Is there an optimum temperature for consistency?

If so, 'splain your theory.

I want to help my car with atmospheric changes just a little bit. It's really good, just need it to get a touch better.

The period approaching and just after dew point temperature is hard on me.

Being that "lean is mean", would I jet down a bit and raise my starting line temperature, to help "dry" the fuel charge?

I stage at 130, have forever, and the car is jetted rich enough that I can pick up or lose .02 with 20 degrees either direction. Colder is faster.

Yes, the power difference between the "mineshaft" air season and the dog days of humidity has always been near .3 between quickest run of the season and slowest. Fat.

I'm thinking of dropping 1 or 2 sizes all around and staging at 150-160

Thoughts?

We stage at 160 on alky and 160-170 on gas.

It's sometimes difficult to build heat on alky in the cooler temps but we always shoot for pretty much as hot as we can easily get it. The gas car gets to 160 quickly then we just use the 2nd fan to keep it from getting any hotter.
Our stuff repeats pretty damn good, I'd like to stage the alky car at 180 but that's too much work.
Without looking at past tickets I'd say .2 or less from best to worst on gas, 1/2 that on alky.

When on gas I staged at 160. That was a temp that was easy to repeat if we started running back to back in late rounds. I really had a hard time keeping it any cooler. I would find a temperature that is easy to maintain and go with that. You may be slower or faster than normal but consistent is what you want. On gas my et swing from summer to fall was never as bad as yours, .15 at worst. I did change the jets two sizes iirc all around. Leaner starting in May thru August.

Yes, your car will run faster in better air, all of ours do. With a carb changing jets between good air and bad air may not be helping anything.
If the carb is right then it should not need a jet change for different weather as the carb by design will flow more fuel into motor as air gets heavier and or moves larger volume of air. Over a certain RPM say 2000 you are riding on the main jets and even at part throttle the carb works good because the boosters only draw as much fuel as the air going into the motor needs. Same with wide open. If the air is heavier and as it moves more air in then it will draw more fuel. Just because car is faster in good air as it should be does not mean that you need more jetting the carb when set up right does it on its own.
Water temp if it is faster at certain temp then it is probably getting peak performance and efficiency and should be more consistent there. Choose a temp that is close to that and that you can easily repeat between rounds.

I personally stage cooler than others on here are saying when on gas. I try for about 140 when bumping into the beams with water pump and fan on

When I ran gas, I got it as cool as I could on water temp, oil temp is more important. On alky, again oil temp is more important, but I try to get it to about 210 or so and let it heat soak, and never make a pass below 180-190 on water temp, as car performs best in that range.

quote:

Originally posted by racerdude2054:
I personally stage cooler than others on here are saying when on gas. I try for about 140 when bumping into the beams with water pump and fan on

This is pretty much exactly what I shoot for. Strangely enough, when it creeps higher than 140 on the starting line, sometimes it picks up, sometimes it slows down. I've never seen a pattern on starting at a higher temp so I just try to keep it the same all the time.

Go Alky its magic

quote:

Originally posted by RacerVX54:
Go Alky its magic

Ran alky for over a decade

On injection it ran best staging at 165ish, it would actually cool off some going down track

Still like gas better

140 but I have a large radiator, 55 gal pump and usually come back to trailer at 160. I always make sure to heat soak everything to keep oil temp as consistent as possible.

The OP wants consistency and should try raising the un-tried operating temps to 160+ and chart the results over different conditions. You can’t have fastest jetting / operating temp and most consistent in same package given the DA imho. Take your pick of either.

My 2850# door car moves .18 from -700 to 4500 DA. It’s predictable. Others could be slightly more consistent given the same DA.

Have you found 160 to be more consistent? I am absolutely open to testing that out.

quote:

Originally posted by markemark:
The OP wants consistency and should try raising the un-tried operating temps to 160+ and chart the results over different conditions. You can’t have fastest jetting / operating temp and most consistent in same package given the DA imho. Take your pick of either.

My 2850# door car moves .18 from -700 to 4500 DA. It’s predictable. Others could be slightly more consistent given the same DA.

That's a nice tight spread, I need to get closer to that, and I'm willing to sacrifice the mineshaft air bonzai ET's a little for it.

I think if the weather station lines up, I'll just raise the temperature to 150 this week, and see what that does.

quote:

Originally posted by BG7X77:
Have you found 160 to be more consistent?

No. When it was MFI I tried 150’s , then 160’s, 170’s, 180’s. At 180’s it was very close or same as 170’s and I went back to 170’s and have stayed there for 10+ yrs. Now it’s EFI, on same fuel, and I have more control of how I want it to run.

I’m a do same thing, expect same results racer. I’m always looking at what can be changed slightly for improvement. Can always go back if it results aren’t improvement, but don’t know unless tried.

I ran my last race of the season Sunday and just switched from a 1435 cfm throttle body to a 1150 cfm and hope to do a T+T before the tracks close here to see the results which I expect/ hope are exact same et as larger TB. Want to use this in 2024 if it works.

When I was running E-85 & VP X85 that fuel liked the starting line temp at 170* for fuel vaporization/consistency. When I switched back to VP C12, I did the same thing & found pretty much the same results.

I've been racing with higher starting line temps ever since. While I may lose a little ET; I don't care, it's bracket racing! I'll take the improved consistency.

I think the higher temps aid in fuel vaporization/distribution in the engine.

2BKING

quote:

Originally posted by Goob:

quote:

Originally posted by markemark:
The OP wants consistency and should try raising the un-tried operating temps to 160+ and chart the results over different conditions. You can’t have fastest jetting / operating temp and most consistent in same package given the DA imho. Take your pick of either.

My 2850# door car moves .18 from -700 to 4500 DA. It’s predictable. Others could be slightly more consistent given the same DA.

That's a nice tight spread, I need to get closer to that, and I'm willing to sacrifice the mineshaft air bonzai ET's a little for it.

I think if the weather station lines up, I'll just raise the temperature to 150 this week, and see what that does.

This was last Sunday, racing eliminations off the trailer, overcast in 50’s, 1300 DA weather, on an Ok track. Good car, crappy old driver.

Started creeping my starting line temperature up this past weekend, and I think I am going to like it.
Didn't get as much data as I wished, the atmosphere stayed pretty stable, and the car was a little quicker than I might have guessed considering the humidity.

What temp are you starting to creep up on?

2BKING

quote:

Originally posted by B KING:
What temp are you starting to creep up on?

2BKING

150

with my Mopar factory big block I would stage @ 160 where possible . Above 180/185 power would drop off definately by 190 .
I now have a World iron saimese block and it is better @ 170/175 stageing but can go 195 hot lapping and does not have power drop off , it almost seeme to buld a little more .

Tex