors throughout, and it was too long and technical for the average reader IMO)

The misconception is the product of an observation; when you increase the size of an exhaust pipe on an NA motor there is a point beyond which the engine begins to suffer performance losses. The simple explanation for this phenomenon is that the increase in pipe size has decreased backpressure and therefore a certain amount of backpressure is necessary. This simple explantion is incorrect. The real reason this happens is because as you increase the size of the exhaust pipe, you slow down the exhaust gas (Bernoulli's principle). The higher the velocity of the exhaust gasses, the more efficiently exhaust gasses are extracted from the engine (this is due to the scavenging effect), and therefore if the exhaust gasses are slowed down the engine must work harder to expel the exhaust. On the other hand, if you decrease the size of the pipe too much, there will be too much backpressure. A correctly sized exhast pipe then must be 'tuned' to produce the highest exhaust gas velocity while producing the least amount of backpressure for a given mass flow rate (a function of engine speed). Since an exhaust system must be tuned for a certain mass flow rate, all exhaust system are efficient for only a certain range of the rpm band. This is why a well-engineered exhaust system isn't as simple as increasing the diameter of the pipe, using smooth walled tubing, a staight-through muffler, and decreasing the number and angle of bends in the system.

 

^ just as a warning, there has recently been a lot of controversy over the clutch adjustment mod. I personally did that mod several months ago and my clutch point has returned to stock, and I feel that it did create excessive wear on my clutch. Nissan techs (i think) claim that this adjustment will decrease the amount of clamping force and allow for increased wear.

Just as a personal experience, one time when I was pulling through 1st and 2nd, after the shift when i put the power down, i felt the clutch slip for like half a second before fully clamping. This is after my foot was already completely off the clutch. Scared the hell out of me.

But on a better note, glad to see you're happy w/the spacer... i'm thinking about doing that next

ChiShi

 

I never got involved in this PEDAL adjustment thing cuz I see it as another Fad. Mine is fine and always has been ----But if u do it u better *** know what ur free travel is supposed to be before u start adjusting it so it is more "comfortable" for u.
Free travel is the amount of distance ur pedal travels before it starts "doing its thing" and that travel is best -----well, ONLY felt by pushing it down with ur hand. Free play is the distance between top dead center and the point ur M/C starts to pressurize fluid.
If ur free travel is less than spec'ed ur clutch will slip---If more than spec'ed then u will not get full disengagement------------MAYBE the reason some of the guys are having that 6th - 5th grind

 

^ i never had any grind issue whatsoever in those upper gears. I lowered the pedal so that it was even with the brakes... a very mild adjustent actually, and it felt amazing. But like I said, i started experiencing those problems.

ChiShi

 

I tried the clutch adjustment a while back, and I didn't have a good experience
with it in a long run.
However, I found a solution called JWT clutch

 

JWT is the best adjustment