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Discussion Starter #1
I have an opinion, not going to state it and bias the thread.

Let’s say 3,000pph nitrous level on a 580ci engine or something similar.

If you miss the tune up, is rich going to hurt stuff faster? Or lean?
 

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I kill parts
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I would say timing plays a roll either way, but rich has now gotten me twice around 2500PPH and lean never has as of yet. Been lean and under timed and hurt nothing, been rich an wounded some ring lands.
 

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He's not here anymore (RIP Monte Smith) but do a search on his replies...We all know his point of view.
 

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To me, a tad rich is more forgiving if you timing is aggressive and the weather changes, or motor runs hotter from being hung out on the line etc... this is on small blocks with over the amount pph u asked and all over 2000pph. I'm talking slightly rich again not pig rich!
 

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I'm surprised more have not jumped on this ???
I guess it depends on how much you miss by??

At that level, if your off in left field either way - shit is gonna fry. Your big choice is do I want to bash the ring lands out of the pistons or do I want to weld the pistons to the cyl walls?
Will
 

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Discussion Starter #7
nice to see a few replies.
 

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It seems "most" racers / tuners think that Rich is the least of the 2 evils, between Rich & Lean. Neither is a good situation, as stated above. I think most err on the side of too Rich, for fear of going Lean. Personally, I am more careful to stay away from Lean, because the damage will generally be worse / more expensive with a Lean condition.

Just my 2 cents.
 

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Troy, to many variables in this situation?

Induction also plays a big part of this equation? I know your using Foxwell SR20 modded heads. I think alot of the guys spraying that much are spreadports, 9-18 deg stuff. The SR20's are fairly new compared to the other heads out there and "could" also be the issues? Chamber work and port work can cause issues as well that can make either the lean/fat condition worst. 2 foggers on a A99 Hemi for example made the nitrous tricky to tune due to the nature of the heads.

Also, if you pushing this thru that single plate can also and not 2 foggers can also be problem? Best to start small and work your way up. I'm sure you have the flow info from Steve. Try chassis dyno it and work your way up to your goal with an eye on the plugs and data logger.

Good luck.
 

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It seems "most" racers / tuners think that Rich is the least of the 2 evils, between Rich & Lean. Neither is a good situation, as stated above. I think most err on the side of too Rich, for fear of going Lean. Personally, I am more careful to stay away from Lean, because the damage will generally be worse / more expensive with a Lean condition.

Just my 2 cents.
Ronnie. We found FAT to be worst with better/faster heads. Lifting ring lands was one of the issues with GOOD heads and FAT nitrous. Recall local car, ran 6.80's with a liberty. IF it was a bit FAT, and mild puff of smoke on 2/3 gear change, lifted ring land. 2 fogger in SM intake, 2 Bob Book carbs 500 inches.

FAST/GOOD heads are 520+ CFM stuff with hi velocity.
 

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Efficient chamber (fast burn) heads will not tolerate timing naturally aspirated and even more sensitive with NOS
 

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Nitrous is an oxidizer......does anyone know the definition of oxidizer?? I think that pretty much sums up 95% of the question assuming the rest of the engine is tuned somewhat correctly, carb/efi.


Can anyone show me pictures of parts of a nitrous engine that has been leaned out?
 

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Made a pass once with the fuel solenoid disconnected, in a rush to make the next round. Car sounded different, but wasn't much off on numbers. Thought it hurt a plug. Plugs looked a touch cleaner but were good. Thats when we found the the plug not connected. 90 pill in a big shot plate. 16* total on a sbc. Hooked it back up and off we went. I'm a firm believer in lean and mean with little timing. No where near the level of spray the OP is suggesting though.
 

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I think a lot of the perceived issues from the tune swinging lean is if the tuneup is on the rich side to start with, and hence heavy on timing to try and clean that rich tune up. The rich tune is letting you get away with the excess timing, and then when it goes leaner with all that timing in it, it'll hurt it. But that's the excessive timing that hurts it; not so much the leaner AFR.

If the tune is fairly clean and not being overtimed to start with; swinging lean will be less likely to hurt it.

JMO.
 

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I started a thread called, (I got lucky last night ) back on page 16 about this subject when i forgot to hook up the fuel line and made a pass which was my best pass ever and didn't hurt a thing , All the replies were very helpful.
 

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Discussion Starter #18
I think a lot of the perceived issues from the tune swinging lean is if the tuneup is on the rich side to start with, and hence heavy on timing to try and clean that rich tune up. The rich tune is letting you get away with the excess timing, and then when it goes leaner with all that timing in it, it'll hurt it. But that's the excessive timing that hurts it; not so much the leaner AFR.

If the tune is fairly clean and not being overtimed to start with; swinging lean will be less likely to hurt it.

JMO.
Exactly 100% what we have learned sir.
 

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I have found if we have an optimal tune and we rich it up by 5 to 10 pph of fuel. It barely if any slows down and is more forgiving to weather swings from early evening to later on. If we are lean as takes to make power and weather swings even if we take out timing it kills ring tension sooner. Again talking high pph and 2 or 3 kits etc.. honestly when using that much nitrous you can hurt stuff anyway. I agree with the low timing and lean tunes, but when we richer up the optimal tunes a bit rings last longer and nothing gets hurt. Mostly on small blocks also.
 

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From my experience too lean will hurt ring lands on problem cylinders much more and will kill ring tension and ring roundness.
 
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