Drag

I was watching NASCAR Daytona qualifying today. They were talking about getting every possible drop of speed out of the cars. They were talking about reducing the size of the hood pin cables and other minor details. The even make a recess for the cable to slide into. The run lighter weigh oils and turn he oil pressure way down to keep oil splash down inside the motor. The pull the brake pads off the rotors with springs. They also mentioned getting the car as polished and smooth as possible. That seems to be very logical. BUT,

Isnt it true that if the surface is very smooth the air with actually seperate from the surface at r near the high points? I have heard that a very fine saitn finish makes for better boundry layer attachment across the entire surface. The reason I think it would be better to have the air attached all the way across the car is it would help the wings at the back of the car be more efficiant. I think it would be helpful to have the air attached to the car all way around the body. I haveeven heard that if you have the air on the surface it can give a little "push" as you go through....

I know they spend time in the wind tunnels but I was just wondering what your thoughts on it are....

Am I crazy??

Don't know about that, but if you want to see some REALLY fast cars, tune-in to ESPN-2 today, Feb. 11th: 8 pm Eastern, 7 pm Central, 6 pm Mountain and 5 pm Pacific, for Final Eliminations from the NHRA Winternationals in Pomona. John Force's daughter, Ashley, qualified in Funny Car yesterday at 4.79 seconds. Tony Schumacher led Top Fuel with a 4.47. This is gonna be a good one!

Mike Keville

Doug,

I think you have answered your own question in acknowledging the fact that these teams have access to wind tunnels.

Can we not assume that the data gained from wind tunnel testing is telling them what to do at the track?

It is my understanding that the Toyota F1 team has *two* wind tunnels at its disposal and that both are in operation nearly 24 hours a day. Yes, I know that a lot of their testing involves little doo-dads up here which direct the air just so back there, but all the F1 cars are nicely polished; it is hard to imagine that any advantages to surfaces which are less than slick and polished have escaped the collective notice of these folk.

Dan

>Doug,
>
>I think you have answered your own question in acknowledging
>the fact that these teams have access to wind tunnels.
>
>Can we not assume that the data gained from wind tunnel
>testing is telling them what to do at the track?
>
>It is my understanding that the Toyota F1 team has *two* wind
>tunnels at its disposal and that both are in operation nearly
>24 hours a day. Yes, I know that a lot of their testing
>involves little doo-dads up here which direct the air just so
>back there, but all the F1 cars are nicely polished; it is
>hard to imagine that any advantages to surfaces which are less
>than slick and polished have escaped the collective notice of
>these folk.
>
>Dan
>

I never said it did. I was just looking for some conversation on the subject.

Replies below lead to some of what I was talking about.

I saw that stuff yesterday. AWESOME!!

It just seems if the air was attached all way around it would "punch" through the air easier and make itself "smaller" while doing so.

Think of air flying off teh car all over the place in all different directions causing turbulance all around it. Or think of it smoothly slipping through. But somewhere I read the satin finish helps keep the air on the object all the way around. Less turbulance around the object.

Doug,
When I was invloved in Nascar racing 1963-64. Columbus GA. We use to rub the car with talcum powder before the qualifing run. No kidding. I did not know if this helped but it helped your brain drive faster.

I don't know, but I've seen the CEO of Ford running a wind tunnel test.

Howard Rush

The issue they are addressing is boundary layer seperation. In any fluid the layer of fluid molecules directly against any surface does not move as the surface moves thru the fluid. This is the boundary layer. It drags the surrounding fluid it is moving in along with it. The adjacent layers of molecules next to the boundary layer will at some point along a surface not be drwawn perfectly with the boundary layer and will seperate from it. This is termed boundary layer seperation. There is drag associated with this phenomena and eddies will form when the molecules seperate from the boundary layer. The eddies get larger as they progress along the object until all the layers are seperated except the boundary molecules themselves. Decreasing the drag from boundary layer seperation is a big deal drag wise at all velocities.

As a rule, the further back along the surface boundary layer seperation can be induced to occur the less drag there will be because the eddies once they form just increase in size and crate more drag.

Some areas of research have involved changing the shapes of surfaces to delay this, especially when lift is involved this can be very critical. Some airfoils are actually designed to work with very delayed seperation and if seperation occurs too far forward they loose lift dramatically. These are called laminar flow airfoils.

Very very smooth surfaces can delay or in some cases prevent laminar flow seperation from occuring. This is the avenue that the NASCAR vehicles are following. Also though there will be a rule in the rule book that prohibits the other solution so they are relegated to makeing the surface as smooth as possible.

The other solution to the problem is to actually place something in the fluid flow ahead of where seperation will occur that causes seperation to occur but in very small controlled eddies. These smaller eddies than the big ones that occur when natural boundary layer seperation occurs are able to then to dissipate and reattach flow to the surface. This decreases turbulance overall, decreases drag overall, and increases lift on the surface if it is an airfoil. They are usually call vortex stimulators. You will see them on wings of many jet and now many private aircraft designs. They look like little triangles or trapezoids projecting up 90 degrees to the wing surface. They are very effective.

There are more effective things as well. The most famous one was developed by 3M for the America's cup back in 1987 when Dennis Connors went down to Austraila and won the cup back the first time. His boat was hugely faster than anything else. So much so that they had metal pipes they would push out thru the side of the hull during preliminary seires of racing to keep people from realizing how fast the boat was. These were called ribblets. They were a plastic coating that was placed on the outer surface of the hull. Under a microscope they appear as little v'd chevrons at angles to the flow of water around the hull... v's forward. They caused local eddy stimulation and delayed boundary layer seperation way back on the hull. The material was made illegal in all subsequent yacht racing after that series. I am sure NASCAR and all auto racing bodies have made them illegal also. Poor man's ribblets is to wetsand the surface to about 600 grit. It delays boundary layer seperation by a good bit on a racing sailboat. It is so important most olympic level sailors wetsand before launch at every race.

Sailplanes have proved laminar flow wings work well and can be created on airfoils. An issue is bugs. Bug's smashed on the leading edge screw it all up. A number of Burt Rutan's designs were lost to this issue in the homebuilt aircraft scene back in the early days of composite homebuilt construction. One of the reasons Burt no longer licenses anyone to build ony of his designs.

Probably more than anyone wanted to know. Sorry. Spent too many years dealing with it. Tried to forget. That's what you get for rewaking me.

Bob Branch

Hi Bob; I thought you explained it very well. Airfoils can be very interesting to talk about, especially the different kinds required for the different events. Most guys are only familiar with C/L stunt airfoils, and if you look at them over the years, it's interesting to note the changes in thicknes, location of the high point, shape of the leading edge, and in recent discussions here on SSW the shape of the trailing edge, as in sharp or square, and it's relation to drag.
I guess the first real use of the laminar flow airfoil was in the P-51 Mustang wing. Some people are real surprised at it's overall shape, as apposed to what the "stereotype" airfoil looks like. And some are surprised to find that the top of the wing is filled and painted, even on natural finished or polished airframes. Full scale high performance sailplane airfoils have that odd look that gets people scratching their heads also.
Free flight models is where airfoils really run the wide gammet of shapes, depending on the event and speed of the model. On the slower speed events you see the use of turbulators a lot. I remember reading an article by Dave Thornburg, I think, where he believes that the best airfoil that you could have is just 10% better than than what you could draw around the outside of your shoe. I've built some P-30 rubber models with what was refered to as "Addidas" type airfoils, and was amazed at he performance they had,
NASCAR stock car design, to me, take all of the known principals and combine them into a whole seperate science. The cars have to be fast to be competitive, but they also NEED to be stable, so they can be controled and driven and keep the rubber on the tires as long as possible. A lot of people don't see the attraction to this type of racing, but if you can getthem to really watch it, and see what the cars are doing as they go "roundy round", they can sometimes develope an appreciation for it. I was watching the Bud Pole race yesterday evening, it was interesting to watch the cars getting buffeted around by the turbulance created by the pack, but the down force crated by the airdamns and spoilers also help stabilize the car and keep it controlable. Several times, cars "got loose" for one reason or another, but the drivers were able to regain control as long as they were able to get the nose of the car pointed in the right direction! That's where the drivers talent comes in!
Dan McEntee

Jim Marske told me that he believes that wet sanding the wings of his Genesis II sailplane would have improved its performance in its first and most successful appearance at the U.S. Nationals. He regrets that the team undid his efforts and flew with polished wings.

Bob,

Awesome! Good stuff.

Ted Fancher

>I was watching NASCAR Daytona qualifying today. They were
>talking about getting every possible drop of speed out of the
>cars. They were talking about reducing the size of the hood
>pin cables and other minor details. The even make a recess
>for the cable to slide into. The run lighter weigh oils and
>turn he oil pressure way down to keep oil splash down inside
>the motor. The pull the brake pads off the rotors with
>springs. They also mentioned getting the car as polished and
>smooth as possible. That seems to be very logical. BUT,
>
>Isnt it true that if the surface is very smooth the air with
>actually seperate from the surface at r near the high points?
>I have heard that a very fine saitn finish makes for better
>boundry layer attachment across the entire surface. The
>reason I think it would be better to have the air attached all
>the way across the car is it would help the wings at the back
>of the car be more efficiant. I think it would be helpful to
>have the air attached to the car all way around the body. I
>haveeven heard that if you have the air on the surface it can
>give a little "push" as you go through....
>
>I know they spend time in the wind tunnels but I was just
>wondering what your thoughts on it are....
>
>Am I crazy??


The do so much wind tunnel testing and aerodynamic reasearch that a F1 car at top speed would run on the celing if you could get it up there. Slick is better in this case. One of thew time you need rough is in an intake port to help atomize the fuel.

>
>The do so much wind tunnel testing and aerodynamic reasearch
>that a F1 car at top speed would run on the celing if you
>could get it up there. Slick is better in this case. One of
>thew time you need rough is in an intake port to help atomize
>the fuel.


Actually, not to nit pick, but an F1 car will drive upside down at about 100MPH.

>
>>
>>The do so much wind tunnel testing and aerodynamic
>reasearch
>>that a F1 car at top speed would run on the celing if you
>>could get it up there. Slick is better in this case. One
>of
>>thew time you need rough is in an intake port to help
>atomize
>>the fuel.
>
>
>Actually, not to nit pick, but an F1 car will drive upside
>down at about 100MPH.

I saw that show somewhere. That is an absolutely awesome display of physics.

what is interesting about it (makes lots of sense for cornering, etc.) is that the download running right side up at speed has to have a significant effect on rolling resistance (tires to the ground).

I'll bet these guys have done a "positive/negative" assessment and found just the ideal median.

Ted

p.s. based on that download, I have to wonder how much faster these things would go inverted (with gravity reducing load on the tires).

>
>>
>>The do so much wind tunnel testing and aerodynamic
>reasearch
>>that a F1 car at top speed would run on the celing if you
>>could get it up there. Slick is better in this case. One
>of
>>thew time you need rough is in an intake port to help
>atomize
>>the fuel.
>
>
>Actually, not to nit pick, but an F1 car will drive upside
>down at about 100MPH.

I saw that show somewhere. That is an absolutely awesome display of physics.

what is interesting about it (makes lots of sense for cornering, etc.) is that the download running right side up at speed has to have a significant effect on rolling resistance (tires to the ground).

I'll bet these guys have done a "positive/negative" assessment and found just the ideal median.

Ted

I have read some about the aerodynamic forces in play on the F-1 body. I saw a very cool artile in F-1 Magazine that had the body in a tunnel test and heat sensor picture. The area around the helmet is blue meaning negative pressure. The helmet is actually lifting during driving. The neck of a long time F-1 driver is actaully longer than when he started. This is no joke. Also by having a negative area right around the pilot it can have less force on the pilots head. I dont think that is the intention but a result none the less. The F-1 car is truly and amazing peice of machinery.

Did you know they run 13" wheels. That is right. Same size rim, diameter that is, thot comes on your mid 80s Toyota Corrolla, or Corona if you opted for the stripped down 4 speed version with leather door straps for handles. The only way to slow the cars at one point was to take away their slicks require a max wheel diamter.

Ted mentioned cornering. Jeff Gordon spent some time in Montoya's car at Indy. In the 24 Dupont Chevy jeff needs to brake from full speed at about 250-300 meters from the long straight into to turn one. The F-1 car can wait to brake at 50 meters to make the same turn. The drag around those cars is a serious brake as well. Lifting from the pedal and the brakes are on before you ever touch the actaul brake pedal.

The cars are simply amazing. The drivers arent to shabby themselves.

Jeff Gordon spent some time in
>Montoya's car at Indy. In the 24 Dupont Chevy jeff needs to
>brake from full speed at about 250-300 meters from the long
>straight into to turn one. The F-1 car can wait to brake at
>50 meters to make the same turn. The drag around those cars
>is a serious brake as well. Lifting from the pedal and the
>brakes are on before you ever touch the actaul brake pedal.
>
This is the first of heard about F1 and NASCAR using brakes at Indy.

From watching the CART/USAC/IRL races there, I was under the impression that the big cars didn't use brakes at all. They have enough downforce from all the airoils to just power around the track like a Control Line Racer. They lose a few MPH on turns, but only due to G forces and tire scrub, not coming off the gas or (Heaven forbid) braking.

I can understand why the weight of NASCAR and the extreme HP of F1 might bring brakes into game.

>
> Jeff Gordon spent some time in
>>Montoya's car at Indy. In the 24 Dupont Chevy jeff needs
>to
>>brake from full speed at about 250-300 meters from the
>long
>>straight into to turn one. The F-1 car can wait to brake
>at
>>50 meters to make the same turn. The drag around those
>cars
>>is a serious brake as well. Lifting from the pedal and
>the
>>brakes are on before you ever touch the actaul brake
>pedal.
>>
>This is the first of heard about F1 and NASCAR using brakes at
>Indy.
>
>From watching the CART/USAC/IRL races there, I was under the
>impression that the big cars didn't use brakes at all. They
>have enough downforce from all the airoils to just power
>around the track like a Control Line Racer. They lose a few
>MPH on turns, but only due to G forces and tire scrub, not
>coming off the gas or (Heaven forbid) braking.
>
>I can understand why the weight of NASCAR and the extreme HP
>of F1 might bring brakes into game.

Did you also know that there is a road course layout within the oval track and a portion of the oval is used?

Sure, they put that in for F1.

Golf Course, too.
Although it may have fallen victim to the road course and more seating.

Yes and Jeff drove the F1 dar on the F1 track at Indy which uses the road course mainly and part of the main striaght away and turn 4. Juan drove Jeff's 24 car on the same F1 track as well.

>I'll bet these guys have done a "positive/negative"
>assessment and found just the ideal median.

Yes they have, and it's always a balance between increasing down force which improves cornering speed and decreasing down force which improves straing line speed (due to the lower rolling resistance). The track layout, tire compounds, power available (etc) determine how much down force to run to minimize the lap times. This is true in both F1 and Nascar (although in Nascar it is less pronounced). Not unlike our competition models on cold days versus hot humid days. What is the correct control response, ratio, balance point, and power level for each. Each condition is different. A lot of the time, the pilots adjust to the differences seen by the plane as opposed to adjusting the plane in the conditions to the pilot. Which one is better???? I've done both in the past, and I would prefer to adjust the plane to the conditions given enough time.

As always, everything in model planes and auto racing is a compromise!

Lots of great replies here, doug.
I only know what i have been told and read, the two things i know of that parallel what you are saying is that F1 racing airplanes are often wet sanded and run that way in the race, and so are the propellers. Second, is that I read about Airbus using a machined skin with certain shaped scratches in the surface for drag reduction.
These sound like things that do actually work, but are hard to maintain after a couple of bugs or a dent get in the mix on the cars. So maybe the waxed surface is the next best thing and known to work up to a high percentage of the other technique's value in real world operation. Otherwise they'd all be color sanded satin black, right?!
Chris...

GM built a big wind tunnel here. The first and best true-automotive wind tunnel. The instruments are setup purposely for cars.

All the GM NASCAR teams come here to dial in their cars. They say that an 8-hour shift in the tunnel is better (and infinately cheaper) than a month at a test track. They have to pay GM for tunnel time in the middle of the night. Within a few months, the GM-UAW operators knew everything their is to know about dialing in race cars.

The cars sits on four different load cells, one for each wheel, that measure both weight and side forces.

I had a chance to look at a YF-17 and a Ukrainian Mig-29 side by side a few years back at the Hawthorne air fair. The leading edges on the Mig were nice and smooth, with good sheet metal work. The rest of the sheet metal looked like farmers used large hammers to make everything fit. Not pretty. The YF-17 was smooth everywhere. The bottom line seemed to be that once the airflow had started to separate, it didn't make much difference in performance. Note that the US military flies planes with both the low visiblity finish (matt surface) and highly polished. Has anyone heard of any performance difference? And then there was the British experiment on the Spitfire with split peas simulating protruding head rivets....

With stunt planes, I'd bet there is more effect from exposed spars on unsheeted wings (Twister) or possibly uneven paint trim lines near the leading edge. Not because we run out of power, but because the lift characteristics are affected.

Dave Hull
LA_Flyer

I'd bet that, too.

Howard Rush

Just as a side note, On the Nextel cup cars specific to Daytona, If you watch the cars run you will see that the nose is not drooped as on some other tracks. The intent of this is to get the nose up and block the air from hitting the rear deck spoiler. By doing this they reduce drag and depend upon other aero and suspension alterations to stabilize the car.

>Just as a side note, On the Nextel cup cars specific to
>Daytona, If you watch the cars run you will see that the nose
>is not drooped as on some other tracks. The intent of this is
>to get the nose up and block the air from hitting the rear
>deck spoiler. By doing this they reduce drag and depend upon
>other aero and suspension alterations to stabilize the car.

For qualifying, yes. For the race they will be a lot more conventional, by the end.

Brett

Are these the new design NASCAR car? or real race cars.
The new NASCAR design is designed to be slower, more controllable for three wide racing, and easier to change things so they can keep the speed under control. Plus it is supposed to be a lot safer for the driver in a crash.

Interesting discussion. The talk about sanding before races brings this to mind:

When I started at McDonnell in St Louis, we were making an unbelievable number of F4s for Nam. The talk at that time was that one of the experimental F4s was fixed up with thousands of added rivet heads glued to the mold line (surface). It actually flew faster!

Of, course in aircraft production we are very attentative to "Zone 1" aerodynamics, mostly (but not exclusively) defined as leading edge surfaces, for a predetermined distance aft. Allowable height of flush rivet heads and steps and gaps of panels and doors are held to rigid limits depending on which zone they are in. In many cases "Zone 1" flush rivet heads are installed slightly high and then shaved to get the best possible flushness.

We did our best to make the rivets and panels "disappear". (This is why I have always scoffed at "Jet Styled" stunters with all those painted lines and rivets.) But sometimes you have to join the club to get the points.

Applied to stunt wings, bumps, spars, paint ridges,etc., would probably have more affect in areas forward of the airfoil high point. This sort of makes the beautiful "I-beamers" questionable??!!

Now how do they fly so well? I have also seen the planes with the sheeted beautiful surfaces and the I-Beamers. Which is best. I have heard talk of changing the VSC to the Billy Wewage get together because he has won it so many times with his I-Beamers.
DOC Holliday

Tom,

Interesting about the F4s! Thanks.

Most I-Beamers I've seen have slightly sagging covering between the ribs, sure, but very little disturbing 'edges' spanwise. The ribs are chordwise, no? The only 'steps' to the airfoil may be the rear edge of the LE piece, and any paint trim edges. Most of the top fliers make sure there is little to no raised edge on the trim lines...

No surface spars. The boundary layer depth is likely deep enough, by the time the flow reaches the TE piece, that any step there is much less significant. Flap movement, sealed hingelines, Billy W's convex flap sections are all serious, but necessary, from the hingeline aft, of course, but the major lifting surface should be pretty clean chordwise.

My thoughts, FWIW, on the I beam wings its possible that the rib contours act as a stall fence to reduce the spanwise flow of air across the wing, which in my limited knowledge would possibly reduce the drag resulting from vortices ?
For some time in the late 90s I was workin go nncrop dusters, and one of the technologies being explored, hm actualy in retrospect it was mostly for homebuilt and light planes, was an STC for props wherein they added a series of dimples to the prop, just aft of the leading edge. My understanding was that it added energy to the boundry layer when the prop was pulling hard, supposedly from what I remember it shortened take off runs and increased rate of climb rather significantly.
We also installed Vortex Generaters on all of our aircraft. small aluminum extrusions in the shape of a "T" that were about 18 " back fron the leading edge in a herringbone pattern a few inches apart. Same theory, excited the airflow at the boundry layer maintaining lift to higher angles of attack.

I am ashamed to admit that I added an obscene amount of drag to the F4E. It wasn't all my fault, though.

Howard Rush

Speeds in the corners are important too!
I believe drag figures in this to, as in corner sideslip.
The straightaway ain,t the only place to get an edge

Right! There are four corners and only two straightaways, handling is very critical!!

Don

I guess you can just run illegal fuel as well. It sounds like Mikey Waltrip got busted with this today. Schumacher's team got busted with some sort of illegal fuel as well, back when he was running with Benneton.
Steve

>I guess you can just run illegal fuel as well. It sounds
>like Mikey Waltrip got busted with this today.

Oops! An inauspicious start to Toyota in Nextel Cup...

Brett

I'm trying to picture the Dukes of Hazard- General Grant was an orange Camry, right?
The image if Daisey is a little more clear.
Derek

>I guess you can just run illegal fuel as well. It sounds
>like Mikey Waltrip got busted with this today.

Sterno, reportedly, although I find it hard to see how that would help.

Brett

>>I guess you can just run illegal fuel as well. It
>sounds
>>like Mikey Waltrip got busted with this today.
>
> Sterno, reportedly, although I find it hard to see how that
>would help.
>
> Brett


People have tried running alcohols and ethers to try to introduce extra oxygen now and then on restrictor plate engines, presumably you can jet it excessively rich and hope the oxygenates give you enough extra burn for some detectable power increase. Smearing the manifold with sterno must be done in the hope the fuel mist would wash the sterno down into the motor on the qualifying lap, but it certainly sounds like a desperate maneuver, and obviously the sterno didn't wash down into the motor if it was detected after the lap.
I've seen reports today that it was a jet fuel additive, but I don't know what additive is in jet fuel apart from the stuff designed to prevent coking on burner cans and afterburner rings, which would be no help whatsoever to race motor. It will be nice if NASCAR reports on exactly what it was and how it was supposed to work.

Steve

I heard today that the additive costs $600 smackers per gallon. It left a purple residue in the fuel line. They said it was supposed to add pwer while great increasing mileage. Therefore they can carry less fuel on the qual lap and the car would be lighter... I am not sure how true this is but speed channel was reporting it. Sad thing is Waltrip was running really good in the 125s. No reason to cheat. Another thing I found interesting this weekend was how at the interview before the qual laps the drivers would talk about how their Crew Cheif was going shave off .2 or .3 of a second. They were real relaxed about saying it as well. Idiots I tell you, Idiots. They are sending out the red flags for NASCAR to pay extra special attention to those cars. Borris was mid pack in practice and at his pre qual lap interview was very humble and just wanted to make it in, he ended up 5th I think. Wasnt suspended for cheating either.

>I heard today that the additive costs $600 smackers per
>gallon. It left a purple residue in the fuel line. They said
>it was supposed to add pwer while great increasing mileage.
>Therefore they can carry less fuel on the qual lap and the car
>would be lighter... I am not sure how true this is but speed
>channel was reporting it. Sad thing is Waltrip was running
>really good in the 125s. No reason to cheat. Another thing I
>found interesting this weekend was how at the interview before
>the qual laps the drivers would talk about how their Crew
>Cheif was going shave off .2 or .3 of a second. They were
>real relaxed about saying it as well. Idiots I tell you,
>Idiots. They are sending out the red flags for NASCAR to pay
>extra special attention to those cars. Borris was mid pack in
>practice and at his pre qual lap interview was very humble and
>just wanted to make it in, he ended up 5th I think. Wasnt
>suspended for cheating either.


Purple residue??? Maybe they got their hands on some of Randy's Aero-1 additive and tried to run it [photo not recovered: devil.gif]

>>>I guess you can just run illegal fuel as well. It
>>sounds
>>>like Mikey Waltrip got busted with this today.
>>
>> Sterno, reportedly, although I find it hard to see how
>that
>>would help.
>>
>> Brett
>
>
>People have tried running alcohols and ethers to try to
>introduce extra oxygen now and then on restrictor plate
>engines, presumably you can jet it excessively rich and hope
>the oxygenates give you enough extra burn for some detectable
>power increase. Smearing the manifold with sterno must be
>done in the hope the fuel mist would wash the sterno down into
>the motor on the qualifying lap, but it certainly sounds like
>a desperate maneuver, and obviously the sterno didn't wash
>down into the motor if it was detected after the lap.
> I've seen reports today that it was a jet fuel additive, but
>I don't know what additive is in jet fuel apart from the stuff
>designed to prevent coking on burner cans and afterburner
>rings, which would be no help whatsoever to race motor. It
>will be nice if NASCAR reports on exactly what it was and how
>it was supposed to work.
>
>Steve

My guess is that the application of Sterno to the exterior of the manifold will cool the manifold by evaporation thus increasing the charge density as it is pulled through the manifold. Sounds like it didn't evaporate completely. It's a perfect material for that application being a jellied alcohol. It clings and the evaporation rate is slowed.

Most of us old 60's drag racers will remember packing the intake with ice prior to a run looking for that elusive tenth of a second. Even tried running the fuel line through an ice container... not really sure that little trick was an advantage.

>Even tried running the fuel line through an ice container...
>not really sure that little trick was an advantage.

One of my karting buddies tried that once. It was really inconclusive, but the requirement of a suitable coiled length to exchange heat may have compromized it some.

SK

As far as I know, there is only one additive in Jet-A (kerosine)"Prist," at least it's the only additive in the fuel we sell. Ethylene Glycol Monomethyl Ether. Added to the fuel (Jet-A) to reduce ice crystals at altitude and to prevent fungus (microbes)developement in the fuel tanks. Evidently...when added to 102 octane racing fuel it boosts the octane further.
Norm

>>Even tried running the fuel line through an ice
>container...
>>not really sure that little trick was an advantage.
>
>One of my karting buddies tried that once. It was really
>inconclusive, but the requirement of a suitable coiled length
>to exchange heat may have compromized it some.
>
>SK
>
>
>
>

You really want to try this when Vapor locking is a problem. Had a friend with a very fast 79 Camaro. Lots of vapor locking though. Not much clearance under the hood and it really retained heat all around the motor. The intake was basically baking in there and the fuel would evaporate upon entering the manifold. Fuel through and ice bucket would help alot. BUT the ise would melt in no time and multiple changes were needed.