TURBO vs N.A

[Falc]

The below should be text book stuff.

I thought too rich, one will lose power also. So at 9.6, u got black smoke?

 

Air/Fuel Ratio Limits

6.0:1 Rich run limit

9.0:1 Low power, black smoke

11.5:1 Rich best torque at WOT

12.5:1 Safe best power at WOT

13.2:1 Lean best torque at WOT

14.7:1 Chemically ideal

15.5:1 Lean light load, part throttle

16.2:1 Best economy, part throttle

18-22:1 Lean run limit

[Elfenstar]

You do lose power running rich.

Black smoke... my car...

hmmz... errm...

 

 

 

 

 

 

 

 

 

 

 

 

hahahha yeah, but only when i hit boost. Perfect for tailgaters

 

I have to run richer mixtures than the ones you stated as my ECU is also tuned for 101 octane fuels while the max from petrol kiosks in aust is 98 octane. fortunately the super rich AFR tomei ecu means i dun have to adjust it.

 

I have a feeling that my car used to have a fair bit more on her before she came to aust and the ECU was tuned for that. Am saving up to get the new Tomei Reytech (spelling???) ECU as it is a full replacement and comes with all the necessary cable and programs to do the adjsutment via a computer.

Edited July 4, 2005 by Elfenstar

[Thumbs]

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.

 

And you believe this is normal? Have you ever considered it might be because your concepts of what is a proper AFR for a given engine, at a given load/RPM, are totally wrong?

 

You haven't answered my question on lean cruise.

 

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.

 

The only thing I realize is that it's useless trying to explain things to you because you believe your cars are "highly tuned" and are fixed in your perception that what you're doing is right.

 

Fuel efficiency and emissions are the last of our concerns.

 

Way to go, Mr Tuner.

 

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).

 

I call BS on this.

 

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.

 

I call BS on this too. Unless what he is describing is antilag but that is a whole other topic.

 

Anyway, I'm not going to bother responding any more to this topic since you are fixed in your thinking.

[Littleblackalfa]

Guys, guys, guys... OT liao. for VERY long liao... let's not confuse the poor thread starter shall we? go argue in another thread like "AFR debate" or something like that.

 

i'm sweating now.

don't think i can fully understand a N.A engine.

now turbo kicks in. and u guys keep emphasizing how good it is...

should i join the league?

 

Ok, look. it's very simple. you know your normal cars? the Sunnys, Corollas? Those cars have no Turbos. Those are NA engines. Naturally aspirated engines. Turbos have turbines. There are different kinds of turbos. LPT (light pressure turbos), Full (normal) Turbos, and Twin Turbos.

 

The comparison should not have been Turbo VS NA. It should have been FI VS NA. FI being Forced Induction, which includes Supercharging.

 

But the true comparison, should have been: weak assed engine with ginormous turbo VS big assed NA engine. It's not fair to compare 1.8L of engine when both will give very different results. The best way to compare both, would be based on yields. Say, a 2L turbo engine with 250bhp VS a 3.2L engine with also 250bhp. That's a better comparison. But like dat also cannot really match. if you're talking about FC, then you have to look at weight as well. because, power to weight ratio plays a part. if you're dragging a heavy car, the engine burns more. if you're dragging a lighter car, it burns less. Then you have to look at driving style as well. If you got a heavy foot, you burn more, and vice-versa.

 

Me? I'll take a big CC NA engine anyday as opposed to FI. More evenly distributed power ON-DEMAND. only thing in SG? bloody road tax.

 

Why do I say big CC NA? because a 147 GTA (3.2L NA) will overtake a WRXSTi (2L Turbo)(stock) from 3rd gear onwards. This has to do with gear ratios and final drive. took me a long time to understand this too. The GTA will lose for the 1st 2 gears and 120km/h duration. This is where the big CC NA engine will have the advantage. Big CC cars are not built for sprints. they're too damn heavy. they rule on rolling starts.

 

Clearer now?

Edited July 7, 2005 by Littleblackalfa

[Thumbs]

Me? I'll take a big CC NA engine anyday as opposed to FI. More evenly distributed power ON-DEMAND. only thing in SG? bloody road tax.

 

What're you talking about? The SL65 AMG (6L V12) produces 1000 Nm of torque @ 2000-4000 RPM. That's a big fat torque band right there. By way of comparison, a Dodge Viper Competition Coupe (8.3L V10) only has 732 Nm of torque @ 4600.

 

Why do I say big CC NA? because a 147 GTA (3.2L NA) will overtake a WRXSTi (2L Turbo)(stock) from 3rd gear onwards. This has to do with gear ratios and final drive. took me a long time to understand this too. The GTA will lose for the 1st 2 gears and 120km/h duration. This is where the big CC NA engine will have the advantage. Big CC cars are not built for sprints. they're too damn heavy. they rule on rolling starts.

 

Clearer now?

 

Your perspective is too narrow. There's something called aerodynamic drag... the power required to overcome drag is the cube of velocity, so you need 8 times the power to double your speed. Since the frontal area and coefficient of drag of an STI is far worse than an Alfa, and these 2 factors have a direct bearing on the equation, it's not hard to see why the sleeker profile needs less horsepower to catch up and overtake.

[Falc]

Since the frontal area and coefficient of drag of an STI is far worse than an Alfa

 

Websites listed the Cd values for 147 as 3.2, and wrx sti at 3.3. Hardly any difference here i would say. Perhaps gear ratio does have a greater effect here?

[Littleblackalfa]

who am I talking to? you want to get technical? go do it yourself. I'm trying to explain this simply to someone who knows nothing about these things. you want to show off then by all means go ahead. but not at the expense at others... he has trouble understanding NA engines. you want to bring drag coefficients in? what kind of person are you?

[Littleblackalfa]

could be gear ratios. using butt dynos, (yeah, my butt has great feel to it. heh.) the STi seems to have longer 4th, 5th and 6th gears, whereas the GTA I know has long 2nd, 5th and 6th gears. Not sure about the final drive though... aiyah. show me gear ratio I also dunno how to read. heh.

[Falc]

Actually i feel it's good to get more technical, coz that will make things more objective. Something i find IMHO abit lacking in local forums compared to overseas ones. But just my 2c.

 

Anyway, me think the original poster has had enough info earlier on already. If he has further qns, he certainly did not follow up by asking here.

[Genie47]

Another difference. Big 4ss displacement cars V6 or V8 are very easy on oil. Very little stress even at high RPM. IL4 very stressful on oil. With turbo, even more demanding. Lots of analysis on oil from V6 and V8 showed that the oil hold their grade very well and can even run up to 20k or more! IL4 with turbo. 10k considered good already.

[Genie47]

It has to be gear ratios. How else could Kancils and Kelisas go toe-on-toe at traffic lights with other cars? Old trick but so useful for grocery getters.

[Thumbs]

Where did you get the Cd values from? I'm willing to bet that they're wrong. BTW even a 0.1 Cd difference is significant.

[Falc]

Posted all over the Web dude. Googled it and u can find a couple of links stating those same values.

[Falc]

That must be the last reason for anyone to ditch I4 for V6/8. But curious why huh? And turbo is worse becoz oil must go thru turbo in addition to engine?

 

Oh man, we are so OT.

[Thumbs]

No it isn't. Look carefully. There should be a zero in front of the decimal point. A Cd of >1 means it's about as "slippery" as house of bricks.

Edited July 8, 2005 by Thumbs

[Genie47]

In a way yes. Turbo is high temp. Synthetic oil recommended. In short turbo has increased cost to run comared to NA. Well, this is so obvious besides the fuel consumption.

Edited July 8, 2005 by Genie47

[Littleblackalfa]

It has to be gear ratios. How else could Kancils and Kelisas go toe-on-toe at traffic lights with other cars? Old trick but so useful for grocery getters.

 

yeah... but gear ratios will only push you so far. without the necessary foundation, a short gear ratio can still leave your engine running out of breath by the time you hit 3rd gear. So I guess it's the total package.

 

BTW, the 147 isn't as Aerodynamic as ppl think. It looks sleek, yes, but compared to the 156, it's much worse. All you have to do, is look at the wind screen. It's almost upright!!! The 156 windscreen is very laid back. The whole car is much more streamlined than the 147... :(

[Genie47]

Not streamlined eh? Like a fat bulbous Aveo?