# TECH ARTICLES - By 034 Motorsport



## Issam Abed (Feb 12, 2004)

As these become available I will post them up. http://****************.com/smile/emthup.gif 

_Quote, originally posted by *Spark Timing Myths Debunked* »_








A widely-held myth is that maximum advance always means maximum power. Here’s what’s wrong with this thinking:
The spark plug ignites the mixture and the fire starts burning. The speed of this flame front depends on the mixture, this means how many air and fuel molecules are packed together in the combustion chamber. The closer they are packed together in the same volume, the easier it is for the fire to jump from one set of molecules to the other. The burning speed is also dependent on the air-fuel-ratio. At about 12.5 to 13 air-fuel-ratio the mixture burns fastest. A leaner mixture than that burns slower. A richer mixture also burns slower. That's why the maximum power mixture is at the fastest burn speed. It takes some time for this flame front to consume all the fuel in the combustion chamber. As it burns, the pressure and temperature in the cylinder increases. This pressure peaks at some point after TDC. Many experiments have shown that the optimum position for this pressure peak is about 15 to 20 degrees after TDC. The exact location of the optimum pressure peak is actually independent of engine load or RPM, but dependent on engine geometry.
Typically all the mixture is burned before about 70 deg ATDC. But because the mixture density and AFR in the engine change all the time, the fire has to be ignited just at the right time to get the peak pressure at the optimal point. As the engine speed increases, you need to ignite the mixture in the combustion chamber earlier because there is less time between spark and optimum peak pressure angle. If the mixture density is changed due to for example boost or higher compression ratio, the spark has to be ignited later to hit the same optimal point.
If the mixture is ignited to early, the piston is still moving up towards TDC as the pressure from the burning mixture builds. This has several effects:
* The pressure buildup before TDC tries to turn the engine backward, costing power.
* The point where the pressure in the cylinder peaks is much closer to TDC, with the result of less mechanical leverage on the crankshaft (less power) and also causes MUCH higher pressure peaks and temperatures, leading to knock.
Many people with aftermarket turbos don't change the spark advance very much, believing that earlier spark creates more power. To combat knock they make the mixture richer. All that happens really then is that the mixture burns slower and therefore hits the peak pressure closer to the right point. This of course reaffirms the belief that the richer mixture creates more power. In reality the flame front speed was adjusted to get the right peak pressure point. The same result (with more power, less emissions and less fuel consumption) could be achieved by leaving the mixture at the leaner optimum and retarding the ignition more instead.
Turbo charging or increasing the compression ratio changes the mixture density (more air and fuel molecules are packed together). This increases the peak pressure and temperature. The pressure and temperature can get so high that the remaining unburned mixture ignites by itself at the hottest part in the combustion chamber. This self-ignition happens explosively and is called 'knock'. All engines knock somewhat. If there is very little unburned mixture remaining when it self-ignites, the explosion of that small amount does not cause any problems because it can't create a large, sharp pressure peak. Igniting the mixture later (retarding) causes the peak pressure to be much lower and cures the knock.
The advances in power of modern engines, despite the lower quality of gasoline today, comes partially from improvements in combustion chamber and spark plug location. Modern engines are optimized so that the flame front has the least distance to travel and consumes the mixture as fast as possible. An already burned mixture can no longer explode and therefore higher compression ratios are possible with lower octane fuel. Some race or high performance engines actually have 2 or three spark plugs to ignite the mixture from multiple points. This is done so that the actual burn time is faster with multiple flame fronts. Again, this is to consume the mixture faster without giving it a chance to self-ignite.
Higher octane fuel is more resistant to self-ignition. It takes a higher temperature and pressure to cause it to burn by itself. That's why race fuels are used for engines with high compression or boost. Lead additives have been used, and are still used to raise the self-ignition threshhold of gasoline, but lead is toxic and therefore no longer used for pump-gas. Of course a blown engine is toxic to your wallet.








_Klaus Allmendinger is the VP of Engineering for Innovate Motorsports, a division of Innovate! Technology, Inc. Innovate develops digital tools for tuning internal-combustion engines. _



_Quote, originally posted by *Application Note: You Can Be Too Rich!* »_








_By Klaus Allmendinger, VP of Engineering, Innovate Motorsports_
Many people with turbochargers believe that they need to run at very rich mixtures. The theory is that the excess fuel cools the intake charge and therefore reduces the probability of knock. It does work in reducing knock, but not because of charge cooling. The following little article shows why.
First let’s look at the science. Specific heat is the amount of energy required to raise 1 kg of material by one degree K (Kelvin, same as Celsius but with 0 point at absolute zero). Different materials have different specific heats. The energy is measured in kJ or kilojoules:
Air ~ 1 kJ/( kg * deg K)
Gasoline 2.02 kJ/( kg * deg K)
Water 4.18 kJ/( kg * deg K)
Ethanol 2.43 kJ/( kg * deg K)
Methanol 2.51 kJ/( kg * deg K)
Fuel and other liquids also have what's called latent heat. This is the heat energy required to vaporize 1 kg of the liquid. The fuel in an internal combustion engine has to be vaporized and mixed thoroughly with the incoming air to produce power. Liquid gasoline does not burn. The energy to vaporize the fuel comes partially from the incoming air, cooling it. The latent heat energy required is actually much larger than the specific heat. That the energy comes from the incoming air can be easily seen on older carbureted cars, where frost can actually form on the intake manifold from the cooling of the charge.
The latent heat values of different liquids are shown here:
Gasoline 350 kJ/kg
Water 2256 kJ/kg
Ethanol 904 kJ/kg
Methanol 1109 kJ/kg
Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13. Let's assume the optimum is in the middle at 12.5. This means that for every kg of air, 0.08 kg of fuel is mixed in and vaporized. The vaporization of the fuel extracts 28 kJ of energy from the air charge. If the mixture has an air-fuel-ratio of 11 instead, the vaporization extracts 31.8 kJ instead. A difference of 3.8 kJ. Because air has a specific heat of about 1 kJ/kg*deg K, the air charge is only 3.8 C (or K) degrees cooler for the rich mixture compared to the optimum power mixture. This small difference has very little effect on knock or power output.
If instead of the richer mixture about 10% (by mass) of water would be injected in the intake charge (0.008 kg Water/kg air), the high latent heat of the water would cool the charge by 18 degrees, about 4 times the cooling effect of the richer mixture. The added fuel for the rich mixture can't burn because there is just not enough oxygen available. So it does not matter if fuel or water is added.
So where does the knock suppression of richer mixtures come from?
If the mixture gets ignited by the spark, a flame front spreads out from the spark plug. This burning mixture increases the pressure and temperature in the cylinder. At some time in the process the pressures and temperatures peak. The speed of the flame front is dependent on mixture density and AFR. A richer or leaner AFR than about 12-13 AFR burns slower. A denser mixture burns faster.
So with a turbo under boost the mixture density raises and results in a faster burning mixture. The closer the peak pressure is to TDC, the higher that peak pressure is, resulting in a high knock probability. Also there is less leverage on the crankshaft for the pressure to produce torque, and, therefore, less power.
Richening up the mixture results in a slower burn, moving the pressure peak later where there is more leverage, hence more torque. Also the pressure peak is lower at a later crank angle and the knock probability is reduced. The same effect can be achieved with an optimum power mixture and more ignition retard.
Optimum mix with “later” ignition can produce more power because more energy is released from the combustion of gasoline. Here’s why: When hydrocarbons like gasoline combust, the burn process actually happens in multiple stages. First the gasoline molecules are broken up into hydrogen and carbon. The hydrogen combines with oxygen from the air to form H2O (water) and the carbon molecules form CO. This process happens very fast at the front edge of the flame front. The second stage converts CO to CO2. This process is relatively slow and requires water molecules (from the first stage) for completion. If there is no more oxygen available (most of it consumed in the first stage), the second stage can't happen. But about 2/3 of the energy released from the burning of the carbon is released in the second stage. Therefore a richer mixture releases less energy, lowering peak pressures and temperatures, and produces less power. A secondary side effect is of course also a lowering of knock probability. It's like closing the throttle a little. A typical engine does not knock when running on part throttle because less energy and therefore lower pressures and temperatures are in the cylinder.
This is why running overly-rich mixtures can not only increase fuel consumption, but also cost power.


_Quote, originally posted by *Fuel Pressure Regulator Basics* »_








_By Javad Shadzi, ,President , 034 Motorsports_
When it comes to physical hardware involved in tuning your fuel system, the Fuel Pressure Regulator is a key component and its function is often misunderstood. In this article we'll do a quick overview of FPR's, the types and how they function.
*THE BASICS*
A FPR's basic function is to regulate the pressure coming out of the fuel pump and going into the injectors. Its performance is critical to safe engine operation. The FPR has a few parts that make it function, its actually quite a simple device:
_Body_ - Made from steel or aluminum, the body houses the inlets/outlets and pressure regulating devices
_Inlets/Outlets_ - allow fuel to come and go through the regulator, virtually all regulators are a bypass type meaning that extra fuel flow not needed to maintain pressure is bypassed back to the fuel tank.
_Diaphragm or Plunger_ - inside the body is a diaphragm that isolates the fuel pressure inside from the atmosphere, and also seals the body for control pressure to function
_Spring_ - a spring inside the body determines the base fuel pressure, it acts against the diaphragm, fuel pressure on the bottom of the diaphragm acts against the spring opening the valve.
_Valve_ - inside the body and controlled by the diaphragm/spring assembly, passes fuel through the regulator allowing fuel pressure to be varied and controlled.
_Pressure Adjustment_ - many regulators feature a screw that preloads the spring inside the regulator which allows an increase in base fuel pressure.
_Manifold Reference Port_ - featured on virtually all EFI Bypass regulators, this port connects and references to the engine intake manifold, maintaining consistent pressure differential across the injectors.
Virtually all fuel pressure regulators for EFI cars are Bypass type, meaning extra fuel flow not needed to build pressure is bypassed back to the fuel tank. This means that regardless of fuel pump size or flow, the regulator will retain just the right amount of fuel pump flow to maintain base pressure (determined by the spring). The only limit exists when the pump outflows the regulator's ability to bypass, which will result in a base pressure increase over spring pressure. To further emphasize the function, the greatest amount of fuel will be bypassed when the engine's fuel requirements are least, as engine load increases, fuel load increases, and less fuel will be bypassed as it will be required to build pressure.
*MAIN FUNCTION*
A FPR's main function is to maintain a consistent pressure differential across the injectors and the intake port pressure. What causes fuel to spray out of the injector and into the intake port is the fact that pressure is higher inside the injector than inside the intake port. For example, if base fuel pressure desired is 43.5 psi (a very standard 3BAR), then in order to deliver a consistent flow of fuel to the engine, a pressure differential of 43.5psi must always be maintained. 
What this means is that during vacuum conditions, the manifold reference will actually lower fuel pressure as the intake is literally trying to suck the fuel out of the injectors. Under boost conditions, fuel pressure will be increased at a ration of 1:1, again, to maintain the reference, thus under 10psi boost, gauge pressure will be 53.5psi but the actual differential will still only be 43.5psi.
This is the most misunderstood function of the EFI bypass regulator, if you can wrap your head around this concept you'll understand the function of this part.
*TYPES*
There are two types of regulators, both perform virtually the same function but are housed and mounted slightly differently.
*External Regulators*








Shown above is an external type FPR with its basic components. The advantage of external regulators is that they can be packaged anywhere there is room in the engine compartment, away from the fuel rail. External types are also available in a large variety of sizes and flow rates to meet virtually any performance requirement. Most External type regulators feature a pressure adjustment screw so that base pressure can be increased.
*Internal Regulators*








Internal regulators are named such as they are internal to the fuel rail as in most OE applications. They function the same as an external regulator, but have a housing built into the fuel rail to facilitate inlet and outlet functions. Virtually all have manifold reference ports, and some (pictured above our own 034 regulator) have adjustment screws. The advantage of internal regulators is that your application may already have one, they are compact and suit many applications. Due to their small size, they can limit running high flow fuel pumps - the way to test this is if at idle the regulator cannot maintain base fuel pressure with the manifold reference disconnected.
*Pictured below, an OE type Bosch internal regulator*








*An Internal Rail Regulator in an Audi A4 application, note the hose connecting the regulator to the manifold reference*


----------



## Issam Abed (Feb 12, 2004)

*Re: TECH ARTICLES - By 034 Motorsport (Wizard-of-OD)*


_Quote, originally posted by *Dispelling Wastegate Myths* »_
*An explanation of wastegate function, bigger isn't always bigger.*








_By Javad Shadzi, ,President , 034 Motorsports_
Here at 034Motorsport, among many things, we spend our days helping people all over the world put together turbocharger systems to meet their engine power requirements. By far the most misunderstood component we find is the wastegate. Like many automotive tuning principles, wastegates are the reverse to intuition or common knowledge. Ironically they are simple devices, read further and we’ll explore some of the basics about wastegates.
Many we talk to are convinced that high power engines with huge turbos must need huge wastegates as well (bigger is better, right??!), we even see many tuners and race teams falsely implement wastegates much larger than are needed (Ever see an 800HP 4-cyl engine running 40psi boost with 2 huge wastegates on the header collector?) This myth extends to the misconception that internal wastegates also are not high performance and that external wastegates are the best way to control boost – which I’ll explain isn’t necessarily true.
*THE BASICS*
Fundamentally, wastegates are simply valves, the top of the valve is connected to a chamber isolated by a diaphragm or plunger, this creates an upper and lower control chamber. Turbocharger pressure acts on this chamber (usually the lower chamber to force the valve up and open), much like the effect of an air spring. The valve is kept shut by a spring inside the diaphragm chamber to keep the valve shut and also to offset the actuation pressure. In summary, the spring keeps the valve shut, and boost pressure forces it open, this is how the valve is controlled.








The basic task of the wastegate is to vent exhaust gas away from the turbo inlet, the less exhaust gas that flows through the turbo, the less boost pressure the turbo can produce. Thus the wastegate “wastes” exhaust gas and lowers boost.
A typical example of how a wastegate would function, specifically our Tial 44mm Wastegate and one of our favorites.
This particular wastegate is supplied “off the shelf” with a 2.0 BAR wastegate spring or about 14.7 psi atmospheric pressure. Thus, as the turbo begins to spool up from 0psi, the valve remains shut as the spring exerts 14.7psi on the valve. As the turbo continues to spool, boost pressure climbs past 5, 10 and finally by 15psi the pressure in the lower wastegate chamber overcomes the pressure of the spring and begins forcing the valve up and open. As the valve continues to open, more gas is routed around the turbo thus causing the turbo to slow down, and the turbo pressure falls into a synchronicity with the wastegate spring pressure and the 14.7psi of boost pressure is solidly maintained.
A wastegate cannot control boost any lower than the pressure of its spring, the above wastegate will never be able to provide a boost level below 14.7psi. In order to run lower boost, a softer spring would be required.
And now I know what you’re wondering…
*HOW TO INCREASE OR MANIPULATE BOOST PRESSURE*
Up to this point we’ve discussed how a wastegate works with only the spring pressure inside it and without any outside control systems. Using spring pressure is a good way to control boost as it results in flat and stable boost pressure. Base spring pressure won’t compensate for temperature variations (and thus boost pressure variations), and high levels of boost become ridiculous to control with only spring pressure as the spring rates go through the roof. Bolting the wastegate back together could require literally hundreds of pounds depending on the design of the wastegate. In almost any case, applications over 15psi boost, its recommended to use an outside control system to increase boost pressure. These systems always manifest it 2 basic ways:
*1* – By bleeding off control pressure to the lower diaphragm and thus causing the wastegate valve to not open as far
-or-
*2* – By pressurizing the top diaphragm and offsetting the boost pressure to the lower diaphragm, essentially lowering the pressure differential across the diaphragm and not allowing the valve to open as far.
We won’t go into too much more detail about these systems in this article, but this point simply emphasizes the way the wastegate works and how it controls boost.
*DISPELLING THE MYTH*
By this point you should have a good fundamental understanding of how wastegates work, and thus should be able to deduct why some of the myths are false.
Since a larger wastegate has the capacity to bypass more exhaust gas than smaller wastegates, in a given application, larger valves are actually better suited to less boost and lower HP applications. Saying a larger wastegate is necessary for more power is like saying cars with bigger brakes make more power, when in fact bigger brakes assist in making the car slower, not faster. The highest boost wastegate is no wastegate at all, with out a wastegate a turbocharger would produce its maximum boost capability at all times.
*CASE STUDY*
One example of wastegate sizing constraints is in our very own 80tq project. In various configurations we were forced to change wastegate sizes to achieve different boost control strategies.
Configuration: GT40R turbo with .95AR, stock 30mm Audi wastegate, free breathing 20v 5-cyl turbo. With this configuration, the lower boost limit was 18psi at 5500rpm, boost would quickly taper to over 30psi by 6500rpm on simply spring pressure with no outside control. The reason for this boost taper increase was that the small 30mm wastegate could not bypass enough exhaust gas to maintain springe pressure boost, causing boost to increase. Counter-intuitively, this very small wastegate was perfectly suited to running 30psi or higher at 600 crank HP and above. The only reason to put a larger wastegate in this application would be to lower boost. By fitting a Tial 44mm wastegate we could maintain a 20psi boost curve all the way to redline, a 60mm wastegate could have been fit to run lower boost curves in the 10psi range, or about 300 crank HP. With such a large turbo and a free flowing motor, large amounts of air go through the motor, thus large amounts must be bypassed to control boost. With a smaller turbo, like a GT3071R for example, the stock Audi wastegate is effective at holding 20psi to redline since overall airflow levels are so much less.









_GT25R with built in Internal Wastegate_

*THE DIFFERENCE BETWEEN INTERNAL AND EXTERNAL*
This is another commonly misunderstood area; common knowledge has firmly established that external wastegates are superior and most just run with that “knowledge”. Both are very effective and reliable ways to control boost, most OEMs use internal in their turbo systems.
*Internal Pro’s:*
-Compact, the wastegate valve is typically integrated into the turbine housing, the actuator bolted to the compressor housing, gases are vented around the turbo inside the turbine housing.
-Supplied with many turbos direct from the manufacturer, properly sized and engineered.
-Eliminate the wastegate inlet tube in many fabricated manifolds that is usually the failure point (the tube that goes from the header collector to the wastegate inlet, since the wastegate is so heavy and expansive forces great, it will stress the welds on the collector and cause them to break and fail).
-Eliminates a need to dump exhaust back into the downpipe or exhaust system.
-Effective boost control with external devices.
-Leak proof design, no problems with loosening hardware.
*Internal Con’s:*
-Due to the way the wastegate vents directly behind the turbine, the venting can cause turbulence which can adversely affect boost control and turbo flow. Proof of this effect is rare and its effect seen more rarely.
-Spring rates inside the wastegate are difficult to change and require a new actuator.
-Turbo clocking not as flexible as the wastegate actuator mounting forces the compressor housing into specific locations
-Limited in size, typically internal wastegate valves measure in the 25mm range, which doesn’t make them as useful for very low boost applications.
*External Pro’s*
-Large range of sizes means flexible boost tuning options, smallest are 30mm and go as large as 60mm. Multiples can be used for high-waste applications
-Easy to change out spring rates to set base boost pressure.
-Flexible mounting options as the wastgate can be mounted remotely from the turbo
-Limitless brand and size options on the market to suit any turbo and wastegate, choices can be made independently of each other.
-Wastegate dump can be facilitated far from the turbo turbine outlet reducing turbulence problems.
-V-banded wastegates like the Tial 44mm are leak proof and stay tight.
*External Con’s*
-Can be large and bulky, difficult to package depending on the application.
-Require a vent tube in the collector of the manifold, which can often be a point of header failure.
-Models with 2-bolt flanges have chronic problems keeping hardware tight; we’ve seen them literally fall off.
Bottom line, both are effective ways to control boost and have their pro’s and con’s, don’t discount internal wastegates as a reliable, solid way to control boost. Ironically, internal wastegate’s biggest flaw is that due to their smaller size, they are not as useful for low boost applications. The other big criticism of internal wastegates, that they cause turbulence behind the turbine wheel, is minimized as boost increases due to less flow out the wastegate and more through the turbo.


----------



## magics5rip (Mar 17, 2004)

*Re: TECH ARTICLES - By 034 Motorsport (Wizard-of-OD)*

I always love reading articles like this. That graph on cylinder pressure vs timing is a good one http://****************.com/smile/emthup.gif


----------



## 2pt. slo (Jan 4, 2004)

*Re: TECH ARTICLES - By 034 Motorsport (magics5rip)*

very nice info


----------



## MKippen (Nov 6, 2000)

*Re: TECH ARTICLES - By 034 Motorsport (2pt. slo)*

Awesome! - very well written articles.
I found the article on running rich very interesting


----------



## dubdoor (Apr 23, 2006)

*Re: TECH ARTICLES - By 034 Motorsport (theflygtiguy)*

http://****************.com/smile/emthup.gif


----------



## GTijoejoe (Oct 6, 2001)

*Re: TECH ARTICLES - By 034 Motorsport (Wizard-of-OD)*

Nice accurate information, well written http://****************.com/smile/emthup.gif


----------



## shortshiften (Mar 29, 2005)

*Re: TECH ARTICLES - By 034 Motorsport (Wizard-of-OD)*

nice


----------



## heuer21 (Jul 22, 2006)

nice write up


----------



## shortshiften (Mar 29, 2005)

how often do these come out ???
i want more brain food.


----------



## yohimbe (Jun 13, 2005)

*Re: (shortshiften)*

abo for new artikles 
very good write up http://****************.com/smile/emthup.gif


----------



## Turbo_Pumpkin (Feb 22, 2002)

*Re: (yohimbe)*

Thanks for posting these.. http://****************.com/smile/emthup.gif


----------



## eggman95 (Dec 4, 2002)

*Re: (Turbo_Pumpkin)*

good read http://****************.com/smile/emthup.gif


----------

