So what would you say is too Lean? Too Rich ? Opinions Pls.
 

This is a topic to which i hear a very wide array of awnsers,
This is all based on a WOT situation with the engine on load as a typical dyno run would be performed , for the sake of simplicity.
What do you think a desirable AFR curve should look like N/A or F-I ?
What number would start to get you worried ? N/A or F-I?

Also what is your point of view on Rich conditions, and what is .. too rich ?

It would be nice to share opinions on this subject.

Opinions are nice and all but experience probably trumps all.

All I know is documentation from badnoodle and tuners on this platform have basically followed this except your previous choices tuners.
@jamesm may shed more light on this.

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14.7 baby! just trolling for post counts, don't mind me.

On FI under WOT(full boost) I wouldn't go any leaner than 13-1. And would tune as rich as 10 or 11. On my eclipse, I consistently tune to 11-1 AFR at wide open under full boost. It's easier for me to replace 4 spark plugs than it is a block.

On NA under WOT I think I would want to stay around 13-14. It's been awhile since I've messed with an NA though...but if memory serves right, you would get the most power the closer to stoich you are.

Based on my limited experience with tuning, the sweet spot for N/A AFR at WOT is between 12-12.5 to 1. The AFR from stock o2 sensors is not that accurate, so most tuning I've seen done here lately keeps a bit lower at 11.5-12 as a safety margin without any loss of power.

on pump gas...

NA: low 12's tailing to mid-high 11's above 6.5k or so. this is because the car is crazy knock-prone up high and you can usually make more power by richening it up a bit and keeping more timing. the rich afr's we run on these cars has nothing at all to do with an O2 sensor (the car doesn't even use the O2 sensor in open loop), it's because it buys you knock resistance, and this car is extremely knock sensitive. higher DI ratio + slightly richer than typical AFR allows you to run a lot more timing and ultimately make more power.

FI: 11.6-11.4:1, again maybe richening up a bit as you get above 6.5k... for the same reasons as above. I've found that range is a really good spot for power... still allows you to run decent timing without having to give up a bunch of power going rich. power drops off pretty hard as you get into the very low 11's or down into the 10's.

As far as what AFR is 'safe' there is no right or wrong answer. There are obvious limits: if you're running 14:1 under load NA or 13:1 under load boosted that's obviously bad... but the car can start to knock just a few tenths of a point leaner than target if it's tuned fairly aggressively. The key is just to make sure that the AFR is consistent and stays where you put it... this means minimizing fueling error to less than 2% across the board and turning off LTFT in open loop, basically. You'll never have a consistent AFR with LTFT acting in open loop and high fueling error.

You mean every car is different??!?

You think every car/engine is the same??!?

Missed sarcasm is an epidemic.

:D

I want a thicker head gasket,

Is this to lower the compression ratio?

yup

Why do you want to lower the c/r?

Please avoid the flaming if this is irrelevant or incorrect, but wouldn't a thicker head gasket ruin the quench area of the combustion chamber?

This can vary so wildly. and can vary even more when you ask what afr you'd run with e85.

Let me tell you what my engine likes to give you an idea.

On regular E10 pump gas:

anywhere from 12.8 to 13.2:1 afr basically produces exactly the same power

On e85:

12.3-12.5 produces more power than anything leaner than that. I actually lose a few horsepower running leaner than 13:1

My buddy has tuned a LOT of cars.

Generally n/a on pump gas (non DI engine) you'd run 12.5 to 13
boosted on pump gas you'd run anywhere from 11.0 to 12.0 (supercharged tends to run better on the leaner spectrum)
Now one thing you can do pretty easy with supercharged since they're linear is taper. run leaner like 12.8:1 afr at low boost and then taper downwards once you pass 3-5 psi down to 12:1 afr settling maybe at 11.8:1 near the rev limiter

e85 changes all this. On a boosted vehicle (turbo) you can EASILY pick up 30 more horsepower richening the afr from 11.5:1 to 10.5:1.

This is all on a k20 honda engine of course. Every engine is different but i hope this gives you an idea of what works and what doesn't.

If he's boosted, it makes sense. Lower compression means more boost safely. Higher compression means lower boost safely.

It's a trade off though; with lower compression, can you pick up enough power from boost to make it worthwhile?

See the post above by jamesm, he has a lot of tuning experience on this platform specifically, and finds that running richer than you're suggesting is the key to making more power. Your figures aren't a bad starting point, but definitely aren't optimal on this car.

You'll never get a significant drop in C/R from a thicker gasket alone, you'd have to run stacked gaskets or a head spacer. If you're going to pull the heads on this car, you might as well pull the engine and run forged pistons. You can run a lot of power on the stock internals, especially with e85.

because 12.5 is a stupid high CP , a s2000 was 11.1 and made more power, the high cp is why our engines are so finiky are sensitive to gas. try and find another NA engine that has this kinds of CP and mass produced . its not a good thing that were the only ones.. its all for emissions and fuel efficiency at all for performance. take stock brz dyno it with 91 in the tank and it is impossible it will make the same power as the recomended 93 or with good 94.
12.5 for anyone who has built engines without knock detection knows 12.5 is better run with a touch of race gas or a absolutly solid 94 , where one bad tank of gas costs you a motor. 11.5 would have been more than enough its not that hi CP that gives us the power thats mearly for fuel economy im sure of it. C.A.F.E

I agree with that, but I was simply referring to WHY someone would want to drop CR. Not so much how to go about doing it.

Umm.... high CP is so that they can build more power with a small engine. There are tons of examples of mass produced engines running 12.5 or higher, take the new Mazda 6 running 13.0. Our engines are finicky about gas because they squeeze every last drop of performance out based on the higher octane.

You can't say that because one engine design for the S2000 was lower CP and made more power than the BRZ that the CP was the reason for it making more power.

Let's look at the early S2000 engine compared to itself with increased compression. In the US it was 11.0:1 and made 237hp. In Japan it was 11.7:1 and made 247hp.

theres nothing hard about making 100hp per liter these days, whats hard is having it comply to CAFE standards and Carb etc.. the mazda is a 2.5 with 13:1 and only 185hp/185ftlbs DI engine, showing again that the high cp isnt there for performance but more for fuel economy, that in conjunction with direct port injection and VVT can dramaticly increase fuel economy, but look at real world engines that have no knock sensors and are horsepower at its purest form, and such a high cp is indeed very demanding on octane levels, so for the average person putting 91 or even 89 this is detrimental to the engine, it can only compensate so much. im just saying from a longevity and basic common sense point of view these hi cps are not ment for 91octane gas, nor should they be marketed for all mass production. we will indeed be seeing this trend more and more, with engines running thinner oil, and inevitably engines failing prematurely the 20yr old engine will be a thing of the past, lucky to get 10yrs out of these modern engines.

And i am sorry, but there is nothing hi performance about our engines from the factory, i honestly felt like crying after having recivied my car, the interior was cheap,the engine had no pull,and the handleing was nothing to bragg about, even for a girl car it felt crappy, i dont know what peoples idea of "performance" is these days but the stock brz definetly is not one of them, now i can say after countless headaches and thousand spent it pulls and drives like a performance oriented car, but from the factory it feel had mad body roll, crappy tires, and abosloutly no guts. but it was and still is great on gas.

You bought a new $28k car, not an M3.

There isnt much, if anything, that competes with the twins when you compare overall performance for the dollar.

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31+taxe for me. theres are, mustang v6, genesis coupe, civic si, focus st tramples it, list goes on. if you want to talk just performance prob 70% of cars in a strait line beat it. cars in the same price point

having owned multiple new cars and trucks i can say this car at 31000 is not a good value i would have seen it more in the 26500 27000. basicly the US price but for in canada. mine is a sport tech ... the gps is the cheapest ive had in any car, the interior is the cheapest ive ever had the doors are flimsy, and its the lowest performing car ive had in a long time, i sold my ecoboost fx4 to my buddy and he absolutly destroys me even tuned. as for on a track i dont have acess to a track and secondly why would you buy a brand new car for beating on a tracK?? when there are tons of s2ks and 370s flating around ??

i do like the car, but everytime i jump in te s2000 i realize how cheap the brz feels, and how smooth the s2000 is. yes it was a 54,000 dollar new not at all in the same ball park, but used 22-25000 for ap2 :) if it would have been better priced i would shut my mouth but 31,000 + taxe starts to tickel the nut sack of some pretty nice cars.

all just to say, its more directed towards a economy car and not a performance car, it was overhyped when released with lowest center of gravity since the lfa and best steering feel of any sub 30 000 car bla bla bla, marketing is a beautiful thing. i like the car as it sits, would i do it again , not a chance.

F20C's are port injection only, direct injection TOTALLY changes the game. Mazda SkyActiv engines are as high as 13.5:1 and run on 87 octane. 12.5:1 with DI is nowhere near the ragged edge. Turbo cars used to be 9:1 or less, but now you can get factory turbo engines around 11:1.

There is WAY more to performance than just a straight line pull. If you want a budget straight line car, buy a V6 mustang. $23k brand new and it'll run 13's. There is simply nothing even close to the price point that is as complete of a performance package. If you want a nice interior, decent power and decent handling, buy a GTI. They're not even comparable as a drivers car though.

I've lapped with AP2 S2K's, and they're not really any faster up the straights (they are a TINY bit, but they're not running away from me), and comparable under braking and in corners. Despite being down 40hp, it really comes down to the driver between these cars and an S2K.

You're also comparing much more expensive cars that are now a few years old to a brand new car. While we're at it, why not compare a used Cayman S or Boxster S? They're $70k+ new, but a used one can be found for about the price of a new FRS. Total cost of ownership will be way higher if you buy a used Porsche than a brand new Toyota/Subaru.

[ame="http://www.youtube.com/watch?v=T9_hZqvY5RM"]Drag race : Subaru BRZ VS Honda S2000 (Motorsport) - YouTube[/ame]

aha im just trolling you guys :P this car was never ment for acceleration .it is a good bargain for the price. back to topic. with E85 i understand you need to inject more , but will the afrs be the same as with strait gas ??? like a ethanol blend would 12.5 be the same as 12.5 with strait gas ? or does it read higher/lower ?