robsayers

A buddy of mine has a wideband kit he uses for tuning his supras. I'd like to borrow it to fine tune my carb, but beforehand, i wanted to find out a couple things.

Where would be the best place in the exhaust to mount the o2 sensor? As close as I can get to the ports or a furhter back?

Also, I had read that rotaries make best power when they run a little rich. This contrasts what I'm used to from piston land where you generally go lean to make better power. What sort of af ratios should I be looking for to make the best power?

Thanks in advance.

Rx7carl

I'm gonna move this to a better location for you. Rotary performance. More info there about it.

robsayers

Cool, I should have thought of that myself, thanks!

edmcguirk

Wideband oxygen sensors use a calibrated current to generate accurate heat inside the sensor. The accuracy of the heat will dictate the accuracy of the reading.

If you put the sensor too close to the exhaust port it will be too hot and will not get a good reading. You want it far enough away that the heater has to work to keep the heat correct.

On a car with a cat you want it as close to the cat as possible because you can't go any farther. On a car with no cat it can be as far back as convenient but I think it should be a few feet from the exit.

I believe that the port for a narrow band oxygen sensor is usually just a hair too close to the engine but it will usually work.

ed

Evil Aviator

It is not possible to "fine tune" an engine with an AFR meter. You will need a dyno for this. An AFR meter is simply a tool that is used to speed up the tuning process.

That is what the dyno is for. I have yet to see an AFR meter measure hp.

BTW, if you have the option, it is better to use a lambda readout as opposed to an AFR readout. This way you can get a better baseline that will not vary as much with different fuel.

robsayers

Well i realize it cant measure HP, but when you know what ideal AFR's are, it can help a lot. That and the only shop that even had a dyno closed some time ago, the nearest one I know of is about 3 hours away.

A few of my friends who tune with an FJO have had pretty good success. Of course they are all running boosted boingers.

edmcguirk

Certainly a dyno makes it easier but you can get pretty good tune with careful records. Find a good hill so you can get slowly changing RPM at WOT and have your co-pilot write the values down.

For a NA carbed car I would see if I can get close to 12.5 for most of the RPM and then start making small changes and clocking acceleration with a stopwatch.

You can get within 3% of your true HP with a flat hill and a good stopwatch. You don't even need to do the last step to get HP, you can just work on best time through each 1000 RPM.

Part throttle tuning is a little harder but after you get WOT you'll have a pretty good idea what you need to do to dial it in.

ed

gonzz

What is the ideal air/fuel mixture on a streetport with a holley setup? 14.1 AFR? I'm getting a wideband in 2 weeks so need to learn this.

Evil Aviator

There isn't one, and this is what I have been trying to explain to you guys, lol.

Where do you guys get the idea that tuning an engine is all about targeting a magical AFR number? I would really like to know this, because somebody, somewhere, is giving you really bad information, or you are misinterpreting it. As a moderator for this EMS forum, I would like to know the source so that I can hopefully have some words with them and find out what this is all about. Web links, phone numbers, email, or book authors & titles are appreciated. You can send me PM if you don't want to post this information in public.

bill Shurvinton

Having looked at a lot of dyno plots posted I can say that I have yet to see a US chassis dyno measure HP. It measures some mythical number, but that ain't HP.

If you adjust fuel/spark until you get a peak, fine, but using a dynojet and then claiming xxHP is just wrong.

On this side of the pond we use coast down losses to try and correct for the tyre/roller interface. If calibrated properly works well, to the point where you can do a run in 3rd, 4th and 5th gears and get the same corrected HP +/-1HP.

Evil Aviator

It measures torque, and then it calculates hp. I know what you mean about comparing dyno numbers, though, lol.

... which is why you tune by trends, and not by numbers. Peak HP will always be indicated by the dyno, regardless of whether the actual hp number indicated is valid for comparison to other HP standards. An AFR gauge is not capable of this in any way, shape, or form.

Example (using rpm, just to simplify things):

Can you tell me where the peak HP is?
1000rpm / 13:1 AFR
2000rpm / 13.2 AFR
3000rpm / 12.7 AFR
4000rpm / 12.6 AFR
5000rpm / 12.4 AFR

OK, now can you tell me where the peak HP is?
1000rpm / 56 HP
2000rpm / 88 HP
3000rpm / 134 HP
4000rpm / 156 HP
5000rpm / 152 HP

Do you see my point now? This is why you cannot accurately tune for power without a dyno. Whether the 156 HP is DIN, SAE Net, SAE Gross, or anything else, it is still the peak HP. This is not about bragging rights for a dyno queen, this is about getting the most HP out of the engine.

Additionally, I would like to point out that AFR numbers are also inaccurate with variations in temperature, pressure, exhaust reversions, air pumps, fuel type and grade, etc., so it is not just dynos that produce numbers that are not comparable with those produced by other equipment or under otherwise different conditions.

robsayers

Personally I just know a lot of supra guys who will tune like this. On a flat road they will try and hit a certain AFR for most of the rpm range while at WOT. I know some people using different combinations, but most people I know are using AEMs with FJO's

Evil Aviator

OK, that is great for basic tuning, but what about fine tuning for power? How do they know, for example, that an 11.001 AFR yields more or less power than a 11.002 AFR reading at the same load and rpm?

robsayers

That I'm not sure of. I'll ask a buddy of mine... if I had to guess though, he is just using it for basic tuning after swapping turbos, map sensors, etc.

Great info though, thanks!

bill Shurvinton

Bit more info needed here... I have had some long email discussions with Klaus at Innovate on how to correct for all the anomalies with the LM-1 and I am confortable that he has all the bases covered and that his meter IS accurate under all conditions. And I have been very searching in the questioning. Some of the meters you see are not this well designed (actually most of them)

But back on peak power. Will you not agree that tuning for peak HP is not always the best solution. For example, peak power on any engine is likely to occur at or around 12.5:1. However if you tune for this peak on a turbo engine it will last maybe 20 miles before killing itself.

So neither raw dyno numbers nor raw AFR figures actually allow an optimal AND safe tune for a car. Its not black and white, more a muddy grey.

Bill

RICE RACING

Ditto, not one car I have owned nor one I have tuned *been many* has been used or set up on a dyno, though this has not stopped many of them winning dyno competitions !!!

I tune to what I feel is right and safe, I go by my own feelings while objectivley looking at the performance as felt by me in the passenger seat. Always going on the safer side rather than the dyno max power figure (AFR and timing) at all costs approach.

Again, never tuned a car to make RWHP on a dyno ! Always tuned for real world conditions and durability, either track or street......

And show me a AFR meter faster or more accurate than the LM-1, and I will show you a Lesbian that has never used a *****

TO4E-SE

good info guys . i guess i wont be able to self tune like i thought i was

Evil Aviator

Well, that's my point. You can't accurately compare LM-1 AFR numbers to AFR numbers generated by another AFR meter, just like you can't accurately compare dyno numbers. This is especially true when using AFR instead of Lambda, as most of the people on this forum don't even know the difference between the two. Also, I am not aware of any O2 meter than can correct for errors in the O2 sensor. While I do maintain that this is not significant for anybody besides engineers and scientists, this also applies to dyno numbers that you have rightfully accused of being incorrect in the same manner.

Agreed, and this is why I try to encourage people to get their engines fine tuned by a professional rather than attempting the fine tuning on their own, armed only with an AFR meter and some notes from the internet and their teenage street-racing buddies.

Yes, but you do not blindly target a single, all-powerful, all-encompassing, all-knowing, AFR number, do you? If so, then please tell us what it is, and give a technical explanation of why this particular number is better than any other, and you may just end the discussion on this subject. After which, I would suggest writing an SAE paper, and then all EMS products of the future will automatically tune to this number, and the world will live happily ever after.

Most of my friends tune by your very same method, and they can tune just fine. However, they know what they are doing, and they use the AFR only as a general guide. I am not stating that a dyno is required for tuning, just that you can not accurately tune for full power without one, otherwise you would not see winning race teams wasting their money on dyno tuning. Winning a dyno contest has nothing to do with this, as the winning engine may have well been capable of more hp had some time been spent on the dyno. Also, the issue here is fine tuning for power, not for "safety", economy, or other factors.

If you have tuning experience, you can tune the engine pretty darn well with just an AFR meter. The kicker here is that you need the tuning experience, regardless of what tools you use. The AFR meter is just a gauge, not a bible.

You can learn a lot by watching somebody tune an engine, especially if they explain the process along the way. This is one of those things that you can't learn over the internet.

TO4E-SE

definetly right evil aviator . i will go to a dyno and get it tuned by proffesional there thanks

bill Shurvinton

Well start by defining the errors in the sensor and I can tell you whether there is a problem. The Innovate is factory calibrated against a gas test rig and the sensing algorithm used corrects for everything except water balance, which seems to be more of an issue with the L1H1 sensor than the LSU4 due to differences in the contruction of the nernst cell.

So unless you are using serious water injection, if you use an innovate LM-1 then you are accurate to within the company specified tolerance. So now you are aware of a meter that can correct for the sensor.

Pretty much all the LSU4 meters have a free air calibration as well. Air as you know maintains a constant Oxygen percentage so is a readily available reference source.

So please don't knock all widebands. Some are better than others.

BTW I thought serious race teams generally had engine dynos. These are a different beast altogether.

Bill

Evil Aviator

That isn't my point. I still have not received an answer to my original question about targeting a single AFR number for best power, as I maintain that this is not possible.

Absolutely. However, my point is not to say which dyno is the best, or which oxygen meter is the best, only that dynos indicate power, while oxygen meters indicate oxygen.

More advanced thinking from Evil Aviator: EGT meters indicate temperature, MAP sensors indicate pressure, and tachometers indicate engine rpm. I don't understand the conflict with such ideals.

RICE RACING

Anybody who knows anything about motorsport or is more importantly involved in it knows that real tuning and triming is done in the real world, not on a dyno chassis or engine.

You can get a base line on a dyno (regardless of type) but all final triming is done to suit the track, wether and nature of circuit conditions. If you think that it comes of a dyno and performs perfectly onthe track or road you truley have no F*&king idea of what *professionals* actualy do to make engines perform in the real world

Doe not matter if its FSAE, F1, or a enthusiast tuning his mega HP road beast. Best tunes and set up are obtained in the real world & NO you dont need an almighty number generator to achieve best performance form your engine, anyone who does this all the time will tell you that ! It can help you get in the ball park on the tune but none more so than an experience operator can either on the road or at the track from scratch.

There are many magical AFR numbers that work on certain combinations wether they be defined by engine type, fuel type, or other limiting factors. It all comes down to experience. And you dont gain this experience of the internet, you gain it by working on cars and going up against your peers or listening to people who do this on a regular basis.

To answer the original question in this thread the AFR you need to shoot for is 13.1:1 for your set up, that will yeild you some good figures and be very safe & WOT and high revs.

RICE RACING

Vehicle acceleration/terminal speed indicates real power, not some artificial figure achieved on a roller. With proper analysis tools settings can be adjusted and tweaked untill the ultimate acceleration rates are recorded while staying within proven durability limits for all settings (AFR and timing) once this is achieved then the car will make no more power. I have done this many a time and taken a few different cars to dyno set up competitions and blown away everyone there, your point is again ???

Setting up a engine to make maximum power on a dyno is a BIG NO NO !!! Especialy if you want durability from it, so many variables change once the vehicle is out in the real world that the tune up can vary drasticaly and what performed well in Hollywood mode does not do the same in the real world mode My 2 cents worth inclusive of state taxes

RICE RACING

13.1:1 +- 0.3 AFR points will do you well

bill Shurvinton

Well If you score a copy of Ricardo or Olsen, or Taylor you will find that they had worked out that the best power arrives at Lambda of between 0.85 and 0.9 (except in those days they used the inverse calculation so around 1.15. This is best power. Not safe for all engines and operating conditions, but best power. Richer than that and you lose power, leaner than that and you lose power. However you often have to run additional in cylinder cooling fuel to prevent heat build up and detonation. this additional fuel always causes a power drop, but that is the nature of the beast. Compromises have to be made. For a normally aspirated rotary I do not have any evidence that running at best power mix is a problem. Turbos are another matter and not one I am experienced enough in to comment on.

BTW: Lambda meters do not measure oxygen per se. They measure the partial pressure of a number of gasses in the exhaust.