Quickin

I know I should know this by now, but I don't.

I thought I understood it until someone told me you get more power with more degrees of timing and higher octane gas

Yelo

kinda......
you are able to advance timing more with higher octane gas to produce more power.....more timing = more power (to a degree), but to advance timing more you need higher octane to prevent detonation

glen

iTrader: (1)

No, Nope, Nada, Nyet. Timing is more a function of engine combustion efficiency. The more efficient the chamber the less timing you need. The old SBC needed upwards of 40* to get it to make power. Put a Vortec type head on the same motor and the timing needs will change. GM recommends starting at about 32*. In a perfect world the engine would require no timing advance at all. Now if GM left some on the table with a conservative timing map than perhaps more MIGHT help, but it is not a given.

Now, on to octane. The HIGHER the octane the SLOWER the BURN rate. You really want the fuel to burn as rapidly as possible W/O ping, hence the different levels of octane. If your motor doesn't require it, no additional power will be gained and tests have shown a loss of power by too much octane ( to put it simple).

Its all about what the engine wants. Which is why we give cars feminine
names, cuz they are just like women in that respect.

MyLS1Hauls

iTrader: (2)

Distortion69-you should've got some sleep before you typed that

All of these numbers stated in degrees mean degrees of crankshaft rotation before the piston reaches the top of the compression stroke. Since it takes some time for the fuel to ignite and actually start burning at a fast rate, the spark plug needs to be fired before the piston actually is all the way up. This way, maximum cylinder pressure occurs at the correct time. If you fire plug too early, the combustion starts pushing on the piston when its still on its way up. If you fire it too late, the combustion starts when the piston is already on its way down. Also, as the rpm and load change on the engine, its timing needs change. The plug needs to be fired earlier at high rpm vs. low rpm. If the plug fires too early for the fuels octane rating, then you get that "ping" sound as the piston rattles side to side in the bore.

AustinL911

iTrader: (-1)

where does camshaft timing come into play on this?

gun5l1ng3r

Camshaft timing is a WHOLE different ball park!!!!
That has to do with timing in respect to the camshaft and crankshaft rotation.

AustinL911

iTrader: (-1)

so basically, there's 2 types of timing in an engine?

JZ'sTA

iTrader: (23)

This is defentially a topic that I am not "the sharpest tool in the shed" on.
I have a 408 with a 242/246 cam and 11.8:1CR.
On the dyno the other day running 93 octane I made 437RWHP but had 19-22* of timing. The tuner kept pulling timing out to get the car where it had no sparknock.
I have been told by 3 different LS1 engine builders that 11.8 would be fine on pupm gas and should still beable to run 26-28* of timing.
What do you guys think? Is this too much compression for 93 octane? With 11.0 compression and the timing being between 26-28* I would have probally made the same amount of power correct?
Thanks

distortion_69

iTrader: (20)

2 types of timing. Cam timing allows the valve to be in the correct position relative to the piston. Theres very little room for error, because if a piston is all the way up and the valve is all the way open.. kaboom

Josh

Quickin

Who is Distortion69?????

So if someone says to me, what does timing mean?

Its the degrees of rotation of the crank before the piston reaches TDC. (the piston next in line to fire)
If an engine is running perfect than adding more timing will not increase power. Unless a higher octane gas is used.

So why am I told to run 100 octane when I spray my 150 shot? And how is the timing going to change automatically?

glen

iTrader: (1)

Ignition timing is the is when the spark plug goes boom in relation to the piston. The higher the RPM the more advance you need to a point. There is what is called INITIAL timing and DISTRIBUTOR or COMPUTER timing added together you have TOTAL TIMING. Simply adding timing does not mean more power if the engine doesn't need it. Simply adding a higher octane with or without more timing does not mean more power. A 150 shot is nothing if installed properly and timing is REDUCED. But someone doesn't want to retard his timing, supposedly to make more power, so they believe that by using a higher octane it will protect his motor. In theory it's possible, but a 150 shot is 150, you think you might see 10 more by leaving or advancing your timing? Not my motor, knock your self out.

Yelo

so.....esentially what I typed was the answer he was looking for......correct ??

JZ'sTA

iTrader: (23)

Who is Distortion69?????

He made a post a 5:37AM this morning with no sleep but that post has now disapeared.

MyLS1Hauls

iTrader: (2)

IMO, thats just not possible...11.8:1 on pump gas isn't good, especially with a bigger than stock bore. The bigger the bore, the more detonation sensative a motor becomes. Which builders said it would be ok? Most of the time, you will make more power with a conservative compression ratio and more timing...Somewhere around 10.8-11:1 would have been plenty.

As for N2O and higher octane....Nitrous basically does the same thing as adding a supercharger or turbocharger...it stuffs more oxygen into the motor than it could normally use...now take that extra amount of air and compress it down into a space that was designed for NA use and you've now incresed the motors running compression ratio, which makes the motor more detonation prone. Adding high octane fuel will ensure that detonation wont be a problem, as long as the proper A/F ratio is maintained and the correct heat range plugs are used.

distortion_69

iTrader: (20)

I erased the post because I went to read it, and I couldn't understand half of what I was saying. I ran all the words together.

Josh