Question About SHO Tuning "Potential"

[YamahaRick]

I've had my (totally stock) 2015 SHO about six months now. I'm now looking into performance option upgrades.

A tune from GH rates high with many folks here, for good reason. It is amazing how they can change the performance of your car with one of their tunes. I do have a question about tuning the SHO, and I wonder what the limiting characteristic is. Please review the graph:



The tune w/ downpipes has max HP at about 3500RPM, then drops off. The standard GH tune more closely mirrors the stock tune, maxing out at about 5250RPM.

Why the drop off with the former? Insufficient flow of gas/air/exhaust? A safety measure to keep from blowing up engine or transmission? Turbo flow limitation?

What other changes would it take to get to 550WHP (max stock HP + improvement via tune & downpipes at its max HP)?

More is always better, of course. But what is the required additional work/cost?

 

[BradM]

Commenting here so you can see my signature. I would ask what your goal is. Do you want a maximum dyno number? An 11 second quarter mile? Just more fun on the street? Each cost is different. The biggest limitation that I (and others here) have experienced is the torque management system shutting down the party.

 

[YamahaRick]

So the ECU, in order to protect the transmission, tapers what the engine is capable of doing?

 

[BradM]

Yep.

 

[YamahaRick]

Can that be "tuned" off (to a certain degree)?

 

[BradM]

I've read that someone disabled torque management and the ECU wouldn't work right without it. Even if you did, our stock transmissions are lightweights and will be the weak link. Then the PTU, then the diff. In my opinion, this isn't the platform on which to do a go-nuts build. It requires too many upgrades.

 

[SM105K]

HP drops because the stock turbos aren't big enough to support more hp in the upper RPM.

 

[76FoMoCo]

1st 100 hp 1100.00
Next 100 hp 8500.00
To put it in simple terms.
Ask me how I know

 

[kryptto]

HP drops because the stock turbos aren't big enough to support more hp in the upper RPM.

where I am in my build as Brad told me, "So the log looked good but the one thing I do see is that I think we mentioned before is your turbos are probably not in the best of shape. They are fine at normal and tuned boost but they are maxxed out now. At about 5300 RPM I'm having to throw 100% wastegate duty at them to try to hold boost and they are dropping pretty bad. After 5300rpm and to 6000rpm your boost drops to about 13 psi in 2nd gear and 14 psi in 3rd gear. That is fairly normal though on used turbos of this size. But with keeping the throttle open and all that wastegate you are getting boost spikes probably around 19 psi so riding that wave is adding power"

 

[SM105K]

where I am in my build as Brad told me, "So the log looked good but the one thing I do see is that I think we mentioned before is your turbos are probably not in the best of shape. They are fine at normal and tuned boost but they are maxxed out now. At about 5300 RPM I'm having to throw 100% wastegate duty at them to try to hold boost and they are dropping pretty bad. After 5300rpm and to 6000rpm your boost drops to about 13 psi in 2nd gear and 14 psi in 3rd gear. That is fairly normal though on used turbos of this size. But with keeping the throttle open and all that wastegate you are getting boost spikes probably around 19 psi so riding that wave is adding power"

Yep, I know all about that life.......