GLE in, what changed?????

[buddy]

Yes, all turbos flow the same amount at a given pressure, in a fixed volume (engine displacement). All the advertising otherwise is misleading.

There is the benefit of lower backpressure, which is very good. The turbo that requires less work to produce the boost allows the engine to do less work (less fuel burning). Making it a better turbo, drops IATs, EGTs and makes whole truck more efficient.

Boost, is pressure, try to do the math and youll notice volume is intertwined and no way to increase one without the other.

 

[GJF]

:biggthumpup:

 

[Matt Bachand]

As usual, i'm probably way outta my element here commenting, but I think this makes sense.

The entire benefit of a turbo is Boost, or positive manifold pressure.

The negative of a turbo is that it takes energy to make energy, and the more energy it takes to spin the turbine (back pressure) the more HEAT it creates, and the less energy the engine has to spin the crank.

Turbos are exponential on themselfts, faster they spin, faster they CAN spin, creating more boost, which can spin them faster, which creates even more boost, etc.

Every turbo design and efficiency is different, and once they are out of their efficiency range, they fall on their face and take trememdous energy (backpressure) to continue on, usually creating trememdous heat at the same time. This energy is robbing the engine of its power to drive the rear wheels.

Now a turbo with less backpressure makes it easier to spin, less drain on the engine to spin, less heat created to spin, making the engine spin faster, to spin the turbo faster, etc, that is exponential on itself and benefits are great.

As far as boost, numbers are numbers. Math is math. If the math says you can't change V without changing flow or pressure, then that is true.

But efficiency is key here. IF you're running 10lb boost that for example takes the engine 20hp to create,

or

Your running 10lbs of boost that takes the engine 10HP to create

Your going to get better numbers all around with the less work to create same boost turbo.

By the tiem your spending the same 20hp as the old turbo would take to create that 10lb of boost, the new turbo could be pushing 15+ using that same hp, creating in effect much more HP with much less energy wasted.

 

[GJF]

Matt you pretty much have it except, turbos unlike blowers do not use power to run them. A blower will require HP in order to run them. So let's say a 671 requires 50HP to turn it and the motor duynos at 500HP it actually makes 550HP but the blower robbed the 50HP first. The bigger the blower the more power it robs as well as the more overdrive the more HP it takes as well till it exceeds it's efficiency.

Volume can be increased with less pressure! Problem is most don't take into the equation that the inducer and exducer are larger therefore moving more volume of air. There is no way a 500cfm pump moves the same volume of air a 1000cfm pump at the same psi, it's impossible. The variables change everytime you alter dimensions requardless of what engine displacement it is going on.

Most people don't realize the turbine and compressor needs to map out to the displacement on the given engine they are being fitted to. A turbo that can spool fast with the least amount of back pressure is a plus and the ultimate goal of a turbocharged engine used on the ground. I say this because in aviation they don't put turbos to make alot of power but rather to simulate the engine is at ground level so it will make as close to the averaged power to substain air speeds at higher altitudes.

I could continue but let's leave it at this.

 

[buddy]

Unfortunately you have to take into the effect of backpressure, which the engine has to do work to create to spool a turbo faster for more power. A well matched turbo will boost to the levels you want using the waste heat already provided, but eventually you get into a loop of needing to burn more and more fuel to get more boost to get more power and there is diminishing returns if the engine has to compress the exhaust to some 30psi of backpressure, compared to just pushing out the exhaust at little to no pressure.

With a fixed volume with a fixed outlet size (displacement) you cannot increase flow (volume) at lower pressure. Unless you can post definitive evidence through physics and math then you cant dispute it.

 

[GJF]

When heat is applied (back pressure) to a closed gas system, the temperature increases because the molecules begin to move faster. Faster moving molecules try to expand the volume. If the volume can't increase, the pressure increases. If the volume is allowed to change, it will increase and pressure will remain unchanged. (Charles' and Gay-Lussac's law)

If the temperature is constant, when pressure on a closed gas system increases, the volume of the gas decreases. When pressure decreases, volume increases. Gases such as air are elastic, they bounce back. (Boyle's law)


Equation
The mathematical equation for Boyle's law is:


where:

P denotes the pressure of the system.
V is the volume of the gas.
k is a constant value representative of the pressure and volume of the system.
So long as temperature remains constant at the same value the same amount of energy given to the system persists throughout its operation and therefore, theoretically, the value of k will remain constant. However, due to the derivation of pressure as perpendicular applied force and the probabilistic likelihood of collisions with other particles through collision theory, the application of force to a surface may not be infinitely constant for such values of k, but will have a limit when differentiating such values over a given time.

Forcing the volume V of the fixed quantity of gas to increase, keeping the gas at the initially measured temperature, the pressure p must decrease proportionally. Conversely, reducing the volume of the gas increases the pressure.

Boyle's law is used to predict the result of introducing a change, in volume and pressure only, to the initial state of a fixed quantity of gas. The before and after volumes and pressures of the fixed amount of gas, where the before and after temperatures are the same (heating or cooling will be required to meet this condition), are related by the equation:

 

[GJF]

Based off from what YOU are saying, the locked displacement of a given engine (6.5 in our case) no matter what the size of the turbo, at a given psi the volume will always remain constant. So basically ANY turbo at a given fixed pressure would give the exact same performance. If this is the case then a turbo off a 1.9 TD Rabbit, GM-X turbo, ATT, my hybrid or any other turbo will give the same exact peformance as long as the backpressure is the same????

 

[SmithvilleD]

These "more volume at less pressure" discussions aren't really getting at the most relevant charge air unit = air mass per unit time.

Turbo compressor maps use lb/min units because it's the mass of air that fills the cylinder that's relevant. You need the air's pressure, volume, & temperature to know the air mass.

a 650 cfm @ 15 psi turbo spec tells you the compressor is capable of flowing that volume per minute at 15 psi. Until you know the temp that charge is coming out of the compressor at, you don't know the air mass.

My past gasser turbo project's ECU's typically used hot-wire MassAirSensors to measure airflow into the engine so the ECU could calculate the appropriate fueling. I'd like to figure out some type of laptop based datalogging & then run a MAS temporarily. So I could datalog mass air flow thru the engine throughout the entire rpm/boost range. Collect that data for my OEM GM-4, the Holset combo I'm working on, & a wastegated Mitsu turbo combo I may also try.

 

[Monarkman]

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=1747&highlight=improvements+programming

This is from link:
Kennedy

did a steering column swap (Passlock) and used the 98+ programming in his Tahoe. IMHO, this programming is the best out there. A reflash WILL give you more upper rpm fueling, but not much.

I dyno tested a 99 stock vs. the towing program for my 96. The 99 program had 20lb/ft on the performance program, and the performance program had 8 HP. This was on a Mustang dyno with the "Crayola" drawing charts. Had I been on a Superflow...


The OE programs from 96-97 seem to have 62mm max. The 98+ have a "torque bulge" to 75-77 mm around 2500 RPM, then drop back to 62mm.

The reflash IMHO seems to lack one key thing: LOGIC. If I do a foot to floor brake stand, fuel goes to max regardless of RPM. Tying the fuel rate to the APP DOES give more response, but this is more of an illusion. The timing is also better in the OE programming as the reflash seems to be more flat like the 94-5 chip data was just loaded forward.


The turbo is the bottleneck...

This is from 2003 and newer aftermarket flashes are better but shows that the last oem flashes made more power in the midrange than earlier "F" programming. With the computer pulling fuel on top end explains why the horsepower was never rated higher.
The GLE may be an improvement on 96-97 trucks but may not be a signifigant improvement over 98+ programming.

 

[buddy]

There is less pressure, but its on the backside. The smaller turbo will require more backpressure or "turbine" pressure to create the same amount of boost pressure.

So there is more volume with less turbine pressure, just not more volume with less boost pressure. And youre more likely to get more air mass, just not boost.

 

[Dave01]

Going back to the question of GLE performance - I installed mine last fall. I noticed the extended glow cycle helped starting, much smoother shifts, better roll-on power. I didn't notice much going from a stop, but from 30-50 there was a definite improvement. Also, no smoke at any speed.

So, I was happy with the results, but certainly wasn't a huge power difference.

 

[Matt Bachand]

Going back to the question of GLE performance - I installed mine last fall. I noticed the extended glow cycle helped starting, much smoother shifts, better roll-on power. I didn't notice much going from a stop, but from 30-50 there was a definite improvement. Also, no smoke at any speed.

So, I was happy with the results, but certainly wasn't a huge power difference.

Since I never tow, and don't plan to, (maybe I'm at the wrong place, lol) I think when I chip i'm going for the GL4 instead of GLE. Seems the difference of conservativeness can be controlled with my dunce foot.

 

[Dave01]

In my case, I had stock exhaust and no immediate plans to change that, so Bill suggested the GLE. He said that without opening up the exhaust the GL4 didn't make sense.

Since he doesn't offer the towing chip any more I assume the GLE is preferred for towing, gives the power with lower EGT, but not sure about that.

 

[Matt Bachand]

In my case, I had stock exhaust and no immediate plans to change that, so Bill suggested the GLE. He said that without opening up the exhaust the GL4 didn't make sense.

Since he doesn't offer the towing chip any more I assume the GLE is preferred for towing, gives the power with lower EGT, but not sure about that.

I wonder if the GL4 holds the shifts points higher, which in my case would be a bad thing for me.

 

[Dave Barbieri]

Going back to the question of GLE performance - I installed mine last fall. I noticed the extended glow cycle helped starting, much smoother shifts, better roll-on power. I didn't notice much going from a stop, but from 30-50 there was a definite improvement. Also, no smoke at any speed.

So, I was happy with the results, but certainly wasn't a huge power difference.

As mentioned in my earlier post, I saw the same improvements, plus better mpg and better transmission control. I see it as a 'work in progress'. By adding this chip, I've built the electronic base for future mechanical improvements: injectors, turbo, FTB, cold air intake, transmission, etc. For all practical purposes, I'll never outrun this chip. Yet, while I plan future mods to take advantage of the performance/efficiency built into the chip, I enjoy the benefits I've listed right now.

The GL4 has been a super performance investment. Light years better than my 401K! :rolleyes5: