Timing: Racegas & Pump w Alky

[howracer]

"Race gas requires high timing to burn properly..alky usually works better on lower timing.. " from a 03 Razor post...

my question:

given 25 psi boost... what would be optimum timing advance for 116 and what would be opt timing for pump 93 and alky?

i am most interested in the difference between the two in degrees rather than the actual number as i run a rotary.

thanks and hello to all on the greatest AI board on the net.

howard coleman

 

[Razor]

Howard, I think you should run timing up as the motor responds to it in a favorable fashion. What works for one application may not work for another. I know of customers who run way more timing than "race gas" programs would typically do on pump gas and alky.

To me I look for detonation, EGT, and HP. If you increase timing your EGT will come down.. which is a benefit.. but at the same time be more susceptible to detonation. And typically increasing timing will net more HP.. if it doesnt, then you know where the limit is.

I know on some applications figuring out if its detonating is difficult. And reading plugs, looking for puffs out the tail pipe, and increased EGT's are the only way I know off. Aside from audible pinging.. but this is too late if you can hear it.

I would run low timing and generate a baseline. From there make decisions. These decisions then are based on knock(detonation) and HP.

 

[howracer]

thanks for the help.

i have a friend's racegas map and was simply curious as to the general differential racegas and pump/alcohol w re to timing.

i do not plan to run racegas but am interested as to whether he is running more timing than i am. i am aware as to how to reach optimum timing using the various metrics.

so what's a general differential number?

thanks,

hc

 

[Razor]

thanks for the help.

i have a friend's racegas map and was simply curious as to the general differential racegas and pump/alcohol w re to timing.

i do not plan to run racegas but am interested as to whether he is running more timing than i am. i am aware as to how to reach optimum timing using the various metrics.

so what's a general differential number?

thanks,

hc

I think its like 6-7 degree's difference is a rule of thumb on most applications i'm aware of.

 

[moose]

I'm running 22-23 timing on razors alky with pump gas and alky set on #5 and everything works well with no knock. Hope this helps.