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Discussion Starter · #1 ·
I got a built 4V shortblock with 11cc dish pistons ( around 9:1 compression ratio) The block was built for boost but long story short i'm running it N/A now and plan to spray a 125 shot on top of it. My N/A tune has 27 degree total timing. I've been talking with a guy at the track with a mach1 and 150shot and he is running 19 degree total timing on 92 pump gas. I'm wondering how much timing i can run on a 125 shot and 92 pump gas since i only have 9:1 compression ratio ?
 

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27˚advance is well past MBT. Chances are the engine was detonating at that number. The salvation for the engine was that it was not supercharged.

The best way to determine how much timing for starters is, do not exceed recommended timing for a n/a engine and no nitrous. When you add nitrous take baby steps and increasingly add fuel in the tune while backing off your timing as you increase the shot for safety. You can always begin to bring timing back later. If you break the engine - time for a rebuild and a new start! A 125 shot is not gigantic but it is also not a wimp either. Always go conservative initially with your nitrous and timing.

Adding nitrous is very similar to supercharging. It will burn a piston in a New York minute if you are over zealous. Again, take baby steps read what your nitrous system provider recommends and look at some competing providers and what they recommend. Where there are differences explore them and ask why? Nitrous has been around long enough that a 125 shot is not a big deal tuning wise. Irrespective of what is recommended start conservative.

This is a separate paragraph because it is important; Make sure your fuel system can deliver more fuel than you will require for whatever shot you experiment with.

Ed
 

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Discussion Starter · #3 ·
The car was remote tune by eric brooks with 28 degree of timing. I removed 1 degree and it did not affect et or mph so i let it at 27 degree. I was loosing 1/2 mph with 26 so 27 seems like the sweet spot. my idea was to start with a 75 shot with low timing and work my way up from there.
 
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