Low numbers with aftermarket internals?

[dnlsnow]

I'm looking at possibly buying a '99 GS-T, but I'm a little worried about the dyno numbers.

It has at least the following mods:
APEXi Power FC engine management system with commander
EVO III big 16G
race head with porting, titanium valves, valve springs, retainers, lifters, etc
Venolia pistons and rods
cams
phantom grip limited slip
injen intake
front mount intercooler with the short routed 2.5" piping
custom 3" turbo back exhaust with cat converter and resonator
manual boost controller
550cc injectors
walbro 255 lph high flow fuel pump
coil over plug ignition set up
Symborski shifter kit
short shifter
Greddy BOV

Tuned and Dynoed at 251 whp at 97 degrees outside on ~20 psi

This seems low in my opinion, especially considering my cousin had a GSX which dynoed at 305 with stock internals and 18psi.

Whats going on?

 

[viperlp01]

Hmm those numbers are actually decent considering his tuning device and his injector size.. Its pretty much at evo horsepower at 20 psi.. Engine internals dont make horse power unless you increase compression.. They just hold the amount of power you put to it.. Your cousin's gsx made 300hp at 18psi on alot bigger turbo i bet.. PSI is mainly just a number. Yes the velocity of the air helps with torque ect. but airflow=power... your cousin 18psi is pushing more lbs/min of air the that car at 20psi..

 

[Rob10_99]

Being in Virginia I assume its 80% humidity or more? I would do a compression/leakdown test on it.

Are you sure those are Ti valves and not Ti retainers? huge difference.
Who tuned it? sounds like they suck. Have any logs?
How about an FPR, might have caused some issues with fueling.

 

[dnlsnow]

Yea, the humidity would be somewhere around there.
Not sure about the retainers/valves, I'm just going by what the guy told me.
The motor was rebuilt about 30K ago...so the compression is probably (hopefully) ok?
Tuned by MachV motorsports. He probably has the logs but I haven't seen them.
I would assume it has an FPR but he didn't say anything about one.

 

[viperlp01]

Did you even read my post... 20 psi on a 16g is only going to net between 240-270hp max unless your running meth or race gas and a ton of timing..

 

[Dewayne Waldron]

retuneWith the right tune and injectors I've seen up to 420 hp from the 16g

 

[viperlp01]

retuneWith the right tune and injectors I've seen up to 420 hp from the 16g

You have personally seen this.. It is possible but with meth i gaurantee... at 25 psi on my 16g in at 38lb/min and im taking away 2 degrees of timing on a 11.2 a/f.. The intake charge gets tooo hot.. You would have to push 30+psi on race gas or e-85 with meth..

 

[Dewayne Waldron]

Yea, your right. If I can recall right he's running meth. sorry.

 

[dnlsnow]

Yea Viper, thanks for your input. It's reassuring. However, my cousins only had the big 16g and it seems like there are many others on here making 300hp with 16gs.

It also has a 1g throttle body and intake. He also said it made 303hp on alcohol injection at 24psi. The injection system no longer works though.

 

[viperlp01]

Im over 300hp on my 16g. I used my time slip to est hp... A dyno should strictly used as a tuning device. They are all different and they are designed to be heart breakers..

I bet what is really hurting you is all that porting and a semi small turbo.. That build needs a big turbo to really open it up..

 

[dnlsnow]

If I get the car, a bigger turbo would certainly be one of my first upgrades.

Dumb question- with a build like this, if the boost was set low and it was driven conservatively, what kind of reliability could I expect? Almost all the work was done by a professional shop and the car seems to be well taken care of.

 

[JEFFREYCASTGSX]

Oh my..... dynos don't mean !@#$ its just a tuning device, and that's it. There's a lot of variables that can make more or less power; compression, boost, timing, afr's and even that coil on plug ignition that's on the car. Also those

 

[dsmfa9nutter]

They are all different and they are designed to be heart breakers..

Other way around actually, most dynos have inflated numbers.

Dynos are best for testing how effective something is via before+after testing as well as getting a baseline to see how effective your tuning may be. 1/4 mile mph numbers are pretty good indicators of hp numbers.

 

[1992awdlaser]

Just because you have a built bottom end does not automatically mean you will make sick power. You have to have a combination of right parts for the specific amount of power you want to make or times you want to run. And it has to be running and tuned correctly.