Just a tidbit of information

A good general rule is 1.5-2 degress timing retard per 50HP of Nitrous

 

Cool this was my next question, so on a stock internal lt1 on a 100 shot retard maybe 3.5

 

yeah that sounds about right 3.5-4

 

Actually if the car is stock as far as tunning also there is no need to remove timming.
Dave

 

I found on mine, with a 125 shot I was retarding 5 deg. and it liked it
but I have pcmforless tuning that I also tweeked a bit.

I tried 4 deg. and 6 deg, and both where bad, lost lots of power with those.

I didn't think 1 deg difference up or down mattered but it sure did.

 

Hmm, maybe I should try pulling a little more timing.

I'm pulling 3 degrees right now, and am pretty happy. If pulling a little more will get me more power, cool.

 

Your plugs can tell ya if your tune an timing is right, heres a link to help.

http://www.4secondsflat.com/Spark_plug_reading.html

 

I'm retarding timing 2 degrees on a 100 shot with a MadZ28 PCM tune....on my fifth bottle with no issues.

 

THere's some AWESOME info there. THanks!

 

If your plugs are the wrong heat range ya wont get a good reading on the ground strap, keep that in mind. When your plugs are right ya can tell alot from them. They are your only window to the combustion chamber. I run a MSD 4 stage retard box that pulls timing as each stage of spray turns on, that way ya can have your motor timed right an each stage of spray timed for best performance independently, no compromising on any setup.

 

I have heard it stated many times that you should reatrd x degrees per volume of nitrous. Frankly, I doubt this is really the best way to go, though it may be a useful rule of thumb. Why do I doubt it? Well, starting with theory, the reason to retard timing with nitrous is that nitrous speeds up combustion. Too much timing and faster combustion can cost power, as it moves peak cylinder pressure too close to TDC. But I would be very surprised if the degree that combustion is accelerated is in direct proportion to the amount of nitrous. My experience on the dyno bears this out. On my combo, I found that pulling four degrees made the most hp with anywhere from a 50 to a 200hp shot. Now, I was starting with very little timing in the first place (26 degrees), and my combo is a blower plus nitrous setup. So, YMMV. But it certainly makes me doubt the rule of thumb being discussed here. I would say that the correct timing is best determined on the dyno, or if that is not an option at the track looking primarily at trap speeds. Reading plugs is kind of a lost art. And it's a PITA on a 4th gen. It's hoard to get at the lugs on a hot motor, and the best readings are obtained if you shut it down immediately after a run. And then, you need to find an old guy who knows how to do it! Besides, the main utility of plug reading is mixture anyway, not timing unless the timing is WAY off.

Rich

 

I don't use the X-degree rule of thumb, every motor is differant in what it wants. I don't have a dyno to use only rely on mph an et for best results an I hate to admit it but I'm becoming an ole guy way too fast, I still look at the plugs to see whats going on inside even using gloves sometimes. I have a friend Ed Steffy that runs ProMod an he still reads plugs between runs to see if he hurt the innurds at all. Its just another view of the combustion chamber that most hotrodders can use, an it does tell ya some interesting things that ya might not have known if ya hadn't pulled a plug. Not saying its the best way but its free info. I am speaking more of a race type motor too, newer street engines burn so clean ya can't tell easily.