This is my dyno in January when it was ~40 degrees cooler. I only had test pipes, pulley, and Pop Charger at the time along with a bad exhaust leak.


Anyone want to volunteer?

 

what was the temps at which you tested it at? it was fairly warm this past weekend in LA.

the 40 degree difference might play a factor in the HP difference,

so you're saying you went from
leaky exhaust, popcharger, pulley & test pipes to

everything + MREV, headers, and full catback?

its gonna be really really hard to do "dyno comparison" when you dont have the same mods and the weather is different.

 

I forgot to mention the temperature in the shop was around 93-94 degrees.

Yeah, I have all the mods in the signature on the current dyno sheet. There was another Z that dyno'd 20whp more than I did with just about the same mods.

 

1. check your spark plugs for residue/white flash marks consistant with pre-detonation/lean condition
2. check for leaks at the headers and /or lower plenum
3. was your car hot or cold during the pull? i.e. were you first in line or toward the back
4. same wheels as b4?

 

I'm definitely gonna pull the plugs and double check them. It surely doesn't sound like I do but I'm going to double check. I do have a minor leak at the y-pipe and mid-pipe.

I was sort of in the middle, my car was probably somewhat warm I'd guess.

The last dyno I had the stock Touring wheels on

 

In the first dyno, You are running far too rich for N/A, especially in the higher RPM range.
My car likes 13.0-13.2 AFR the best.

Check out the AFR in this thread if you haven't seen it already, where I made best power on the dyno.

https://my350z.com/forum/showthread....ighlight=tuned


Also, heat soak can play a huge role in HP #'s. I have seen 10-15 hp differences easily just by squirting some water on the plenum and intake tube.

Cooler intake temperature + cooler ambient temperature = much higher HP #'s


My best guess is that your tune is all out of whack (this has been seen many times with headers), and that if you get tuned you will get back to where you should be.

 

Every car is different. Some Z's make best NA power at 12:1 A/F, right where he is. Although because of the power loss, Id have to think that his likes the leaner tune.

 

Possible, but definitely less likely in this particular situation.

In any case, I assume you agree tuning is in order.


If a particular engine is making better power at richer AFR compared to another engine, that means the combustion chamber is less efficient and you need more fuel to get all the O2 molecules to combust. This could indicate problems with fuel atomization. Of course, "rich best torque" takes place over a RANGE of AFRs, so anything can happen and you're right, each engine is different.

 

+1

 

whats up with all the exhaust leaks?

yea, get a tune (i'd recommend a Reflash) the jagginess of the AFR might be an indication that your car is seeing a lean condition and maybe over compensating by going rich.

oh yea. whats up with the 4th gear pull? is this an auto or stick? sticks should always pull in 5th!

 

Well, when I bought the exhaust for some odd reason the shop didn't give him gaskets

I'll look into buying the hardware kit, just putting it off a little since the leak isn't too bad.

My car is a 6spd but for some odd reason, it's always dyno'd higher in 4th than 5th gear.

I'll be getting a UTEC soon hopefully and let them tune it.

 

it's because the gearing in 4th gear WILL result in higher numbers.. 5th gear is the closest to 1:1 gear ratio

why? for what you're aiming for, simple reflash will take care of it at a fraction of the price.

 

I'll be going FI in a year or so and I'll be running nitrous in the mean time.

I thought it was the other way around normally. From what I've seen from other threads, normally 5th gear would give a higher number.

 

you lose hp, just from general wear and tear... that's a bit too much.

 

Yeah but its only been three months. I honestly wouldn't have thought my previous dyno would have been that high considering I had about 78k miles on the motor.

 

like 5/8 the price? and that's just for one reflash. consider the potential for 5 maps in the UTEC and it's no contest baby. reflash = waste of $$$ if you *ever* need to get an "adjustment". (I know the 2nd time around is discounted, but still).

 

I agree, the up-front cost of a utec is pretty steep, but after the intial cost, it becomes very economical and makes more sense. Plus a good tuner can get a utec closer to an optimal tune better than simply a 'best-guess' re-flash.

Plus the utec can store up to (5) editable maps (provided the tuner hasn't password protected them), can set global parameters, has a dashboard, and logger all at your finger tips. There's even better dashboard & logging software available now (MPS & UCC) to access the utec, or you can just use the standard hyperterminal.

 

I didnt see anyone mention that the difference between the dyno's could be from the higher dyno having a correction to DynoJet numbers figured in . The DD dyno is a load base dyno and will read 8 to 10% lower than a dynojet dyno . Also...on a load base dyno , lower gears can be used with out loss of power read out . SO any gear will do .

 

Hopefully I'll be getting a UTEC soon. As stated before by others, it has selectable maps which I'll need when I add some nitrous. I'll also be going FI in about a year or so.

They mentioned that they always use correction when its an NA car but they never use it when its a boosted car.

 

i don't think it's necessarily what the Z likes, i think it probably equates to the octane of the gas being run. The higher the octane the leaner the mixture can be and more aggressive the timming can be.