Turbo vs. Naturally Aspirated

  • Thread starter Thread starter Nightmage82
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thanks for all the replies guys, except that random conversation between gtr guy and shinez, LOL! :D but in light of what takumi said,

Originally posted by takumi64
If you're planning to use Turbo get yourself a Misfiring System. It combines the advantages of Turbo and NA
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something straight out of initial d i know, but does a misfiring system make a difference? does anyone know how? and could it be applied to NA?
 
Ummm what is a misfiring system? I've tried to think of what I can relate that to as far as electronic systems or mechanical and I just can not get my head on it.

Turbo charging an orginally N/A motor is a bit dangerous. Not only that but getting your motor to last. It all depends on what the compression ratio is on the motor. Turbo or supercharged engines are lower compression than N/A as they use boost to create the higher pressures in the cylinders to make power. Where as N/A are already have higher pressures to start with.

The average turbo or supercharged engine will be from 8-1 to 9-1 compression while high reving N/A's start at 10-1 and go up from there.

Things to worry about are "knock" , "pre-ignition", or "detination". In other words the mixture in the cylinder fires before it is suppose to via the sparkplug. This will damage the tops of your pistons actually creating small craters in them. Think of it as a mini explosion instead of a nice clean burn. Basiclly your getting a desil effect in your petrol/gasoline engine. That is a very bad thing. It is why also many factory turbo cars have an intercooler to cool the intake charge and help prevent detination. Most aftermarket ecu's come with or you can get some sort of knock sensor the help detect it.
 
From what I understand the fakeness of it...it's supposed to cause missfires..so you don't lose spooling through sharp corners with a bigger turbo..dunno how it works...sounds coo though
 
Misfiring system detects whenever the turbo is slowing down in a corner.. from my knowledge it injects fuel directly into the muffler so it causes a little fireball and an explosion IN the muffler... this makes the boost pressure stay up so the car wouldn't have to spool up again
 
From what you guys are saying it sounds like anti-lag. I have never heard of any system that dumps fuel into the exhaust system other than from the movies to create flames out the exhaust pipe.

Anti-lag is systems are pretty complex to set up right but easy to explain in technical terms. So the simplified tecky on turbo lag and anit-lag in depth.

Enjoy.

First Engine Power - Engine Power is created by one thing only. BMEP (or Brake Mean Effective Pressure). This is the Dynamic (or actual) pressure created within the cylinder during the combustion process. BMEP is the "be all and end all" of the engine power game. Everything we do to create power in any engine is done in an attempt to raise BMEP in a controlled manner.
During the combustion process many things are happening, but of particular interest to tuners is the raise and fall of BMEP within a complete cycle of the engine. During the intake stroke, air and fuel are drawn or pushed into the cylinder, the intake valve then closes and the upward stroke of the piston compresses the mixture. As the piston approaches Top Dead Center (TDC) a spark ignites the mixture and the combustion process begins.

On a scale of 1-10, the actual compression pressure of an engine is about 1 or 2 when no spark is made. The pressure created by the burning and rapidly expanding air/fuel mixture rates about 7 or 8.
This rapidly increases until such time as two things happen.
1. The piston is forced down by its expansion (power is created) and the space created by the piston moving down in turn, creates a pressure drop within the cylinder.
2. The burning/expanding rate begins to slow down due to air/fuel depletion.

Climbing those peaks - the point at which BMEP is at its highest is called "Peak BMEP". Its position within the firing cycle is studied by engine designers and tuners all over the world. It is generally agreed that the point of peak BMEP should fall within the 14-16 degs after TDC.
If you think of ignition spark as the beginning of the combustion process, and we can establish that it takes 46-48 crankshaft degrees (the usual average) to reach "Peak BMEP", then an assumption can be made that we should set ignition timing to start at 32degs before TDC. (32+14=46). Have a think about this and understand it, because it is important.

Now let's do something rather interesting: Let's retard the ignition timing to something like 10degs after TDC. Suddenly we have a threoetical Peak BMEP at 56degs after TDC. Power has dropped signficantly. In fact, we have virtually no power - Why? Simple: the next step in our engine cycle is the exhaust stroke to vent the spent gases, and this is happening just after our retarded Peak BMEP. So, effectively our precious power producing charge is now burning and rapidly expanding inside the exhaust manifold. This is not much good for making power, but it really makes the turbo spin hard!
So if the turbine is spinning hard it mst be making heaps of boost right? Well yes, but we are not making any power because the Peak BMEP is all going out the exhaust valve.

So what good is? Easy. During a race we want instant boost. - the moment we get back on the throttle we want it there ready to go., just waiting for us. So how do we do it?
Anti-lag should only be operational during off-throttle conditions otherwise power will be lost by retared BMEP.
The first thing we do is keep the throttle open about 10 %, so there is air available for the combustion process. Then we retard the ignition timing by a huge amount which creates retared BMEP, and large turbine driving pressures within the exhaust manifold. This in turn, creates strong boost even though the throttle is closed, but when you open throttle again and the ignition timing returns to normal, the turbine is already spinning hard and making boost - so we have instant power.

Want more? Ok let's now say we want even more exhaust gas pressure to really get that turbine spinning at max revs, because we are off the throttle and not trying to make power. Why not introduce some completely unburnt air/fuel misture into the exhaust for even more rapdi expansion of the turbine driving exhaust gases? Good idea.
The easiest way to do that is to introduce an ignition-based missfire which will dump a complete compression/firing cycle of air/fuel misture into the manifold. There it is rapdily ignited by the next cylinders flame front. Now have got some serious amounts of boost in anticipation of the throttle opening. This is how anti-lag works. What I have discribed is a very simplified explanation of anti-lag and it can only be said that, in real life, there are many many many more variables that come into play. Such as Actual degrees if retard and throttle opening are very different to the numbers I have described, but I have used these as ease explanation.
 
Originally posted by RazorGTR
an ignition-based missfire which will dump a complete compression/firing cycle of air/fuel misture into the manifold.
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let me guess, this isn't employed on most stock turbo systems because the lifecycle of ur exhaust manifold is limited to a few hours right?

thanks for the explanation razor, its precisely what the misfiring system is.

i hate it when people explain something complex and then say "its a really simple explanation" heh but for the benefit of shinez and anyone else who may not have understood, here is what i think is a more simple explanation:

when you let go of the throttle on a turbo car, the turbo will start slowing down (i.e. when you enter a corner) but since you are about to punch the throttle again (on exit of the corner) you want there to be maximum power (in the form of boost pressure in the turbo) available to you. so the car deliberately delays the spark in the cylinders (when u let go of the throttle) causing most of the power + heat to go into the exhaust instead of to the wheels. since you don't need the power at the wheels (when you are corenering or slowing down) that power is used to massively spin up the turbo. therefore when u exit the corner, the turbo is spinning as fast as it was before you let go of the throttle and hence you have maximum boost. maximum boost means maximum power. hope that helps!

razor do you work with engines or did you pull out that explanation from a magazine?
 
Originally posted by Nightmage82
heh but for the benefit of shinez and anyone else who may not have understood, here is what i think is a more simple explanation:
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OOOOOOO :ouch: shinez .......i can wait to hear this response..:lol:
 
when you let go of the throttle on a turbo car, the turbo will start slowing down (i.e. when you enter a corner) but since you are about to punch the throttle again (on exit of the corner) you want there to be maximum power (in the form of boost pressure in the turbo) available to you. so the car deliberately delays the spark in the cylinders (when u let go of the throttle) causing most of the power + heat to go into the exhaust instead of to the wheels. since you don't need the power at the wheels (when you are corenering or slowing down) that power is used to massively spin up the turbo. therefore when u exit the corner, the turbo is spinning as fast as it was before you let go of the throttle and hence you have maximum boost. maximum boost means maximum power. hope that helps!
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The funny thing is is the first half of that I had already mentioned prior....And I understood completly what Razor meant, I don't know if you noticed it but I tend to not be serious most of the time, you probably didn't catch that though...Second, no schiet max boost means maximum expected power. However you have to take into consideration how much the turbo itself can take, and how much you're running it at right now..As you say, Maximum boost? If the turbo set up you have going is set up the "Power used to massively spool up the turbo" could have a damaging affect. Second...There are alot of cases in which you DON'T want full boost exiting a corner, for instance Solo II, if you have full boost coming out of a corner you have a higher chance of wheelspin, along with that you're car is dead through the corner, meaning you're losing even more momentum, and if this action is supposed to take place every time you let off the gas, it's really going to distrupt how you take your corners.
 
when you let go of the throttle on a turbo car, the turbo will start slowing down (i.e. when you enter a corner) but since you are about to punch the throttle again (on exit of the corner) you want there to be maximum power (in the form of boost pressure in the turbo) available to you. so the car deliberately delays the spark in the cylinders (when u let go of the throttle) causing most of the power + heat to go into the exhaust instead of to the wheels. since you don't need the power at the wheels (when you are corenering or slowing down) that power is used to massively spin up the turbo. therefore when u exit the corner, the turbo is spinning as fast as it was before you let go of the throttle and hence you have maximum boost. maximum boost means maximum power. hope that helps!
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The funny thing is is the first half of that I had already mentioned prior....And I understood completly what Razor meant, I don't know if you noticed it but I tend to not be serious most of the time, you probably didn't catch that though...Second, no schiet max boost means maximum expected power. However you have to take into consideration how much the turbo itself can take, and how much you're running it at right now..As you say, Maximum boost? If the turbo set up you have going is set up the "Power used to massively spool up the turbo" could have a damaging affect. Second...There are alot of cases in which you DON'T want full boost exiting a corner, for instance Solo II, if you have full boost coming out of a corner you have a higher chance of wheelspin, along with that you're car is dead through the corner, meaning you're losing even more momentum, and if this action is supposed to take place every time you let off the gas, it's really going to distrupt how you take your corners.:banghead:
 
Well I read 2 peoples take on it...one alot more trusting than the next, but will informed either way, and neither included a fail safe...So...Doesn't sound that great
 
..I've never really heard of anything actually being used as such, simply because of the more negative affects it could have as apposed to the positive
 
Originally posted by Nightmage82
let me guess, this isn't employed on most stock turbo systems because the lifecycle of ur exhaust manifold is limited to a few hours right?

thanks for the explanation razor, its precisely what the misfiring system is.

i hate it when people explain something complex and then say "its a really simple explanation" heh but for the benefit of shinez and anyone else who may not have understood, here is what i think is a more simple explanation:

when you let go of the throttle on a turbo car, the turbo will start slowing down (i.e. when you enter a corner) but since you are about to punch the throttle again (on exit of the corner) you want there to be maximum power (in the form of boost pressure in the turbo) available to you. so the car deliberately delays the spark in the cylinders (when u let go of the throttle) causing most of the power + heat to go into the exhaust instead of to the wheels. since you don't need the power at the wheels (when you are corenering or slowing down) that power is used to massively spin up the turbo. therefore when u exit the corner, the turbo is spinning as fast as it was before you let go of the throttle and hence you have maximum boost. maximum boost means maximum power. hope that helps!

razor do you work with engines or did you pull out that explanation from a magazine?
Click to expand...

I wrote most of it myself. I work part time for a local tuner, the same one who chipped my GTR. I also know two others very well. The data in which the numbers were quoted I got from the tuner. I added in my explanation as it was partly explained to me over three years ago.

Actually on the EVO7, and EVO8 anti-lag is part of the OEM software in the ecu direct from the factory. It is however not as aggressive is it can be. While it does retard the timing during the closed throttle period, as when either upshifting or down shifting. I also believe from memory it will NOT be effect while the car is stationary so the ecu must be sensing or reading the car's road speed before it will work.

A quick note though on the "lifecycle of your exhaust mainfold". Since the volumne inside your manifold is much greater than that of your cylinder, and there is now "closed" or "sealed" space the pressures are no where near as great as you think they are. As an example I am sure you have heard and seen cars back fire and flames come out of the exhaust pipe more on racing cars and even on street cars. That is unburnt air/fuel mixtures igniting in the very hot exhaust manifold. The happens when you back off the throttle and only then.
Also any time you back off the throttle on a turbo car, even if you have a blow off or relieve valve, the turbine will slow dramaticly. In the real world this is called turbo shock. Since the wheels of a turbo will spin at over 100,000 rpms under boost the instant your throttle closes that will slow down to less than 15,000 rpms without a blow off valve, and upwards of 50,000 with one. As you can see that is a huge drop. Now if you had a way "anti-lag" to keep the turbine spinning at say 85,000 rpm or more, when you reopen the throttle boost pressure and power are nearly instant.

That is one of the reason rally cars do not need a blow off valve as they have no need for it since the anti-lag systems keep the turbines spinning at near max revolutions. The popping you hear as they are entering and going through a corner is the anti-lag system igniting air/fuel mixtures during the exhaust stroke when the exhaust valve is open.

Is anti-lag good for a turbo? Well yes and no. It does shorten the life of them yes. You are adding a tremendous amounts of additional heat into the exhaust housings of the turbo not to mention to the turbine wheel. This also super heats up the bearings in the center core. I have seen not only pictures of a turbo glowing orange/red but have also seen that in real life. So would a race car driver/tuner/owner care? Not hardly but on a daily driven street car it is not really a practical option. Yet there is no "shocking" of the turbine that is causes by the closing of the throttle. That is also very damaging to the turbo. Keep in mind the shaft which holds the turbine wheel and compressor wheel is only approx. 6mm or .25 of an inch in diameter. On some turbo cars such as the skyline which have ceramic exhaust wheels bonded to the steel shaft, this shocking effect over time will cause turbine wheel failure. The wheel's bonding is actually what fails. On a steel wheeled turbo it is the bearings and seals that take the brunt of the shock. This is another explanation of why turbo cars have that distinct oil burning. As the seals wear oil that is supplied to the bearings seaps into either the exhaust snail or the compressor housing of the turbo, in turn which burns.

i hate it when people explain something complex and then say "its a really simple explanation"
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If you notice I did say
So the simplified tecky on turbo lag and anit-lag in depth
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not a really simplified explanation. I am sure you poms can read better than that. It is disturbing when someone tries to quote what you are saying when in fact they probably have no idea to start with. There have been "simplified" explanation before yet it seems there are a number who still wanted more.
If you needed a really simplified explanation a quick phone call to any decent tuner, or alternatively a quick search on the net you would have found what you were looking for.

Skyline Guy after seening what Nightmage82 had to say, I feel there is no need for me to go more into depth. I am sure he can explain the entire aspect of Anti-Lag from start to finish all by his lonesome self. :lol:
 
Originally posted by RazorGTR
Skyline Guy after seening what Nightmage82 had to say, I feel there is no need for me to go more into depth. I am sure he can explain the entire aspect of Anti-Lag from start to finish all by his lonesome self. :lol:
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yeah but nightmage82 does not own a skyline so his expanation dosn't mean **** to me.....

J/K nightmage82.......:lol:

I dont think nightmage82 meant to explain it all by himself... I think he just wanted to paraphrase what you said in other simpler terms for the people like shinez ;) who cant undestand :lol:

BTW you said the EVO8 had a anti lag feature in the stock ECU...is that feature available in the US version or was it removed?
 
SCREW THE EVO 8...besides..it's stock turbo is too small for it to be a necesity, it wouldn't lose enough spool to matter since the turbo can be spooled fairly easily by a B16A1 let alone a 4g63T...And if you bolted on a bigger turbo,I'm not sure if the tuning would call for it at the correct time..or cause enough of a reaction to do any reasonable change..it might just delay the enevitable so to speak.
 
hmmm i seem to have upset at least two people here. i neither meant to suggest ur explanation wasn't good enough razor, nor that you were incapable of understanding it shinez. why do you assume i DON'T own a skyline gtr_guy? :P

i appologise for any insults that might have inadvertently been incurred. thanks for the explanations razor.
 
Fair enough nightmage.

Just because someone own's a Skylined doesn't make them knowledgable with them, or other aspects of the automotive industry. I know plenty for example who own turbo skylines such as the GTS-t, GTS4, GTT, and GTR who don't even know how to properly change the plugs. You would be suprised at the numbers who have contacted me about how to be careful with the frail coil packs so as not to damage them.

I am always happy to help out with input where I can. If I don't know I won't say. I may how ever mention "I thought" which is not to be confused with a proper statement.
:)
 
Originally posted by RazorGTR
Just because someone own's a Skylined doesn't make them knowledgable with them, or other aspects of the automotive industry. I know plenty for example who own turbo skylines such as the GTS-t, GTS4, GTT, and GTR who don't even know how to properly change the plugs. You would be suprised at the numbers who have contacted me about how to be careful with the frail coil packs so as not to damage them.:)
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Thank you for pointing that out. I feel the worst thing out there is some hopped up car that some Chach is driving and he couldn't even pour oil into the engine to save his or her life. You would never fully respect and enjoy a car if you don't have a good sense of knowledge on it.

As for this conversation on turbo or supercharger. . . I actually would have to say this. If I could drop a 502 into my Iroc-z, I would be putting a blower on it. That would considerablely compromise my all-go, no show attitude though.
 

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