People looking to do e85 tunes need larger injectors.

 

+1 and people who don't want to buy twice go big and tune with DSMLink (or others) so we can think about something else

Have you ever saw on fwdconnection how the injector fuel spray is over 1000cc ? If you ask this question it's because you haven't seen it ! Fuel injector clinic FTW !

 

Exactly. It takes a lot more of e85 to make a proper mixture. However, e85 is very high in octane and allows one to run more boost/timing.

 

Keep in mind also that it is never wise to overrun an injector(or any part on your car). I have seen dozens of logs where people are running injectors to there max duty at 100-103% even more sometimes! Not only do you start to lose accuracy of amount of full being injected. But imagine if your 880's are maxed for duty and you need just a little more boost to meet your hp or trap speed goals. Even worse an overrun injector fails and causes you motor to lean out and BOOOM! Time to rebuild.

I personally refuse to run anything to 100% max on my car, IMO you are just asking for trouble. Now take into account what these other gentlemen have added before me, and it should be making more sense.

 

I personally refuse to run anything to 100% max on my car

Except a small turbo

 

I have a few reading articles for you on stoichiometry. It takes more e85 to make a proper mixture than it does for gasoline.

1. http://en.wikipedia.org/wiki/Stoichiometry

2. http://en.wikipedia.org/wiki/E85_in_standard_engines

Particularly:

E85 gives particularly good results in turbocharged cars due to its high octane. It allows the ECU to run more favorable ignition timing and leaner fuel mixtures than are possible on normal premium gasoline. Users who have experimented with converting OBDII (i.e., On-Board Diagnostic System 2, that is for 1996 model year and later) turbocharged cars to run on E85 have had very good results. Experiments indicate that most OBDII-specification turbocharged cars can run up to approximately 39% E85 (33% ethanol) with no MILs or other problems. (In contrast, most OBDII specification fuel-injected non-turbocharged cars and light trucks are more forgiving and can usually operate well with in excess of 50% E85 (42% ethanol) prior to having MILs occur.) Fuel system compatibility issues have not been reported for any OBDII cars or light trucks running on high ethanol mixes of E85 and gasoline for periods of time exceeding two years. (This is likely to be the outcome justifiably expected of the normal conservative automotive engineer's predisposition not to design a fuel system merely resistant to ethanol in E10, or 10% percentages, but instead to select materials for the fuel system that are nearly impervious to ethanol.)

The following table shows the range of air fuel ratios typically used for burning gasoline, E85, and pure ethanol (E100) under an assortment of assumed operating conditions:

Fuel -- AFRst -- FARst -- Equivalence

Gasoline stoichiometric 14.7 0.068 1 1
Gasoline max power rich 12.5 0.08 1.176 0.8503
Gasoline max power lean 13.23 0.0755 1.111 0.900
E10 stoichiometric 14.0 - 14.1 ? ?
E85 stoichiometric 9.765 0.10235 1 1
E85 max power rich 6.975 0.1434 1.40 0.7143
E85 max power lean 8.4687 0.118 1.153 0.8673
E100 stoichiometric 9.0078 0.111 1 1
E100 max power rich 6.429 0.155 1.4 0.714
E100 max power lean 7.8 0.128 1.15 0.870

 

100% just means that injector is flowing ALL it can flow. If you are still cramming more air than fuel in a bad ratio into those cylinders...

You will still run lean and melt / break / detonate something into little rattling pieces.

What don't you understand? 100% IDC still means "X" fuel, if you still need more than "X" fuel, you're fucked.


With the advancements in both injectors and management, you can run larger injectors without the side effects that typically came with them, to work the injectors less... and leave head room should you upgrade something else down the line and require more fuel.

It's really quite simple...

 

Also back in the day,
old school dsmers raised the base fuel pressure to get away with smaller injectors before advancements like 'Link came along. Since thats no longer the best way to do things , Like egt gauges, you wont find many doing it that way anymore.

Well on a 16g @ 20something psi with a rewired 190wb, my rc550's were @ 100% Duty Cycle.

 

Read my post.

I don't get what you don't get Sleeps.

What makes the car require more fuel? Do you have a turbo on your car? <hello> How about some common sense. More boost! More air in the form of better VE, cams, FMIC, piping, intake... bigger turbo... etc.

More air = a larger fuel requirement. And something as simple as a 16g can absolutely vaporize the stock injectors sub 20psi. So how about 750's? Yeah... an E316g with a welded WG can eat most of those up too on the right car.

So what about people with real turbos? 30R? 35R? Holset?

It requires much more fuel, a lot more actually.


I maxed out 550's on raised FP with a good pump, and -6AN lines. On a 14B. That is a stock turbo.

Sleeps, you're just being a little retarded.
:dunno:

 

What makes the car require more fuel? Do you have a turbo on your car? <hello> How about some common sense. More boost! More air in the form of better VE, cams, FMIC, piping, intake... bigger turbo... etc.

More air = a larger fuel requirement.

Sleeps, you're just being a little retarded.
:dunno:

Commen sense? More air needs more fuel. Ya, where are you getting more air? And so much so that is requires almost double your fuel amount? I mean a 2.0 liter motor can only hold 2.0 liters of air/fuel.

The air amount in the cylinder cant change, just the speed at which it goes in? Is that not correct? How can you stuff more air into the same space??

Higher PSI means faster air movement, not volume? Now a bigger turbo can move a higher volume, but its still going into the same place as the stock turbo's air was. The size hasnt changed, so why has the amount of fuel changed? This is what I dont understand. How its assumed you somehow crame more air into the same size cylinder??? Since the air fuel mixture needs to stay the same for your engine to be drivable, or more so correct and efficient? Or am I missing something?

 

Lots of good info in this thread so far. Sleeps, any more questions you may have, don't be embarrassed to ask. The more you understand about dynamic engine performance, the more you'll know to be able to decide on the proper setup for your goals, and the easier it will be for you to learn to tune.

 

Great thread. I feel like I just got a P.H.D in injector theory.

I understand about having to small of injectors. But is it possible to have to big injectors.
Can you tune a stock car to run on 92 octane with 1000cc injectors? Or will it still be to rich at the lowest duty cycle?

Just wanting to learn more.

 

With the right management THESE days it's not normally an issue with way too large of injectors.

In the days of retarded tricker boxes like the AFC and other simpleton electronics that fudged numbers going to the ecu to adjust for fueling requirements... fuck NO you couldn't do it. Not only because it would adversely effect timing to the point of stupid fuckery... but also because it was not addresses dead time either. Big injectors don't open or close as fast as little injectors. Which may not matter (as) much at WOT. But it sure as fuck does at idle. For example. DSM injectors and Evo injectors. The Evo injectors are larger, they're both denso, so they would open slower right? Wrong! Because of the improvements over time, they actually respond FASTER than the stock 450's! Meaning you would have to adjust dead time negative!


The other large factor is the injector themselves. They are better now than they ever were. Getting a big ass injector to do idle level pulsewidths used to be a horrible PITA because of the dead or (dwell) time issue that was not addressed... but also the way they delivered fuel as well. Think super soaker...

That kind of spray pattern does not happen to benefit idle whatso-fucking-ever. All those gas molecules are sitting in a puddle. The new ones atomize fuel 200-500% better than the old injectors did. This makes it easier to light the mixture, and will show in a large improvement in idle quality since we're already trying to tell a VERY large injector to only deliver fractions of what it is designed to.

Finally management. The ability to dial in injectors @ the ecu level makes for a much better running car without "side effects" from tricking it to do what we want. Plus we can adjust dead time too. So we cover both the global sizing of the injector, and the opening characteristics. On top of that, such as with ECMlink, you can even edit airflow tables to iron out inconsistencies in the cars setup. So you don't have to spend years trying to dial in a car's fuel curve to match injectors and the airflow/fueling changes that are effected by other things. (And subsequently would never line up.)

This is what changed.

 

Too much good info to be in the Lounge, is there a better place for this?

 

Thank you Professor Asmo. I had to read it twice but I got it.

That helps explain how these new flex fuel vehicles work. They have to have some good size injectors to run E85 but still be able to run gasoline also.

 

I've discovered that your lack of understanding is due to an incorrect understanding in the laws of physics. First law, air is compressible. The more the pressure (boost), and all other factors identical as you'll see in the next part, the more molecules of air. So you CAN fit 6 liters of air into 2 liters of space. Easy way to understand this concept, you'll notice it requires a lot more air to fill your car tire than to fill an inflatable pool tube thingy, though they're roughly the same volume.

Next, simplifying the ideal gas law equation to exclude a constant, it reads like this:

PV=nT

P= pressure
V= volume
n= number of molecules of air (in moles)
T= temperature

Let's also remove the T, and assume for now that the temperature of the air doesn't change. So now, the equation looks like this:

PV=n

So, changing any of these factors directly affects the others. So looking at it like this, Volume is constant in an engine. 2 liters is 2 liters. So if you increase the pressure on one side of the equation, that means something else has to increase on the other side to keep the equation balanced, aka number of molecules of air.

 

I'll also add that this is basically the same concept non turbo motors use. But since they have no turbo, they can't increase the pressure, so instead they increase the volume. This is why muscle heads go for the bigger is better mindset.

 

Moved to Gen Tech/Tuning.

 

Forced induction means exaclty that right? Your forcing air into the engine. So how does compressing air not have anything to do with speed? Your car cannot suck in more air than its engineered to get.

I think of a straw even, a smaller straw will move air faster but less of it than a much larger straw with the same air pressure moving through it.

So if the more air and fuel in your engine, the bigger the bang, thus the more "power" your car can make. So then people blow stuff up because the load at which your making in your cumbustion chamber is greater than what your moving pieces can hold. Right?

I understand needing more fuel because of porting, or bigger cams, or allways boring out your engine for more space, ths changing the amount of air your car can allow in. But stock I just simply dont understand how one can change the amount of air and fuel your car was designed to use without changing the efficency of your car. Or is really the whole point to bigger injectors, saftey. Safer to run rich, and thus its just accepted to run bigger injectors because of it.

Last thing, if 11psi requires a 30% dusty cycle stock, then why would 20psi all the sudden use 100% duty cycle? Even on a bigger turbo, the numbers dont add up. does someone have a actuall graph or print out of where turning up the turbo shows the duty cycle changing so dramaticly?

Also, do bigger injectors have the same opening time? Obviously they are bigger and thus dump more fuel at the same time rate, but using bigger injectors seems like you would almost have to speed up the rate at which it opens. Unless the required amount (of air) is so much more that it evens itself out at the same rate? So really the limiting factor in our fuel system would be the ECU since it has all the info and controlls the pulse and fuel rate...???

 

Forced induction means exaclty that right? Your forcing air into the engine. So how does compressing air not have anything to do with speed? Your car cannot suck in more air than its engineered to get.

I think of a straw even, a smaller straw will move air faster but less of it than a much larger straw with the same air pressure moving through it.

So if the more air and fuel in your engine, the bigger the bang, thus the more "power" your car can make. So then people blow stuff up because the load at which your making in your cumbustion chamber is greater than what your moving pieces can hold. Right?

I understand needing more fuel because of porting, or bigger cams, or allways boring out your engine for more space, ths changing the amount of air your car can allow in. But stock I just simply dont understand how one can change the amount of air and fuel your car was designed to use without changing the efficency of your car. Or is really the whole point to bigger injectors, saftey. Safer to run rich, and thus its just accepted to run bigger injectors because of it.

For the 8th time, air can compress.

AIR CAN COMPRESS.

AIR CAN COMPRESS.

 

You still don't get it, the answer is already in this thread. If you want a log look for one. there are plenty of 'link logs posted up.

 

Not to be a jerk or anything but seriously how do you have 489 posts and a join date of Oct 2009 and yet you know nothing about the functionality of a forced induction, internal combustion engine? I would like to apologize if my post is rude but honestly you haven't listened to any of the previous posts much less read the links to informative threads that were suggested. Read and search. :chair:

 

The same way I thought I knew alot when I first started working on cars. There is alot of uninformed poeple out there spewing what they think is truth. When you start questioning and digging deeper though, you start finding fault in alot of theories. I do know how an engine works, and I understand the concept of compressed air, but Ill have to find something that explains to me where I can understand it more. Where I can understand how almost anyone can "bolt on" different parts, and somehow come out better than the engineers who designed it, without any real effects. Or maybe 90% of "tuners" dont elaborate on why their junk doesnt work cause maybe they dont really know.

EDIT: Ok so really my questioning is more like this, HP numbers can be made with more fuel and more air, burnt at the right mixture...sure. But taking an engine that was built and set at 190hp, and putting on bigger exhaust, intake, turbo and fuel, cramming it all in there, and getting higher numbers... does or does not truly affect your efficancy and your durablility?

Here is the myth im going after, not anyone can really "tune" and or "build" a stock engine and truly think he can make it better all around than the engineers? Now if one was to take it down to block and build it for a purpose from there then I understand the need for bigger and different stuff...I just dont want the idea that creating usable horsepower is as easy as bolting on parts, like people make it out to be. Is that understood?

Im trying to find the basis as to where all this theory for the parts and sizes we use come from.

 

I give up. My 90% idc's on 1000cc injectors are impossible on my non ported 2.0 liter, back to 450's.

 

Porting a head does'nt necessarily mean the motor will need more fuel. Too many DSMers get caught up on porting and polishing. I've worked in a race shop/machine shop for most my life. I'm sure I have several thousand hours on the flow bench by now. I can tell you from experiance that porting & polishing is not always about peak power production. When we build a motor we have to take into account what the motor is being used for, what spec cam(s) are being used, the valvetrain components being used, the amount of lift at which the motor will be doing most of it's grunting.
People automaticaly think that porting and polishing, a multi-angle valve job, and a big cam are all that is needed to make big power. This could not be further than the truth. You could spend a ton of money on your cylinder head(s). 5 angle valvejob,high lift cam, yada yada yada. But if your building the car to make it's power lets say at X amount of lift at X,XXX rpm's. Well than you have to see what type of valve job works best for that duration,lift,profile cam. Just doing the most expensive service your machine shop offers does'nt assure that you're motor will perform any better. It just means you've spent more money. This method is like baking a cake and just tossing all the ingredients in the mixing bowl without measuring them out,than baking it at some random temp for no set length of time. That would be one fucked up cake.
My motor in my Talon drag car has a 3 angle valvejob. When people hear that they say "why did'nt you get a 5 angle valvejob?" Well,because the motor would'nt perform to it's peak ability if I had just gone into the motor with no rhyme or reason and started just taking massive amounts of material out of the head,and going way beyond what actually makes useable power.

And by the way it's water that cannot be compressed.


Sorry guys. My thoughts are a little scrambled right now. I have'nt slept in nearly 3 days.

 

If your increasing the size of the valves and how far they open than yes,you may benefit from porting. But to gain any substantle power the head must be flow benched by the same operator every time,under the same conditions. It's easy to minipulate readings. This is not something that you just guess at.
And yes,you can definately make more power by adding more fuel, increasing the boost levels, and properly tuning it. This can most certainly be done on a stock motor.

Sleeps,what do you mean when you say "engineered to get"?

 

I read the entire thread but I guess I will paraphrase some things sleeps is hung up on understandably.

Velocity does not equal volume or mass.

Boyle's law explains the relationship of a gas in respect to volume/temp/mass/pressure. Those are all values directly related yet independant.

Thats how a larger turbo can flow more air at a lower pressure than a smaller turbo. It is more efficient at the given operating conditions that fascilitates that.

You can compress air to increase its mass for a set amount of volume. This is expressed in various terms but really your flow should be indicated as lbs/min as the pressure per square inch is not really proper when describing total amount of air being moved which is what matters when tuning.

Do you see what is happening now? The 4g63 , stock, has 2 litres of volume. Using a turbo allows one to lower the volume of the air it ingests allows for a higher mass of air to enter the motor. This allows for the use of more fuel to stay proportional to the mass of the air in the cylinders.

Its easy to initially confuse volume and mass.

 

Sorry:dunno: I guess I just have a way with words.lol

 

Here's a little experiment for you sleeps, and this isn't meant to offend you. Take 2 balloons and fill them both about equal, to the best of your ability. Put one in the fridge, one in the freezer, wait an hour. Take them both out, and set them on the counter. believe it or not, same amount of air in each. don't believe me, wait another 5 minutes.

 

Volume is one of the parameters for density, the other being mass. Volume measures how much space a substance occupies. Mass measures the amount of matter in the substance. Density then shows the amount of matter in a given space for a substance.

Density Formula
The mass of an object divided by the volume of an object equals the density of the object (mass / volume = density). Density is often presented as grams per cubic centimeter (g/cm3).
Increasing Density
If the volume for a mass of substance is decreased, the density increases. For example, compressing a gas into a gas cylinder increases the density of the gas.
Decreasing Density
Increasing the volume of a mass of substance decreases the density. Releasing a gas from a compressed gas cylinder will decrease the density of the gas that was contained.
Compressibility
Changing the volume of a mass of gas is relatively simple, and gases are regarded as compressible. Liquids and solids resist changes to their volume and are considered incompressible.

Design and Function of a Turbocharger: Compressor The turbocharger's basic functions have not fundamentally changed since the times of Alfred Büchi. A turbocharger consists of a compressor and a turbine connected by a common shaft. The exhaust-gas-driven turbine supplies the drive energy for the compressor.

Compressor
Turbine
Control system
Bearing system


Design and functionTurbocharger compressors are generally centrifugal compressors consisting of three essential components: compressor wheel, diffuser, and housing. With the rotational speed of the wheel, air is drawn in axially, accelerated to high velocity and then expelled in a radial direction.

The diffuser slows down the high-velocity air, largely without losses, so that both pressure and temperature rise. The diffuser is formed by the compressor backplate and a part of the volute housing, which in its turn collects the air and slows it down further before it reaches the compressor exit.

Operating characteristicsThe compressor operating behaviour is generally defined by maps showing the relationship between pressure ratio and volume or mass flow rate. The useable section of the map relating to centrifugal compressors is limited by the surge and choke lines and the maximum permissible compressor speed.

Surge lineThe map width is limited on the left by the surge line. This is basically "stalling" of the air flow at the compressor inlet. With too small a volume flow and too high a pressure ratio, the flow can no longer adhere to the suction side of the blades, with the result that the discharge process is interrupted. The air flow through the compressor is reversed until a stable pressure ratio with positive volume flow rate is reached, the pressure builds up again and the cycle repeats. This flow instability continues at a fixed frequency and the resultant noise is known as "surging".



So a turbo compresses air and changes the mass, but the volume stays the same. Then a larger turbo would give more volume and mass, and thus the reason for more fuel. So Your stock injectors are set up to accomidate your stock air volume and mass, but when you change that, the computer sees way to much air not being used, and thus opens the injectors longer untill, as its put the duty cycle is over 80%, resulting in "not enough fuel" being provided.

Could that be cured with a higher volume pump, and regulator then. Is it that the injectors run out or the pumps pressure not being enough to get it in there fast enough. Or at this point, both are relavent.

 

the computer sees way to much air not being used, and thus opens the injectors longer untill, as its put the duty cycle is over 80%, resulting in "not enough fuel" being provided.

Could that be cured with a higher volume pump, and regulator then. Is it that the injectors run out or the pumps pressure not being enough to get it in there fast enough. Or at this point, both are relavent.

Answer : Combination of both, its not always the amount going through the injector, that's why injectors are set at different levels of efficiency, because as stated in responses above as well, spray pattern is a factor. Running the fuel pressure too high can also cause premature damage to the pump, lines and other componets of the fuel system.

 

It could not be cured by a higher volume pump and regulator. 450cc injectors flow just that...450cc. If you have a bigger hairdryer on your car you may need 550cc (or larger) injectors to run 11.4:1 (read my previous reply) in boost. This is because you have more air crammed into the same space.

That's just it my man. The air compresses into the same amount of space. Since you have more air crammed into the same space you need more fuel.

Do you seriously think, with all of the technology and cars running 6 second 1/4 miles, people would ever upgrade their fuel injectors if it didn't need to happen? DSMers are cheap bastards. A lot of DSMers cut corners. More air = more fuel. More air goes into the same space, but you don't have enough injector to put in the more fuel. Upping your fuel pressure does not solve your problem. A bigger injector does.