Dyno Noob Related Question

[DjLiquid]

I know alot about cars and engines but everybody always has to learn something new otherwise they'll always be missing out. My question is dyno related.

What's wideband and how can you tell how to tune your car from a dyno sheet to make it run better?

[c-rad]

I know alot about cars and engines but everybody always has to learn something new otherwise they'll always be missing out. My question is dyno related.

What's wideband and how can you tell how to tune your car from a dyno sheet to make it run better?

A wideband is a sensitive oxygen sensor that can tell what the exact air/fuel ratio is. Most dyno shops use a sniffer that attaches to your muffler now. Anyway, a turbo car on pump gas should generally be around 12:1 air/fuel ratio. A lower ratio like 10.5:1 would indicate a rich condition, and a 12.5-13:1 would indicate lean. You always want to start rich and lean it out slowly without getting any detonation. When you do a dyno pull, the computer will map the A/F ratio along with the RPMs. You just adjust the area that is not at the desired ratio.

[biosehnsucht]

For this to actually work I suspect you should have a test pipe fitted instead of a cat as otherwise you'd not be getting the real readings.. ? I've always wondered, don't understand how it could work properly w/ a cat..

[iliketocrash]

now that you mention it. that's a good point. o2 sensor placement makes a little more sense now.

[81na ZX]

Well, it depends. Some places use sniffer-type widebands - put into tail pipe. Whole bunch of problems there Other places need you to have a bung on your housing for them to put their O2 sensor into.

Your average O2 sensor will read 0V to 1V and is only accurate right around 14.7:1.A "Wideband" O2 sensor will read 0V to 4V and is accurate between ~10:1 and 16:1.

So, where tuning with a stock O2 sensor is more or less a guessing game, tuning with a wideband sensor is repedable, and knowledge can be transfered from car to car.

[Turbogixxer]

Anyway, a turbo car on pump gas should generally be around 12:1 air/fuel ratio. A lower ratio like 10.5:1 would indicate a rich condition, and a 12.5-13:1 would indicate lean.

There is really no set a/f. On the dyno, you can find out what your Rich Max. Brake Torque and Lean Max. Brake Torque.

BTW, there is no different in a/f on pump and race gas. You can not run race gas lean because it is race gas. All octane is, is the resistion to knock.

A "Wideband" O2 sensor will read 0V to 4V and is accurate between ~10:1 and 16:1.

Wideband is 0v to 5v, and ~9.5 to ~20 a/f.

[c-rad]

There is really no set a/f. On the dyno, you can find out what your Rich Max. Brake Torque and Lean Max. Brake Torque.

TYPICALLY, turbo cars run a high 11 low 12 A/F ratio on 93 octane. You'd be hard pressed to find a turbo car running 13:0 or greater A/F on 93.

BTW, there is no different in a/f on pump and race gas. You can not run race gas lean because it is race gas. All octane is, is the resistion to knock.

I disagree. Whether you are running race gas or 93 octane makes a HUGE difference. You can get away with a leaner mixture running race gas because it is less susceptible to knock.

[Turbogixxer]

TYPICALLY, turbo cars run a high 11 low 12 A/F ratio on 93 octane. You'd be hard pressed to find a turbo car running 13:0 or greater A/F on 93.

Ask yourself this. What makes the difference between running low 11's in boost, then running what you said? Or running a leaner mixture?

I disagree. Whether you are running race gas or 93 octane makes a HUGE difference. You can get away with a leaner mixture running race gas because it is less susceptible to knock.

Disgree with what? Research what octane is. You will gain more power with more timing (thus more octane needed) then leaning the car out.

One more thing, What is the difference in race gas that makes it better to run leaner then pump?

Also, would you run 91 octane richer then 93 octane?

[slownslurious]

I don't know what your first question is asking, but C-rad is technically correct on the fact that you can run leaner on race gas, and it usually makes more power that way. I think you are arguing things that aren't being disputed.

[Turbogixxer]

I don't know what your first question is asking

If you can not understand/answer my question(s), then you say he is right with NO reasoning.

C-rad is technically correct on the fact that you can run leaner on race gas, and it usually makes more power that way

Why can you run leaner on race gas? What is "techincal" answer? What is more power? 1whp? 5000whp?

I think you are arguing things that aren't being disputed.

I think you are arguing with things you do not understand. Opinions are cool, eh?

[biosehnsucht]

having a real AFR readout also helps you tune if you have any ability (as in equipmentwise) to do so. I.e. if you see you're starting to lean out at the top end, add fuel up there. If you have 6:1 at idle obviously you need to fix that.

[slownslurious]

If you can not understand/answer my question(s), then you say he is right with NO reasoning.

Why can you run leaner on race gas? What is "techincal" answer? What is more power? 1whp? 5000whp?

I think you are arguing with things you do not understand. Opinions are cool, eh?

no need to be an unreasonable fellow.

Modified by float_6969 at 7:55 PM 6/20/2005Modified by slownslurious at 8:58 PM 6/19/2005

[fanta]

Try to keep it clean. No sense in locking threads that can further understanding.

[Turbogixxer]

no need to be an unreasonable fellow.

No reason to post without explaining what you stated.

Modified by float_6969 at 7:56AM on 6/20/2005/

[float_6969]

What the crap is with you guys the last couple of days? This is the second post I feel I'm going to have to step in on and clean up. Will you guy's chill out? You're making me Moderate, and I don't like that....

[float_6969]

And to add to the information on this thread, Turbogixxer is correct on all accounts. The only reason you might be able to run race gas leaner is that it will resist detonation, but it won't gain you any power. If it does, you were either running to rich in the first place, or you need to add more timing when running race gas. When tuning my car, I have every intention of running the car as lean as possible with out loosing power. I intend to correct any detonation problems by retarding the timing. Running too rich is a "fix" for too much timing. If you run too much advance and detonating, you can richen the mixture and it will stop. My understanding of this phenomenon is that the extra fuel slows down the flame front and reduces or eliminates the detonation. Although this may be a resolution to the problem, it is most certainly not the most effecient way of going about it.