Tuning...just what does that mean??

[bruce]

Originally posted by Two Lane
I appreciate bruce giving the data behind his advice.

Sure beats: "Do "this", then "that" (cuz I sez so).
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bruce, you've done a great job pointing out the potential hazards
from running injectors that are too small.
Any functional downside to running larger injectors, e.g., 72 or 83s, for moderate street/strip duty?

So far, I haven't actually used 72s or larger injectors.
So far I've wasted alot of time, since I hadn't figured out the sizing stuff til recently.

That aside, I don't see where the 72s could pose any problems, and Carl Ijames has passed an emission test with them, so they can't be to bad to work with.

With the peak and hold injector type, the suggested operating times are 1-5 msec., so you should be right in that range for idle and light cruise. FWIW, on the saturated, ie high ohm style it's 2-10 msec..

 

[bruce]

Originally posted by turbov6joe


A)I would be reluctant to say that 1600º EGT is "rich" with OE headers...by any standards. I think for your application, 1600º is right about on the safe/pushing the envelope line. I like to tune for 1580º-1600º myself. This ensures there is enough fuel for the safety net minded individual. I would NOT give much credit to the O2 voltage readings your seeing. The OE style O2 sensor is NOT wide-band, and is NOT able to give you accurate readings entirely.

B) Anyhow, I'm done with this short book (especially before what I say is coined psyco-babble.) Hope any of it helps!

A) ditto
B) psyco-babble?, seems to mean something that is actually factual in nature. At least as used in that other post.

 

[azgn]

1600 would not be rich by any means if the reading were valid....what I wanted to verify was that he wasn't burning fuel in the manifold and getting a false high reading......he had already checked that, so need to look elsewhere

I still think there is way too much slip in the drivetrain, particularly if that converter is supposed to "lock"...if it really locks, you should have little, if any, "slippage" other than normal auto trans losses

 

[strikeeagle]

Back to the original question.

"Tuning" is the thing that sets 2 cars having the same build-ups apart.

"Tuning" is free.

"Tuning" is the thing that takes an enormous cranium and countless hours to pull off.

"Tuning" is never as good as a big azz front mount or a set of aluminum heads...

 

[87LtdT]

"Tuning" is the thing that takes an enormous cranium..."

Now I know why I didn't understand

Bob

 

[Steve Wood]

Tuning can be a very broad category and may mean different things to different people.

Tuning is made easier by having a combination of parts (turbo, converter, IC, injectors, cam, tire size/diameter) that complement one another.

It would be nice to have a chip that commanded a similar air/fuel ratio thru out the run with regard to rpm....a wide band O2 with logging capabilities should be very useful to a competent chip maker....

Once the A/F curve is reasonably flat, one can begin a series of iterations adjusting fueling to see if the car goes faster or slower with changes of fuel pressure...adding pressure should move the curve down, numberwise... and removing it will lean it out or move the curve up, numberwise...It is nice to have large enuf injectors so that these changes always keep the pressure within a reasonable range....in my opinion, no more than 50# at idle...yeah, you can crank it way up in some cases but it will affect the idle and normal driving charateristics...

I may be wrong but I don't believe in magic numbers so I think that one has to determine what works the best with HIS combo rather than aiming for 11.5 to 1 or 12.2-1, etc. A chip with a flat A/F delivery curve should help to optimize this process....

Then one can play with the timing to find out what the car likes.....One may well find that what the combination likes at 24# of boost is not what works best at 28#.....in my opinion, one should err on the side of more fuel, less, timing, and less boost from the best performance just to leave a margin of safety in case the air is a bit better than anticipated, etc. Serious racers go for the edge, others back off a bit...it's up to the individual....

Some chips allow you to optimize the launch curves, top end curves, timing, etc. without having to reburn the chip....

With or without a wb O2, one should have a loud knock alarm and an EGT and take note how they react in a normal run and stop and find out what is going on if there is a change. I believe in zero detonation/retard ,but then, my back aches quickly leaning over the fender to pull the heads.

Besides playing with fuel, timing, and boost, there are iterations required to determine tire pressures, air bag pressures, launch boosts, and so on...one must learn to minimize parameter changes on each run and keep notes....don't compare a 70 deg day with a 100 deg day, etc...

Remember that in drag racing, on the strip, some of the easiest time improvements come in the first 60'....spend as much time on improving launch as you do all the way thru.

Then there is alignment specs, wheel bearing load, spark plug gaps, ad infinitum....how far do you want to go for another .01?

Above all, one must be sure that the combination is in good mechanical and electrical tune before tryiing to tune it for performance. An engine with 40# of compression in one cylinder does not help. Nor does one with the cam sensor 180 degs out, leaking headers, bad valve springs, etc......