SonnyakaPig

I got this from "KenneBell.net" It has an excellent "Tech" section. This is some general knowledge about AFR that some may find usefull.

Kenne Bell provides pages upon pages of info, so if you are interested, spend some time on their site. They are a leader in supercharging and have run thousands of tests. So, their tech information can be quite helpful.

And I'm not saying that they are the gospel, as others may have different experiences, so if so, please add your own opinions.

This is some good information for people that are trying to learn more about tuning and their cars. Even though, a lot of this information applies to cars with forced induction their is also plenty of good information about NA cars and tuning/dyno.

Does fuel pressure affect fuel mixture? Call it air fuel ratio. Yes. At WOT, every 10 psi of fuel pressure alters AF ratio 8%. 5 psi = 4%. However, at idle and part throttle most systems lean out or take away the added fuel from increased pressure and maintain a stoichiometric (14.7) air fuel ratio. If it can't the system will set a "rich code." That's not good.

What is the ideal air fuel ratio (mixture)? 13.5:1 for maximum power - but it requires higher octane fuel. Lean mixtures always require higher octane fuel. We recommend 11.0:1 for supercharged or turbocharged street engines using 92 octane. Want a little more power? Run 12.5:1 and increase the fuel octane. For idle, part throttle and cruising 14.7 is ideal for best fuel economy.

How do I measure air fuel ratio? We use only Horiba Air Fuel Ratio meters. They're about $10,000 each. Outside of the OEM's, these devices are unaffordable for most shops. Therein lies the problem. Anyone can set and tune for ignition timing but it takes an expensive air fuel ratio meter to accurately analyze fuel.

How do I get my vehicle dyno tuned without a Horiba? Forget the "wide band" oxygen sensors and any device that utilizes the voltage signal from the stock oxygen sensors. They're fine for emissions control 14.0-15.0 but not precise enough for tuning richer 9.5-13.5 mixtures. The only good alternative we'd rely on is the AFM1000.

*sorry about the yellow writing, I copied and pasted from their site.

*I want to clarify something: I didn't post this thread to show that we can't trust the many dyno shops and tuning facilities around the world because KB says their way of testing AFR is the best. I acknowledge that without this caveat, this OP may have the tendency to be interepreted that way. I did, however, want to expose other members to the language, parameters, and experiences that are often discussed in this forum. I would have preferred to post the PDF, but I could only post a link to it, so I thought I would just add some relevant content to this OP, and that's why I included the above question/answers.

SonnyakaPig

http://kennebell.net/KBWebsite/Commo...tVariables.pdf

Also, if you are interested you can read this 7-page pdf, but numbers "9-17" are especially relevant to many of our conversations on this forum.

SonnyakaPig

Here is an index for numbers 9-19. I can't copy and paste from Kenne Bell's PDF. Each number has a corresponding paragraph of explanation and experiences.

9. Torque converter lockup
10. Octane
11. Fuel octane, ignition timing, and boost
12. IAT sensor
13. ECT
14. Engine Knock
15. Torque Management and electronic throttle control
16. Catalytic Converter
17. Tuning
18. DynoJet accuracy
19. Testing one product at a time (*Superlubricity will appreciate this... Jim Bell, Kenne Bell's owner says "Any Kenne Bell employee that brings me a multiple product test will get a blood and urine test." haha)

C63newdude

I have had at least 12 cars tuned and never blown them. Kennebell exagerates a little just like people exagerate when buying parts.
I see a lot of people jumping the gun and buying a fuel pump without even knowing their injector duty cycle or getting an aftermarket fuel rail just assuming the car wouldn't flow enough or buying a pressure fuel regulator when the stock can hnadle a whole lot more and off course buying a set of injectors when like I said in the beginning the IDC is low enough where you don't need them.

There is no perfect condition for tunning, if they are going to be picky then you need to realize that lean condition exists on some car cylinders before you even touch them, Subaru has a cylinder that always fails more than the others due to being away from the throtle, then you have different compression reading accross the cylinders.

Unlike Kennebell , I think a good wide band, a good Zeitronic counting knocks and a good software and a good tune and you are golden. One of my last cars(sold it less than 6 months ago) a 95 Mitsubishi Eclipse GSX put down 190whp on a Mustang Dyno but after many mods it put down 409whp(to all 4 wheels), the car had 95000 miles on stock internals and we tuned it with a simple wide band and DSM Link, in all, I had no knock/detonation ,it never overheated and the car ran stupid fast.

KenneBell wants to be to technical but the truth is that 99.999999% of the tuners out there tune with innovative big screen wide band($400) and they tune the cars fine. Many other tuners just use the standard wide band probe from the dynos and nothing happens.

Speedriven1

Great post.

SonnyakaPig

Thank you for adding your experiences. You have a lot of personal experience with performance.

Clearly, though, 99.99999% of tuners are not tuning cars right. My guess is the number isn't even close to that.

Personally, I have seen that with newer cars, tuning is often a work in progress and it's not uncommon for tuners to need some time to get things right. And some tuners and AFR measurement devices are better than others.

For instance, some C63 tuners would only recommend certain dyno facilities because many dynos/AFR devices are not accurate. I have seen this with my own cars.

Kenne Bell speaks in very specific and technical terms because they have a huge responsibility to a large customer base that spans many makes and models of cars. Plus, Jim Bell has been tuning for a long time.

Jim Bell even states that one of his top dealers/installers was measuring AFR wrong for one year and incorrectly blamed Kenne Bell. Obviously, there are two sides to every story, but just the fact that he states that he has seen this happen with someone within his vendor/installer network which is highly exclusive, says a lot about how common incorrect AFR readings can be.

SonnyakaPig

Thank you, Speedriven!

sflgator

I was running too rich with the RENNtech ecu flash tune (which is apparently the same as stock) at 10.2 AFR. Now, Jeremy at OE Tuning leaned it out a bit, and I'm now running ~ 12.7 AFR...one reason he was able to extract more power!

SonnyakaPig

I hear what you're saying. RT's tune may have been that rich, but I have been told from several tuners that stock C63's do not have AFR in the 10's.

But, admittedly, I have heard from a very experienced MB tuner that stock AFR is in the 10's.

But, I'm pretty sure that's not accurate.

I have spoken to Jeremy (great guy to speak with on the phone) and he also told me that he likes to target 12.7, especially for a 91 octane tune. And even that is a little conservative for our NA engines, but precaution is far more valuable than a few extra horsepower.

Good to hear, Jeremy was able to extract that extra power.

sflgator

Well, when Jeremy at OE Tuning looked at my RENNtech ecu flash file (before overwriting it with his ecu flash file), he mentioned that it appeared that RENNtech had not touched the AFR (from stock). btw -- and I'm running on 93 octane, so I guess 12.7 AFR still leaves plenty of room, but like you said, I would rather run just a wee bit too rich than too lean.

SonnyakaPig

You're in even a better position than us 91 octane guys. So, I'm sure you're safe.

Regarding what stock AFR is for the C63, I have tried to get to the bottom of this, but I have heard 10's to high 12's.

And the tuner that told me 10's was corrected by his fellow employee. So, I don't know, I'm just opining that I believe it is higher than 10's based on the overall feedback I have received.

And I'm not dismissing what you were told. And I trust Jeremy. So, it still leaves me a little confused on this issue.

My car stock read 12.5 AFR. But that was from a sniffer placed in the tailpipe.

SonnyakaPig

I just finished reading the bottom of the PDF document. There are great tips for dynoing your car. So much information. Even if you have different experiences, there's still something to be learned.

RStevens63

I think we're missing out on the fact kenne bell builds and knows superchargers very well. They are not experts on naturally aspirated motors. Try googling Reher Morrison and looking at their tech page. Those cats know what theyre talking about.

SonnyakaPig

It depends how you define "expert." In the legal world, Jim Bell and his engineers probably wouldn't have a very difficult time being deemed experts on NA engines by a judge.

I will check out that page. Thanks for the tip.

LZH

HUH??? I beg to differ. Every internal combustion motor starts life normally aspirated. So, to be an expert building blowers, you HAVE to also be an expert on understanding how ANY NA motor works

SonnyakaPig

I was thinking along those same lines.

I understand what RStevens was saying, though. There are companies that focus 100% on making dependable NA power, which is of course relative to the particular use of the motor (i.e., dependable for a race or dependable for years).

But, I agree with you.

RStevens63

That is simply not true, no crazy emoticon necessary thanks.

How many motors come from the factory with forced induction? You don't think the engineers took compression ratio into account, what about ringland thickness, piston and rod composition? LOL. That statement is very off-base.

Forced induction is the worlds greatest band aid. Case in point look what it did for the 55Ks vs the 55s. The supercharger compensated for 3v heads that flowed ok but not great, and smallish cams, and the cars are now animals running high 10s at 130+. Goes to show you don't need a crazy good top end like you do NA to make power.

You don't see UGR doing any nasty NA builds, nor Heffner or Hennessey (puke), forced induction is altogether a different world (that goes for both the bottom and top ends) and the ones at the top of the NA game are not the same folks that hold the supercharger and turbo crowns. They are completely different animals and just because someone is good at or can do one doesn't automatically mean they can do the other.

You don't ring a shortblock the same way for boost as you do NA. You don't spec a camshaft the same way either. Same goes for tuning (obviously). This is not even a discussion.

All this by the wayside go ahead and call KB up and ask them how many NA cars they've tuned. I gave a far greater reference to NA performance and tuning than what was posted on the KB page, sorry if that offended you, it seems pretty much everything does?

If you're as into racing as you claim to be you know who RM is and what theyve done.

A master engine builder once said to me "Any jackass can make 1000HP with the right blower or turbo, but it takes real talent, skill and knowledge to do it NA". I think that pretty much sums up the differences.


Good day

RStevens63

No one's saying KB doesn't know their stuff, but if we can find more relevant data why not use & absorb it as well?

Man this forum is getting catty already and the tracks are still open, whats it going to be like in January and February? LOL!!!

SonnyakaPig

It's going to be exciting with the hopefully new PB's and records. Plus, we will see more tunes and bolt-ons perform. Hopefully we can keep it civil. haha

I know you're not saying KB doesn't know their stuff.

And I agree more relevant info will only help us all learn. I just wanted this thread to offer some reference and tips, which I believe it does.

http://www.rehermorrison.com/blog/?cat=3

Thanks.

LZH

The only thing that offends me is people who don't know what the hell they're talking about. And that sir, is you. I don't need to call the guys at Kenne...I've spoken to them many times and they built a motor for me not too long ago as well as for my buddies Challenger that he just had built that puts down 700 at the wheel. I'm very familiar with what they do. And their understanding of N/A motors is second to none. Most of what they do is strapping their blowers to N/A motors so their understanding is, IMO, expert in the N/A field. That was the question at hand....not sure why you felt the need to go in a rant about F/I builders etc...my only point was that Kenne Bell are experts in all engine configurations, F/I AND N/A. The fact that they don't build N/A motors that spin up towards 20,000 revs like F1 builders has nothing to do with it - that's not what they do and is not their niche. If you can't understand that I don't know what more to say than peace out.

RStevens63

Actually KBs largest market is replacing the Eaton aka Heatons on 03/04 Cobras and GT500s. Factory FI cars.

Regardless I respect KB (never said I didn't) and others so take it fwiw.

The part in bold basically negates the rest of your post btw. There are experts and then there are experts as you just stated.

My point was tuning meaning the entire package from harware to software is different in FI motors vs NA. I'm sure we can agree on that and if we do then I guess I do know something

I have no want or intent to argue with you about this, I was just trying to make a positive contribution, please excuse me if I took your reply too personally.

Thank you