Go race your friend in his track . . .interstate pulls. Stock for stock you should inch him. With your mods you should pull easy.

The plenum will not hurt you. You guys need to get that out of your head. The plenum is a good mod, and the second one coming out is solid proof. You may not see as good gains with the test pipes, but it wont hurt you.

 

Sith, I've been told that the ingen exhuast actually chokes the the z compared to nismo and borla TD. Might be something worth checking into.

 

BTW, NICE VIDEOS!!!! I LIKE!

 

Ok, here's your check real world numbers from the 350Z sports magizine dyno shoot out. Look at torque and where the power is delivered and over what range. Love the sound of the Injen, power wise I'd take the Stillen over all, Nismo next.

Borla (car 2) = 8.2 Hp - 2.7 ft/lbs torque (peak values)
HP increase from 5500 rpm to 6500 rpm range. Lost HP & torque below 1800 rpm. 60mm pipe. Weighs 52lbs.

Stillen (car 1) = 8.1 Hp - 7.3 ft/lbs torque (peak values)
Hp and torque increase starting around 3000 rpm to redline. Lost a little Hp & torque below 1800 rpm. 60mm pipe. 74lbs - 10 lbs heavier than the stock system.

Injen (car 1) = 7.6 Hp - 5.1 ft/lbs torque (peak values)
Small torque loss at 2800 rpm. Torque gain starts at 3300 rpm. Small Hp increase starts at 3300 rpm, maxing out from 5800 rpm to redline. Major loss in Hp and torque below 2200 rpm. 49lbs.

Nismo (car 1) = 6.3 Hp - 4.5 ft/lbs torque (peak values)
Developed torque and Hp over wide rpm range. Torque increase starting at 3000 rpm. Most HP increase from 4800 rpm to redline. No power losses below 1800 rpm. 54lbs.

 

From the moment that last bolt was torqued down on my crawford pleneum and with the very first trip through the gears, I knew without a doubt that every penny I'd spend was well worth the gains that I felt. It effect's the power band exactly as advertised. Cannot recommend highly enough here.

 

If you think you have a vacuum leak, which as Doug said earlier, I doubt, you can torque the bolts on the plenum to just above spec. Don't go nuts with it because you will snap the heads off, but a little extra clamping force can be had if it will give you some peace of mind.

Dan

**EDIT**Oh and FlyByZ, D'oh, and myself were discussing this in another thread. Dynos are emphasized too much. You pulled pretty well on a stock Z, and held up with an Evo, so in all reality, you are seeing real world gains. Dynos are not inaccurate per se, but they are not the authority on how much power your car makes either. Obviously you have made the car quicker, and even marginally lighter, so enjoy the gains on the street. Who cares what the rollers say.

 

The A/F ratio seems fairly normal for those mods.
Just curious--What were the A/F ratios for the stock Z?!

 

Yeah i can't remember what his A/F was but i'll call him here after awhile and have him tell me... But if i remember right i think they were actually worse then mine if not the same...

As far as the Plenum goes that would be my only suspision because i've heard talks about the plenum not making good gains with certain mods. When we put it on I really didn't notice a difference taht was huge except at redline where it definetly feels stronger...Everyone else that i took for a rid said they could feel a huge difference...

And what are you supposed to torque the bolts 2? When i first put it on, one of the bolts you put in under the plenum to plug the holes, i snapped the head off so we just torqued teh rest down to 12 lbs i think. We made sure that nothing got into the engine though.

Who knows i know my car hauls ***, and i love her but she just let me down on the dyno.

 

Oh and another thing... On the dyno it once i got past 5000 rpm's it didn't seem to want to climb through like it usually does. Seemed to take awhile and i'm not sure if it was teh dyno or the car but it seemed to kind of stutter a couple times....Watching the rpm's they would be climbing and then look like they would kinda of take a split second jerk like almost stopping and then keep climbing..

But my Dyno graphs are pretty smooth i don't know if it's cause the SAE correction or what... They are alittle bit more jiggedy then the stock Z's though.

 

My thoughts on this are as follows:

1. As Doug said, wheels will make a difference on the Dyno, been shown in previous threads and discussions. Has also been shown in the 1/4.

2. With the amount of intake and exhaust mods on the car, you have created a greater demand for air. Without the car moving to force the colder air into the intake you will see worse results on the Dyno than on the street. The stock air box might increase your numbers on the Dyno and low end numbers on the street, but I bet the popcharger is helping more at the upper end on the street than the stock air box would. Would be intersting to see numbers with the stock air box on the dyno.

3. With your exhaust setup, I would recommend either getting some headers or going with HF cats instead of the test pipes. Either that or go with an exhaust that has more back pressure like the Stillen or Nismo. I have the Injen exhaust myself and initially wanted to go with test pipes until I got the exhaust on and realized it just didn't have enought back pressure, which I believe is why it performs poorly down low. Adding nice headers like the Crawfords will help reverse some of that loss however, and really open up the performance.

4. Add a crank pulley to help get to higher rpms a little faster so that you get to an rpm range where your car is making more power. Simple and relatively cheap.

 

I'm not sure I understand what you're describing. It might have just been your imagination. What gear were you in on the dyno?

If you're wheels were slipping, they car would rev faster, and if there was a stutter, you may or may not see it in the dyno depending on how pronounced it was. SAE correction does not smooth results. Smoothing does.

What I would recommend is to go to another dyno to check it out if it's really eating at you. I see you live out in a less than urbanized part of the country, so I'm not sure that's an option.

It would have been ideal if you baselined your car before modding it. That's where the real benefit would have come in. All dynos don't measure uniformly relative to other dynos, but they do measure uniformly relative to themselves, meaning that if you use the same dyno the results will be comparable. Your car might have put down a baseline of 215 whp on that dyno. In that case, 246whp is a damn good pull.

Dan

 

Lets see the charts!

Im pretty convinced its the wheels causing the discrepancy

also, happen to get the dyno on disc? If so, please attach the file as well.

 

Ok here they are.....Sorry they are so big aswell..If you guys have problems with them let me know and i can try to resize them.

Here's my Best pull:


Here is my air/fuel and power chart:


And finally here is HIS dyno ontop of My dyno....I am the 2 Yellow Lines and he is the 2 Blue lines....

 

It almost seemed like it was pulling timing or like it was trying to miss or something... Just the RPM's were not going smoothly they were jerky.

And all runs were done in 5th except for 1. and the one i did in 4th gear only put down like 232 if that i think.

 

Your A/F ratio is staying above or just below 14 for quite some time. How long have you had all of your mods on the car? Just wondering if the ECU will still be adjusting at all or not. If they have all been on the car a while I would say you need to look into an ECU flash. Your ECU may have been trying to adjust timing to keep the engine from detonating with what you are describing. Sounds like it did what it was supposed to. What octane fuel are you using?

 

Yeah i've had the mods for quite awhile, I've had the exhaust & Test pipes for over 6000 miles, plenum probably about 4000, and the pop charger maybe only like 500 miles.

And i'm just running Chevron 91 octane fuel....Everyone at the Dyno said my car didn't sound like it's normal self yesterday while it was on the Dyno, sounded like it was flat lining or something.

I also resized the Charts but i can't edit my post anymore... So sorry for that guys, if Victor reads this maybe he'll let me change them but until then sorry for the huge monsters on it.

 

Must be the dyno machine, and if not something is wrong with your car. I dynoed at 252, with Nismo headers, injen CAI, and Injen SES exhaust. My baseline was 228 to 231.

In my personal opinion, I now really doubt the accuracy of any dyno machine? The only way to really tell if a mod is effective is at the track.

 

I agree...Bone stock i went out to the track and ran a 14.1 @ 98mph

With Test Pipes, and Exhaust, and ET Street, i went out and ran a 13.72 @ 101 bogging down the car cause i wasn't used to the et streets. My first run my 60ft was a 1.98 and i ran a 13.82...........my second run was a 1.91 60ft and i ran a 13.72 and it still tried to bog. I know i could of had a 1.8 60ft.

But i gained 2mph in the 1/4 with just those 2 mods and on tires that KILL mph so without the tires i probably could have trapped atleast 104

 

I'm pretty sure optimum a/f should be about 12.5 or so....

Getting a new ECU map should help, as long as it matches "your needs" of course...

A friend's newer camero SS (maybe '02) ran a solid 12.0:1 almost the whole dyno run... bone stock it put out 310hp, and 320ft-lbs.

Obviously it was very "under-rated" (not to take from vette sales) b/c it was rated at 345/350. So 345/320, but putting out 310 means a drivetrain loss of only about 10%, or less. But... Evidently that wasnt fast enough for him... he now as an '03 Z06, 405HP, has not dynoed it yet, but he said other Z06's run about 350rwhp, giving about a 13-14% loss, he said he has seen most Z06's a/f, like his former SS, run about 11-12 a/f.

 

Hmmm...yes, I'd like to see a couple of A/F ratios for a stock Z motor. I remember one stock dyno, and it started at 14 for the A/F and then went down to 13 at 4500 RPM, stayed there, and dribbled down just a little bit more right near redline. I'm not sure if that's normal for stock or not.