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Discussion Starter · #1 ·
If you leave the torque limiter on can you turn up the psi on the turbo charger and increase engine power?
 

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You won't feel the power till third gear but sure.
 

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The answer is no. You can't get anymore psi nor power because the turbo depends on the transmission for building that boost. If you can't produce load on the transmission, you can't produce boost on the turbo... no matter what you diddle with on the turbo. Basically the torque limiter allows the clutch to slip when over its limit's, so essentially the car is off loading the load and dumping the boost.
 

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The answer is no. You can't get anymore psi nor power because the turbo depends on the transmission for building that boost. If you can't produce load on the transmission, you can't produce boost on the turbo... no matter what you diddle with on the turbo. Basically the torque limiter allows the clutch to slip when over its limit's, so essentially the car is off loading the load and dumping the boost.
That's not exactly how it works... ... I guess in simple terms...

The boost has no real connection to the transmission, the motor (ecu) can make the engine produce as much power (and boost) as it wants, up to it's limits, of course.
 

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That's not exactly how it works... ... I guess in simple terms...

The boost has no real connection to the transmission, the motor (ecu) can make the engine produce as much power (and boost) as it wants, up to it's limits, of course.
Not sure what you mean. The car goes into a state of vacuum when there is no load on the transmission.

I do have lots of first hand experience with this. A good example of my statement of boost is dependent on the clutch, is when you order a 04 - 05 manual clutch for an 06+. The different plate slips beyond the limits and causes the car to consistently drop boost (not over boost). The torque limiter basically takes the place of a clutch and acts in a similar matter, so it's easier to explain it in those terms, but all and all, you can not produce power on the car with no load from the transmission. It's probably why a lot of people are not understanding what Robert is talking about in the ARD tune thread, where Robert talks about different loads on the transmission in 1st and 2nd vs 3rd and above.

If you still think that the ECU or Turbo will produce boost with no dependency on the load of the transmission... then go out and rev your engine in neutral and come back to us when you're able to produce boost.
 

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Discussion Starter · #6 ·
I understand, thanks for the explenations guys. That being said, with the torque limiter on can you really make the car increase power in 1st and 2nd gear?
 

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I understand, thanks for the explenations guys. That being said, with the torque limiter on can you really make the car increase power in 1st and 2nd gear?
Under one condition, you increase the torque limiters top slip limit. Otherwise no. That's why most remove it. I could be wrong on adjusting the torque limiter, but I know you're not getting more power if you don't adjust the governor.
 

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I understand, thanks for the explenations guys. That being said, with the torque limiter on can you really make the car increase power in 1st and 2nd gear?
Nope, not in stock form. The limiter is just that, a limiter so no matter what boost you are pushing, first and second gear will always be limited to the specified limit.
 

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then go out and rev your engine in neutral and come back to us when you're able to produce boost.
I was just being a smart ass, it's not going to make power in neutral because the ECU won't let it. You can force it (with ridiculous tuning) to throw air and fuel in, regardless of load... lol

So, realistically you're correct, but theoretically it's not the ONLY way :D
 

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You can force it (with ridiculous tuning) to throw air and fuel in, regardless of load... lol

So, realistically you're correct, but theoretically it's not the ONLY way :D
Unfortunately, it's the only way that most know of.

Boost is connected to rotational acceleration resistance in a motor as well as exhaust volume / heat / and velocity before it hits the turbo.

The main reason Boost builds is because the compressor blows more air than the engine can pump at the current atmospheric pressure for that RPM.

When there is no load on the car, the engine is in a state of vacuum because the combustion chambers can draw in air under the current atmospheric conditions faster than the turbo can produce it… and a lot of that is tied to fuel and the EGT’s that increases volume and velocity under load.

To the OP:

I believe the torque limiter is in place to protect the driveline under trailer hauling when the car see's more load. In that condition, I would bet it also protects the engine under long boost conditions in low gears when the car see's a larger load on the engine. I would also bet the reason we haven't seen much failures with torque limiters removed is that most in the U.S. have other vehicles to tow with, like truck’s vs the Euro guys that primarily tow with their sedans or estates. The guys with torque limiters removed that tow heavy trailers has to be a very small pool to test from.

I also don’t think the torque limiter is deleted in these tunes, but I think it’s raised. I could be wrong on that but I’ve only read a few threads on the subject years back.

Probably the smartest strategy if you are unsure about removing the limiter would be to get a soft tune that you can go back and forth on. No limiter on days where you want to blast along and a reversal tune to go back on if you ever think you'll tow a trailer. Most of the guys here have ran with 400+ with the limiter removed, so a messily 350 or 330 tune would be safe.
 

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Give ARD a few months to get the kinks worked out of their tune and then call or email Lucky. He can do a multimap setup on our cars, so you could have 3 tunes assigned to the various 4C chassis buttons. You could have comfort be torque limited, sport unlimited, and advanced all out [all for probably the price of a RICA or IPD tune at that!]
 

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Unfortunately, it's the only way that most know of.

Boost is connected to rotational acceleration resistance in a motor as well as exhaust volume / heat / and velocity before it hits the turbo.

The main reason Boost builds is because the compressor blows more air than the engine can pump at the current atmospheric pressure for that RPM.

When there is no load on the car, the engine is in a state of vacuum because the combustion chambers can draw in air under the current atmospheric conditions faster than the turbo can produce it… and a lot of that is tied to fuel and the EGT’s that increases volume and velocity under load.
The best example I can think of, is a carbureted non-computer controlled motor.

Imagine - (think of my old Vespa scooter) driving on a flat surface at a constant throttle, your speed and RPM doesn't change. The only thing that I can personally control is the amount of fuel and air that goes into the engine based on the throttle opening. I start to drive up a hill, and it will not compensate for the extra "load" by itself. So, I will have to open the throttle to compensate for the extra load, giving it more air and fuel. This is how the power is made, it has nothing to do with load. The ECU sees load and compensates by adding more fuel, which ends up making more boost, and more air, building boost on itself... You can make boost in neutral. You can tune it to do so. You can run a WOT box for a 2-step, or get a megasquirt setup to run parallel with the ECU and take over the fueling... (which is a bit extreme, but it still works)

 

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When I bought the tow package from Volvo it came with two modules that plug into prewired connectors in the left rear side panel

In addition to making connections with the turn signals/ brake lights on the trailer, the instructions say it connects to the car's computers and MODIFIES the engine/transmission parameters to accommodate trailer towing. ( Don't make me go and find the instructions -- I'm pretty sure I remember this correctly).

So now I'm wondering if that explains why my dyno test results are so much lower in torque and hp from what Viva claims ???? (The Viva modified turbo produces significantly less hp and torque than the factory stock turbo, which has 80,000 miles on it).

Perhaps I need to remove the trailer modules and go back to the dyno and do some more pulls ...
Pete, did you ever get the iPD software running on that laptop? Wondering what the data logger pulls up after pulling the module... you know, log two different runs and compare graphs. I think the secondary ECU right next to the main ECU controls the transmission… so it would be weird if the towing modules affected the hp via the torque limiters ECU. I think you have a project on your hands. ;)

The best example I can think of, is a carbureted non-computer controlled motor.

Imagine - (think of my old Vespa scooter) driving on a flat surface at a constant throttle, your speed and RPM doesn't change. The only thing that I can personally control is the amount of fuel and air that goes into the engine based on the throttle opening. I start to drive up a hill, and it will not compensate for the extra "load" by itself. So, I will have to open the throttle to compensate for the extra load, giving it more air and fuel. This is how the power is made, it has nothing to do with load. The ECU sees load and compensates by adding more fuel, which ends up making more boost, and more air, building boost on itself... You can make boost in neutral. You can tune it to do so. You can run a WOT box for a 2-step, or get a megasquirt setup to run parallel with the ECU and take over the fueling... (which is a bit extreme, but it still works)
Not trying to be a jerk, but I’m pretty sure 90% of the readers got what I said… I fixed your response so it makes sense:

The best example I can think of, is a carbureted non-computer controlled engine.

Imagine – (think of my old Vespa scooter) driving on a flat surface at a constant throttle with the gear engaged, so there is a consistent amount of load on the engine. The speed and RPM doesn’t change, so I’m keeping a constant amount of load on the engine.

In this example, the only thing I can control is the amount of air that is pulled into the cylinders during a vacuum state of acceleration, which is found on all carbureted engines. I know it’s the complete opposite of what a turbo engine does, but I thought I’d share how a natural carburetor engine works. In a carburetor engine, fuel is controlled by the Bernoulli's principle which draws in fuel by creating a low pressure zone in the carburetor via the venturi effect. Since fuel is drawn to a lower pressure area created by the venturi effect, once you open the wastegate, you allow more air to be drawn into the cylinders (a Vaccuum), and fuel is the bi-product of the Bernoulli's principle. When I start to drive up a hill, the engine will not compensate for the extra "load" by itself. So, I will have to open the throttle to compensate for the extra load, giving it more air. I know, I know… mechanically, quite different than a fuel injected car or turbo car, but never the less.

That’s how more power is made! It has nothing to do with load… wait… I did say open the throttle more when extra uphill load is pressed upon the engine… so I guess I sort of realize load is connected to power.

Now, enough with talking about a non-computer controlled engine, I’m going to veer off and talk about a Computer Controlled engine. I know, completely different than a carbureted car that controls air, instead of a computer controlled car that manages fuel injectors for power, anti knock or controlling tempts, but never the less.

The ECU sees more load and will compensate by adding more fuel, which ends up making more boost, and more compressed air (boost). Since load is present, this allows boost to build. You can find this condition during acceleration or cruise control going uphill. Basically more throttle under load equals more boost.
I totally agree with your second quote.
 

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Pete, did you ever get the iPD software running on that laptop? Wondering what the data logger pulls up after pulling the module... you know, log two different runs and compare graphs. I think the secondary ECU right next to the main ECU controls the transmission… so it would be weird if the towing modules affected the hp via the torque limiters ECU. I think you have a project on your hands. ;)



Not trying to be a jerk, but I’m pretty sure 90% of the readers got what I said… I fixed your response so it makes sense:



I totally agree with your second quote.
I don't always get it right the first time. At least you're open to what I'm saying lol
 

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Can the mods change the topic title to "Question on Transmission Control / Torque Limiter Control over the Turbo?" This thread is going to have a lot of useful info if Pete's findings pan out.

Where? Where?
lol, I'm KB... or KillerB

KB

So yes, good idea. I will connect the Dell and log some before/after runs. then maybe you can explain how to load that data on a format/spreadsheet so I can post it here -- the raw data is all bunched in a lump which makes it hard to read.


pete
Pete, do you still have my e-mail? I can convert those for you and post them. I'm working on a computer project in San Diego this week, but can give you a hand with the conversion when you send them over.
 

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So now I'm wondering if that explains why my dyno test results are so much lower in torque and hp from what Viva claims ???? (The Viva modified turbo produces significantly less hp and torque than the factory stock turbo, which has 80,000 miles on it).
Pete, please elaborate,

Last week I saw a Viva Stage 3 put down 11 more whp than an IPD stage 2 at our Denver dyno day on a mustang AWD dyno. And if my wastegate arm hadnt disconnected on the way there, I could have verified what I suspect, that my car isn't measurably faster after spending 5 grand to go stage 3 from stage 2...

Will be able to compare on the highway tomorrow versus other Rica S2 Rs.
 

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Not sure what you mean. The car goes into a state of vacuum when there is no load on the transmission.

I do have lots of first hand experience with this. A good example of my statement of boost is dependent on the clutch, is when you order a 04 - 05 manual clutch for an 06+. The different plate slips beyond the limits and causes the car to consistently drop boost (not over boost). The torque limiter basically takes the place of a clutch and acts in a similar matter, so it's easier to explain it in those terms, but all and all, you can not produce power on the car with no load from the transmission. It's probably why a lot of people are not understanding what Robert is talking about in the ARD tune thread, where Robert talks about different loads on the transmission in 1st and 2nd vs 3rd and above.

If you still think that the ECU or Turbo will produce boost with no dependency on the load of the transmission... then go out and rev your engine in neutral and come back to us when you're able to produce boost.
I'm sorry, but this is really bothering me.

When we talk about "Boost", we are generally talking about the pressure you see on the gauge, right?
In the simplest terms, the gauge pressure is a difference in pressures--atmospheric pressure (14.7psi) and the pressure that your turbo is producing. When you open the throttle instantly, before the turbo begins boosting, the motor is getting atmospheric pressure, or 14.7psi (read as 0psi on the gauge). When you see a positive pressure, that is when the turbo is contributing to the equation.

Just because you're revving in neutral doesn't mean the turbo isn't moving air. An old turbo drag-racing trick that I'm sure many of you know is to floor the throttle several times in quick succession. The gauge is reading only the pressure *after* the throttle. If you had a gauge plumbed into, say, the intercooler, you would definitely see a lot of boost as soon as you slam the throttle closed. The more you get the turbo spinning, the bigger the boost spike will be. And when you take off, the turbo is already spinning, so you get near-instant boost.

Horsepower is an empirical unit of power measurement. Also, as many of you know, horsepower is an equation--meaning it is computed. The equation is [Torque (in ft-lbs) x RPM]/5252. There is no place on the engine you could put a simple gauge and have it read horsepower (the value for the horsepower gauge in the Veyron is pulled from the computer from a bunch of computed values). The "torque limiter" in our cars simply dials back the boost and/or timing when certain values have been reached--I'm guessing fuel flow and RPM being chief. Power production has nothing to do with it--only torque.

It is true that the engine cannot produce power if it is not coupled to a load, but it's kind of silly to think that the load is what governs power production in the engine. That's like dropping the car *into* neutral if it senses that the arbitrary torque limit has been reached. Likewise, putting a stronger clutch in your M66 won't make it produce more power, it just increases the torque-carrying capability.

I have been known to spout off in forums, mainly at some idiotic comment by JRL. If anyone thinks I'm spouting off, then I apologize.
 

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OK, I was going to stay on the low-down until after I've completed all my tweeks (have not installed the Snabb yet, and am going to replace vacuum lines, temp sensor, boost sensor and TCV) and try another set of pulls.

The car is 2006 VR GT with ~ 75k miles on it when I did these pulls, on a dynojet 424x at PSI http://www.psiproformance.com/dyno.php.
I can't remember if it was the spring or last fall -- but it was cool and rainy both before/after. Same tech did the pulls. All pulls done in 4th gear with trac controll fully off, advance mode, all wheel drive.
Gas is Sunoco 93. Oil is Castrol full synthetic 5w30.

A while back when I was installing the Evolve downpipe I saw a hairline crack in the turbo casting between the exhaust port and the wastegate port (this is a common occurance).
That pushed me over the edge so I decided to try George's turbo mod. He wouldn't take my core with the crack in it so I paid full price. Keystone in Berwyn, PA did the install for me.

The power mods I have are: J'ill Kelly CAI; Bell FMIC; Viva CBV with HD spring; IPD tune (II); Evolve 3.5" dp; TME cat-back; IPD HD coil packs; factory plugs replaced at 60K; everthing else is stock (although I removed the foam sock over the factory air filter, which I replaced before these runs).

I did pulls with the stock factory turbo, then had Keystone install the Viva turbo, drove around for two weeks to let the ECU get used to the new turbo, then went back to PSI.

What I saw was a significant loss of peak hp and torque with the Viva turbo over the factory stock turbo. Now let me say that George says you must get his tune to optomise his turbo mod, and I don't have the Snabb or a high-flow filter on the intake side, and I don't have his ultra expensive coil packs, or the water/meth injection. Nevertheless, it was my assumption that the ECU would "learn" to adjust to the higher flow of the modded turbo. I expected a little more turbo lag, but not losses of peak torques and power ????

Butt dyno says the car is nice -- I'm amazed how well the car pulls in this very very hot weather we're having now. (thanks Bell !)

Anyway Phuz saw my post a while back and commented that he was not surprised by my results -- his theory that clipping the turbo vanes is not such a good idea.

His sense of the engineering is this: if you want more power, get a bigger turbo.

That said, I seem to be the only person with the Viva turbo mod that has not seen a power increase -- but then nobody seems to have done a "before" pull.

My feeling on this: It is my sense that ALL the power increase comes from the actual tune, and that none of the "bolt-on" flow mods (intake/exhaust) make any practical addition, except at the very very top of the RPM band -- a place we rarely, if ever, visit other than a flat-out dragrace.

Curse me for not asking for an extra port on my Evolve downpipe to install a wideband sensor (I have a Zetronix module with wideband sensor and exhaust temp probe ... sitting in the parts bin for years now http://zeitronix.com/Products/LCD/LCD.shtml).

Once I finish installing all the parts I have in the bin I'll go out and see if I can get a more precise tune.
Wouldn't it be true that with, say, the intake, fmic, and 3" downpipe [relatively easy bolt ons], that even if your peak hp/tq did not change on factory tune, the higher intake volumes, cooler intake temps, and faster exhaust evacuation would cause your power band to fatten up, aka, you have more power available at lower rpms than before, and more power throughout the entire band?
 

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So the hybrid turbos need the enem cams as well as an intake manifold upgrade.
 
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