TurboCharges and Supercharges

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first of all could somone please explain to me the difference between a turbocharge and a supercharge (im kinda a newbie at this stuff). and then please tell me the advanteges and disadvantages of both and which one u think is better and why. also if there are certain brand i should look for it would be great if u guys could explain if it has any advantages of disadvantages. also someone PLEASE let me know what the deal is with this sts turbo stuff (heres the website www.ststurbo.com). i have never heard more mixed reviews on any one thing in my life. some say its awsome others say its by far the worst and the website makes it sound like its the most efficient and best preforming one out there, which could be bs. so someone please explain this to me. thanks

posted by  MasterC117

dont know to much but i do know, A supercharger has the potential for greater VE than a turbo because of the backpressure,, turbo improve the piower to weight ratio what im trying to say is a turbo can boost an engine's horsepower without increasing its weight, which is the huge benefit that makes turbos so popular, i think supercharge is what like 35hp and turbo is well not to sure how much turbo adds but it spins a turbine or some shit well did the best i could.. maybe someone else can do better hope it helped

posted by  EzMustang

the main difference..aside from the way they look..is when they start to make power. A supercharger will make power as soon as u start give the car more gas because it is driven by the crankshaft so as soon as the crank spins the charger spins...a turbo however is spooled up by the exhause from the motor. Thats why there is turbo "lag" because there isnt enough exhaust flowing to spin up tyhe turbo....so a supercharger will give u a smoother horsepower curve while a turbo will start to give u power in the higher rpm range depending on the size of the turbo because the larger the turbo the more it needs to spool up.

I ran into someone at english town raceway and he had a 98-02 camaro SS with a remote turbo setup from STS and he couldnt say enough good things about it...and if your looking at the engine all you see is polished piping runing down which could easly be confused as just an aftermarket induction system...so it has sleeper written all over it.

posted by  chevypwr6

Superchargers don't add any noticable weight either, so this point is moot.



No. Not every super or turbo charger makes a set amount of power. There are different size turbos and you can run them at different levels of boost. A turbo can add as much as a thousand or more hp, or could make as little as 100 or even less.





No. There may be exceptions, but for the most part superchargers are driven by a belt.




Not necessarily. A supercharger won't make a smoother power curve, it just may start making extra power sooner.

posted by  abless

the belt on the supercharger runs to the the crank...thats what turns the charger...right or am i thinking of something else?

posted by  chevypwr6

Yes you are correct, but the SC is connected DIRECTLY to the belt.

posted by  abless

right...the belt which is connected to the SC then goes to the crank pully

posted by  chevypwr6

Not all superchargers are created equal, centrifugal s/c's don't make instant boost, roots type blowers will make almost instant boost but at the price of high intake temps, a twin screw blower will also make almost instant boost but with much cooler intake temps-also higher boost levels are possible with a twin-screw or centrifugal type s/c. But I'm wasting my time because we've gone over this 2 or 3 times already since March and the threads are usually over 20 posts each time and cover all the pros and cons.....bottom line...

YOU F*CKERS SHOULD BE USING THE "SEARCH" FUNCTION FIRST!!!

Also, chevykid, you can restore a '70 chevelle SS from the ground up but you don't know the workings of a supercharger? Yeah, you just lost your credibility, indefinitely.

posted by  Sick88Tbird

I couldn't agree more. Getting the same questions gets old pretty quick.



You know this kid is experienced when he has a "Nismo Oil Cap". :orglaugh:

posted by  abless

im sorry...where exactly did i show that i didnt know how a SC works...because i said that the pully on a roots style SC runs to the crank? tell me that im wrong there...if i am then ill bow out without question...but for someone to say that i dont know the workings of a SC is kind of retarded when i just made a few remarks...i could get into it but the user who started this thread seemed like he didnt know anything so i didnt get in depth about it...if he wants me to i can...SO SHUT THE HELL UP!

posted by  chevypwr6

yes i think we know that turbos dont add a set amount.. you can buy up to 3 different stages plus you could get 2 turbos on some cars

posted by  EzMustang

you can also add multiple centrifugal super chargers on an application..depending

posted by  chevypwr6

Oh shit, reading those last 8 or 9 replies just made my body go numb. Please hide this thread before somone sees it. Some of you guys are just asking to get schooled.

"i think supercharge is what like 35hp and turbo is well not to sure how much turbo adds"
Awww man thats going in my Almanac of funny ass shit.

posted by  DSMer

good for you

posted by  chevypwr6

Okay slick, you can't even keep track of your own thoughts....you were asking a question here not making a statement, you weren't sure how such a simple device as a s/c worked. So you need to shut the hell up dipsh*t. THINK, TYPE, SUBMIT....you are apparently missing the first part and the second part is even a little sketchy.

posted by  Sick88Tbird

Right Pondscum. Did'nt I tell you don't voice your opinions. We've allready established that you don't know anything about cars. So after you aquire some more knowledge you may then, and only then, proceed to have your replys taken for more than just chicken sratch.

posted by  DSMer

are you done yet? god i hope so.

posted by  chevypwr6

hey now i did clearify the turbo thing up ok.. now you cant tell me what i said was nonsense and bullshit because when it comes to pullys turbos and supercharges i know i bit.. but again i dont know everything about them

posted by  EzMustang

Is a twin screw or roots supercharger go directly to the cylinders without the intake manifold. Is the supercharger before or after the throttle body??

posted by  CarEXPERT

No, all there is an intake manifold. It depends on what kind of supercharger you're speaking of. Centrifugals(the ones that resemble belt driven turbos) are located before the TB. Wheras Roots or Twin Screw(the ones that are mounted on the top of the intake manifold) are located after the TB.

posted by  DSMer

Oh. My. God.

An internal combustion engine is an air pump. Burning an air fuel mixture in the proper ratio creates power. The more air and fuel you can burn, the more power you make. The amount of air an engine moves is determined by displacement and ability to get that air in and out of the engine.

Supercharging is the act of compressing outside air and delivering that compressed air to the engine. If you compress the air coming into the engine to, say, twice the density, then the engine can make twice the power it would with ambient air pressures.

The mechanical devices that compress the air before delivering it to the engine are called superchargers. ALL of them.

Thus all turbochargers are superchargers, but not all superchargers are turbochargers (kind of like how all oaks are trees, but not all trees are oaks...). Turbos are particular types of superchargers that use the energy in the engine's exhaust to spin the compressor. Any of the superchargers that use a belt or gears to drive the compressor are simply called superchargers, even though there are numerous types (Roots, Latham, centrifugal, etc).

Both types have advantages and disadvantages, of course. Turbochargers use less engine power to run, but there is always a small amount of time between teh time you add throttle, and the engine starts to speed up, spinning up the impeller that drives the compressor and it starts to deliver boost. Superchargers, being driven directly off the engine, use some power to run, but start to deliver boost as soon as you give it throttle.

Search this subject, as there's more to it on this site, as well as howstuffworks.com

posted by  ChrisV

I know how they work but I just dontknow where they are. A roots or twin screw goes after the TB ok but Where is the intake manifold. On superchargers there is the supercharger and then 4 ports that go to the engine head. With a supercharger does anything changes, like air intake, sensors, cuz the supercharger is big.

posted by  CarEXPERT

The intake manifold is teh part that sits between the head(s) and the supercharger. Here's an example from a V8 car:

http://www.rpmcat.com/images/44488.jpg

This is the intake manifold. the supercharger (in this case a Roots type) bolts on top of it, and the injection or carbs sit on top of that. On many of the factory setups, the injection is off the back of teh supercharger, to keep the overall profile low. here's an example of that, with the manifold being the lowest part of teh supercharger setup, the actual supercharger being the ribbed case, and the TB off the rear of the supercharger (the part opposite the front pulley, the front being to your left in this picture):

http://www.tomhenryracing.com/technical/images/523.13.jpg

Air goes in the air cleaner, through the TB, into the supercharger, then into the engine. Simple, really. If it were on a 4 cyl car, then the intal manifold would look slightly different. Something like this:

http://motortrend.com/autoshows/coverage/112_0011_sema10_g.jpg

The black tubular structures are the individual runners of the intake manifold.

Now, to move on to a differnt setup. This is a Paxton brand centrifugal supercharger. Still belt driven, but it looks a lot like a turbo.

http://bradbarnett.net/mustangs/shows/sema04/SEMA-321.jpg

The supercharger is that unit at the front of the engine, to YOUR right in this view. At the far right is the air cleaner. The air goes into the air cleaner, through the supercharger, then on to an intercooler (not all centrifugal superchargers use an intercooler, but they CAN), and then up to the TB (center of the image) then into the intake manifold (directly behind the TB: the black individual runners shown) and then into the engine. This is similar to a turbocharger layout, except that the turbo is not belt driven, but sits on a custom exhaust manifold, to use the energy in the exhaust to drive it.

posted by  ChrisV

ChrisV, in a roots or twin screw they look pretty much the same right?

On your picture of the roots s/c, the air goes through the opposite of the s/c pulley which is the throttle body and then goes through the s/c and the air goes down to the intake manifold? In a V8 or V6 I can understand but what about in a 4 cylinder, like in a honda?

Thanks ChrisV :thumbs:

posted by  CarEXPERT

He allready showed you what a Roots/Screw supercharger looks like on a 4cylinder engine. Your problem is that you don't read. There is no way you could have missed this element of his guide. It has a friggen picture attached

http://motortrend.com/autoshows/coverage/112_0011_sema10_g.jpg

Just like on most other applications. The supercharger is mounted to the Intake as pictured here. The actual supercharger is the cylindrical unit at the top of the picture. It has a pulley sticking out of it to the left. Thats is the supercharger. To the right of the unit and the very top is where the throttle body would be located. There is an opening to allow air into the entire system. The black tubular structures running down are the intake runners. They will bolt directly to the cylinder heads.

The air comes through the air cleaner, through the throttlebody, through the supercharger, down the intake runners, and into the engine.

posted by  DSMer

DSMer I read about that part and already saw the picture but it looked kinda weird. DSMer, so does the roots s/c compress air by pushing it into the intake manifold.
Im not sure what compression ratio is but is it the ratio when the air pressure is just going into the cylinder to the pressure of when the piston moves up and compress it? I dont know if its right or wrong so please clarify it for me DSMer.. :wink2:

posted by  CarEXPERT

All superchargers and turbochargers compress air AND THEN push it into the intake manifold. That's the point. it's conmpressed IN the supercharger or turbocharger, not in the intake manifold (kind of like how a shop air compressor compresses air IN the motor part on top, then STORES it in the tank and is USED in the hose to the air tool)



The compression ratio is the ratio of the volume of the cylinder at the bottom of the piston's stroke to the volume of the cylinder when the piston is at the top of it's stroke. in a 9.0:1 compression ratio, the volume of the cylinder is 9 times as small when the piston is at the top of it's stroke (and thus any air brought into the cylinder is compressed to 9 times it's natural density).

posted by  ChrisV

[QUOTE=ChrisV]All superchargers and turbochargers compress air AND THEN push it into the intake manifold. That's the point. it's conmpressed IN the supercharger or turbocharger, not in the intake manifold (kind of like how a shop air compressor compresses air IN the motor part on top, then STORES it in the tank and is USED in the hose to the air tool)QUOTE]

ChrisV I 99 percent sure your wrong on this. the ROOTS s/c doesnt compress air IN the s/c. It pushes the intake air to the manifold which compreses it. That is why the roots gets the hottest air compared to the other superchargers. The twin screw is the one that compresses air IN the S/C because the screws spin inward to compress it while a roots spin ******d to push.

Thanks, that cleared up the compression ratio issue :thumbs:

posted by  CarEXPERT

Remember this for posterity:

CR = (swept vol. + clearance vol.)/ clearance vol.
i.e. = (swept vol./clearance vol.) +1

The rest of the thread isn't worth correcting.

posted by  Wally

Are you sure. I thought compression ratio was like,
cylinder head volumn + gasket volum + swept volumn DIVIDED by something elese I cant remember.
I remember it was more that that to get CR.

Walley can you please correct one thing that was wrong that I said so I know that im wrong.

posted by  CarEXPERT

yes I am sure. Clearance volume is basically everthing on the compression side of the top ring and piston top = combustion chamber, piston dish, gasket volume, top ringlands, etc. Swept volume is the actual full stroke displacement, not cylinder volume.

no I won't attempt to correct this thread, there are too many issues.

posted by  Wally

Is what ChrisV said about compression ratio true? How would you test a compression ratio of a cylinder? Do you have to buy something to put it on the spark plug?

posted by  CarEXPERT

I'm sure you know the answer to both questions, but for the readers:

no you can't accurately dynamically test your CR with a gauge. You can however get a very poor ballpark figure by measuring absolute manifold pressure and absolute compression pressure on a dead pot while the engine is idling, but it is very dependent on valve closing angles, rod length and stroke.

posted by  Wally

Bahh, what would you use a term like swept volume and clearance volume? You have to keep in mind that he does'nt understand the basic concepts of an engine. Wich is probably why he is more confused than helped by your "information".

I'll try to put this as simple as I can.

Compression Ratio is the relationship between the cylinder volume (clearance volume) when the piston is on TDC(Top Dead Center) and the cylinder volume when the piston is on BDC(Bottom Dead Center)

TDC- Top dead center is the maximum distance a piston can travel up in the cylinder.
BDC- Bottom dead center is the maximum distance a piston can travel down in the cylinder.

Now lets say you have an engine at BDC inside of a cylinder. From the Tip of the piston head to to top of the cylinder wall measures 6". So thats a total of six inches between the top of the cylinder and the top of the piston at BDC

Now when the piston moves up to is compression stroke at TDC lets say you have 1" of distance from the top of the piston to the top of the cylinder wall. It its obvious that 6" of cylinder volume has been compressed into 1". So therefore you have a compression ratio of 6 to 1(6:1)

posted by  DSMer

*sigh* You can mount a roots type to the side of an engine and run a long tube to the intake manifold if you want. The compression, like in ALL compressors (latham type, roots type, centrifugal, etc), is done IN the compressor. The increased pressure is FELT in the intake manifold on all types, as well. You've got the act of compressing the air mixed up with where the compressed air ends up.

http://www.sportcompactcarweb.com/tech/0107scc_supercharger08.gif

http://www.sdrm.org/roster/diesel/emd/history/roots-1.jpg

posted by  ChrisV

Oh? We're trying to simpify things for the beginners.

posted by  ChrisV

I think you do a very good job and thus avoid taking issue with you, but I have two reservations:

1) that the forum seems by default a nursery when it comes to anything technical;
2) I'm not convinced that trolls are extinct on the forum or else God help us all. :wink2:

posted by  Wally

1) unfortunately true. But, to much tech at once confuses people regardless of being on this forum, or any type of knowledge. Getting them thinking abiout the baiscs correctly can lead to understanding of the systems, so they dont'have a problem incorporating teh exceptions to the rules into thier knowledge base. Giving them to much formulaic knowledge up front usually limits their ability to incorporate teh exceptions, and makes their thinking rigid and say things liek, " but I learned it this way, so how could that be?" and then argue with you because the exception to the rule doesn't fit their formula. That makes them bad diagnoticians later, as they are unprepared for the variety of things that are out there OR be able to incorporte new thinking.

Once they understand the basics and the processes, then you can give them the formula, as they will fit the formula to what they see, rather than try to fit what they see to the formula.

2) I really have ceased to care about trolls. It takes too much energy to try and separate trolls from regular idiocy. If they are misinformed, educate them. If they argue, shoot them. Pretty simple, really. :laughing:

posted by  ChrisV

ChrisV already said what compression ratio is, but it just cant be that easy because I read a magazine that said the formula for c/r and it was like, piston volumn + gasket voulum+ cylinder head voulum DIVIDED cylinder voulum +.....+.... = compression ratio. C/R like ChisV said is the pressure of the air when the piston is at BDC of the intake stroke to the pressure of TDC of the compression stroke. It depends about the pistons length and rods and the bore and stroke like you said of the cylinders.
DSMer I dont think it can be just that easy to find the compression ratio like that and I know what swept volumn is and know the basics of an engine. You all think I dont know basics about engines but i do.

ChrisV, I know the other S/Cs compress air in the S/c but the ROOTS s/c doesnt have an internal compression ratio. Like I said in twin screw s/c the 2 screws spin inward with each other which compresses them. In roots the lobes are spinning ******d with each other which pushes the air to the outlet of the s/c.I read all this in a magazine so I think im right

posted by  CarEXPERT

When the air/fuel ratio is 14.7 is that the best to get the most power out of the engine? What about forced inductions, should the ratio be the same? I noticed that on air/fuel dynometers or charts where they test the ratio when the speed goes it, the air/fuel ratio is never the same. Like when the wheel speed goes faster, the ratio of air/fuel is less to like 11:1 which is rich. Is it supost to get richer to get the most power when the wheel speed go up or would you get more power with a 14.7 ratio?

When your running too lean on fuel you get less power but if you run too rich will it be better or worse? I think the richer is better because it insures all the oxygens get burned from the fuel but I dont know.

With forced inductions, I know that you have to add more fuel cuz of the more air pressure but why do you need aftermarket fuel pums, injectors, rails just to get mroe fuel into the cylinders. Can't the OEM fuel things just add more fuel pressure when the MAP senses more air pressure in the manifold? I read that fuel pumps typically be able to flow about 1/2 gallons per minute! Thats impossible to use all that in a minute. What im asking is when you have more air pressure coming in, the computer should sense it and add more fuel so why are there aftermarket fuel things such as injectors that flows 50 lbs per hour! I dont think the engine uses that much.

When the engine is at idle, what happens to the throttle plates? Does the throttle plate open a little to get the air in or does the air bypass the throttle through an air bypass control.

posted by  CarEXPERT

I can assure you ChrisV said nothing of the sort. He mention nothing about pressure of air. He said VOLUME. He even put the words VOLUME in italics. If you're going to sit there and argue what you thought you knew against what the truth is then stop asking for help. You repeatedly tell us that you "know the basics" when you repeatedly ask so many BASIC questions.

Why is that one whom can't says he can?

If you knew the basics, this discussion would'nt be eminent. If you're confused about something basic, then you don't know it. Just admit you don't know(its ok you have to start somwhere), stop arguing, read, and re-read until you understand.

The information I gave you on what a BASIC concept of compression ratio was from a highschool basic engine functions books. Thats how its figured out. Measurements and other formulas come LATER once you understand the basics. Its the difference between the VOLUME of the cylinder at BDC and the Volume of the cylinder at TDC. Thats what ChrisV said. Its just that simple, and thats all you need to know for now until more complex variables, definitions, and forumlas come into the equation.

posted by  DSMer

Of course you do, so why bother asking anyone?

posted by  ChrisV

Measuring Air/Fuel Ratios
Before a programmable management system can be effectively tuned, the air/fuel ratio needs to be measured. As described below, the air/fuel ratio will need to vary in different conditions, and so the meter needs to be accurate across a wide range of ratios. While the oxygen sensor found in the factory management systems of all cars can determine rich/lean scenarios, it is not accurate enough to be used in the tuning of programmable management.

Air/fuel ratios are typically measured using a so-called "wideband' air/fuel ratio sensor. This is usually just a normal oxygen sensor that is a little more linear in its behaviour away from the 14.7:1 'switchover' point (where the sensor output voltage suddenly changes from high to low) than a typical oxy sensor. More sophisticated sensors use UEGO or oxygen pump designs, but in tuning workshops these are still almost unheard of.

In addition to this high speed measurement, some workshops use a slower speed gas analyser, logging its results during dyno power runs so that they can compare those readings with the oxygen sensor system. The disadvantage of gas analysers is that they are too slow to get the instant results which are needed when tuning real-time. But for setting the steady-state light-load cruise mixtures, for example, a gas analyser is fine.

Most workshops have high-speed air/fuel ratio metres than read too rich at the rich end. All meters will be able to read around 14.7:1 mixtures in light-load, closed loop cruise - but that same meter may read a full ratio too rich at 10:1 air/fuel ratios. Meters typically read too rich because the exhaust gas temperature compensation is poor. Mixtures around 9-10:1 (ie ultra rich) will cause the car to blow black smoke, but even when workshop meters are displaying that figure, smoke is rarely seen. However, a meter reading richer than reality is in many ways a safe meter - the tuner won't set up the car dangerously lean. But a key question to ask of tuners is: how long since you replaced your air/fuel ratio sensor?

Ratio Requirements
A well-tuned engine used in normal road conditions has an air/fuel ratio that is constantly varying. At light loads, lean air/fuel ratios are used, while when the engine is required to develop substantial power, richer (ie lower number) air/fuel ratios are used.

Bosch state that most spark ignition engines develop their maximum power at air/fuel ratios of 12.5:1 - 14:1, maximum fuel economy at 16.2:1 - 17.6:1, and good load transitions from about 11:1 - 12.5:1. However, in practical applications, engine air/fuel ratios at maximum power are often richer than the quoted 12.5:1, especially in forced induction engines where the excess fuel is used to cool combustion and so prevent detonation.

There is no one air/fuel ratio where all emissions are minimised. At an air/fuel ratio of 14.7:1 oxides of nitrogen peak, while hydrocarbons and carbon monoxide (CO) increase substantially as the air/fuel ratio richens.

1. Cranking and Idle
The amount of fuel that needs to be added during cranking can best be determined by experimentation. This enrichment may be configured by just a one-dimensional variable based on engine coolant temperature, or it may be able to be controlled in a more sophisticated manner. Examples of the latter include post-start enrichment and enrichment decay time. Cold start is one of the dirtiest times in regard to emissions, and so if emissions requirements are to be met, a sophisticated ECU with multiple starting enrichment and decay maps should be used. Reducing the cold start enrichment but increasing cold acceleration enrichment will reduce the total amount of emissions. Some factory systems open the idle air bypass during cold deceleration, presumably to act as a form of exhaust air injection.

The air/fuel ratio required for a smooth idle will depend on the engine's combustion efficiency and the camshaft(s) used. Some engines with hot cams will require an air/fuel ratio as rich as 12-12.5:1 for a smooth idle, while others will run happily at 13-13.5:1. Engines with hot cams that are fitted with sequential injection management systems can run leaner idle mixtures than systems using bank or group fire. Those engines that can be configured to run in closed loop at idle will use an air/fuel ratio of about 14.7:1 when fully warmed, although they will still usually idle better at a slightly richer air/fuel ratio. However, keeping the engine air/fuel ratio as close to stoichiometric as possible will benefit emissions because the cat converter works most efficiently at this ratio.

2. Cruise
Light-load cruise conditions permit the use of lean air/fuel ratios. Ratios of 15-16:1 can be used in engines with standard cams, while engines with hot cams will require a richer 14:1 air/fuel. If a specific lean cruise function is available, air/fuel ratios of 17 or 17.5:1 can be used, normally at the standard light-load ignition advance. However, running too lean a cruise mixture will cause the cat converter to overheat. If a dyno and exhaust gas temperature probe is available, the cruise air/fuel ratio can be leaned out until exhaust gas temperature becomes excessive for these load conditions (eg 600 degrees C+), or torque starts to significantly decrease. Remember, an engine in a road car will spend more time at light-load cruise than in any other operating condition. The air/fuel ratio used in these conditions will therefore determine to a significant degree the average fuel economy gained, especially on the open road.

3. High Load
A naturally aspirated engine should run an air/fuel ratio of around 12 - 13:1 at peak torque. The exact air/fuel ratio can be determined by dyno testing, with the ratio selected on the basis of the one that gives best torque. Rich air/fuel ratios can be used to control detonation, and this is a strategy normally employed in forced induction engines. Thus, on a forced induction engine, the mixture should be substantially richer: 11.6 - 12.3:1 on a boosted turbo car and as rich as 11:1 on an engine converted to forced aspiration without being decompressed. As is also the case for ignition timing, the air/fuel ratio should vary with torque, rather than with power.

Most factory forced induction cars run very rich full load mixtures, with 10:1 being common. This is done for engine and cat converter safety reasons - in case an injector becomes slightly blocked, or the intake air temperature rises to very high levels. These cars will normally develop more power if leaned out. Note that emissions testing does not normally take place at full throttle, so full load emissions can be high without legal problems.

In the engine operating range from peak torque to peak power, a naturally aspirated engine should be slightly leaner at about 13:1, with the forced induction factory engine about 12:1 and an aftermarket supercharged engine staying at about 11:1.

4. Acceleration
During acceleration the engine requires a richer mixture than during steady-state running, with the extra fuel provided by acceleration enrichment. Under strong acceleration, the air/fuel ratio will typically drop 1 - 1.5 ratios from its static level. The amount of acceleration enrichment that is required is normally found by trial and error, and this is best done on the road rather than the dyno. The acceleration enrichment should be leaned out until a flat spot occurs, then just enough fuel to get rid of the flat spot should be added. This approach usually gives the sharpest response. Note that both over-rich or over-lean acceleration enrichment will result in flat spots, and that a greater amount of acceleration enrichment is needed at lower engine speeds than higher speeds.

5. Over-run
In road-going vehicles, deceleration enleanment is used to reduce emissions and improve fuel economy. This normally takes the form of injector shut-off, with the shut-off often occurring at mid-rpm (such as 3000-4000 rpm) and the injector operation re-starting at 1200-1800 rpm. High rpm injector shut-off can, in some cases, have the potential to cause a momentary lean condition.

Conclusion
How a car drives on the road is a pretty damned important part of owning a modified car - and in both the power that is developed and the driveability, air/fuel ratios are a vitally important ingredient

**NOTE**
On the subject of aftermarket fuel rails, injectors, and fuel pumps. Stock fuel components are good enough to supply enough fuel for the maximum and extreme conditions of the original engine characteristics. Once you bring forced induction to a N/A engine, or larger turbos and higher flowing fuel maps the stock parts won't be able to deliver the ammount of fuel that will be needed to supply an efficient enough a/f ratio. Thats why people purchase higher flowing fuel pumps, larger CC injectors, and larger fuel rails.

Also the flowing at .5 gallons a minute is just a measurement. A Corvetter may produce 400HP and 400TQ ar its maximum peak but it never continuosuly produces that ammount of power. Same as with car audio, the units are usually measure by their peak output. The pump can probably flow .5 galons of fuel per minute at one point in its peak of operation, but it should'nt need to flow that much fuel. Its just an operation measurement to give consumers an idea of the equipment they are buying.

posted by  DSMer

I just want to make sure cuz you know how sometimes you read something and you still dont understand it so I just want to make sure...

posted by  CarEXPERT

Not necessarily. best power is achieved when EGT is in a small temperature range (about +55°C) on the rich side of peak EGT. Some guys may over fuel to provide some cooling of the air and limit det during boost (look up latent heat of vapourisation).



Only if they have the available duty. If the pump can't deliver sufficient fuel at a pressure req'd by the injectors to overcome boost pressure, the injectors will under fuel and give a poor spray pattern. Jap turbo cars tend to have sufficiently sized pumps for additional boost. Of course fueling is a little more complex than just recieving instructions from a MAP sensor.

The injectors must also have the capacity to deliver enough fuel for increased boost/power.



They close. You answered your own question.

posted by  Wally

one difference is that turbo charges are more fuel effiecient and better for the eviroment (like in the SAAB ecotec engine). However supercharges are better for going faster i think.

posted by  Private Donkey

DSMer shouldn't you be acknowledging "Autospeed" for the copy 'n paste?

http://www.autospeed.com/cms/article.html?&A=1595

posted by  Wally

How is air going into the cylinder if the throttle plates are closed at idle? Is there liike a air bypass controll?

posted by  CarEXPERT

Why? This is'nt an english paper. Its obviously not written by me, nor do I claim it to be. But if it makes you happy. CarEXPERT and to anyone whom it concerns, the post #43 is not written by me. The first part of the post, in unchanged form, was taken from www.autospeed.com

You happy yet? Or should I give the editor-in-chief a call and let him know I copied his article to help a confused person interested in cars? Oh and thats not a rhetorical question I'm DYING to know your answer... :banghead:

posted by  DSMer

It doesn't hurt to acknowledge a source, if only for the courtesy. I know you have more nerve than mouthful of bad teeth, but don't you feel a whole lot better now you got that off your chest? :wink2:

posted by  Wally

Sure whatever you say. It was so blatently obvious that I did'nt create the information that I figured everyone would atuomaticly know it was from another source. But I guess not since "somone" wanted to get picky about it... Don't know who that could have been, but the problem has allready been cleared up... :thumbs:

posted by  DSMer

Considering what happened with vwhobo, I'm surprised you didn't just post the link in the first place. People on this forum are picky.

posted by  theman352001

all i have to say is VATN. nothing else can compare. If you dont know what that is, google for aerocharger and VATN.

posted by  Low Impedance

Only when it comes to certain people.



They are certainly impressive by most accounts

posted by  Wally

DSMer, that post was hard to understand. When the engine is at idle, why does it say that the ratio have to be rich, shouldnt it be lean at idle cuz the RPMs are low?
On that artical what does engine load mean? engine work, RPM?

DSMER, I forgot to ask you about the 4g63,T engines. Why are the power diffrent and sometimes drivetrain diffrent in the 4g63T, like in the GSX the power is lower than the Evo 8 and dont they use the same engine? Is the Galant JDM?

posted by  CarEXPERT

hey you used ChrisV's insult!!!! i also notice you used the thesaurus insult in another thread which was used on Wally which originally came out of bav.
just a lil heads up buddy :laughing:

posted by  Ki2AY

Right, and since when does ChrisV have copyrights to words or phrases? Hey bet I know one that definetly has to be yours becuase when I look it up in the dictionary it has your picture next to it. Goes something like "dipshit", yeah I think thats the one....

posted by  DSMer

hahah funny! good one "junior"! :laughing:

posted by  Ki2AY

This is true. :thumbs:

posted by  DSMer

hey thats 2 lame jokes in a row.. man your in a roll!!!

posted by  Ki2AY

DSMer, just dont talk to him. Remember he says that he just wants to bother people and get a reaction.

posted by  CarEXPERT

i love how you think... please do help me discipline these geezers...

hey expert, what city you from? im from the 510 haystack (hayward). originally from sf.

posted by  Ki2AY

408 San Ho!

posted by  CarEXPERT

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