So, i add, Kinetix plenum V+, headers, test pipes, pop charger, pulley, dual HKS custom exhaust, UTEC and get tuned and only wind up with 234hp> What the hell is wrong with my car. It's tuned right, A/F is great, timing is on. According to manufacturers specs, i should have added at the very bottom least 40hp.
My base dyno was on a Dynojet at 229hp.
My last tuned dyno was at Forged with 234.1hp
I'm running 13.17 in 1/4 which isn't bad but, damn. Seems every time i mod, i lose.
When i came into Forged, i based at 225, ran 245hp on a dynojet three days before. So, if i add 20hp for the difference in dyno types, i only wind up with 254hp. Isn't 254hp a little weak for all my mods?

Also, i am weak up top, i know the 3.5 rear end hurts me a little. What do i do to get some top back? Anyone added a 1/4 spacer to a kinetix plenum? Will that help?

 

The problem isn't your numbers, exactly. In order for you to be able to accurately compare two dyno numbers, you've got to do your baseline dyno, install your mods and re-dyno immediately afterwards so you can better eliminate different atmospheric conditions and other variables. Dynos made by different companies dyno the same engine at different numbers. Chassis dynos are more an art than a science, so even two different operators on the same dyno can come up with different numbers on the same car during back to back runs.
Also, you can't just add 20 hp to your post-tune numbers to correct between dynos because it just doesn't work that way. SCC had a great write-up about this. Look it up on their website and hopefully you'll feel better about your results. As long as your post-tune numbers were larger than your pre-tune baseline of THAT SAME DAY, you're doing fine.

 

Our demo car at perf nissan had the following installed:
UR pulley, Intake, Nismo headers, high flow cats, nismo exhaust, tilton clutch/flywheel, ( i think it had a technosquare retune, but not sure, and it may have had nismo cams, again, not too sure) and it was putting out numbers hardly above yours, i think in the 260 range. So you're not too far off i don't think, especially with those types of quarter mile times. I would have thought that the UTEC might have helped more, but i guess your car wasn't in need of much tuning to be optimal.

Just cus you have a progamable ecu doesn't mean you'll notice huge gains, it all depends on if your car needs it or not.

 

You cannot assume that aftermarket components from different manufacturers can be used together perfectly in an additive fashion.

2+2 never equals exactly 4 in these situations more than 3 just never 4.

 

there is no reason you should be hurting at top end with your mods, if anythign you should be complaining about Tq I would think until you got tuned.

are you running 13.1 with slicks? if not then don't worry about dyno, it's how the car feels. race another Z from a roll and see what happens. you should pull good on them.

does all the exhaust match up in terms of sizing? if you are hurting up top it has to be an issue with the flow being messed up in your car from the breathing mods... maybe take one or two off and try to balance it out... I don't know how to measure where the problem is, but if you can get a reading on intake side flow and exhuast maybe you'll see a difference.

 

I'm only pulling 20mph more up top. I guess, my vehicle just doesn't like mods. I'm going to take off the Poop charger and try the stock box with a KN filter next time at the track.

 

i hear the plenum your using isnt the best out there also, ...maybey its negativly effecting ur top end aswell.

 

I always look for K&N stickers/decals to KNOW I have an extra edge, especially in warm and Summer weather with my stock air intake system.

 

N/A modifying is just a road of disapointment. Your numbers don't surprise me at all. IMO, they may be on the lower end, but still definitely within the range I would expect to see with those mods.