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You said:




Not an expert here... just askin...

How can you say that adjusting timing does not affect the AFR output from the O2 ?

The reason I ask is that advancing ignition timing causes the fuel mixture to have a more complete burn... despite not affecting the injector's volume of fuel being delivered, how would this not affect the resulting O2 content in the exhaust and thusly the AFR ?

Because if your timing is retarted enough not to get a complete or almost complete burn then your motor would have troble runing let alone making any HP, or you are running way to high of octang (because higher octang burns slower and is the only reason why you can run more advanced timing) and not burning it all. Timing is not about how complete of a burn you can get (although it is a side effect) but about getting your peak cylinder pressure to where it gives you max HP (which is really far from timing detonation). You can not caculate this number because all of the variables, the only way to do this right is on a load type dyno.

Thanks for writing this out man. Youve answered pretty much all of my questions that ive still had after about 4 months of research..........

Say I live on some far off Island and there is no dyno period to tune my car with. and a tribe of madmax style road pirates are going to attack at dawn and kill me and everyone else and steal all our fuel.
our only hope is to tune or cars and out run them. How would I tune the ignition close enough without a dyno?

Thanks for writing this out man. Youve answered pretty much all of my questions that ive still had after about 4 months of research..........

Say I live on some far off Island and there is no dyno period to tune my car with. and a tribe of madmax style road pirates are going to attack at dawn and kill me and everyone else and steal all our fuel.
our only hope is to tune or cars and out run them. How would I tune the ignition close enough without a dyno?

you can't, just try run conservative and not get detonation and your motor will make HP, just not as much.

The best way to find optimal timing for the street and track, is to tune timing at the track. I personally don't like car dynos, simply for that fact that, the optimal timing and a/f on the dyno is not ideal for the street, because the load is just a simulation.

If you throw parts together, then you would need a car dyno to make up for the mess and all the tq dips, but if your engine combo is rpm based and tuned length is calculated, then you'll know where the engine will need more or less timing, as well as what rpm the most fuel will be burned. Depending what combo you have, the peak tq and peak hp will be either at different rpms, or in the same rpm range. Header theory plays the biggest role with this.

Start with the timing maps on the conservative side, but based on your dynamic compression. Push 1 degree more timing where peak tq is and 1 less degree timing where the peak hp range is. Example, 23 degrees from 5500-6500 and then 22 degrees from 6500-7500. If you tune the a/f ratios to be even across, run that at the track. Then you make several other bin files with ONLY TIMING CHANGES in the Hi cam map. One bin will have +1 degree timing, where another bin will have -1 degree timing. As far as the low cam, i keep the timing semi conservative and tune the a/f ratios first of course to achieve targeted lambda.

If you keep tire pressure, launch rpm, and shift points the same, (obviously there are more variables which are endless), you can compare your 1/8 mile time and the second 1/8th mile time, which you get by subtracting the 1/8th mile time from your 1/4 mile time. Also compare trap speeds. No need to really rush, trial and error and patience is key. When you see what timing yields the quickest time with the most speed, then you can go with that timing map, simple as that.

Then next track session, advance your intake cam 1 degree, set the dizzy, then set the a/f ratios to be the same across again, where needed. Run that at the track, and you can play with +1 or -1 timing across. Then the week after you would advance the intake cam another degree, and so on. Give yourself data to compare, and in the real world, you'll see what works, and using your INSTINCT will get better as you keep practicing test and tuning. This is the way i do it, and it works.

It really boggles my mind when i see peeps do a swap, then they need the car dyno for tuning, and they are stuck at the track with no tuning adjustments for a whole season, and they plateau. Just giving my 2 cents.

If you try this you have a good chance of blowing up your car and is not going to give you reliable or peak hp. The statment, "I personally don't like car dynos, simply for that fact that, the optimal timing and a/f on the dyno is not ideal for the street, because the load is just a simulation", is completly wrong, since load type dynos are capable of getting EVERY load that the motor or car will see it is the only effeciant way of tuning a car for the street and track. Even with areodynamic drag it is still how much "LOAD" you are putting on the motor and since you tuned you motor for all of the loads that your motor is capable of seeing it doesnot matter if you are going 20 or 100mph up or down hill.

just taking it off the dyno and driving on the street will show you a different a/f ratio, that tells alot.

i've even done a comparison, and had Jeff Evans give me his best tune, and my street was still quicker at the track with the same 60 foots.

Listening to the engine helps prevent your engine from blowing up and starting with a good basemap. Like i said, car dynos are just a simulation, and what timing and a/f ratios give you the most power on the dyno, can not be ideal for the track.

Car dynos are really not necessary, especially if your looking for the best tune for the track. Datalogging is all you need. Most ppl will say you need the dyno to find the best timing, but like i said, if you build an engine combo and calculate for tuned length, then you already know where the most fuel will be burned, and you can confirm all of that with the wideband reading. Having a monitor and viewing more or less power on the dyno is like tuning blind IMO, you really don't know what your tuning and how it will respond.

I've compared my best track tune with a dyno tune, and the "best" cam timing adjustment on the dyno, was not the "best" timing at the track.

Proper way is to degree the cams, and setting the exhaust cam gives you the tq vs rpm curve you looked for, and the intake cam moves the peak hp.

What is the dyno that was used? (DynoJet, Mustang, Dynapac, ect.)
Did you race it different days when different tunes were used? (this can have a huge impact on ET's)
The same humidity?
Same air temperature?
Same barometric pressure?
Same tire temperature?
Exactly same shiftpoint?
Same launch?
Same lane? (right vs. left)
Same mood? (one of the biggest factors in how well you drive)
All of these factors could have made your tune faster. Who gave your tuner credability; maybe he has made fast cars but still does not really know how to tune properly. Unless you know how to tune properly how can you guage how well a tuner is? I GUARANTEE if you ran you car with a stree tune and then had me tune it not only would you get better gas mileage, streetability, and better ET's but you motor would last longet too.

it's a dynapak actually. Don't get me wrong, because a dyno is a great tool, especially being able to tune partial load, and personally i think it saves time and money for most ppl. Tuning just a/f and test and tuning at a track session takes a longer time to tune and more patience, but as far as finding the "right" tq curve, i've found that the stock powerband, and finding more power in that region, given the stock trannies yields the quickest acceleration, regardless of what appears to be the most average HP on the dyno. Like the saying goes, torque wins, and it's true, because when i even made 7 more peak HP on the dyno, with 2 ft/lbs less across compared to my track tested tune, and the track tune was still quicker by .1 with the same 60 foot, but trapped about the same, up to -1 mph.

If you could run gears 1-5 on the dyno and view your matching tq curves between the multipliers, then that will definitely show you what tq curve yields the quickest acceleration and the most speed, because when you tune for more peak hp, you have to rev that much higher depending what gear you are in.

If tuned in 4th gear and your making 150 ft/lbs @ 5500-6000 rpms, and your peak HP is at 8800 on the dyno, and lets say you make 230hp @ 8800. That means at 8800 rpms your making 138 ft/lbs of TQ to produce 230HP. That's 440TQ @ 8800 rpms in 1st gear!!!

But if you switch there, then think how little tq your making in 2nd gear after the gear switch. You have to figure out where it drops. So take for example:

1.9 second gear ratio divided by 3.2 first gear ratio. Gives you 59%. If you switch 1st gear @ 9000 rpms, 2nd gear will start at 5310 rpms. But if your making 150 tq @ 5310 or even less with your 1:1 multiplier, that's almost 300TQ @ 5310 or so, but not enough to match the 450tq. So after each shift, you lose lots of potential speed. That's the main reason why you will see the same weight, and same displacement between 2 cars trapping the same speed, but one is making 250HP and the other is making only 200HP. It is possible to trap the same, so trap is really not an idication at all of peak HP.

This is a good thread btw.

All the variables you mentioned are all considered and i only test for one "tunable" variable for each track session. of course the weather changes, so that can fuck up any controlled experiement, but just have to know how the engine responds when it's real humid, or real cold and take all those factors into consideration. That's the beauty of the datalogging.

I dont understand your statment about tq; because what you are explaining is just how pullies work. Of course if you go from 1st to 2nd there is going to be a dramatic loss of tq. There is a reason why a 150 hp and 150 ftlb. of torque motor car put down 2000 ftlb. of tq to the wheels. If you look a tq curve from 1st, 2nd, 3rd or what ever gear, ALL of the curves will look almost identical the only difference is that the readings will change up or down depending on what gear you are in.
And true TQ is what makes you accelerate, BUT hp is deived from TQ. So if you are at 6000rpm and are tuning "that" particular cell then you are maximizing TQ in that exact place and not having an affect on ANY other part of the "map" or TQ curve. Only when you tune that 8800rpm is when you will be maximizing HP (remember maximizing hp in a very narrow range also maximizes tq because it is directly derived from tq) in that range, having NO affect on lower end tq, AT ALL. The only time trying to get HIGHER #'s on a dyno "COULD" hurt your lower power is changing your cam timing (yes i saw you talking about it) but the reason that i did not wright about it is because it would take to long to explain and most of this articles readers would not understand

yeah, that was too long.

That's exactly what i meant about 1st to 2nd gear. Your want to tune the tq curve so you don't lose any TQ from 1st to 2nd gear after the shift, and produce the most amount of tq possible, even if you sacrifice peak hp.

So if you produce 7 more peak HP compared to the last cam timing, ignition timing, or fuel adjustment, it doesn't mean you'll accelerate faster, it usually can hurt acceleration and the tq output will be too low after each shift.

Unless you take the tuned gear on the dyno chart, and then calculate for the ideal shift points for the smoothest tq curve between all gears, given your gear ratios.

Biggest problem is that the average person that takes their car to the car dyno will usually just have one shift rpm, which is like moving backwards i guess.

I.

Obviously you did not even read my last post letalone the article. If you are trying to get max HP at any "CELL" (the little box with #'s in it) IT WILL NOT AFFECT THE REST OF THE "MAP" (the thing you tune with that is covered w/ cells). Sory i dont mean to be sarcastic but it is like you dont read my post then post random shit. Read my article again and then read my LAST post and maybe you will understand.

Do you think you could explain tuning cam timing as well?