why torque falls down from 5800rpm??? tuners please help!!!

[NSXZERO]

turbo nsx, gtx35r 4.5psi ,
why is torque falling from 5800rpm?
vtec at 5000rpm, checked voltage (output 12V at 5000rpm) on the ecu, but not on solenoids directly)
possible intake manifold (runners, plates stock) problem? Do people remove motion plates or not on boosted aplications?

revs timing (at 4.5psi on )

4000 33
5000 33.5
6000 33
7000 35
8000 36

boost stable!


I am thinking what should be the problem?
any help very appreciated.

 

[tbnsxt]

More information on setup please.

Induction pipe size, a boost leak, too small of turbo. just some possibilities.

It could also be your vvis plates

 

[Hapa88]

On a stock NA car,
Fuel pump switches from low flow to high flow ~4500rpm
VVIS is supposed to change over at 4800rpm
VTEC kicks in around 5800 rpm

Maybe fuel pump or injector issue? Or VTEC not activating?

 

[E-Nough Logic]

there are quite a few possibilities but keep in mind the gtx35r doesn't flow a lot of air efficiently at 4.5psi.

Honestly I dont think your torque is dropping "that" much, roughly 20ft/lbs. Why did you guys stop at 7000rpm? The graph is scaled from 300-500nm which makes it look like a rather drastic drop. Even if you dropped another 20ftlbs until 8200rpm then you would be at almost 400whp which is good for .3 bar and right about the max the gtx35r can flow at that boost level.

 

[NSXZERO]

fully built turbo car
93.00 pistons 9.0 comp. CP
pauter x beam rods
rc 750cc low impend.
fuel pump resistor removed.
vtec lowered to 5000 rpm (see attached log picture on first post)
angus ap-x turbo kit with gtx3582r
walbro fuel pump
fuel pressure stable
AFR stable 12.2-12.5
boost pressure stable 4.5psi


maybe tomorrow i should check if 12V reaches VTEC valves and i will make dyno runs with VVIS opened/closed.

 

[dynomike]

has the engine ever been apart. It definitely looks like there is no vtec a quick test would be to raise vtec to 9k so that it does not come on if there is no change in power than you definitely do not have vtec engagement. also make sure that both high side 1 and 2 are configured in the software to engage vtec

 

[NSXZERO]

electronic is AEM V2, bought from SOS few weeks ago. The starting map was used map which was included with the AEM (i think it's for SOS twin turbo kit).

 

[dynomike]

what year is your car?

 

[E-Nough Logic]

fully built turbo car
93.00 pistons 9.0 comp. CP
pauter x beam rods
rc 750cc low impend.
fuel pump resistor removed.
vtec lowered to 5000 rpm (see attached log picture on first post)
angus ap-x turbo kit with gtx3582r
walbro fuel pump
fuel pressure stable
AFR stable 12.2-12.5
boost pressure stable 4.5psi

maybe tomorrow i should check if 12V reaches VTEC valves and i will make dyno runs with VVIS opened/closed.

12V at the solenoid doesn't mean VTEC is working. The solenoids could be an issue, or there could be oil pressure problems causing VTEC not to engage. VTEC is very easy to check on the dyno, the tuner would have been able to check this in 30 seconds.

 

[NSXZERO]

dynomike its a 91 nsx

 

[Operator]

This point(5600) your exhaust presure crosses boost pressure.
GT35 ...it just have too small turbine for NSX if everything else
is done correctly.
Just disconect VTEC ..and re-run it ! Your V-tech seems to be ok.

 

[ScienceofSpeed]

We recommend removing the VVIS system on turbocharged NSX:
http://scienceofspeed.com/products/engine_performance_products/NSX/ScienceofSpeed/VVIS_delete_kit/

What turbine do you have on your GTX35R? Even if it is the smaller housing, I wouldn't expect torque to drop off suddenly like this.

The base calibration does not have the VVIS enabled. It is activated by using the LS5 output. If you'd like us to review, please e-mail the calibration file to:
[email protected]

Also, let me know what the unit the power and torque graphs are displayed in.

-- Chris