Jeff: I do remember you posting one time that your car is running lean. Are the CAI/Cats/Catback causing this? Thanks for the input.

 

I feel it's more the Cams than anything else. T/S will fix the problem when I get the car back from the stereo shop.

 

actually, for me there is a little raspiness at 3k+ rpms in 5th. i also have nismo catback and RT cats.

 

I just purchased the RT High flows from Jason at Performance Nissan today! I can't wait to get them installed this weekend. Two questions, though...I have the Injen SES and the Fujitsubo Header is on its way, how loud will it be and will I need something like the Apex'i SAFC II to remove the possibility of a lean mixture?

 

That is not caused only from the high flow cats and it isn't really the same raspiness some people are referring to. Its not like a rattle.

Between 2.2-3.4k rpm is the common resonant frequency of the exhaust piping. The TONE resonates the pipes just like rubbing a finger over a wine glass, that is why you get the raspy louder buzzing sounds. That is normal, the stock exhaust does it too but the muffler helps reduce those sounds.

 

Not too sure, I havent heard them with those header's. That exhaust is loud on its own, I believe there are sound clips on here somewhere where you can hear the tone of it at least.

It should bring out the sound of the exhaust a little more. A bit louder but not that much louder. It doesnt turn the car into a super sonic rocket. But you will hear it a bit louder.

We shoulda walked out to my car and took a listen to mine. Feel free to come by again if you want to and check them out.

 

We shoulda walked out to my car and took a listen to mine. Feel free to come by again if you want to and check them out.


Yeah, hearing them on your car would have been a good idea...I just wanted to beat the traffic on the 10. No worries...I'm still gonna install them on Saturday. By the way, did you dyno tonight? what were the results? Thanks for your help!

 

I did dyno. About to post now...

 

yes i know the cats amplify the tone of the nismo catback. thats why it doesnt really bother me

 

I personally LOVE the sound of the Nismo.

 

I had my dyno pull after driving for an hour to get to Powertrain Dynamics. Talked for a while with a guy from down the row of shops. Laughing about things people came in with attached to their car's to try and make power. The funniest thing was a WEED WACKER as a blower!

Any way to the point of this. MY DYNO!

My car was warm from driving for an hour, out side temp was similar to the previous DYNO. On the same DYNO

Previous DYNO 11/01/03 = NISMO Cat Back Exhaust
Latest DYNO 11/18/03 = NISMO Cat Back Exhaust & Random Technology High Flow Cat's

11-01-03 = 241.4 Actual RWHP / 231.3 Actual Torque (ft-lbs)
11-17-03 = 248.0 Actual RWHP / 239.3 Actual Torque (ft-lbs)

Gain = 6.6 RWHP / 8 Torque

I am VERY pleased with the Torque gain down low and how the gain is across the full span of the powerband. I loose TQ and HP on the 6400 mark faster then with only the exhaust. I am hoping an intake of some kind will fix that.

It took me over 3 hours to drive home so I dont exactly feel like bending over my car and putting in the K&N Typhoon.

So! Soon to come, Typhoon Install (tommorow) and Dyno of the Typhoon added to this.

Below is the Pre / Post DYNO sheet and link to a video of the Dyno pull where you can really hear the exhaust in action up to 140+ MPH!

http://members.aol.com/performancenismo/dyno2.avi

 

For some reason I couldn't read the dyno, but because of the write-up, it doesn't really matter to me. Seems like a great modification and the pull sounds awesome! Thanks for the info Jason!

 

Cant read the dyno?

I hope you love yours as much as mine! Please bring your car by after you have installed them! I would love to hear them with your exhaust!

 

I just relized there was something different between this and my last dyno. HE DIDNT HAVE THE FAN RUNNING!

Grrrrrrrrrrrrrrrrrrrr..

What do you think? Think that might make a big difference? I think.

 

No pressure in the front airdam could make quite a difference for the intake.

Well, I guess we know the RT cats make at LEAST 6.6 and 8tq.

Mr.Twisted gained ~13 on that same dyno with just those HF cats.

 

what A/f do you consider lean? I guessing your running optimum right now at between 12-13 if so where do you think test or free flow cats would put you?

 

Well, I'm not too sure...

Jason's pre-randomtech run, he's dips to 12.5 between 3k to 4k range, but after the new cat install, he's up to 14 from 3 to 4.5k.

My A/F is pretty much a solid 13 across the midrange... so it may push me up to 14.5

Nothing to really worry about I guess, im just being careful since I really don't want to do any ecu programs right now.

 

Regardless where the numbers stack up
229.6 hp 230,4tq Intake, exhaust ,ground kit 11/1 Today 252..6 243.2 tq added Random cats pulleys and TS ECU tune. Thats 23 hp divided up with 12.8 tq increase. Cost??? $1664

Random Cats $500 install $ 80
PULLEY (set) $275 install $170
Belts $32
Ecu upgrade $595 included

First 20 hp ?? $1675
Stillen Exhaust $ 1150 install $70
injen Cai $240 instal $50
Ground Kit $ 140 install $25

So 35 to 40 HP cost $3340 not including dynos or about $100 per Horse Power.... Sounds about right

I think each airflow mod makes the car run leaner and leaner. and thats why you do the ECU last to streighten that back out. We need Daytona350Z a stocker to put on RTs first to see what's what.

 

The leaning effect (going from 12.x:1 to 14:1) shown on the dyno seems WAY too much for just putting in higher-flow cats, so I wonder if something here is amiss. Is the wideband probe simply stuck in the tail pipe? If that is the case, from what I understand the reading can be skewed based on the catalytic converter efficiency. Since the probe is simply measuring the leftover oxygen in the exhaust, the reactions of the catalytic converter DO change the this original composition that left the engine. Perhaps the probe is already adjusted to compensate for this, BUT I just wonder if the characteristics of these new cats are significantly different than a stock cat setup. So in reality you aren't actually running leaner, but the probe is mistakenly reading leaner. Now, if the probe was installed on the engine side of the catalytic converter then the issue is moot.

 

Darin that is a very good theory. The place we've all been getting the dyno has in fact been using a probe in the tailpipe.

Anyone have any more insight to this?