So I took the Z back to the dyno tonight. Got more this time. 8)

Last time I ran 17lbs of boost with a boost leak. Last time yielded 330whp & 409wtq.

New for this dyno run:
20lbs of boost
gutted plenum & plenum spacer
3" cat back

378whp & 445wtq this time.

I was told my car still isn't holding boost past 5200 rpms & that if it did I should be over 400whp. The shop feels it's my internal wastgate flapper not holding.

***Thanks to Yogi for taking me there, driving my Z on the dyno, & helping to try & figure out why my boost is falling off!!!

 

That's awesome Mark!

 

looks like its running a little lean at 3k

 

Looks like a lean spike at 3250. I'm guessing that's where the boost comes on hard. What are you using for fuel control? Looks like it's taking a second for it to kick in and add the right amout of fuel. Also, the rich spots at the end are being caused by either an atmospheric BOV not holding the boost and cracking open, or the wastegate flapper is being forced open causing a drop in boost. Time for a stronger spring.

 

I blame Kam

 

That slightly lean spike only occurred on that run, it didn't show up on the other two runs. And yes that is when boost kicks you in the ***. JWT ecu with Apexi AFC.

Well something is not allowing me to hold boost at the higher rpms that's for sure. My wastegate actuator has two valves on it to hold the flapper stronger than the stock one could. Not sure what else to do with it.

 

Sounds like you don't have your fueling indexed to boost, but rather to rpm. I'd suggest changing that. Get some kind of boost dependant fuel controller. Either something mechanical, like an FMU or something electronic, like an extra injector controller. You can see that boost starts to build at 2500 rpm, but your fueling setup didn't start to add extra fuel until 3250 rpm. I'm guessing on your other runs, boost came on either a little later or ramped up slower. That's why you didn't see the lean area. You ran lean enough to cause a dip in power. That kind of thing scares me on a turbo car.

As for the boost dropping off on the top end, it might be time to start looking at external wastegates. Something in a 35-40mm unit.

 

Nice numbers Mark!

 

Actually all 3 runs looked exactly the same except for that slight lean area.

I am looking into getting an external wastegate.

 

Good job! I hope you be able to fix it out what wrong with it.


BTW last time i smelled 100 octane on you car.

 

I mostly run 100 octane mixed with 91. THough I have run just 91 with no noticeable problems. JWT told me that with the amount of air I'm flowing that I should run 100 octane all the time. I don't drive it much so I don't mind spending the $$$ for 100 octane to ba safe.