[ProDigit]

Just curious if you'd think it's a good idea to adjust the turbo wastegate to a higher PSI, on the hot weather we're getting here in summer?

I hardly ever press the pedal past halfway, even when accelerating on a highway onramp, but 100+F temps do have quite an amount of heat soak.
If I do press the pedal to the metal, I notice there's a power boost I barely ever feel riding the car normally.
So I'd say the engine has some potential laying dormant.

I just feel like the engine lowers acceleration pretty much above 3k RPM, at half throttle, which is why I usually shift before the 3k RPM mark.
If I press the pedal to the metal, it accelerates fine to 4k RPM, before lowering in acceleration.

What I want to achieve is to continue acceleration torque to 4k rpm, even with the pedal halfway pressed. So, in other words, get more boost from 3-4k rpm.

Thoughts?

 

[anthonysmith93]

Just curious if you'd think it's a good idea to adjust the turbo wastegate to a higher PSI, on the hot weather we're getting here in summer?

I hardly ever press the pedal past halfway, even when accelerating on a highway onramp, but 100+F temps do have quite an amount of heat soak.
If I do press the pedal to the metal, I notice there's a power boost I barely ever feel riding the car normally.
So I'd say the engine has some potential laying dormant.

I just feel like the engine lowers acceleration pretty much above 3k RPM, at half throttle, which is why I usually shift before the 3k RPM mark.
If I press the pedal to the metal, it accelerates fine to 4k RPM, before lowering in acceleration.

What I want to achieve is to continue acceleration torque to 4k rpm, even with the pedal halfway pressed. So, in other words, get more boost from 3-4k rpm.

Thoughts?

Adjusting stock wastegate is a huge nono, it's already weak and not made to be adjustable and the car won't run properly. To negate power loss as much as possible in hot weather, use a higher octane gas up to 93, and you'll need to have the AC completely off or it'll be extremely slow no matter what you do, especially if you're not tuned. The vehicle shouldn't really lose power until 5200rpm (if you're flooring it) so if your AC is off, and you're using 93 octane and the car is a dud starting at 4000rpm, something may be starting to go wrong.

 

[jstahliv]

Switching from 87 to at minimum 89 and now ONLY 93 sunoco gas, i have no more power loss/hesitation as i did on 87 from 2500-4000 rpms. Try one tank of 93 and see if it helps, Helped me A LOT.

 

[ProDigit]

Changing to premium fuel did very little to the process to me, at regular temps (below 95F).
I just haven't been able to verify the claims of 91 Oct fuel on a hot summer day, since the weather only seems to get hot when I just fueled up, or when I need to fuel up, we have temps in the high eighties; and as such, I only have used 87 Oct fuel, which has proven okay on most cases...

Unrelated to fuel type is the turbo wastegate, which I accuse of robbing mid-rpm power.

Anyway, rather than adjusting the wastegate arm, I was thinking of hooking up an extra spring, to add extra tension. A low spring of about 1 to 2 lbs per inch, which should translate to 3 psi boost, so the wastegate will still allow stock travel, but just at slightly increased tension.

The mod is a simple one,
Tying a $2 spring in the hole on the waste gate axis, that stretches out to a $2 clamp on the wastegate body.
Can be inserted and removed, without signs of tampering, so the jdweld-type of substance on the arm is not affected.
I really feel on my 2011 Cruze Eco, the wastegate starting to open up around 3k RPM, and being fully open around 5k RPM under load, being the cause of the sensation of power loss after 3k RPM.
It's very mild, but unless you do full throttle, you'll notice the acceleration lowerig.. could also be due to the other (high flow) valves opening up.

Anyway, ordered a box of different length springs that cost me $10, with different tensions already.

The idea came after a friend did it to his car, and improved the boost from 19psi to 22, and noticed a huge performance boost.

My engine is a steel engine, that puts out 148BHP.
It's less than the more modern all aluminum blocks that produce 153HP, while structurally stronger.
Since most engines are created with a good 20% headroom, I just wanted to tap in to that 20%, but only at half the throttle.
The spring I'll be using is a longer spring, with more than 3" travel, which means that most boost is gained at the point of the wastegate opening, and barely 1 PSI of boost at full open.
If I were to use a short spring, with very little travel, it would prevent the wastegate to fully open up, resulting in higher peak hours, but that's not what I'm trying to achieve here.

With a longer spring, and the wastegate fully open, it has exactly the same psi as stock. The spring will just force it closed for a little longer, before opening all the way, which should result in more of a mid-bump in performance, but does nothing different to low acceleration, nor full throttle acceleration.
Meaning, it should do nothing to performance when driving at low throttle positions, with the wastegate closed.
I think the wastegate is too mild to the engine, and may be a setup specifically to my engine.

 

[ProDigit]

I'm beginning to think that there could be a hole in the thinking process..
Like, why does it accelerate more linear at full throttle to 4k Rpm, and why does it accelerate only linear to 3k RPM at half throttle, before the torque lowers?

Might be another issue than the wastegate.

 

[jblackburn]

Don't touch the wastegate. You'll throw it in limp mode or cause internal engine damage.

The Cruze builds full boost relatively early because the turbo is the size of a tennis ball. Everything is controlled/modulated by the computer and tune from there on out. It hits a predefined torque target when it is safe for it to do so (1850 RPM on the automatics)

And don't use 87 octane if it's hot. Just don't.

 

[ChevyGuy]

Two things you need to consider:
1) The Cruze is throttle by wire. The computer controls the real throttle. That pedal just tells the computer what you want to do.
2) The entire engine is managed by the computer. It will only produce as much power as the computer allows.

Changing the wastegate is more likely to confuse the computer than produce more power. Even if it did produce more power, the computer is likely to throttle it back.

I think you'd be better off giving your computer an attitude adjustment with a tune. BNR also sells a wastegate actuator that works with their tunes (it will NOT work with a stock tune).

 

[anthonysmith93]

A stock Cruze exceeding 19psi will have engine lights due to overboost. Being that your Cruze is a 2011, it's likely one of the unfortunate problem-prone ones and could have a plethora of other issues going on.

The wastegate is usually fine on not tuned cars, the fact that it's weak doesn't matter until you're making higher boost. The only issue I've ever seen with it is when the clip on the rod breaks and the whole thing stops working.

Running premium is factually better in turbo vehicles, no matter if the vehicle is made to also run lower octane, the measly HP these cars make stock is achieved with 91-93oct fuel. You'll not feel a seat of your pants difference in power, but the fact that your engine is running better and having less knock will be a good thing in the long run.

Aside from all that, I think you have something else going on, unrelated to fuel and the wastegate.

 

[ProDigit]

Thanks for the input,
I've laid the project to rest, as I understand it's not a good idea.
Still, I would have wished to see the same results as a friend, who had his accura boosted by 3PSI this way, and gained about 15-20HP!