Cylinder Skew Tuning - Ideas, Tips?

[ForcedFirebird]

EMC = Engine Master's Challenge.

It's a contest where the contestants have to use pre-1985 heads and carb. manifolds to scientifically extract as much power as possible on a brake dyno...

http://www.popularhotrodding.com/enginemasters/challenge/0901em_2009_engine_masters_challenge/index.html

Sorry, I was under the impression that they had reached nearly 3hp/ci, but wasn't that high. Still impressive to see almost 600hp from a 380ci engine (2.6hp/ci), that still equates to a 400+ hp N/A 3400.

[bszopi]

And yes, the more that I think about it, you could use egt's on each cylinder, combined with a single wideband. As long as all egt's are reading the same, each one would be more or less equal to the wideband reading. But you would still need some monster transmitter that is capable of reading 6 thermocouples at once, and display all that info, preferably output to datalog.

However, the OP wants to fine tune each cylinder, by changing the pulse width on each injector. You could be there all day waiting for those thermocouples to react to each minute change. I just don't see how you could get accurate enough results with thermocouples to even warrent this experiment. Like we were estimating that each cylinder should already be within 5% of the next.

Look at my second link above, as PCS has a unit that is capable of reading up to 8 EGTs.

And if you look at what the OP said, he wanted to mount a WBO2 on each cylinder, so he would need 6 sensors and controllers, and then datalog each one. Either way, it is WAAAY overkill.

EDIT : Reread his post, and he wants to just swap the WBO2 between cylinders. I could be wrong, but logging one cylinder at a time, and then shutting the engine down, swapping the sensor to another cylinder, etc.. would not get you very accurate results. By the time you got to the end, if you go back to the first cylinder again, pretty sure you would get different results than the first time around.

[SappySE107]

You would def want to test them all at the same time.

To modify with wide bands would still require you to hold rpms to test mapped points if you are going to get down to the nitty gritty. Hope you have sponsors

[Schmieder]

So basically the tuning ability I have described is only good for a certain range of accuracy. Given minute differences in air temps, fuel quality, engine temps, RPM differences it becomes too complicated to get good results.

So....assuming factory settings are 0 skew across all cylinders, is there any ability to fine tune somewhat using the described method I presented?

Knowing I wouldn't get fantastic perfection but could I get something closer to a better balance beyond factory settings?

Anything better then flat line would do something I'm sure.


Thanks for the input guys!

[robertisaar]

there is a difference in the fueling between cylinders 5/6 and 1/2... one pair gets better airflow than the other, but i can't remember which.

[ForcedFirebird]

there is a difference in the fueling between cylinders 5/6 and 1/2... one pair gets better airflow than the other, but i can't remember which.

It depends on what way the tb/uim is facing

[robertisaar]

It depends on what way the tb/uim is facing

for sake of sanity and how common it is for the TB to be nearest to 5/6....

lets just put it that way

[SappySE107]

Depends on the upper intake:P 96-99 3400 is about -5% on 5/6. 00-05 3100/3400 is practically 0%. 3500 is about 0% 1-2, -1.5% 3/4, -5% 5/6.

EGT would get each cylinder close to the next using the skew, which is what the EGT is for. You can nitpick it down to binary if you want, but for the basics, you use EGT on each cylinder and a wideband to tune at a higher level of precision. Using your method to move it around would be worth a test if you have the time and money to make that happen. 6 EGT at once however would be the only way to know precise differences to skew the injectors.

[Schmieder]

Depends on the upper intake:P 96-99 3400 is about -5% on 5/6. 00-05 3100/3400 is practically 0%. 3500 is about 0% 1-2, -1.5% 3/4, -5% 5/6.

EGT would get each cylinder close to the next using the skew, which is what the EGT is for. You can nitpick it down to binary if you want, but for the basics, you use EGT on each cylinder and a wideband to tune at a higher level of precision. Using your method to move it around would be worth a test if you have the time and money to make that happen. 6 EGT at once however would be the only way to know precise differences to skew the injectors.

Understood, thanks.

I'll try the WBO2 method some day. It's not really high priority. In the mean time, when I weld up the turbo manifolds I'll include the bungs for independent WBO2 and bungs for EGT if there is such a thing. I never really looked into EGT much but will be now.

If the EGT's use voltage differences to send temp data, I could rig them up to my sound card on my desktop (6 audio in) and have my bro help me write a simple program to display the readings in real time. Nothing fancy, just a blank screen with 6 voltage variables. As long as I can read real time differences, either voltage or temp, it can be done.

I hack computers more then I work on cars. Having that knowledge entering the auto market would be nice. Seeing that every car is going high-tech these days. I keep hearing a mechanic that has a strong education in the technological computer systems will do very well.


EDIT:
God forbid if vehicle PCM's go wireless. Hackers like myself could easily break in and lean out your car..kabooom!

Funny, the school geeks of the 80's are going to have all the power, lol.

[ForcedFirebird]

You can buy EGT bungs just as easy as WB bungs - any supplier will have them.

[Schmieder]

Depends on the upper intake:P 96-99 3400 is about -5% on 5/6. 00-05 3100/3400 is practically 0%. 3500 is about 0% 1-2, -1.5% 3/4, -5% 5/6.

Are those figures calculated into factory tuning? If not, is that a reliable first step in skewing?

[Schmieder]

You can buy EGT bungs just as easy as WB bungs - any supplier will have them.

Good, they're getting welded on.

Most likely they won't be used until I get a short block built up for high boost. And once I get used to tuning. I don't want to f*** up a new block worth over $4k.

[Schmieder]

for sake of sanity and how common it is for the TB to be nearest to 5/6....

lets just put it that way

idk about others, but it seems cylinders 5/6 are the closest to the TB. 1/2 are the furthest. Brain fart?

1 3 5
<< TB
2 4 6

[robertisaar]

idk about others, but it seems cylinders 5/6 are the closest to the TB. 1/2 are the furthest. Brain fart?

1 3 5
<< TB
2 4 6

that is entirely correct...

[SappySE107]

The runner aren't identical, so no, you cannot use those numbers to skew injectors with any accuracy. You should use sensor feedback to make those decisions.