Okay here is the deal. We had a dyno day for the Panhandle Z group. We had 5 naturally aspirated 350Zs dyno. Here is some of the information on each car:

Light Blue: My Car http://350z.civichatch.com
Red: Stock 350Z with only drop in K&N
Green: Stock 350Z with only crawford intake manifold
Dark Blue: AEM intake, 5/16" spacer, test pipes, HKS dual titanium exhaust
Brown: Injen cold air modified to warm air intake and Invidia exhaust

Here is the dyno plot of everyone's car on a 5th gear pull. All runs were of course on the same dyno on the same day and are all SAE corrected:



As you can see from the results the more stock 350Zs made more power and the brown one made the least power because it went so rich in the top end. Also you can see that my car was making the least power most of the time due to the air fuel ratio staying near 15:1 the entire time. Now here are all 3 of my runs. The first 2 are 4th gear and the last was a 5th gear run. The dyno shop was worried to run my car in 5th gear because it was so lean, but I told them go for it:



After that day of course I was worried about my car. I haven't changed any mods on it in a long time and it has always run strong. Well I obviously ordered a PLX wideband this week so I can keep tabs on the air fuel ratio. I don't think the dyno was messed up because everyone else that dynoed on it the air fuel seemed fine. I was thinking maybe my plugs or MAF was messed up so I pulled them all and did a compression test today. All 6 cylinders were 210 +- 4 psi so compression is fine. I re-gapped the plugs and I alcohol cleaned the MAF. I will see how it runs this week and will install the PLX next weekend hopefully. Any suggestions, questions, or comments?

 

that blue one is running pretty lean..

 

Thanks Captain Obvious. I believe I stated that already as that is my car, and I have tuned a few cars in my days. Now do you have any solutions as to how to remedy it. I don't trust piggybacks that just trick the computer, and I'm not a fan of re-flashes as it takes all the tuning ability out of my hands.

 

u were a lot nicer when i first joined the boards =\.

Honestly it seems to be systematicly erranous. What was ur A/F at idle? Whoever did your dyno may have placed teh sensor in a bad spot accidentally.

 

Nice post King Tut!

I had similar AF ratio experience, but I ordered Cipher to monitor fuel ratio and timing. You will see that ratio fluctuates a lot but at WOT its falling steady, although slowly. I don’t worry any more. You just lost peak power, so you can either start taking off your breathing mods or buy UTEC and find good tuner for it.

Good luck.

 

I'm still nice, it was a joke man. That's what I thought so after the first run I had them check the positioning. I wasn't the only one there with dual exhaust and my buddy with a Vette that dynoed right after me had a perfect air fuel ratio so the machine was working properly. I figure this just goes to show that it really all depends on how your ECU is feeling the day you go to the dyno. Either that or there is something wrong with my car which I doubt.

 

I'm definitely not removing any mods, and unless you switch to a MAP sensor the UTEC still just manipulates the MAF voltage which to me is not the answer by any means. It is just a fancier version of an SAFCII or any other device that tricks the ECU by messing with the MAF voltage. The ECU can learn the tricks and then you are back to square one. I'm leaning toward a reflash if with my wideband I determine that my car is in fact running this lean. I figure I can send AAM my dyno sheet, and let them know what my wideband says and then when I get it back I can verify that the reflash did help.

 

I think that UTEC can drive your fuel injectors without MAP sensor and without ECU saying.

 

do you guys think that the injen intake contributed to the brown cars low numbers. Any of you prefer cold-air versus short-ram? I have the injen setup as short ram, and iam looking to get rid of it because every one i see with it has low numbers, including myself..

 

It come to my attention that cold air intakes and plenum spacers can work against one another and cause hp loss. If you have your injen set up as short ram you should be ok. A heat shield would be nice, but given the small hp upgraded associated with aftermarket intakes, it's probably not necessary.

 

I tested this on the drag strip a long time ago. DO NOT use the Injen Air Filter if you set the Injen CAI up as a short ram. The Injen Air filter actually blocks the cold air and sucks in hotter air when setup this way. You would need a filter like the JWT Popcharger on the Injen intake for a short ram setup to work properly. I can't remember exactly but I lost somewhere around 0.5-0.7 seconds in the 1/4 just from switching the Injen Intake from a CAI to a short ram setup!!!!! That was on the same day, same track, with a 5AT that is pretty darn consistent otherwise.

 

So would the MREV 5/16 spacer and Nismo CAI together cause a negative effect for HP?

 

How come the red car, made 242 HP, 235 tq on the first chart and only 233 hp,217hp on the second? Pretty big delta.

 

Wow how rude, lol. jk

Interesting thread!

 

The second chart is only King Tut's car and doesn't include the other 3 cars from the first chart.

 

As stated don't just look at the images READ BEFORE YOU POST. The FIRST chart is a comparison of all 5 cars. The SECOND chart are MY 3 RUNS. Hope this clears up any confusion. I have the Dynojet data files for everyone's runs. Here is another chart of an APS TT car: