Curious about what you guys who run alcohol think in regards to how important water temp is to Consistency.Is 20 degrees + or - a big deal from run to run

For my MFI water temp is very important along with oil temp. Mine likes 170 – 175*. Leave at 160 and I can lose 1 or 2 numbers. This will easily take 50 rpm out of my stall rpm when measured at 0.65 after launch.

This is why I like Primer Plus with my MFI. I can quickly achieve and maintain 175* in the lanes and prior to entering the water box. When I switch to the MFI prior to entering the box, it’ll maintain 170 steady because the Barrel Valve is adjusted to run the engine with the fan off at this temp.

I ran a Rons system for 5 years in both a door car and dragster with a 565, I always tried to pull into the water at 160 to be consistent

I’m still learning but here’s what I think I know about MFI. The car will continue to get faster the hotter I stage it. At least up to 180.

Staging at 160 vs 180 caused the car to slow .03+ Last time out.

I have heard this behavior attributed to an overly fat tuneup. But The tuneup was pretty close for the conditions. I think if I had increased the main by about .003 (leaner), the car would have slowed down.

That is normal BJ, you just learned the hard way. I won't do my burnout or go to the ready line until i am at temp.

Everything counts here but oil tmep is also important, you can leave at say 140 with 100 degrees of oil temp and also 140 with 160 oil and will get two different results!

In general, the colder the water and hotter the oil, equals more HP all else equal.

quote:

Originally posted by markemark:
For my MFI water temp is very important along with oil temp. Mine likes 170 – 175*. Leave at 160 and I can lose 1 or 2 numbers. This will easily take 50 rpm out of my stall rpm when measured at 0.65 after launch.

.

Trans oil temp is another variable,, hotter usually means faster t brake release time, higher stall rpm and slower ET all else equal.

Gday
Same for me, stage at 180, try to have engine oil temp at least 160 before i get out of the staging lanes, trans temp has caught me out when doing back to back runs almost.
8 minutes between rounds at the good end of eliminations , engine oil and water pretty much tbe same, trans hotter, car will run a couple of numbers quicker.
Cheers

I have seen a .01 change for every 10* temp. Hotter will be faster because the hotter the combustion chamber is the more fuel it will want. Add it how much alky being cool will expand with extra heat.

As stated all things change motor and trans with heat.Would not be surprised if rear gear oil temp has effect. So who has tracked it and will tell?

For the first warm up of the day get it up to 180+ then let it sit for a good heat soaking. Then for the rest of the say make sure you enter the burnout at around 160. But anything between 150 and 180 should run about the same assuming the engine was heat soaked well to begin the day.

As others have stated oil temp plays a big roll. If you like to run the thick stuff (20w50 for example) then the warm up and heat soak procedure is more important.

As stated trans temp can play a roll but I feel only if it's cold. Driving around the pits doesn't warm up a trans sufficiently. Do things like brake tourque it in high gear up to say 3000 and hold it there for 10 seconds. That will warm one up.

I haven't found the rear diff fluid temp to play much of roll unless a person is using the super thick molassis like stuff. In drag racing we don't go long enough to get the rear end hot anyway.

Scott

Gasoline is more volatile than methanol, for this reason you wanna keep the intake cool on gas. Mixture with methanol is managing the amount fuel not evaporated in the manifold a to b according to observed consistency on the timeslips. When you talk engine temp, trans temp, fuel temp, think in terms of Intake manifold temp if you're talking consistency. Manifold temp is a part of the tuneup. A warm manifold is a good performing manifold on methanol. Keep the hood on it.

This message has been edited. Last edited by: Mike Rietow,

Setting the leanout every time we start the car to build heat is mildly annoying but the only way to get up to temp before a pass unless we are in a round robin. Driving around on high idle also bugs me a little (although it does sound cool with the stacks and zoomies)

I was thinking about adding an electric leanout solenoid and turning on a step retard at the same time. Anybody done something like that and have any tips?

I was also thinking about building a little external primer system for first start on a cold day. Cap the return and hook up an external pump gas tank/pump with a needle valve on it. I’m concerned though that I could still contaminate the fuel cell through the mechanical pump. With the stacks I don’t think there’s a good way to be able to run a primer all the time.

quote:

Originally posted by Mike Rietow:
Gasoline is more volatile than methanol, for this reason you wanna keep the intake cool on gas. Mixture with methanol is managing the amount fuel not evaporated in the manifold a to b according to observed consistency on the timeslips. When you talk engine temp, trans temp, fuel temp, think in terms of Intake manifold temp if you're talking consistency. Manifold temp is a part of the tuneup. A warm manifold is a good performing manifold on methanol. Keep the hood on it.

It's funny you post this about intake manifold temperature and alcohol. Recently at the division 1 bracket finals they hot lapped us pretty quickly the last three rounds. I was able to manage water and trans temp reasonably well but in the final round the car had a horrible stumble coming off the enhancer going to the chip. Being that methanol boils/evaporates at 148.5° I was leaning towards the intake temperature being hotter than I'd ever seen and the cause of my stumble.

I've never seen one that won't stumble with the leanout open, that will stumble at any rate of emulsion.

Something that may work for you as well.

So many variables from engine to engine, different fuels, and different ambient temps will all have an impact. With methanol you have to have sufficient BTU available to vaporize enough fuel early, but not too much. Best idea is to run a test session, get the car warm to start then try a variety of temps. Methanol may want anywhere from 130 to 170 leaving the lanes, once you figure what your combination wants realize that cooler weather you have to adjust the engine temp 5 to 10 degrees up to compensate as ambient temp plays into vaporization. My suggestion is to keep your temp leaving the staging lanes consistent, within 5 degrees.

quote:

Originally posted by ActionRacingPhotos:

quote:

Originally posted by Mike Rietow:
Gasoline is more volatile than methanol, for this reason you wanna keep the intake cool on gas. Mixture with methanol is managing the amount fuel not evaporated in the manifold a to b according to observed consistency on the timeslips. When you talk engine temp, trans temp, fuel temp, think in terms of Intake manifold temp if you're talking consistency. Manifold temp is a part of the tuneup. A warm manifold is a good performing manifold on methanol. Keep the hood on it.

It's funny you post this about intake manifold temperature and alcohol. Recently at the division 1 bracket finals they hot lapped us pretty quickly the last three rounds. I was able to manage water and trans temp reasonably well but in the final round the car had a horrible stumble coming off the enhancer going to the chip. Being that methanol boils/evaporates at 148.5° I was leaning towards the intake temperature being hotter than I'd ever seen and the cause of my stumble.

Dennis
I would say you are on the wrong track here. A warmer intake would aid fuel atomization. Your stumble , which was likely caused by a lean condition, was caused by something else. I have seen many combo's that are normally fine but get caught at the line with too cold motors and they stumble bad! This is usually compounded with cooler or cold air temps which were likely the cause of the cold motor to start with.

Without more info it's a crap shoot but I'd check to make sure your fuel lines aren't picking up heat from the motor which could get the fuel to hot and then it would likely boil once it get to the fuel bowls on the carb. Also where is your fuel tank, near the rad? another source of heat.

Dragsters usually don't have heat soak issues also.

quote:

Originally posted by TOP38:
Dennis
I would say you are on the wrong track here. A warmer intake would aid fuel atomization. Your stumble , which was likely caused by a lean condition, was caused by something else. I have seen many combo's that are normally fine but get caught at the line with too cold motors and they stumble bad! This is usually compounded with cooler or cold air temps which were likely the cause of the cold motor to start with.

Without more info it's a crap shoot but I'd check to make sure your fuel lines aren't picking up heat from the motor which could get the fuel to hot and then it would likely boil once it get to the fuel bowls on the carb. Also where is your fuel tank, near the rad? another source of heat.

Dragsters usually don't have heat soak issues also.

Motor definitely wasn't cold and had no issues down into the 40s at the same race. Really sucked having it show up in the final round.

Heating the fuel could be a possibility. Fuel tank is behind the seat and my fuel filter sits directly below the radiator.

quote:

Originally posted by ActionRacingPhotos:

quote:

Originally posted by TOP38:
Dennis
I would say you are on the wrong track here. A warmer intake would aid fuel atomization. Your stumble , which was likely caused by a lean condition, was caused by something else. I have seen many combo's that are normally fine but get caught at the line with too cold motors and they stumble bad! This is usually compounded with cooler or cold air temps which were likely the cause of the cold motor to start with.

Without more info it's a crap shoot but I'd check to make sure your fuel lines aren't picking up heat from the motor which could get the fuel to hot and then it would likely boil once it get to the fuel bowls on the carb. Also where is your fuel tank, near the rad? another source of heat.

Dragsters usually don't have heat soak issues also.

Motor definitely wasn't cold and had no issues down into the 40s at the same race. Really sucked having it show up in the final round.

Heating the fuel could be a possibility. Fuel tank is behind the seat and my fuel filter sits directly below the radiator.

Colder air can cause this alone if your a tad lean, normal summer temp's are fine but it can come up in the early spring and fall when you race in the colder temps. A cold motor just makes it worse.

If you did your burnout with no issues when you stabbed the throttle, no bog or stumble, it isn't normal for it to do it on the run but you may want to check the rate of your enhancer, some of those suckers can really pop the carb to WOT fast which will make matters worse.

I would guess that any hot fuel from heat soak would/should have been eliminated in your fuel system by the time you staged, especially with no burnout issues! I'd go over the fuel system and filter. If you find any UFO's in the carb, that could also be the cause.

quote:

Originally posted by ActionRacingPhotos:
Being that methanol boils/evaporates at 148.5° I was leaning towards the intake temperature being hotter than I'd ever seen and the cause of my stumble.

The air temp in my manifold is close to 300* at 1/4 mile finish line when I have the Procharger spinning to make 22 lbs of boost. 270* at lower boost numbers. This is before the EFI injectors.

Just food for thought in this discussion - obviously way different combo.

quote:

Originally posted by ActionRacingPhotos:


Motor definitely wasn't cold and had no issues down into the 40s at the same race. Really sucked having it show up in the final round.

Heating the fuel could be a possibility. Fuel tank is behind the seat and my fuel filter sits directly below the radiator.

I've had that happen a time or two and Al's right, it was after a nighttime temp drop with much cooler/denser air and in my case would create a leaner barrel valve mixture, my solution was to forget about the old "I hardly use any fuel when I set my barrel valve real lean" statement and make sure my BV was biased rich (or with a carb turning the idle mixture screws out a tad more) about 1 degree of increased engine temp with car in gear about every 30-45 seconds with fan off, raise the staged "on the enhancer" rpm to 2200 (I'd bump it on before staging and work the throttle to get in and mat it after I let go) and extend the TB/Enhancer release time to 1.1 second (which makes sure the converter reaches the same stall every time) instead of the programmed .8 (timer will say 11.11) that Digital Delay boxes come with.