Da1WiTsKiLz

Hey guys, I finally had the time to get my car on the dyno after running this setup for the last 3 years. I'm disappointed with the power, I thought the car had another 20-30hp in it, but it was a Mustang dyno so the numbers aren't as high as they could have been at a different shop.

1999 LS, stock engine with 80K miles
-Greddy turbo manifold
-Td05h-18g
-Custom 3" A/C compatible downpipe -> 3" QTP cutout -> 2.36" Apexi WS2 exhaust
-Greddy wastegate with helper spring
-2" hot side piping, 2.5" cold side piping
-350hp Spearco intercooler
-Skunk2 intake manifold

-450cc DSM injectors @88% duty cycle
-190LPH Walbro fuel pump
-Hondata s300 with boost by gear

Corrected numbers were 235hp/220tq, the dyno chart below is uncorrected

Open 3" downpipe, 14PSI

Video:

wantboost

iTrader: (2)

healthy setup.

does your downpipe still use the Greddy cast elbow? the reason I ask is most Greddy 18g setups with a full 3" downpipe are fairly close to 300hp, even making 300 or a tad more with a better wastegate actuator.

wantboost

iTrader: (2)

ohhhhh LS motor lol. I was thinking vtec head. doh

a good set of cams and a Skunk2 IM would see a good power increase, especially in the midrange and topend (more opened) from where the graph turns into a wave to rev limit

Da1WiTsKiLz

Nope, my downpipe uses a modified 3" T25 turbo outlet designed for a 240sx in place of the Greddy casted elbow. This goes into a full 3" downpipe, and right out a 3" exhaust cutout.

The car is already running a Skunk2 intake manifold, but I still have the stock LS cams.

I was expecting to make around 265hp/245tq with this setup at 14PSI. The timing is pretty aggressive at 18* (plus base timing), and the 450 injectors are at 88% duty cycle. I saw a couple of other LS's with less timing and less PSI make 250hp/240tq. Any thoughts on where I could be losing so much power?

Muckman

iTrader: (2)

Ive been replying to your thread over on TI but Id rather we'd bring it over here. I think you'll find more information and more help here. Like I said on TI, you need to get ignition maps and logs to really compare data. Otherwise its just a list of parts we are comparing.

Your torque curve tapers off harder than the others you are comparing to which indicates a loss of flow. Could be as simple as a poorly flowing air filter or a boost leak.

blackeg

it almost does look like an inconsistent boost. almost looks like the boost spikes when it first comes on, then settles and may even taper off a bit.

we all know that the ls drops tq pretty bad above 5500-6000 rpm but that drops real hard. that sk2 pro series intake manifold which should really help a lot with it not falling off tq a lot. also its kinda a bumpy curve for the smoothing to be on 5. in for timing maps and boost plots. id say it could either use a few more degrees, or its loosing 2-3 psi

LightningTeg

Damn that thing sounds exactly like my greddy setup did. How much boost?

Boyle.R

Those Greddy cast manifolds suck big time, i'd change that out and you'll see much better power at same psi.

CaliforniaDad

iTrader: (6)

Sounds good, Looks like to need to replace your motor and torque mounts. That engine moves allot.

Da1WiTsKiLz

I'm working on getting the datalogs into a format that is actually readable outside of Smanager. I will post those up as soon as I can. The boost pressure was actually really stable at around 14-14.5PSI, and the timing was very smooth right across at 18-19*. IAT's were in the 120* range.


Between 14-14.5PSI. It was actually very stable. With the helper spring in the wastegate it produces 12-13 PSI with no boost control. Add in boost control through hondata and it made 14.5PSI but it wouldn't really get past that.

The mounts are fairly new. Beck Arnley rear mount and torque mounts.

TheShodan

iTrader: (14)

What wastegate actuator are you running? If it is still IWG, did you port the wastegate exhaust portal and actuator door?

LightningTeg

Throw some inserts in the torque mounts and you should be good. Doesnt add too much vibration after they are 'broken in'

motoxxxman

us prelude guys often just fill the front and rear motor mounts with 3m WindowWeld, it's a 60a urethane. helps tremendously with engine movement and barely adds any vibration

Da1WiTsKiLz

Im running the standard Greddy internal wastegate. It holds 6 lbs of boost on its own with a little preload on the arm. I then added an external helper spring (a 19lb spring IIRC) and together the combination makes a stable 10.5 PSI with the full exhaust and 12-13 PSI with the open downpipe. The turbo is completely unmodified, no porting whatsoever. I am using a custom 3" downpipe which eliminates the Greddy cast elbow.

I had 75a Innovative motor mounts but they had way too much vibration for my taste. I may try some inserts or filled OEM mounts when the weather warms up a bit.

TheShodan

iTrader: (14)

Change the actuator all-together and it'll get even more stable. Helper springs.."help" the issue, but an actuator replacement helps the boost controller keep the boost pressure even more steady than the helper spring.

Nice going by staying with the GReddy Kit!!