TURBO vs N.A

[Magfocus]

But if you get such a car and worry about fuel prices and what not..then whats the point?

[Thumbs]

Do you work on cars at a workshop and have the opportunity to test out various settings to see how they affect the engine?

 

Irrelevant. I've got equipment that workshops don't even have. Your point being?

 

I do, and I do that every weekend and as much as i can during normal weekdays.

 

So what? Does a person driving a fast car mean he's a good driver?

 

In the example i used about coolant temps, it was on the same car with different AFR settings.

 

Show me the difference in coolant temp between running at 12.0 AFR and 14.7 AFR at idle.

 

As for the O2 sensor, you were the one that said ppl run the car richer to allow it to reach operating temps faster not I. Please be consistant.

 

Read it again carefully.

 

Let me make it very clear now in case you misread it. The only time the engine runs rich to bring the engine up to operating temp is during cold start, typically this lasts less than 20 seconds. That was in response to your idea that running rich lowers engine temp which is obviously incongruent to cold start strategy. Besides this, AFR has no significant bearing on engine coolant temps. Got that?

 

Also yes i may not know what chemically ideals is, but for every car that i have tuned which has failed emissions tests (with a safer AFR), all i did was bump it the AFR up to near early detonation levels and they passed.

 

Interesting... so what are "early detonation levels"? What spark advance and AFR are you talking about here? What engines?

 

I explained partially it with an example in the next sentance which you quoted. Besides its a general statement on what constitues a lean mixture (with the lower limits in the next sentance) not a definative answer of what would a lean mixture in a particular engine be.

 

You said this:

 

>>Any car with a ratio of approx 12.0:1 will already be considered to be running lean and in danger of cracking a piston.<<

 

And I said it is BS. Because there are many cars out there running this AFR with no short or long term ill effects.

 

Obviously FI cars would run lower ratios (than their NA equivalent)due to the increased cylinder pressure when on boost. (Go look at any FI car and the NA version of the engine and see for yourself).

 

True but irrelevant. Stick to the point. You said running 12.0 AFR will cause a "danger of cracking a piston".

 

You do know that early detonation within the main powerband of the vehicle is more likely to cause your piston to crack than when it is not in this powerband right?

 

Again, irrelevant. See above.

 

When in lean crusing at your AFR levels, the timing is retarded to lower the likelyhood of early detonation at a huge expense of power, but since you're cruising you don't need that much power. Kindly show me a car that runs at a AFR of 15.0:1 or higher as i have never seen or heard of one.

 

Absolutely incorrect, lean cruise is directly opposite of what you're talking about. During this phase of engine operation, load is light, and the goal is fuel efficiency, therefore ignition is advanced and AFR is high (lean). That's why it's called lean cruise. Didn't you say you have a wideband O2? Why don't you go out and verify yourself? Come back to us when you find a car that has lean cruise AFR of under 12.0 since this is your definition of lean.

 

>>The only time factory fuel maps allow for a AFR of approx 12.01:1 (usually less) and above is when it low in the rev range, and on part throttle only (and this AFR is only for newer cars).<<

 

Again, BS. You have no idea what you're talking about. Do a search on Google for cars running on high boost, high load, full acceleration run on the dyno. Practically all of them are between 11.5 to 12.0 AFR with only a few exceptions.

 

If you noticed i said factory fuel maps (not tuned).

 

Doesn't change the fact that what you're claiming is BS. Factory maps do not have lean cruise in the region of 12 AFR. It's much leaner than that.

 

http://www.stealth316.com/2-air-fuel-flow.htm

 

Also most of the cars with those settings have lower cylinder compression, and are likely to be running race fuel (possibly even strengthened internals).

 

Stop. Just stop. The more you go on, the more you make yourself sound silly. And we don't really want to know how far that goes.

 

Besides you just proved me right. Your said cars are running less than 12.01:1 AFR at full throttle. (i said it inversly, "12.01...above... on part throttle..".) They only go above that AFR when not on high throttle. Obviously the tuners who tuned your quoted cars know exactly what i'm talking about.

 

Answered in the 2nd paragraph above. BTW you didn't even prove anything in the first place.

 

I apologise i meant rich/lean mixture. (in other words our definitions of what constitutes a rich or a lean AFR). Obviously now i was wrong on that bit as your definition has seemed to change to something more similar using a mix of imaginary ratios (15.0:1) and actual ratios (11.5:1 to 12.0:1).

 

Hello? 15.0 AFR is certainly not an "imaginary ratio"!

 

I'll do better next sat, i'll get the pneumatic dynosheet and the EBC dynosheet (off the same car) and post them up for you.

 

Looking forward to them.

 

Like i said i don't know why, but i do know that it happens.

 

Maybe you can publish a paper on this undiscovered phenomenon and be famous.

 

Btw, there are incabin pneumatic controllers, and you can even mount any of them incabin provided you don't mind the boost spiking.

 

Sure I knew that too. Your point being?

 

The reason EBC's are not affected is because they adjust the size of the bleeder hole size(of airflow to the actuator)to allow for this difference in weather, temp, and altitude while the pneumatic types have a fixed (or 2 fixed) bleeder hole size for the flow. Do you even know how these boost controllers work??? (Note: not all work by bleeding air, but they all have a way to allow only a certain amount of pressure geting through them to the actuator).

 

Sure I know how EBC works, the most common methods are to use solenoids or stepper motor, but it's irrelevant because this is not a pissing contest. Stick to the topic. If you can understand how BC works, I'm still puzzled why you can't understand something simple like AFR.

 

You anology is wrong, I'm using a correlation argument... i.e. when x factor (EBC)is in place y happens (increase in ramp up and spool up speeds). It doesnt explain why or how. Thats why i hypothesised the reasons. My reasons maybe right, or they may be wrong, its just a hypothesis.

 

Hypothesis is not a statement of a fact which you expressed in the first post.

[Thumbs]

It may also cause your plugs to foul early.

[Elfenstar]

Tell you what, I'll go get the dynosheets, rehash what i've said and post them up (i.e. start from scratch with the explanation and with dynosheets to demonstrate what i'm saying). Easier that way than arguing it back and forth bit by bit... getting dizzy coz both of us have ultra long posts....

 

Also lets end the EBC debate since it's off the topic though i'm sure i said

Am guessing that its either denser gases as its cooler or more gases as less molecules are combusted and everything else comes out.

and that was my hypothesis for the increase in speed. The spool and ramp speed issues i will combine with the dynosheets, but pls don't expect a reason (will try and find out why but dun expect it).

[Elfenstar]

Sorry, missed a couple of things i needed to answer...

 

Also yes i may not know what chemically ideals is, but for every car that i have tuned which has failed emissions tests (with a safer AFR), all i did was bump it the AFR up to near early detonation levels and they passed.

 

Interesting... so what are "early detonation levels"? What spark advance and AFR are you talking about here? What engines?

 

early detonation level are near pingin levels (i.e. any leaner and it would start pinging)

 

These are the 2 i remember as the first was my first GTR and the second was the first car i learnt this on (did it under instruction from the head mech while he was watching over my shoulder).

1) 1989 RB26DETT manual. Timing was 20 deg BTDC @ 650 rpm. (Advanced by 5 deg). AFR was 11:1. (increased to 12:1, and dropped boost to 15psi for emissions retest)

2) 2002 SR20DET (JDM S15) Timing was 13 deg BTDC @750 rpm (retarded by 2 deg). AFR was 8.5:1. (increased to 11.6:1, boost was dropped to stock 8psi for the retest).

Edited July 3, 2005 by Elfenstar

[Thumbs]

This is what you wrote originally:

 

Your car runs cooler from running rich (and vice versa for lean). Running lean means lower emissions :p

 

From this statement of yours, it is taken to mean:

 

1) Running rich leads to lower engine temps, lower emissions

2) Conversely, running lean leads to higher engine temps, higher emissions

 

You also said this:

 

Also yes i may not know what chemically ideals is, but for every car that i have tuned which has failed emissions tests (with a safer AFR), all i did was bump it the AFR up to near early detonation levels and they passed.

 

You also wrote this:

 

These are the 2 i remember as the first was my first GTR and the second was the first car i learnt this on (did it under instruction from the head mech while he was watching over my shoulder).

1) 1989 RB26DETT manual. Timing was 20 deg BTDC @ 650 rpm. (Advanced by 5 deg). AFR was 11:1. (increased to 12:1, and dropped boost to 15psi for emissions retest)

2) 2002 SR20DET (JDM S15) Timing was 13 deg BTDC @750 rpm (retarded by 2 deg). AFR was 8.5:1. (increased to 11.6:1, boost was dropped to stock 8psi for the retest).

 

Do you see the big-time contradiction? If running rich means lower emissions, why did you raise the AFR towards stoichiometric i.e. leaner?

 

In your own words, you admitted that AFR was 11:1, it failed, and the retest was at AFR 12:1, high AFR means leaner.

 

Second case, S15 at 8.5 AFR, wow I'm amazed this car can even be driven... do you know that a stock-ish JDM Evo 8 is only running 10.14 AFR (0.69 lambda) at WOT in 4th gear and it already exhibits symptoms of running too rich? Plugs fouled?

 

Now I'm curious, which workshop are you affiliated with?

[Sirium]

Am also curious to find out with workshop you are affiliated with... a tuner who cannot get lean/rich ratios right? And a tuner who does not understand the characteristics and mechanics of a car - but tunes it by guess work? Thats scary sh*t!!

[Elfenstar]

This is what you wrote originally:

 

Quote

Your car runs cooler from running rich (and vice versa for lean). Running lean means lower emissions :p

 

From this statement of yours, it is taken to mean:

 

1) Running rich leads to lower engine temps, lower emissions

2) Conversely, running lean leads to higher engine temps, higher emissions

 

I think you're kinda misreading me... for both 1 and 2 the first part of the statements are correct, but you got the 2nd bit wrong, I said that running lean means lower emissions ( as per what you quoted me).

 

Now for the S15, its standard AFR is 10.5:1, however, it was tuned for japanese 101ron fuel, and he added another 8psi over stock (i.e. 16psi). With the 2 deg retard in timing, she still was pinging (he was pumping 95ron as his area did not have 98 ron) when the AFR was at 9.0:1 and stopped , and stopped pinging at 8.8:1. Taking the huge temp variations of between 3deg (winter) to 42 deg (summer) we dropped it to 8.75:1 (sorry got the figure wrong for this one, went to check earlier today). Sure he lost some power, had a popping exhaust when he changed gears (partially coz of the atmo BOV- he loved that), but it beats cracking his piston. Besides we did retard the timing further initially but he didn't like that much of a power loss (it was more than when running rich) after discussing it with him and discovering that he changed his sparkies every 5000kms, we decided to lower the AFR to the said levels.

 

 

 

Let me see what i can start clearing up...

 

We both agree (generally) that on higher loads, AFR's of over 12.01:1 are not ideal for piston safety.

 

We both also agree that the closer we get to 14.7:1, the lower the exhaust emissions (Still don't understand how you could have misread that when i said word for word that lean mixtures have lower emissions).

 

We disagree on the engine temp issue and the spool up speed when running richer AFR's.

 

Have i got everything thus far? (with regards to what we agree and disagree on)

Edited July 4, 2005 by Elfenstar

[Elfenstar]

Who said anything about guesswork? Its done on the dyno, then on the road, (x3 for both).

 

Kindly enlighten me what chararteristics and mechanics we're talking about here?

[Sirium]

Don't know for sure. Am guessing that its either denser gases as its cooler or more gases as less molecules are combusted and everything else comes out. Its dyno proven anyway.

 

oh, lets not forget the many times you got your lean/rich AFR ratio wrong... oh... and how you thot that running lean will reduce emissions... ahh... I got proper work to do... so you tune in Japan?

[Elfenstar]

>>oh, lets not forget the many times you got your lean/rich AFR ratio wrong...

wherabouts???

 

>>and how you thot that running lean will reduce emissions...

If you re-read my posts, you would realise that my tunes have never gone past 14.7:1, and by that, you would realise that running leaner would have lower emissions than in running richer.

 

>>so you tune in Japan?

I wish i could go there to learn, not even tune...

[Genie47]

Most cars coming to Australia are "rejects" from Japan. They failed their yearly inspection and they get exported out. No mods done so they all require the high quality RON101 gas for performance models.

[Genie47]

Ever seen a gas stove using town gas using yellow flame instead of a powerful bright hot blue flame?

 

It must be drilled into people's heads that lean will give better emissions in the form of cleanly combusted products like CO2, water. The example I give above is so clear from daily life.

 

Problem is that a car engine is no gas stove. Have anything close to the blue hot flame of gas stoves and the car will become Chernobyl!

[Elfenstar]

aye, i know that lean mixture are cleaner, i believe i said that, and thumbs misread that bit. Sorry, just need to know, (might be the way i type) but what made you think that i said richer mixtures are more clean burning?

Edited July 4, 2005 by Elfenstar

[Genie47]

No way! Rich mixtures give all kinds of nasties just from using Mk1 Eyeball Visual Flame Spectrometer.

 

If you have goofed, I didn't see it.

[Elfenstar]

>>If you have goofed, I didn't see it.<<

 

Its alright then, but thanks anyway!!!

[Thumbs]

I think you're kinda misreading me... for both 1 and 2 the first part of the statements are correct, but you got the 2nd bit wrong, I said that running lean means lower emissions ( as per what you quoted me).

 

OK, that part was misread, mea culpa.

 

But that still doesn't change the fact that you're wrong on the other parts.

 

Here it is again one more time, for the understanding-impaired.

 

The stoichiometric ratio of 14.7 applies only to petrol engines and at this AFR, the reaction is said to be chemically ideal with the least amount of byproducts. Deviating anywhere from this, either richer or leaner, means you're going to get more pollutants. Car makers let the car idle slightly rich at 14.4, 14.5 AFR because the engine will idle better, and the catalytic converter can take care of the hydrocarbons.

 

Now for the S15, its standard AFR is 10.5:1, however, it was tuned for japanese 101ron fuel, and he added another 8psi over stock (i.e. 16psi). With the 2 deg retard in timing, she still was pinging (he was pumping 95ron as his area did not have 98 ron) when the AFR was at 9.0:1 and stopped , and stopped pinging at 8.8:1. Taking the huge temp variations of between 3deg (winter) to 42 deg (summer) we dropped it to 8.75:1 (sorry got the figure wrong for this one, went to check earlier today). Sure he lost some power, had a popping exhaust when he changed gears (partially coz of the atmo BOV- he loved that), but it beats cracking his piston. Besides we did retard the timing further initially but he didn't like that much of a power loss (it was more than when running rich) after discussing it with him and discovering that he changed his sparkies every 5000kms, we decided to lower the AFR to the said levels.

 

Let me see if I understand what you're trying to say. In the absence of high octane petrol, you can make a car run at much higher boost, slightly retarded advance, add a lot more fuel of much lower octane, and have it hold together? Either the factory maps are overly conservative or you just set a timer on a bomb. So you think changing plugs at 5000 km is not a problem, and you had to lower the AFR to make things worse? Lower AFR = running rich = more fuel, in case you're confused.

 

We both also agree that the closer we get to 14.7:1, the lower the exhaust emissions (Still don't understand how you could have misread that when i said word for word that lean mixtures have lower emissions).

 

I said that, don't take credit for my words. This is what you said:

 

In a car engine, cylinder compression and fuel quality affects the AFR needed to prevent early detonation (in addition to a few other factors), thus a lean running car will still have a AFR of less or equal to 14.7:1. Any car with a ratio of approx 12.0:1 will already be considered to be running lean and in danger of cracking a piston.

 

By YOUR reasoning, if running 12.0 AFR is considered "running lean and in danger of cracking a piston", isn't 14.7 AFR leaner and thus in even greater danger of cracking a piston? So what you're saying is that car makers are purposely trying to crack their cars' pistons when they are running 14.3, 14.4 AFR at idle, even leaner than that during lean cruise?

[Elfenstar]

Let me see if I understand what you're trying to say. In the absence of high octane petrol, you can make a car run at much higher boost, slightly retarded advance, add a lot more fuel of much lower octane, and have it hold together? Either the factory maps are overly conservative or you just set a timer on a bomb. So you think changing plugs at 5000 km is not a problem, and you had to lower the AFR to make things worse? Lower AFR = running rich = more fuel, in case you're confused.

 

Well that pretty much sums it up, and that the S15 was a bomb, but the boost level is what the owner wanted (he insisted that he would run it at 16psi because he spent $$$ on his FMIC), the fuel is what he puts in for convenience. The fuel maps are fairly agressive for the JDM S15's (definately more than the AustDM). We advised him to turn the boost down and use better fuel, so we could make the car run better, but in the end, he didn't listen, and its his car. All we could do was lengthen the timer before it killed itself. Anyway he subsequently killed his pistons and head by running without an air filter (for 2 months). As for the plugs, its a personal choice. Most of us use regular copper ones and change them every 5000km (regardless of condition) as it works out cheaper and with a better spark than most of the platinum/iridium plugs.

 

In a car engine, cylinder compression and fuel quality affects the AFR needed to prevent early detonation (in addition to a few other factors)...

 

true you have to admit.

 

thus a lean running car will still have a AFR of less or equal to 14.7:1. Any car with a ratio of approx 12.0:1 will already be considered to be running lean and in danger of cracking a piston...

 

I apologise as you are partially right, because this is not entirely true (as i did not specify the load), however it is 100% true on wide open throttle (WOT). That is why the cars you quoted used ratios similar to what i said on WOT. At idle and low loads pinging is not as dangerous to the engine as on high loads.

 

You have to realise that the cars I work on are all pretty highly tuned, and have highly stressed engines, and we cannot allow for a chance of damage/weakening of components through pinging even at low loads. Fuel efficiency and emissions are the last of our concerns. Even our lean cruising AFRs are in the 12's:1. I've got a "lean" cruising AFR of 11.5:1 and a AFR of 9.61:1 on WOT on my car courtesy of the Tomei ECU (came with the car from japan- which might i add i cannot tune as there are no facilities in Aust for it). Would you rather have a cracked piston or fouled sensors/sparkies (yes we both forgot to mention that running richer accelerates the speed that the sensors foul up)?

 

 

Oh btw, i did a little asking on why richer mixtures cause the faster spool up and ramp up speeds and I was told that it had something to do with thermal expansion (or something like that). If you do know something about that concept let me know pls.