I purchased this car with the mods (see signature) about 2 months ago. Based on others' posts with similar mods, I expected around 350 hp at the wheels, but was only able to muster a disappointing 324 hp on both pulls (see attachment)! It was typical Charleston summer day - hot and humid (95F/90%)!

Of course all the ussual unknowns regarding dyno accuracy...blah, blah, blah... My A/F readings stayed in the low 12s for the pulls but it smelled very rich - borderline bothered our eyes after the 2nd pull, so I'm not sure I believe the A/F numbers. I'm relatively new to this, but I did confirm simple things like no knock retard, no codes, no damaged or shorted plug wires, no vacuum leaks, butterfly is against the stop.

The car runs fine, but there are a few things that I question: I do notice that the rpm doesn't drop immediately when I take my foot off the pedal (compared to my mostly stock 99 Z-28 that I had previous to this car) - i.e. I don't get much engine braking until a couple of seconds after I lift off the throttle. I thought I would mention this because my previous car didn't have this couple of second delay when I cut the throttle - maybe a symptom of something not right...? Also, my fuel mileage is not as good as my previous car. Initially I attributed it to having a new toy and driving it hard, but I've settled down and the fuel mileage is probably 80% of what I used to get with my old Camaro. Again, running rich....?

I did drive around tonight while looking at Predator monitoring data, but not knowing what exactly to check or what expected ranges are, coupled with limited info display on Predator, I didn't really learn much other than O2 sensors in the headers seam to be all over the place (50 to 900 mV) and I most of the time couldn't account for radical swings or variation between bank 1 and bank 2 and the O2 sims seem to cycle back and forth between 385 and 800 mV. Again, not sure if this is good/bad, or typical.

From some of the searching and reading I've done, it looks like I need a dyno tune or mail order tune at a minimum to take full advantage of the mods I have, but I'm concerned that this still won't get me where I should be or there is something else wrong. It is my daily driver, but I still want to make the most of what I have....

Thoughts, comments, and suggestions are appreciated....

 

that's about what I made with the same mods except I didn't have an LS6 intake, no ported TB and, was not running 18 inch wheels yet. If those things are like my 18"s they weigh 10 LBS more each over the stock 16"ers. I've heard you'll loose about 20 HP to the wheels with that kind of extra weight in the wheels. I've done a Dyno run after I put on the new wheels, added the intake and a very bad tune (10:1 AFR) I was 20 HP short!

 

that's about what I made with the same mods except I didn't have an LS6 intake, no ported TB and, was not running 18 inch wheels yet. If those things are like my 18"s they weigh 10 LBS more each over the stock 16"ers. I've heard you'll loose about 20 HP to the wheels with that kind of extra weight in the wheels. I've done a Dyno run after I put on the new wheels, added the intake and a very bad tune (10:1 AFR) I was 20 HP short!

So, I threw in a CAM. That makes up for it!

 

I thought about the added weight of the wheels too. Not sure what the stock 16 or 17 inch wheel and tire combos weigh, but when these were shipped to me with just cardboard taped on the front and back sides (minimal packing weight) they weighed 60 lbs each. The rims are definitely lighter than stockers, but the tires are heavier so even if the wheel tire package weighs the same, it's all at the OD so it will have some impact, but 20 hp seems like a lot.

I would like a cam, as it seems like the next logical step as far as hp for the money, but I want to make sure I'm getting the most out of what I have first.

 

Ya that nearly what I put down with FIPKII,TBbypass and !muffler...and it was july,hot,humid and sticky.

 

I did my 02 z06 there yesterday afternoon and had lower numbers also. That shop is like an oven.

 

Minytrker, have you had you car on the dyno before and can confirm that their reading low? As much as I would like to blame the dyno, I only have one data point so I really have no data! Also like I said the fuel smell in the building was pretty strong after I ran on Saturday, so I’m probably a little rich regardless of what the A/F ratio shows. I think I need to learn more about O2 sensors and confirm mine are okay, and then I think I will get a mail order tune from RWTD, or do you know anyone local to the Charleston area that has a good track record for dyno tuning LSx cars?

 

That was the first time my z06 was on a dyno. One of two things happened or maybe both. My car got to hot on the dyno from lack of air and it pulled back timing which is what I think, or there dyno is lower than others. I am thinking about either going back and having my car cool off before the run or trying out the dyno off of remount road. I dont have anyone here for tuning, I wish I did. I am either going to North Carolina or Columbia for a tune.

 

its also a bit rich,it would probably pick up powA if u leaned it out a bit. i like to run mine at 13.3-13.5 afr on motor.

 

dynojet or mustang? take it to the track!

 

its a dynojet

 

Weird, I make similiar numbers and mine is an A4 with stock manifolds.

 

My uncle's shop has a Mustang Dyno. That thing is sooo much more accurate! I love weighted dynos.

 

I think having it tuned will help to unlock it's potential...I hope. That seems to be the difference between my car and other cars with similar mods that make more power - they've been tuned and mine hasn't. Suposedly a stock car can gain 15 hp with just a tune, so would it be unreasonable to expect 25 hp increase if I had a decent calibration? On the same dyno I ran the baseline, I think 350 hp is in the ballpark for way the car is set up. Also, it would be nice to say the dyno was reading low, but not sure that can be proved, at least not easily...

 

O2 sensor readings should be swinging up & down. The sign of the sensor going bad is when the swinging slows down.

The weight of my stock 16" rims w/RSAs are ~45-46 lbs. So your 60 lbs rims/tires are heavy. HTH