Ned Head

Thanks Trevor!
How is the Water-Pump driven? Or is it a thermo-syphen system?

I am quite sure my old company had an argument against your statements about fin area differences and so-on but they never raced their engines. Peugot have -- with success....?

It is all very interesting and I do have an idea why Nick´s (exPeter Tibbets) Bantam went so well last season and how it seemed to go quicker later in the last race at Cadwell which I had the good fortune to witness....

All the best!

John ,
The coolant flow is by a 12v electric pump , it can be best described as pump assisted thermo-syphon , water enters at the lowest point on the barrel and points the inflow under and around the exhaust duct . Outlet is at the highest point on the head water jacket , at the rear . Confirmation that the system functions well was illustrated in one race when the pump wiring fractured and the temp went up to 90*c but the engine survived despite going slower and slower when power dramatically fell away .
The technical director at Aprilia declared that their 250 engines lost 1.5bhp when water temp rose from 50 to 55*, but the next increase of 5* lost 2.5bhp and so on in an exponential fall .
One can only wonder how an air cooled engine would cope under these conditions , bearing in mind that no recent 2t race engine was air cooled and it would be seen as an act of madness to advocate its use .

Cheers , Trevor

Of course Trevor, you are absolutely right: theoretically (and most times practically) water-cooling is more efficient than air-cooling. That´s by virtue of careful establishment of how-much cooling is needed and WHERE it is needed!!


So I shall leave this one be -- except to observe what might be said by makers of successful Bantam systems and hearing what experts might have to say -- and close by saying that a well-planned sytem of air-cooling a Bantam engine CAN -- many times -- perform much better than a "thrown-together" water-cooled version.

I wonder how many WC Bantam engines are being over-cooled?

Thanks again Trevor -- keep posting.

Cheers!

Trevor/ Ned/ John, and all

fascinating subject this one, been ragged for years too. does a formula bantam need to have water cooling to compete the answer to this is NO, but the fastest Bikes all appear to be water cooled,

the air cooled orginal bike builder Martin Palmer/who sold it to Nick T then Peter T then Nick B, is certainly not the quickest air cooled Bantam more on this in a moment but lets just state one fact: - The fastest Bantams are not air cooled, they have always been water cooled, since it was allowed,

it's quite a known fact Peter's Bantam is not the fastest but it has the results to prove its very quick, but more consistent round a circuit, and has been for many a year been the most successful air-cooled, but this is certainly not a good example to show in the wage against the extra knowledge or complexity you get or need with water cooling, and you do need it, to make water cooling work reliably!.

For those like Trevor and a few others this extra complexity or engineering expertise to build / make use work, is not a problem, but I have to agree with Ned who I feel edges towards air-cooling as its so dammed simple/easier to set-up or for the new guy or one who has been running for few seasons to embark on building a water cooled barrel, often the thinking is "it will automatically be more powerful" and be quicker, "it will certainly will not be", only if you have the knowledge to make it so, and its so much easier to develop this knowledge with an air cooled engine first.

you have all seen my requests for info on building a water cooled barrel before, I'm sure even Nick has asked about what you need or where to start constructing a water cooled barrel, with only one person answering properly, Trevor!!, others who run water cooled barrels stay quiet "it does make you ask why this is, after all we are all on the same playing field, kicking around the same balls, at some point to score a goal you need to pass the ball.

Who could challenge argue against Trevor's comments they are indeed accurate "water cooling for racing 2t is superior, On an extraordinary water cooled Formula Bantam it allows all sorts of bigger/additional/correctly directed/shaped and size ports, that one could find impossible to get into any air cooled engine, one of the reasons for allowing the alloy barrels in in the first place was its availability and simplicity, what should have been far better would have been to ban the use of water cooling, as there are very limited number of people who know how to make these work, "is this fair in a Formula class "? who knows" but I'm not suggesting or asking.


Incidentally just wanted to correct one error, they still manufacture air cooled 2t for racing engines - Kart's/model Planes, cars and boats.

kind regards Derek

Last word on this topic.
I said in my last posting, "I wonder how many WC Bantams are being over-cooled...?" and I should have added, how many appear to be working efficiently at say a 90°c water temperature (with normal pressure-cap) or at say 95°c (with 2psi) over-pressure cap when they are not ... (working efficiently, I mean).

An engine that suffers an overheating failure can confuse its owner by having its water-temperature guage say that the water was not overheating when in fact a `Hot Spot´has developed ... This comes about when the water flow stagnates at a turning junction (for example) and a volume of superheated steam forms. The water continues flowing -- although restricted -- around the hot-spot. I have seen evidence of this with diesel engines using both water-pump and thermo-syphen cooling systems. The latter was with the Chinese "Peasant Tractor" where only small modification was made to the combined cylinder crankcase casting (a single cylinder diesel engine) and their company engineers would not believe that such a thing was possible until they cut one open and found evidence of the localised boiling having happened. I have seen similar´on several other makes of multi-cylinder diesel engines where the high pressure steam attacked the metal to actaully erode it... but never -- of course -- on a Bantam...

What this says is that you can have your Water Temperature gauge telling you everything is OK when in fact some part of your engine is getting too hot.

CheerS!

Hi john never knew they boiled to steam, ! but super hot points on a bantam barrel we found with a thermal imaging camera checking with a thermal lazer temp gadget, usually under over and either side of the exhaust top sides and btw and the port lower edge floor being v/hot, interestingly another point is at the bottom of barrel on the inlet side!!, I always assumed this may have been to do with it being the thrust face!, or lacking lube.

regards Derek

Sounds interesting Derek. Would this thermal imaging show steam in the cooling passages? We only assumed there were pockets of steam because of seeing the eroded surfaces -- once we´d cut open the cylinder block and and head (it happens there too!!) ... Where there´d normally be a rusty scale it´d be as if the metal surfasce had been sand-blasted where the superheated-stem had formed. It would be intersting to see how the water still flows around the outside of such a steam pocket because it obviously did....

I have seen instances of where such erosion has caused holes in steel liners but this is, of course, after thousand of road miles and of no concern nor of interest to Bantam engine tuners.

Is it true, though, that Water-Cooled Bantams are the ones doing all the winning?

And what happened to Nick?

Cheers!

Hi John

answer to water passages\cooling ducts is NO, it does not show this, its a thermal imaging camera not an X-ray camera, sadly I do not know if there is such a thing,

my tests have been done with an air cooled iron and alloy cylinder barrel, and a probe in a short tube on the front pipe while its under load, not been able to put a resolver on it that would give thermal temps through the stroke rotation,?? one thing it does show up is how in-accurate under plug temp gauges are, they are clearly just a guide, to be taken seriously as they do move quickly, but it does seem all dependent on where I position the cooling fan at the front of the bike\motor before a run.

Derek

Hi Derek!
Didn´t think it would. I haven´t kept abreast of electronic instrumentation and I did hear from my Son that spark plug washer temp-senders are only a rough-guide. With Water Cooling the temperature gauge thermocouple must -- of course -- be situated in the place where the water is at its hotest. Which, I reckon -- quite frequently, is not...?

This is all a lot of hot-air (from me) because the only useful thing about the temperature gauge is when warming up to go out for practice. "Get it up to working temperature --" the warning goes, "-- before you go out...."

After that, if it seizes, you might be lucky enough to get a quick view of an astronomical number before declutching or sliding off on your poof....

To do water cooling properly both a water-pump and a fan are necessary which must subtract a bit of hard-won power ... The fan for the obvious reason of air-flow through the rad when the bike´s road speed is low and acceleration is under high load. And the right sizer of water-pump is necessary to ensure adequate minimum flow at all times and all conditions because the cooling efficiency depends on both air-flow and water-flow being at an optimiúm for the amount of heat being abstracted. Ideally to prevent over-cooling ( and hence loss of engine performance) both water pump and fan would be micro-processor controlled so they only operate when the temperature goes over the set limit.

Which might suggest that many radiators -- on Bantams without cooling fan and computer-control -- are too large....? This would show when out on the circuit, going fast and the temperature gauge shows a drop in temperature.

Humble apologies for repeating the obvious, which everyone knows.

I seem to remember somebody saying the frontal area of the radiator is less important than the depth although the frontal area must suit the designed heat tranfer minimum requirement for handling maximum heat output. . i.e. Which really means (when the depth is greater) the air travels a longer distance thro´ the radistor and has more time to transfer heat...

I wonder if Trevor has a comment -- or two -- on this....

Cheers!

Hi Derek & John.
Just to let you know, electric water pumps that regulate their flow rate dependant on coolant temperature are commercially available (look in the demon tweaks catalogue).

I will also ask those of you that have built a water cooler barrel, why is the whole of the barrel water cooled. Not a single water cooled barrel by any manufacturer has a water jacket that covers the transfer ducts. All the heat produced is above the transfer ports and the last thing you want to do is heat up the incoming charge. Or is it an attempt to remove heat from the crankcases.
I look forward to theories & explanations.

Mick.

Not quite accurate Mick ,
The last of the works Aprilia barrels feature a water channel through the inner wall of the transfer duct . Temperature stability here will ensure a cool , thus more dense , gas charge entering the cylinder and cooling the piston crown on it`s way . One very important feature is keeping the entire exhaust duct cool
so that the returning ex pulse stuffs cool gas back into the combustion chamber , overheating of the piston and possible detto is kept at bay , and again , cooler gas is more dense that hot and you`ll get a bigger bang for your buck ! Trying to chop up the outer water jacket to place water in some areas and not others is a nightmare , simple expediency dictates here . But, who is to say that water at 60* running around an entire cylinder is not more efficient than around just the upper half , and , we are talking Bantams here , a specialised race engine where more modern conventions won`t necessarily apply . There are other , structural , features to consider as well , but as I may do a post on a" wet " barrel in the near future I will mention all of that then .

cheers , Trevor

Thanks Mick,
I take it the fan -- on such an arrangement -- also regulates its coming on and going off in similar manner. Perhaps not -- if the rad is big enough....?

I often wonder about these professional racers who stand up on the rests -- clapping themselves at winning -- that no one had told them of the "heat sink" factor that used to be a known cause of engine seizure at the end of a long race. I wonder if knowing that the water-pump increasing its coolant flow gives that degree of confidence of the engine NOT SEIZING that they can do that.

Didn´t Fred Launchbury´s mishap come about because of engine seizure at the end of a race -- or have I got it wrong and it was a racing accident??


Cheers!

Sorry Trevor I missed your post and caught Mick´s...

I´ve often thought about an extra cooling for the transfers because of the crankcase compression increasing the air-charge temperature. There are also some wonderful ideas on how one could cool and increase the air-charge but they might be breaking the Formula rules.

You are right about applying general rules to the Bantam Racer: engine, bike and blokes are all UNIQUE!

Take care!

Cheers!

I cannot resist this...

An engineer was talking about golf balls being dímpled to increase lift and distance but he could not explain why the dimples did that. I´d suggested earlier in the discussion that since the surface area is increased by the dímples the drag will increase and hence would slow the ball rather that speed it up. Perhaps the dimples induce spin which gives more lift -- or perhaps it´s to do with the old lamina-flow effect.

Who has the answer? Come on you golfers, time to check your balls.

Obviously the dimples increase the surface area which would improve the cooling efficiency of a radiator
. So why not have dimpled radiator passages and have dimpled on air-cooled engine´s fin-surfaces??

Or, do they alraedy exist?

Cheers!

John ,
It is that old turbulence again , with a smooth ball the air flow is laminar and creates a lot of drag at the rear of the ball as speed tries to goes up , Dimples creates turbulence , flow detaches and creates less drag so the ball travels a lot further and faster .
Barrel fins need a coarse, dimpled surface to reduce boundary flow , and in this respect sand cast surfaces always shed more heat than smooth die cast ones will do by means of the inherent turbulence at the fin surface . Rad cores also create turbulence , air slows as a result and more time is available for the flowing air to absorb heat and take it away . Double row cores help with this but the effect is reduced because the flow is already warm by the time the second ( or third ) row is reached .
It is strange how turbulence can be both friend and foe in the same application , the trick is to know where and when ?

Cheers Trevor

Thanks Trevor!
Next project: An ultra-light aeroplane with dimpled wing surfaces. Uh oh! I forgot again. I stopped paying my dues to the local aeroclub and I´ll need to win the Lotto. Maybe I´ll rob a bank. One that has money -- of course!

In view of what you said about drag from the rear I recall that golfers goes in for a lot of spin-on-the-ball and `Old Jonesey´ our Hydraulics lecturer was constanly talking of His-Idea to have rotating leading-edges to the wings....????

So, another message to the golfers of the BRC: mind how you spin your balls!

Cheers!


I dreamt I was Grass-track racing again. The wheels fell off. Was a true dream -- looking back my race preparation was awful!

Hi Trevor / Mick/ John, well this topic is really developing some really interesting comments,

dimples and gold balls, its amazing how the simple things can give some interesting results one of the current black op's V.T.O. (VERTICAL TAKE OFF) planes, has dimples on its outer surfaces, its super fast by convention once underway!, VT off" is not new ! other known combat fighters can do vertical T/O, but with conventional wings ad or propulsion, its not fuel efficient to do, reality says anti magnetic propulsion is not new, the Germans where experimenting with it in the early 1940's but it does require huge electrical energy to get it going.

I'm really looking forwards to seeing the very interesting reads on
1) step by step construction methods and or building of a Bantam Racer water cooled barrels- tips and pointers.
2) what the F1 dynamists said about water V air cooled Bantams -that Trevor spoke of.

Mick what's the pump your talking off, a page No, or part number please.

The golf ball and comment on dimples surface area of fins was very interesting to all those with alloy barrels, it you clean the fins you could loose as much as 20% of the fins ability to remove heat, AE released a paper on this at some point. if when we repair/modify we always SHOT blast not sand blast, the beads get every where, good cleaning is absolutely vital, some are glass like, so especially if you do the crank cases.

Trevor some really interesting results on the latest pipe drawing you sent me, PM you the latest results on back to back actually slight more Torque above 10,000, if I have more torque you I'm sure can imagine the other increases, just cannot wait to get her back on the track, I think It now has enough, and ready to try again, and this is without the A/R ignition system discussed. !

regards Derek

Hi Derek, Trevor & All.

I think that this discussion on cooling needs to move to Trevor’s new post (Liquid or gas?).

Derek, look at, www.daviescraig.com. In this site you will find interesting information on cooling pumps & ways of controlling temperature. They are not cheap but I am shore that an enterprising person can find a more cost effective alternative.

 Having said that there are always people who are money rich who can afford the best. But some people are time rich and they can achieve the same result through perseverance. Those who are both money & time rich will always be ahead of the pack.

Trevor, I was fully aware of the benefits of cooling the exhaust duct but have never come across the transfer duct cooling that you described in the Aprilia, I look forward to hearing more of your research into how to improve the humble Bantam.

Mick.

I could n`t agree more Mick , there was a time when the raison d`etre of Bantam racing was to promote cheap racing on an equitable platform of a strict formula . Everyone had a chance , but that has all gone , Bantams now can cost more than an RS and to be even remotely competitive is costly, deep pockets can indeed provide a huge advantage .

If you would like to PM me your email address , I will send you some info on an attachment ?

Derek , I`m eager to see the results you have , re the new pipe , etc . 

Cheers all , Trevor

High guys ! 

Thanks for the info Mick, sadly I dont have the time for racing at the moment, but hope to attend some meetings this year, especially with a few small gains we have over last year.  !

Trevor Im going for my first 2013 track session next week will let you know if I can feel the difference, we will also be trying version two of the !new ignition set up!, will pm you the latest figures, certainly better all round 

I,m very eager to hear your details on building a water cooled barrel, when you go through this, perhaps some sketches and photo,s would be really helpful.

regards Derek

I'm considering getting some Ned heads cast if there is enough interest
from racers sprinters record breakers etc.
Please declare an interest if you would like a brand new Ned head and I'll
do the ground work? Cheers Mike

Hi Mike,

Yeah i would be interested in buying one, how much do you think it would cost per head ?

best regards Luke