M3 JB4 Beta Testing: 491whp/531ft-lbs

[DieGrüneHölle]

Originally Posted by tightie

Thanks Tom/Steve/ Everyone at EAS! You guys rock.

Can't wait to come back with some higher octane.

If anyone was wondering, 3.25 Gallons of E85 and the rest 91. It is basically a 93 RON.

Quit holding out on the pics with the Apex EC-7. Wheel size, offest, tire size? If they are 18's, did you have trouble clearing the front brakes? In another thread, supposedly Apex ARC-8 18x10 ET25 and 18x10.5 ET27 both did not clear front brakes.

[W///]

Originally Posted by Blipit_

Quite holding out on the pics with the Apex EC-7. Wheel size, offest, tire size? If they are 18's, did you have trouble clearing the front brakes? In another thread, supposedly Apex ARC-8 18x10 ET25 and 18x10.5 ET27 both did not clear front brakes.

+1. Very cool picture, but those look surprisingly good for 18s.

[jc05e46m3]

Originally Posted by Blipit_

Quite holding out on the pics with the Apex EC-7. Wheel size, offest, tire size? If they are 18's, did you have trouble clearing the front brakes? In another thread, supposedly Apex ARC-8 18x10 ET25 and 18x10.5 ET27 both did not clear front brakes.

Originally Posted by W///

+1. Very cool picture, but those look surprisingly good for 18s.

I'll go ahead and answer for @tightie since I asked him this exact question earlier. Hes running the EC-7s. Specs are as follows:
18x10 ET 25 square
275/35/18s

[DieGrüneHölle]

Originally Posted by jc05e46m3

I'll go ahead and answer for @tightie since I asked him this exact question earlier. Hes running the EC-7s. Specs are as follows:
18x10 ET 25 square
275/35/18s

Hmmm...so the Arc-8 18x10 et25 don't clear the front brakes, but the EC-7 do. Maybe he is running a spacer.

[jc05e46m3]

Originally Posted by Blipit_

Hmmm...so the Arc-8 18x10 et25 don't clear the front brakes, but the EC-7 do. Maybe he is running a spacer.

He's not. I asked.

[spool twice]

Edit...nevermind. ..read graph wrong.

Good results tightie, and the car looks boss.

[kiloil]

I'm not putting anyone's car down, but running in the 15's is asking for trouble.

[A418t81]

Originally Posted by kiloil

I'm not putting anyone's car down, but running in the 15's is asking for trouble.

You guys apparently haven't had any experience with turbo BMWs. BMW from the factory runs your very car at full boost and basically stoich (~15:1) with some fuel added up top. They've done it this way on every turbo motor they've built in the past 7 years.

I'm glad you think it is unsafe (and if it were port injection, it wouldn't be), but literally hundreds of thousands of stock BMWs run this way daily, and there are thousands more modified cars running much higher boost and power levels than stock with no detriment. They were designed to be leaner burning under full throttle (don't need the extra fuel simply for cooling with DI) ,and it has been proven to be safe even with power/boost levels way over stock calibration.

[swamp2]

How do you have 100 degree F temperatures (that's clearly without AC) and only 15% humidity? Humidity in Anaheim seems to be between 30%-80% in recent days depending on the time of day. The humidity and temperature are pretty well out of phase so the lowest humidity at the time of highest temperature (around 3 p.m.).

[verbs]

Originally Posted by ThomasM4

Thanks for posting SAE, been wanting to see the difference. How much power did the down pipes add? I'm thinking of using the tune only so I wanted to estimate that alone.

This. I hate it that no one here posts SAE graphs.

[W///]

Originally Posted by jc05e46m3

I'll go ahead and answer for @tightie since I asked him this exact question earlier. Hes running the EC-7s. Specs are as follows:
18x10 ET 25 square
275/35/18s

Cool, thanks for the answer. That looks really damn good. If I got an imaginary F80, I'd probably go beefy square 18 setup this time around.

[Mike@N54Tuning.com]

Originally Posted by A418t81

You guys apparently haven't had any experience with turbo BMWs. BMW from the factory runs your very car at full boost and basically stoich (~15:1) with some fuel added up top. They've done it this way on every turbo motor they've built in the past 7 years.

I'm glad you think it is unsafe (and if it were port injection, it wouldn't be), but literally hundreds of thousands of stock BMWs run this way daily, and there are thousands more modified cars running much higher boost and power levels than stock with no detriment. They were designed to be leaner burning under full throttle (don't need the extra fuel simply for cooling with DI) ,and it has been proven to be safe even with power/boost levels way over stock calibration.

LOL I feel like its 2007 all over again. These guys are all new to the n5x motors. They will figure it out sooner or later.

Mike

[Brosef]

Originally Posted by KennyPowers

what wheels / fitment are those? apex ec7? looks great

and commented in the other thread, but thanks for showing the correction factors and conditions.

+1. wheels look fantastic - please let us know specs.

[JStang]

My N54 logs show AFR of around 12 on both E45 and 93 octane. Tuned by PTF.

[Boss330]

I'm not getting involved in what's the safe/best AFR on a S55 that's being tuned...

But, the big difference between the cars you linked to and any modern BMW (or Audi, GM, Ford etc) engine is that they now have DI (Direct Injection).

Fuel is now injected directly into the combustion Chamber and injection takes place only when fuel is needed for combustion. You don't have the fuel there for the compression cycle anymore. Many of these DI engines run what is called a stratified charge (Audi's FSI means Fuel Stratified Injection), meaning that they run like a diesel with excess air compared to the amount of fuel that will be burned. On many of these DI engines that also means that the throttle body is fully open under almost every driving condition. The throttle pedal input on such a engine doesn't actually change the position of the throttle bodu, but only the amount of fuel injected.

This also means that under low load (like regular driving on the highway) the engine can have a excess of air and a AFR of as high as 65:1... You will say that if it's that lean, then it won't burn. That would be correct on a regular fuel injected engine. But on a DI they manage to create a small pocket of air and fuel inside the combustion chamber. In this pocket the AFR might actually be 14,8:1 (or whatever around there). This is where the injector is placed as well as the spark plug. Combustion starts in this pocket and expands.

Note that the above only is for ultra lean and eco driving.

Under full power situations the "total" AFR will be much more like historical numbers. But the DI still has the ability to control fuel amount, fuel injection timing etc and also benefits from being able to inject fuel on the JIT (Just In Time) principle .

Again, I'm not placing any opinion on the AFR numbers on this particular engine or tune. This was just an attempt in clarifying some major differences between a old school fuel injected engine and a modern DI engine.

Some info from BOSCH:

http://www.bosch-automotivetechnolog..._di_folder.pdf

Engines with gasoline direct injection generate the airfuel
mixture directly in the combustion chamber. Only
fresh air flows through the open intake valve. The fuel
is injected directly into the combustion chamber using
high-pressure injectors. This improves combustion
chamber cooling and enables higher engine efficiency
due to higher compression, resulting in increased fuel
efficiency and torque.

[DLSJ5]

Actually Mike and the other guys are correct.

Here are two STOCK S55 dyno's, two different dynojets, pretty much the same AFR curve as the modded runs. One of the dyno's sniffer reads a tad richer, I've seen a difference as well between these two dyno's, but WHP is very close between the two.



Map 1 is not in the 13's in the upper range, it's mid 12's, fine for a direct injection S55 motor on E30, that's in the same range AFR wise, as what SC'd S65 M3's run when on higher octane fuel/mix on that dyno's sniffer.



Here's some more on www.s55dynos.com

You think the M3 runs on the lean side, look a the M5, S63 engine dyno's

http://www.s63dynos.com

Stock M5, same dyno as the M3 in question -


Modded M5 and stock

[jc05e46m3]

S62: NA engine with 11.0 CR (IIRC)
S54: NA engine with 11.5 CR (IIRC)

The comparison of aftermarket boosted engines is completely different.

Anyway, did you ever think for a minute that maybe you were indeed wrong and rather than continue forcing your point, just admit that you were mistaken or are you that incredibly prideful?

Everyone after posted great info for you...this is mostly the fact that they are DI and better control can be had. The other is the Ethanol blends (which can typically run "leaner" just because they burn a little different. In any respect, there's your answer. My simple advice is that prior to carelessly throwing a comment out there, you might post it as a question instead and get educated by those who know. That tends to work out better in the end. Cheers!

Originally Posted by m3heaven

Those are not N5X engines...you linked to an E39 M5 and an E46 M3.

Originally Posted by Got Trails

That's fine.

Explain why it's ok on an N5X engine and not generally speaking, every other F/I engine in the world.

VW also does VERY similar tuning.

Originally Posted by DLSJ5

Actually Mike and the other guys are correct.

Here are two STOCK S55 dyno's, two different dynojets, pretty much the same AFR curve as the modded runs. One of the dyno's sniffer reads a tad richer, I've seen a difference as well between these two dyno's, but WHP is very close between the two.



Map 1 is not in the 13's in the upper range, it's mid 12's, fine for a direct injection S55 motor on E30, that's in the same range AFR wise, as what SC'd S65 M3's run when on higher octane fuel/mix on that dyno's sniffer.



Here's some more on www.s55dynos.com

You think the M3 runs on the lean side, look a the M5, S63 engine dyno's

http://www.s63dynos.com

Stock M5, same dyno as the M3 in question -


Modded M5 and stock

Originally Posted by Boss330

I'm not getting involved in what's the safe/best AFR on a S55 that's being tuned...

But, the big difference between the cars you linked to and any modern BMW (or Audi, GM, Ford etc) engine is that they now have DI (Direct Injection).

Fuel is now injected directly into the combustion Chamber and injection takes place only when fuel is needed for combustion. You don't have the fuel there for the compression cycle anymore. Many of these DI engines run what is called a stratified charge (Audi's FSI means Fuel Stratified Injection), meaning that they run like a diesel with excess air compared to the amount of fuel that will be burned. On many of these DI engines that also means that the throttle body is fully open under almost every driving condition. The throttle pedal input on such a engine doesn't actually change the position of the throttle bodu, but only the amount of fuel injected.

This also means that under low load (like regular driving on the highway) the engine can have a excess of air and a AFR of as high as 65:1... You will say that if it's that lean, then it won't burn. That would be correct on a regular fuel injected engine. But on a DI they manage to create a small pocket of air and fuel inside the combustion chamber. In this pocket the AFR might actually be 14,8:1 (or whatever around there). This is where the injector is placed as well as the spark plug. Combustion starts in this pocket and expands.

Note that the above only is for ultra lean and eco driving.

Under full power situations the "total" AFR will be much more like historical numbers. But the DI still has the ability to control fuel amount, fuel injection timing etc and also benefits from being able to inject fuel on the JIT (Just In Time) principle .

Again, I'm not placing any opinion on the AFR numbers on this particular engine or tune. This was just an attempt in clarifying some major differences between a old school fuel injected engine and a modern DI engine.

Some info from BOSCH:

http://www.bosch-automotivetechnolog..._di_folder.pdf

THESE. Great explanations.

[Mike@N54Tuning.com]

These motors generally run around 14:1 in the midrange and 12.5:1 at high RPM from the factory. They can run leaner due to the direction injection which includes multiple fuel injections per stroke. When using E85 fuel some tuners even keep them in the 13s at higher RPM.

Here is a stock fuel map/curve from a similar N54 motor for reference. EGT is not a big concern when running 14:1 in the midrange on a direct injection motor.

If you are curious why you're getting a roll-eyes type reaction here it's because every couple of months someone like you rolls around in the N54 community coming on strong telling everyone else how it's all wrong. Then you'll eventually get a car, tune it yourself, and learn for yourself what most already know. Wait until you start looking at the ultra low timing curves this motor runs lol.

Mike

[jc05e46m3]

Also, dug up this article I read a couple years back and you can see what happens in cases of overfueling and oil dilution in the Mazda world....



"So I've been thinking about this for some time and got bored and wrote up my thoughts. I'm now considering trying to get it published as an SAE paper. What do yo guys think?

On tuning the Mazdaspeed 2.3L DISI turbocharged MZR motor


Abstract: Reasons for leaning the air fuel ratio of the 2.3L DISI turbocharged MZR motor to levels at or above 12:1 are given. These include basic theory of direct injection, observation of fuel dilution in crankcase oil, collection of fuel and water in an installed catch can, observation of impellor deterioration in the exhaust side of the turbocharger, and one example of catastrophic failure with a vented but not evacuated crankcase.

Discussion: Gasoline direct injection (GDI) engines introduce fuel directly into the cylinder as a finely atomized spray that evaporates and mixes with air to form a premixed charge of air and vaporized fuel prior to ignition. Contemporary GDI engines require high fuel pressures to atomize the fuel spray. GDI engines operate with stratified charge at part load to reduce the pumping losses inherent in conventional indirect injected engines. A stratified-charge, spark-ignited engine has the potential for burning lean mixtures for improved fuel economy and reduced emissions. Preferably an overall lean mixture is formed in the combustion chamber, but is controlled to be stoichiometric or slightly fuel-rich in the vicinity of the spark plug at the time of ignition. The stoichiometric portion is thus easily ignited, and this in turn ignites the remaining lean mixture. While pumping losses can be reduced, the operating window currently achievable for stratified charge is limited to low engine speeds and relatively light engine loads.

The Mazdaspeed 2.3L direct injection spark ignition (DISI) turbocharged MZR four cylinder motor is supplied in three vehicles, the MazdaSpeed6, MS6; the MazdaSpeed3, MS3; and the CX-7. Other popular applications of turbocharged GDI engines are the BMW 335i, the 135i, and the Audi/VW 2.0 FSI. With ever increasing emissions requirements and fuel prices driving improved fuel efficiency as a market force, more and more manufacturers are turning to forced inducted direct injection technologies to meet the demands for power and fuel efficiency.

The MS3 and MS6 are very popular with car enthusiasts bent on increasing the power delivery by modifying various parts of the engine. Popular modifications are cold air intakes, higher flowing exhausts systems, downpipes, upgraded top mount intercoolers, front mount intercoolers, exhaust manifolds, upgraded cam driven fuel pumps, and higher volume turbochargers. Interceptor type engine managements systems are often employed with the goal of optimizing the power from the stock setup and any modifications. This is especially true for the MazdaSpeed vehicles as currently there are no systems capable of reprogramming the ECU. There are several systems available using varying degrees of complexity to intercept and modify mass airflow sensor (MAF) volatage, the cam position sensor, the manifold absolute pressure (MAP) sensor, the wastegate solenoid, etc. but the method for “tuning,” or modifying the air fuel ratio is essentially the same, i.e. modifying the signal from the MAF. What is unclear is what the properly tuned air fuel ratio should be. Figures 1 – 3 show dynamometer graphs of horsepower, torque, and important for comparison, air fuel ratios (AFR) for an unmodified or stock MS6 and a 335i. A quick perusal indicates that there is no real consensus of proper AFR among manufacturers. The MS6 is particularly rich at higher rpms while the BMW and Volkswagon vehicles are, comparing to typical port fuel injected turbocharged cars and the MS6, lean.

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Figure 1. Dynomometer graph from a stock 2006 MazdaSpeed6 with a 2.3L DISI turbocharged MZR.

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Figure 2. Dynomometer graph from a stock 2008 BMW 335i with a DISI Turbocharged Inline 6.

[img width=938 height=768]http://i257.photobucket.com/albums/hh203/dadasracecar/paper/3.png[/img]
Figure 3. Dynomometer graph for a Volkswagon Golf with a 2.0 L FSI turbocharged motor

For combustion to be chemically complete, the fuel-air mixture must be vaporized to a stoichiometric gas-phase mixture. A stoichiometric combustible mixture contains the exact quantities of oxygen and fuel required for complete combustion. The products of an ideal combustion process are water and carbon dioxide. For gasoline, this air-fuel ratio is approximately 14.7:1 by weight. A fuel-air mixture that is not completely vaporized, nor stoichiometric, can result in incomplete combustion and reduced thermal efficiency. If combustion is incomplete, some carbon is not fully oxidized, yielding carbon monoxide and unburnt hydrocarbons.

Conventional forced inducted port-fuel injected motors typically run rich mixtures with AFRs in the area of 10.0-11.0:1 under load and boost. This is done to prevent or minimize preignition leading to detonation in the cylinder due to the high pressures and temperatures associated with forced induction. Because of the inherent cooling effects of GDI it is theorized that higher compression ratios and leaner air fuel mixtures can be used under load conditions than those of conventional port-fuel systems. Examples of this are shown in figures 2 and 3. Both Volkswagen and BMW set their AFR under max load/boost to be 12.0:1 or higher.

The engineers at Mazda set the fuel system for the 2.3L DISI turbocharged MZR four cylinder vehicles to run excessively rich under load, indicated in figure 1. This is inefficient as optimum power is not made in gasoline combustion engines at AFRs below 13:1. Additionally, the excessively rich condition results in unburnt fuel leaking down the cylinder walls into the crankcase. This has been described by Sagawa et al., in SAE 2002-01-1647, "Study of Fuel Dilution in Direct Injection and Multipoint Injection Gasoline Engines.” Fuel dilution reduces the lubricity of oil and will result in excessive wear, heat, and, ultimately, seizure of moving parts resulting in catastrophic failure.
The following are website links to used oil analyses performed on MS3, MS6, and CX-7 vehicles. All indicate significant reduction in viscosity in comparatively short intervals.
Quaker State 5w-30
Mazdaspeed 3 - Castrol 5w 30 - first UOA - Bob Is The Oil Guy

Penzoil Platinum 5w-30 (4,116 Miles)
PP 5W30 4,116 - Mazdaspeed 3 2.3L DISI Turbo - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...60&fpart=1

Quaker State Q Advanced (4,300 Miles)
06 MazdaSpeed 6 Quaker Q Advanced 5W-30 4300 miles - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...70&fpart=1

Mobil1 (4,848 Miles)
Mobil 1 5w-30 (4,848) - 2007 Mazdaspeed 3 (9,621) - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...66&fpart=1

Mobil1 (5,046 Miles)
Mobil 1/ 5046 miles /2007 Mazdaspeed3 - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...39&fpart=1

CX-7 Motorcraft 5w-20 4,404 Miles
2007 Mazda CX-7, 2.3L Turbo, Motorcraft 5W-20 - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...55&fpart=1

Mazdaspeed3 Factory Fill (1,900 Miles)
2007 Mazdaspeed 3, 2.3T DISI, OEM Fill - Bob Is The Oil Guy
http://www.bobistheoilguy.com/forums...00&fpart=1

Figure 4 is a picture of the contents of an oil catch can installed between the intake manifold and the crankcase. Under normal operation the crankcase is under vacuum and evacuating the crankcase. These catch cans were installed to eliminate the oil sludge forming inside the intake manifold, Figure 5. Owners report watery oily residue smelling of fuel when emptying their catch cans indicating fuel leakdown on the walls of the cylinders.

[img width=947 height=768]http://i257.photobucket.com/albums/hh203/dadasracecar/paper/CCcontents.png[/img]
Figure 4. Pictures of the contents of oil catch cans installed between the intake manifold and the crankcase on two MS6s.

[img width=918 height=768]http://i257.photobucket.com/albums/hh203/dadasracecar/paper/intakemani.png[/img]
Figure 5. Image of the inside of the intake manifold of an MS6. The port where the oil sludge originates is connected to the crankcase PCV valve.

Excessively rich mixtures can result in unburnt fuel and reduced hydrocarbons exiting the exhaust resulting in an excessively sooty condition at the tailpipe. This particulate soot also contaminates the flow in the exhaust gas recirculation system (EGR). Figure 6 is inside the cylinder head of a Mazdaspeed6. The valves have been removed but the spark plug and injector port remain. This excessive buildup was observed in a vehicle operating under normal conditions for less than 25,000 miles and likely results from a combination of the oil sludge from fuel diluted oil and the particulate from the unburnt hydrocarbons in the EGR.

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Figure 6. Cylinder head of a 2006 Mazdaspeed6.

The fuel rich exhaust will continue to combust and may actually detonate outside of the cylinder in the exhaust manifold or exhaust housing of the turbocharger. Figure 7 shows the impellor from an MS6 Borg Warner K04 turbo. Close inspection reveals areas of significant deterioration of the impellor blades in an erratic fashion. The damage is not repeated from blade to blade indicating discrete damage events affecting small areas. Also the type of damage on the blades suggests a wearing away or blowing away of material due to heat/detonation. This could only arise from unburnt fuel or partially combusted hydrocarbons passing out of the cylinder and into the turbine housing. Anecdotally, the MS6 and MS3 vehicles suffer from accelerated deterioration of turbocharger function indicated by burnt oil leaking from the turbocharger seals. This symptom may also be the result of excessive heat and/or detonation inside the turbocharger itself.

[img width=796 height=768]http://i257.photobucket.com/albums/hh203/dadasracecar/paper/turbinewheel.png[/img]
Figure 7. Exhaust turbine from a Borg-Warner K04 turbo from a 2006 MS6.

Figure 8 is a picture of the block of a Mazdaspeed 2.3L DISI turbocharged MZR four cylinder motor suffering catastrophic failure. The failure occurred under boosted acceleration after approximately 10 minutes of driving with ambient temperatures in the low 30s °F. This vehicle’s crankcase ventilation system had been modified in that the crankcase was no longer evacuated during operation but an ambient vented catch can was installed on the crankcase side. The intake manifold was, of course, plugged. The oil catch can was vented to the atmosphere constantly so that at no time was the crankcase seeing extreme pressure. The owner reported gradually increasing “knock retard” readings on his scantool during normal operation after installing the catch can in the described setup. The vented, non-evacuated catch can setup was used for approximately four weeks and 1500 miles. Upon failure the owner reported that no residue of any kind was found in the catch can.

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Figure 8. Engine block of a 2.3L DISI turbocharged MZR four cylinder suffering catastrophic failure.

Upon disassembly of the motor, it was discovered that the rod and piston in cylinder number 2 suffered catastrophic failure. The rod was bent in two places and failed approximately 1 inch from the piston wrist pin. The piston shattered into fragments smaller than a 1 in2. The pistons and rods in cylinders 1, 3, and 4 showed no signs of adverse operating conditions. Additionally all bearing surfaces in the rods, including those of rod #2 showed minimal wear and not discrete damage markings.

The most plausible cause for this is catastrophic detonation in cylinder #2. It is possible that the oil was continually diluted with fuel from the ineffectual catch can setup to the point of lubricity breakdown and possible ignition resulting in detonation in the crankcase or oil vapor entering the cylinder and lowering the octane rating of the mixture. Another possible scenario is that some of the buildup observed in these motors was present and broke loose entering the cylinder and began to combust elevating the temperatures in that cylinder.

In a recent article by Luttermann and Mährle titled “BMW High Precision Fuel Injection in Conjunction with Twin-Turbo Technology: a Combination for Maximum Dynamic and High Fuel Efficiency,” SAE 2007-01-1560, it was revealed that the BMW fuel injection system “is able to vary the fuel pressure (up to 200 bar [2900 psi; approximately 1000 psi higher pressure than the fuel delivery system in the Mazda Turbo DISI MZR] and the number of injection pulses [up to three per cycle] in order to reduce the wall wetting. This is particularly important to avoid smoke emission and oil dilution.” Given this information one can postulate that Mazda overcame potential fuel heterogeneities and improper combustion of their lower pressure fuel delivery system by addition of more fuel. Consequently, this results in even more smoke (unburnt hydrocarbon particulate) and oil dilution due to fuel leak down in the cylinders.
Conclusion: Excessively rich fueling conditions result in fuel dilution of the crankcase oil as well as excessive carbon build up in the intake manifold and head. The rich fueling condition may be employed to mask problems resulting from incomplete fuel atomization at the 1700 psi fuel pressure utilized by Mazda. It seems Mazda’s approach was to add more fuel while BMW increased fuel pressure. It remains to be seen what the ability of the turbocharged 2.3L DISI MZR is in terms of leaner AFRs (12:1 and higher) under boost and load.

Acknowledgments: I wish to express my deep gratitude to Jordan Gartenhaus of Custom Performance Engineering and Ron Miller for some of the data supplied and many helpful discussions. Additionally, data and photographic evidence were supplied by PT Performance and Jonathon Martin."

[Boss330]

Originally Posted by jc05e46m3

Also, dug up this article I read a couple years back and you can see what happens in cases of overfueling and oil dilution in the Mazda world....




Discussion: Gasoline direct injection (GDI) engines introduce fuel directly into the cylinder as a finely atomized spray that evaporates and mixes with air to form a premixed charge of air and vaporized fuel prior to ignition. Contemporary GDI engines require high fuel pressures to atomize the fuel spray. GDI engines operate with stratified charge at part load to reduce the pumping losses inherent in conventional indirect injected engines.

Pumping losses is what happens when the pistons are working against a partially closed throttle body to draw in air. As I explained above, these DI engines can run with a wide open throttle valve under normal driving. This way the air enters the combustion chambers with significantly less pumping losses. It's kinda like trying to breathe through a straw vs an open mouth.

(The BMW engines doesn't have a throttle body, but uses valvetronic instead. The principles of pumping losses are still the same though)

[jc05e46m3]

Originally Posted by Boss330

Pumping losses is what happens when the pistons are working against a partially closed throttle body to draw in air. As I explained above, these DI engines can run with a wide open throttle valve under normal driving. This way the air enters the combustion chambers with significantly less pumping losses. It's kinda like trying to breathe through a straw vs an open mouth.

(The BMW engines doesn't have a throttle body, but uses valvetronic instead. The principles of pumping losses are still the same though)

I was just trying to show this guy what happens to engines that are not like the BMW engines and overfuel.

[Boss330]

Originally Posted by jc05e46m3

I was just trying to show this guy what happens to engines that are not like the BMW engines and overfuel.

Yeah, sorry

My comment wasn't aimed at you at all (something I obviously should have pointed out since I quoted your post). I was just trying to explain one of the expressions that possibly wasn't self explanatory