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Technical => Spud Miller's Cave => Topic started by: wideopen231 on April 24, 2018, 06:09:17 AM

Title: Engine heat and nitro
Post by: wideopen231 on April 24, 2018, 06:09:17 AM

 Spud,
 
   Reading nitro notes and noticed a lot of things but one raised a question for me. You noted that cold engine and nitro not best combo. Understand rteason just wondering how much heat should engine have before turning on the fun stuff? Also how much quicker would engine build heat than on alky alone. Understand that percentage plays a part here.Any rule of thumb ? While I will be playing with 20 or 25% for while ,I know me and those numbers will change and change.LOL ALready looking at 11.6 gpm pump and few other changes later on.  Man I am going to have trouble with this thing and trying to mainly bracket race it(alky only). Thinking the need to play will win battle here.

On tune up part.I also noticed that low percentage normally required leaning engine. My basic alky tune is 110 to 120 main depending on if using HS or not(.045),7 gpm pump(flowed) and 36 nozzles. I run 30 to 34* mag. How much am I likely to step on it before getting stupid,figuring to start at base and step on it .005 at a step. Based on normal exhaust temp of 1050 to 1100 which is about 90% burn on plug and idea what temps to watch for.

 I know I am worst than 5 yo asking questions.LMAO

Title: Re: Engine heat and nitro
Post by: Spud Miller on April 25, 2018, 06:07:25 PM

 At high percentages and volumes, things can get colder instead of hotter at idle so you need to make some heat first. However, at low percentages, you'll just want to change over right away because it'll behave like it's hot methanol. It'll make heat on 20 or 25% just like running properly adjusted on methanol. At an idle, 350-450F is a good temp to shoot for. Going down the track, 1100 to 1200, same as methanol.

 Yes, at low percentages, properly tuned means a bit leaner due to the AFR and specific gravity changing at different rates.

 .005 per step at that size pill (120) is a great place to be. Richen it a step or two, make a pass or two, observe plugs and temps, lean a step, repeat.

 

Title: Re: Engine heat and nitro
Post by: wideopen231 on April 25, 2018, 06:21:31 PM

Yea I try to work nozzle and jet so I get around 130 to 150 psi(8000 rpm or 4000 pump) and in the 110 to 130 range jet. Changes seem more consistent or predictable IMO.  I have used you tuneup calculator to verify my setup and my home made flow bench,well pump drive with some gauges and fuster cluck of hoses.

 Thanks for info Spud.