I'd like to boost low/mid-RPM torque. What are my next steps?

[johnmk]

My car: 2015 BRZ w/ PTUNING kit w/ GTX2867R & PTUNING headers & Perrin 2.5" resonated exhaust. Everything wrapped with DEI Titanium wrap all the way to the turbocharger.

The only appreciable differences I'm aware of between my car, and PTUNING's two cars I've seen dyno results for (both GTX2867R) are the diameter of the exhaust system, which I believe don't significantly affect the area of my focus, that being low/mid-RPM torque. Also, in Washington State, the highest octane fuel that's widely available is 92, so what's what I use. PTUNING use 93, which is the highest that's routinely available in Virginia. My understanding is this might affect results a couple of percent.

The difference between my results here in Washington State, and PTUNING's results in Virginia, however, are about a 25% reduction in torque in low-to-mid RPM torque in my car. That's actually far more important to me than torque and power anywhere else, as my primary goal is for a Daily Driver where I can react quickly (when safe to do so) in ordinary traffic conditions.

My tune:
Light red = My torque
Bold red = PTUNING's torque on a near-identical car.



As you can see below, I'm missing a ton of low/mid-RPM torque. On a near-identical car, PTUNING were able to get an average of 40 more torque between 3.0 - 4.5k RPM. Between 3.4-4.1k RPM, the difference is about 55 torque.

Something's wrong somewhere, and I'm not knowledgeable enough to say where that might be. But my research points to a few possibilities:

1) Boost control, or lack thereof:
My only boost control is the 11 psi wastegate spring. When results with the 7psi spring showed max horsepower reaching only 250, my tuner swapped in the 11psi spring to see where that would take me. That bought another ~50 horespower. I've done some research, and apparently one of the functions of boost control is to increase turbocharger responsiveness by keeping the wastegate spring fully shut until you come very near the programmed limit in boost. Without mechanical or electric boost control, I'm at the mercy of the wastegate spring and its proclivity to start opening well-before 11 psi. At least, that is my understanding based upon what I've read. I don't know if it applies to my TurboSmart wastegate (or whatever's included in the PTUNING kit).

2) Exhaust leak? I smell rich exhaust in the interior cabin on hard acceleration. I might expect that if I had an open wastegate, but mine is recirculated back to the exhaust system and should be going out the tailpipe.

3) Perhaps the tune didn't adjust cam timing much? Or they're just not experienced with the PTUNING kit. I believe this might have been their first PTUNING kit installed on a BRZ. It's possible they were operating under the impression that I needed my car back ASAP since I was borrowing my grandmother's Nissan. I'm not sure how time-intensive cam tuning is but I've been told it's quite the time sink if you have no base map to go off and you're starting from scratch with a new kit you've never seen before.

4) Charge/intake piping too voluminous & long, slowing response? I would think if this were the problem, it would show up in the PTUNING dyno charts, but I don't think it does. Either that, or transient response is something that doesn't show up in dyno charts. I really don't know.

Before I install boost control (if I go that route, which is likely), I'd like to know what my options are. I'll probably have the 7 psi spring put back in, as my understanding is boost control can turn a 7 psi spring into a 7 through 14 psi spring. More difficult for me to figure out is which boost control should I use? So many companies make electric boost control products. Can a tuner work with pretty much any boost control, like a coffee drinker adds any cream to their coffee? Or are they quite different and involve differing programming languages/wiring, etc.?

PTUNING has a boost controller that is pre-made to work with my kit & car. If this one better than the rest or are they all the same as far as difficulty of install/tune/reliability, I don't know.

http://www.ptuning.com/subdir/itemde...&ModelDesc=BRZ

I believe my shop usually installs an AEM electric boost control, however. I'm tempted to do everything I can to make sure my results are as close as possible to PTUNING's, however, so all else being equal, I'd looking at their product.

To those who read this far and can offer some helpful advice to this newbie, I appreciate it very much.

Sincerely,

-Chad

[mkivsoopra]

My guess is your tune. You should have Toan @ PTuning do a remote tune for you. I have the bigger GT3076R and my torque curve is flat like a table.

[CSG Mike]

Who did your tune? Are the different results with the same tuner?

[johnmk]

No, they're different tuners. My results are with a local company here in Washington State. The overlayed bold red line was tuned by Toan, in Virginia. Their car used electric boost control.

How much of the difference can be attributed to Toan's use of electric boost control vs. the other possibilities mentioned in my original post? It's also possible I've left off some possibilities, like defective car or something.

[Spartarus]

I'd like to see the boost curve on your graph.

The tuning may be partially (or mostly) to blame, but I'd bet money you have an exhaust leak.

[CSG Mike]

Originally Posted by johnmk

No, they're different tuners. My results are with a local company here in Washington State. The overlayed bold red line was tuned by Toan, in Virginia. Their car used electric boost control.

How much of the difference can be attributed to Toan's use of electric boost control vs. the other possibilities mentioned in my original post? It's also possible I've left off some possibilities, like defective car or something.

Boost control has little to do with when your turbo spools.

[GsxrMe]

Doesn't oil pressure affect the valve timing?

[VitViper]

@johnmk do you have a boost plot to go with the dyno graph? My car on 7psi makes better power through that area than that and it's a "big" 5862 that doesn't come on til after 3500 or so.

[johan]

Originally Posted by Spartarus

I'd like to see the boost curve on your graph.

The tuning may be partially (or mostly) to blame, but I'd bet money you have an exhaust leak.

Originally Posted by VitViper

@johnmk do you have a boost plot to go with the dyno graph? My car on 7psi makes better power through that area than that and it's a "big" 5862 that doesn't come on til after 3500 or so.

:yeahthat: Would be good to see how it's spooling and how it sits throughout the RPM range.

That said, the way the torque is shaped, there's little to no possibility that the tune isn't to blame here.

I'd say though, you shouldn't smell anything in the car under acceleration - unless you have an open breather for the PCV system.

Originally Posted by CSG Mike

Boost control has little to do with when your turbo spools.

This isn't entirely true - you can force the duty cycle to max until the boost reads close to your target and then taper it back to a more reasonable duty. This spools the turbo quicker by making sure the wastegate stays fully closed until you want it open.

[Northwest86]

Apart from boost creep.an electronic boost controller will help reach full boost earlier in my experience. That said peak numbers will be similar once they both make full pressure. An ebc should increase low down torque a bit. Mine for example builds boost steadily with the wastegate but has full boost by 3200 rpm on a gtx30. Apart from that it could be tune for some of the difference and the rest is most likely just a disney dyno or inflated numbers through a dyno queen tune or messing with a bunch of other stuff when doing the run to inflate the numbers

[ptuning]

I generally opt to stay out of threads involving another tuner's tune, but since this is regarding our turbo system, I'll give my input. It's most likely that your cam timing just isn't optimized yet. It's not an easy thing to do without live tuning, but is very necessary with this engine.

You must write it custom maps to live switch the cam timing in order to quantify any power/torque changes on the dyno. Using regular flashing to alter the cam timing often results in dyno data that is difficult to decipher. Using the ECUTek map switching allows the tuner to do back to back dyno pulls with cam timing changes. You can even go back and forth with the cam timing to ensure that you're going in the right direction with your changes.

Whether you're running a 7 or even 5psi WG spring with a manual boost controller or our EBCS or using a 10 psi spring without a boost controller, you should not have ANY torque dip. This is especially true with the smaller GTX2867R turbo.

Lastly, if you're smelling any exhaust fumes coming from underneath the car, it may be possible that you have an exhaust leak that can affect turbo spool-up just a bit. Hopefully this helps.

- Toan

[Matt@Cosworth]

hello
as anyone tried running a very early Gdi injection timing, with some retard ?
as this will create an anti-lag function and spool the turbo early?

[johnmk]

Originally Posted by Spartarus

I'd like to see the boost curve on your graph.

The tuning may be partially (or mostly) to blame, but I'd bet money you have an exhaust leak.

Hi Spartarus (and others),

I requested a boost curve early yesterday and have yet to hear back. When I get one, I'll post back here immediately. Is it usual and customary for boost to be measured and recorded?

[johan]

Originally Posted by johnmk

Hi Spartarus (and others),

I requested a boost curve early yesterday and have yet to hear back. When I get one, I'll post back here immediately. Is it usual and customary for boost to be measured and recorded?

It should be present in any datalog with a WOT pull in it.