27° timing for 100 chip?

[Fred 86 GN]

The chip I am using now has 27° of timing and is labeled a 100 octane chip. Is this possible? I thought that much timing was only for 110+ octane race chips.

Can it be used with lower boost (like 18-19psi) and be safe with 100 octane?

Thanks,

 

[TurboDave]

27* for 100 octane

I run 28 degrees on my 112 chips, and burn pure 114 race gas to maintain zero knock retard at 25+ lbs of boost.
Any more boost than 26# or gas less than 114 would start to tickle the knock retard.

 

[tim87tr]

Using a lot of Dave's info on boost, octane, and timing, I have just begun increasing the timing with the Trans + using Xylene. See my sig for info. It is scaled back over 3000 rpm in all gears with no knock on the below tunes. So what I am using is about the max I have found with early testing.

I think different parts on a car could change the results some. I have a stock turbo and IC, powerplate, TB/plenum bore, and LT1 MAF. Installing the Dut neck IC tonight ! Do a search on my screen name for recent info on boost, octane, and timing.

 

[Fred 86 GN]

Thanks for the replies!

Looks like it is time to put in my JL93 chip and be safe. I suppose if I turn up my fuel pressure with the 93 chip that I can run more boost than 17psi.

Max inj PW seen in DS for JL93 chip = 70%
70% of 42.5#/hr = 30#/hr

30#/hr can support about 390hp...at least it did in my other GN at 45psi static.

So if I turn up the fuel pressure (45-46psi), my blms will be in the 90's but I should be able to run 19-20psi of boost with the 110 race gas I have in the tank. The low timing of the JL93 chip (21°) should help suppress detonation too...one would think.

Maybe 110mph will be possible But I doubt much more than that. What do you guys think?

 

[boostcreep]

How are you guys determining the timing? Take a look here..

http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=108830


It looks like you just can't look at the prom table and tell what timing you've actually got.

Nick

 

[Fred 86 GN]

I determine the timing by what my DirectScan software displays. If it is in error, then at least it should tell me the relative difference between the chips.

BTW, the JL93 chip is in and seems to running OK. Better BLMs now, for some reason. Whatever, I will take 'em!

The O2 numbers do seem to drop as the engine revs through third gear. Start at 780 or so and proceed down to the 760's. No KR, and the car seems to running well. Need to take it to the track and compare. Running 17-18psi of boost with a tank of 110 race gas.

 

[bruce]

Originally posted by boostcreep
How are you guys determining the timing? Take a look here..
http://www.thirdgen.org/techbb2/showthread.php?s=&threadid=108830
It looks like you just can't look at the prom table and tell what timing you've actually got.
Nick

If you look at all the timing corrections and tables they will add up exactly to what the ecm calculates.

Again, the best way to do accurately research into this stuff, is with an ECM Bench.

 

[boostcreep]

How about cranking some numbers here to either prove or disprove that the actual timing is more like 26* rather than the much believed 22* as was posted in that other post?? Inquiring minds want to know

Nick

 

[Mile Hi GN]

Originally posted by Fred 86 GN
The chip I am using now has 27° of timing and is labeled a 100 octane chip. Is this possible?

You bet it is, at least in terms of bottom timing

My 4 100 Octane Chips have low gear timing from 23 - 30 degrees. They all scale back to 22-24 degrees on the top end.

Load is lower down low, more timing is possible. But don't even think about 27 degrees of lead in 3rd gear with 100 Octane fuel - attention race fans, we've had an oil down in the tower lane