Dodge Challenger Forum banner

WOT Spark

30K views 25 replies 11 participants last post by  windwalker438 
#1 · (Edited)
Running u7135 9r29. Been running some higher octane fuel, so wanted to bump the timing up a bit. Went into WOT Spark and upped the MBT and Spark amounts by the same amounts (2 degrees advance at 1-3.8k RPM) as indicated by the prompt. Logged STKR and LTKR. Saw zero knock, so I advanced the timing some more (5 degrees). Still no STKR/LTKR but it feels like it's going in the opposite direction. Feels like it's pulling (retarding) timing, not advancing. So, either something is wrong with my STKR and even though it says zero on the logs, it's not zero and the ECU is pulling timing, or advance and retard are reversed, or I can't read. 5 degrees is a ton, I know, so you'd think I'd start to see some KR by now, but nothing. Also when comparing Spark Advance 1 to Base Spark, Base Spark is sometimes significantly higher at WOT, seeming to indicate I'm pulling timing.

What am I missing?

Thanks.
 
#2 · (Edited)
How many PIDs are you logging? I notice if I log too many on the Trinity, it does not always record properly or does not update some at all.
 
#4 · (Edited)
OK, I finally got some STKR, but just a touch (thankfully). Looks like the timing is advancing when compared to an old log. Getting about +5 degrees in the 1-3k RPM range, only gave it +2 degrees above that. Even with this much timing, I only rarely get 0.5 STKR, max 1.0. For example, my Actual Spark Adv 1 is at 24.5 deg at 2780 RPM at WOT (base 93 CAI tune had me at 19 at the same spot). It backs down to 24 deg after getting 0.5 STKR at 3000 RPM at WOT. Seems like this is the sweet spot.

I'd forgotten how handy the DataView tool is.

Thanks for the help guys.
 
#5 ·
That sounds spot on.......Damn man, that is way more timing than I could ever put in mine. Most I could ever run was 18-19 with 93 oct. and I would still see 1-3 degrees of ST knock. Damn crappy Florida gas.....:)

I would even see ST knock wth the stock tune.
 
#6 · (Edited)
I have a question:

( I have no tune on my car) Would i be hurting my stock engine running 93 oct? Manuel calls for 89oct...

I have a stock 2012 R/T auto, I been running 93 octn, and also using stabil fuel treatment for lubrication for the 10% ethonel which is in our gas..
 
#7 ·
I have a question:

( I have no tune on my car) Would i be hurting my stock engine running 93 oct? Manuel calls for 89oct...

I have a stock 2012 R/T auto, I been running 93 octn, and also using stabil fuel treatment for lubrication for the 10% ethonel which is in our gas..

It will not hurt it at all to run the 93. Thats all I ever ran in the R/T's I had and also its all I run in the 2012 RAM 5.7L I have. Some will say its a waste of money but my datalogs say otherwise. I got knock on the 89 fuel with ALL of the 5.7L's I had and ZERO knock with the 93 oct........
 
#8 ·
Thanks for the fast reply!!!

just curious in these new engines today:

I was told by and old timer that had past away a few years ago, he had told me higher octane will burn alot slower (longer spark) then lower octane which he refer to cheap gas (shorter spark) meaning spark plugs...


he also stated which i will never for get that cheap gas (low octane will burn alot faster then higher octane, which you will find yourself going to the pumps faster then using better octane, saves more gas in the long run..
longer spark keeps your spark plugs cleaner and valves...
 
#11 ·
.crazy talk ;)


Mike, sounds logical to me of what he had told me...

Longer spark meaning longer flame in the combustion chamber with higher octane gives you better combustion = more power, no???



P.S. I need to win A Trinity Mike, I can not afford A tune do to higher gas prices using 93octane....
 
#13 ·
Octane is basically a rating that shows how much heat it can take before igniting. If you have a high compresion ratio or a supercharger/turbo and use low octane it will cause more heat on the compresion stroke and if you have low octane you run a chance of the fuel detonating before the spark plug fires thus causing knock. Now if you had ran a higher octane you won't have that problem.
 
#15 ·
The old timer was correct in that higher octane gasoline burns slower than low octane gasoline this is why you are able to advance timing and get peak HP and not get any knock.
 
  • Like
Reactions: salvy59
#19 · (Edited)
I always thought the octane rating used is basically what compression ratio your engine has. For best performance, the higher the compression, the higher rated octane gas should be used.



Yes and no , its a little bit more complicated then that
higher compression high performance requires at least 93 oct with aluminum heads, back in the day when cast iron heads on high performance cars requires a lot more octane do to heat.... Cast iron heads holds heat which causes the engine to start pinging, alumium heads dissipates heat allows lower octane...


You can run 800HP with say low compression in turbo charges i assume...
 
#23 · (Edited)
I spent most of my working career working for ARCO at their Houston refinery as head operastor on a crude unit.Higher octane gasoline to put it simply contains more btu's of energy than regular, so regardless of tune will simply go farther per gallon. No smoke, no mirrors, as Joe Friday succinctly put it , just the facts.
 
  • Like
Reactions: salvy59
#24 · (Edited)
Let's say we have a vehicle that runs on 89 octane with no knock at all and you throw 91 octane in the tank how is the vehicle going to know that you threw higher octane in the vehicle if there was no knock before? What's going to happen is the vehicle will put the same amount of fuel regardless of wether it's 89 or 91 so you are wasting money right there. Also if you run too high of octane it can lower gas mileage because your vehicle won't get the fuel hot enough to fully burn the all of it so you have wasted fuel that you paid extra money for. The way to fix this is by tunning your vehicle to run higher octane. Correct me where I'm wrong

Sent from my HTC One X+ using AutoGuide.Com Free App
 
#25 · (Edited)
Some things are just to hard to explain lol


Do your own DD, put in 89 then put in 93, come back and let us know please...
if the the 89 feels better to you then use it!!!



My R/t feels so much better with 93 then 89, no tune don't need it...
 
#26 ·
I know this is an old thread but I just read it and thought I would share some info from
Sunoco that might clear up some misconceptions.
Sunoco Race Fuels | Beyond Octane

Here is an excerpt from the above article:
"You might be surprised to learn that some of the highest octane fuels may also be some of the fastest burning fuels!"

Also, some of us go faster with 87 in N/A snowmobiles by a noticeable margin than if we were to use 93. 87 can make big power in some sleds with the right combination of
combustion chamber, compression and timing. 87 has as many BTU's as premium give or take depending on the batch and who is mixing it at the plant. I have seen no evidence or read any articles that state that premium fuel contains more BTU's than regular, ever.

This is an excerpt from the Consumer Energy Center...California:
"There is little difference in energy content of regular versus premium gasoline. They
both contain about 111,400 British Thermal Units of energy per gallon."
Regular Versus Premium Gasoline

I don't know where they come up with that number, maybe it is a California thing but the point is the BTU's are about the same in either premium or regular nationwide.

Here is an excerpt from Road and Track:
"The reason for this has nothing to do with energy content. In fact, depending on its
blending, a premium fuel may actually contain less energy per unit volume than regular. However, its potential for producing more power and enhanced mpg goes back to MBT and that knock sensor. If premium is recommended, this is the engine's optimal fuel. It'll run on regular—albeit with the sensor invoking ignition timing that's less than that associated with MBT. And with less than Best Torque, there'll be less performance and an mpg hit."
Premium Gasoline ? What Does Premium Fuel Do for Your Car?

Octane is simply resistance to detonation and nothing to do with how fast fuel burns or
how much energy it contains per volume.
I used to think of it differently like most of us probably do, or did at one time until
I started paying attention.

As far as timing goes in our cars, it is relative to the fuel we use. Just enough octane
to keep it from pulling timing is probably optimum. Works for me.

Hope some of this stuff helps.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top