I'm not the nitrous guru but i know exactly what i need to have a safe and effective system. My question is on the combo in my sport coupe:

355 4 bolt, arp studs throughout
speed pro forged coated flat-tops(10:1 static cr), scat steel crank
I-beam rods w/arp bolts, air-gap intake, 750dp holley, rpm aluminum heads
compcams nitrous grind- 236/248 and .520/.540 @ .050 113LSA

I want to run a fairly "small" 125hp shot with just colder plugs and a couple gallons of 100 octane...no timing retard. Right now its set at 36* total(18* initial) N/A. At 5800ft elevation, i should be able to get away with it having a forged bottom end, what do you guys think?

 

i personally think you should easily get away with that. however just listen to the motor if you hear it knocking let off and retard the timming 2 degrees and go again.

 

You'll be fine, especially considering the 100 octane...

 

I would retard the timing even with a 50 shot myself. You are supposed to retard the timing 2 degrees for every 50 shot. I would retard the timing 5 degrees, and run a a plug 2 steps colder than what you have. If the N2o will be on the car for awhile, I would look into a Retard box if you have a aftermarket ignition and let that do the work for you.

 

I was doing some reading on MSD retard boxes and it seems like thats the way to go to pull timing remotely.

 

Nitrous speeds up the ignition/burn process. Your motor will want less timing to make max power than you think.
start at 28deg and work up. The extra retard does not kill near the power you think it does, but detonation will kill your motor in a hurry reguardless of the parts in it. Do what the motor's performance indicates. Make up all the performance theories you think fit the results, that you want. I'll bet 30 to 32 is all it will need even with the higher octane. Let the time slips tell the tale.

 

i'll back the timing down to 32* and go from there, so with retarded timing and some 100 octane do i even need colder plugs for a little 125 shot? or i suppose its just added security to change plugs.

 

I did a chassis dyno test a few weeks ago. I ran my 427ci IROC-Z with a 100-shot, 32 degrees timing, and 5-gal of 110 Octane. It made 415 rwhp. I bumped the timing to 34 degrees and it made another 5 rwhp. On the way home with 34 degrees timing (and a heat-soaked motor), I had a high-rpm misfire or 'pop' running on the bottle. Plugs looked ok. I backed it down to 32 degrees and haven't had a problem since.

 

Neil, were you using stock heat range plugs or colder ones?

 

AC Delco R44XLS .040 gap