fuel temp

Does anyone monitor methanol temps with a racepak if so do cooler fuel temps make any difference with tune ups or performance?? just straight methanol not talking anything that uses nitro. thanks

 

i know some promod guys a few years ago were chilling the fuel before putting it in the car, they seemed to think it helped, If im not mistaken nhra has made it illegal to do so now so that by itself should tell you somthing

 

Will.. are people chilling in NHRA, and if so how do they avoid the rule ?
I'm guessing you can chill in the pits, but not the staging lanes.

 

fuel

So if you raced where rules were not a big issue colder fuel would mean better performance? NHRA must check temps once in the staging lanes I would assume.

 

in terms of rough magnitude, how much of a performance gain are we talking with say 6F degree methanol versus say 90F degree methanol? Or is it that there is simply more detonation resistance, which then allows a person to push the tune a bit further?

 

I am interested to know the different methods conceived to chill the fuel.

Dave Koehler
http://www.koehlerinjection.com

 

In Europe, more often than not, we'd have to heat the fuel to get it to 50F in the first place

 

Are there any freezing issues with the butterflies with fuel that cold and how much of a performance increase do you think you realized.

 

It definately makes a differance we did these a few years back and i can tell you it made a differance. I am not sure how others do it or have done it but we would keep the fuel in a large cooler. We then had a home made cool can on the car basically we coiled a bunch of aluminum tubing in a 8" diameter aluminum tank with a lid and we would fill it with ice prior to the run. It was probably overkill being we kept fuel on ice but we did moniter fuel temp and it was more consistant with the can because stagging time was always different.

I basically allowed us to push the tune up farther, cylinder pressure or pressure in general is heat. In an internal combustion engine fuel is what cools the cylinder temp so the cooler the fuel the colder the temp allowing you to increase temp back up to regular egts with either more boost/timing compression etc.

We also tried this on a twin turbo water jacketed engine and noticed the engine temp was lower at the end of each run.

 

So what you are saying is that if you put cold fuel into an existing optimized warm fuel tune-up, then no real gain is realized. Take that tune-up and then optimize it for the now cooler fuel, then there is a gain to be had. Have I interpreted your post correctly?

So generally speaking, if a person runs cold fuel and optimizes the tune-up for same, then how much gain could be possible with say blown meth?

Also, wouldn't adding a bit more excess warmer fuel have about the same cooling benefit as chilling all of your main fuel?

 

Cooling Fuel

In 2010 IHRA ProFuel Dragster we had a medical grade freezer to cool the nitro.
I made 4, 5.5 gallon tanks with thermometers in them to monitor the temperature.
We were able to get the nitro to -20 degrees F.
What this did was to close up clearances in the fuel shutoff
(VERY hard to shut off fuel in Salt lake City!)
and close clearances in the fuel pumps.
Fixed the clearance issures so the pumps and shutoffs would work.
Back in the pits after a pass, I would drain the fuel and it was never OVER +40 degrees F.

We were running 100%, and I think that MAYBE with different tuneup,
and running around 95% there COULD have been an advantage.

We never could get the clutch to catch the engine...
I believe we were WAY over on power and could never hook the car up.
Wrong clutch or the way we were engaging it.

We saw NO difference in performance, just a pain in the ass to deal with.
Fuel cans could NOT be handled without gloves, all the jacking around with tanks, etc.

IF you have a very good tuneup and can get the car down the track everytime,
Maybe there would be some advantage, in VERY hot weather.

The ONLY thing that worked out with the freezer deal was we were able to put those
frozen pop tubes in the freezer and they obviously couldn't melt.
VERY nice on a hot day thrashing.
We named them our "Nitro Pops"....

It was NO advantage to THAT particular setup.
Just a pain in the ass........

Your Pal, Gary

 

Cooling Fuel 2.0

The fuel tank and ALL the fuel lines were fully insulated from the tank to almost the pumps.
Industrial grade insulation.
(GENUINE pain to install!)

Your Pal, Gary

 

Thanks Gary, Mike, and others.

So after playing around with Patrick Hale's Nitro Tuner Program, which has a fuel temp input, I come up with MAYBE at best an air charge drop of 4F at the intake valve, when comparing 90F fuel versus 35F fuel (the lowest temp the program will allow). Theoretically that's worth what maybe 0.4%'ish more power out of the engine, if even that? Sounds like a small gain versus the hassle as Gary has alluded to. Maybe there are other benefits though in terms of the overall tune, that aren't being captured here? Can't understand why the rules dudes would even both to regulate fuel temps if the potential gains are so small?

 

TOL - it's not about the air temperature at the intake valve. Chilling the fuel for a blown car is about the air temperature as it enters the rotors. Look at the "Dry Air Flow - PPS" change in Nitro Tuner when you cool the fuel. Here is something I posted a few years back . . .


Chilling the Methanol

My travels this year working with top-tier NHRA Top Alcohol teams showed how critical fuel temperature was for proper jetting of the blown methanol engine. I saw fuel jugs in freezers, recirculating systems in ice chests to cool the fuel already in the tank, insulating blankets wrapped around the body, and fuel temperature sensors hooked into the data recorder and recorded in the logbook.

Chilling the fuel has 2 effects. The first effect is the change in specific gravity (SG). As the fuel is cooled it gets more dense . . . it weighs more per gallon. Here are some examples for methanol.

methanol @ 50 degF: SG = 0.801, 6.68 lbs/gallon
methanol @ 70 degF: SG = 0.790, 6.59 lbs/gallon
methanol @ 90 degF: SG = 0.780, 6.51 lbs/gallon

As you can see the methanol SG/degF effect is small, 20 degF = about 1% SG. The corresponding value for air is only 5 degF. That is, if you cool the air by 5 degF, the air density increases about 1%. And the colder the fuel injected upstream of the blower, the cooler and more dense the air will be as it enters the rotors. So, the effect of cooling the air is much stronger than the simple chilling effect on the fuel SG.

But wait . . . we all have weather stations mounted on our trailers that measure the density of the ambient air. The barometric pressure, temperature and water grains are all recorded in the logbooks. I wrote a 70+ page book about ambient weather correction that describes all the ways to measure the air and also includes the math used for all these calculations, see www.DragRacingPro.com/Books.html. Isn’t that what matters?

No – not for supercharged engines! You need to calculate the weather conditions at the inlet to the blower rotors, downstream of the injector, to determine the air density. The evaporation of methanol can lower the air temperature at the inlet to the rotors by 40 degF below the ambient temperature. If you chill the fuel you can get a 50+ degF drop . . . down to below freezing (32 degF) in some cases. These blower inlet weather conditions are the only ones to use for determining the fuel-air ratio for supercharged engines, not the “Corrected Altitude” or “Relative Density” of the ambient weather. Why?

All superchargers used in Top Alcohol racing (Roots and Lysholm Screw) are positive displacement pumps. For each revolution they “gulp” a certain volume of air. For example, a 14-71 Roots displaces about 551 cubic inches per revolution, and a PSI “D” rotor right at 422 cubic inches per revolution. In order to determine the lbs of air in each “gulp” we need to know the density (lbs/cubic inch) of the volume of air trapped between the rotors and the case. And the density of this blower inlet air is definitely not the same as the ambient air density we measure back in the pits. Remember, for every 5 degF that the air is cooled, the air density goes up 1%. The evaporation of the chilled methanol is central to this process and makes a huge difference!

Patrick Hale
PHale@DragRacingPro.com

 

Some tuners have asked me to explain more clearly about the "huge difference". Let's use NHRA TAD for this example, where the blower overdrive and use of the PSI blower are fixed by the rules.

Case 1: You don't chill the methanol. The air temperature above the rotors is 45 degF (after all, you do get some cooling from the methanol evaporation). You get a 422 CID "gulp" at this air density for every revolution of the blower. That translates into XXXX CFM of air at ambient conditions entering the injector. You add more fuel with the port nozzles and make YYYY HP.

Case 2: You chill the methanol and get the air temperature above the rotors down to 30 degF. The "gulped" air is denser than Case 1 . . . 15 degF cooler means about 3% more air molecules will now fit into the same 422 CID space. This means that XXXX+3% CFM must now enter the injector to fill the space. You will need to add +3% more fuel to keep the same fuel-air ratio and could make YYYY+3% more HP.

Patrick Hale

 

Hey Patrick, thanks for this post as well as the one above. Helps to clear things up a bunch.

This does lead to a few questions though.....

1) There must be a real tug of war going on above the rotors in terms of actually getting the cold meth to vapaorize, and having enough exposure time to do so, and what of the displacement effect of the vaporized methanol inside the hat volume above the rotos? All of this would affect the "gulp" in terms of the actual oxygen content of the gulp, no?

2) Easily 60% of the chilled meth is going into the ports, so that's going to have a big effect on the trapped manifold volume too?

It must be pretty hard to model all of these complex simultaneous processes! Does Nitro Tuner take all of this into account behind the scenes? By the way, I find your Nitro Tuner program to be really neat, and your weather book just arrived here. I haven't cracked open the book just yet, but I will as soon as I get a free minute.

Thanks
(will send you a PM shortly)

 

fuel

Some very interesting information, guess racing's not just a hobby!! Hahaha