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Posted: Tue Dec 18, 2018 8:33 am
what the Bone s said
solves the blanched almonds problem , and may not need as much water ?
Posted: Tue Dec 18, 2018 10:41 pm
I've read through this long thread about how to calculate/estimate the heat generated by a motor so the guy can figure out how big his water tank needs to be: https://cr4.globalspec.com/thread/4609/ ... -Cooling-S
Its pretty funny in spots because most respondents don't get that it's going in a LSR car, but ultimately he doesn't get the answer he is looking for: a rule of thumb for figuring out the heat passed to cooling system based on how much fuel was consumed.
His system is like Bones suggests, a radiator submerged in water.
(Bones, I've shifted, I'll be up there ... Wallsend/Newcastle ... all over Christmas and the New Year period, give me a call anytime ... be great to get another first hand look over it)
The thing is, if I vent it to the atmosphere then I won't get any pressure build up at all ... but the water will boil at 100degC. If it keeps below that temperature there's no drama. And from what I've heard (keeping in mind there isn't much info out there), LSR water tanks don't seem to get that hot.
I think the Terra Plane guys said their 50ltr tank gets to 70degC and they're pushing a lot more through the air and the motor is fully enclosed. I'll double check.
I'm thinking I'll plumb it all up as is and run the thing in the shed and see how hot it gets. If it rockets towards 100degC I'll go with the heat exchanger.
Posted: Tue Dec 18, 2018 10:51 pm
Yup, from earlier in this Build Diary, Gus said:
"70 degrees c at the end of a 3 mile run. And almost 90 after a second run with about 2 hrs cool down time."
Apparently the LS motors run pretty hot, but being aluminium they probably cool down pretty quickly too. That, plus the radiator, with a fan and the electric water pump that I can keep running when the motors stopped, and 30ltrs in the tank ... I think I'm in with a chance of keeping the temp at TerraPlane sorts of levels.
Having said that, a pressure relief valve away from me and my Almonds is in order...
Posted: Wed Dec 19, 2018 9:06 am
Almonds ?? on tv last night thay said that "Avocardo" is an old Aztex/Spanish word for testicle
Its almost impossible to find reliable information on what is right for LandSpeed,, our sport is so removed from any other motorsport that the best we can do is experience and adapt
Posted: Wed Dec 19, 2018 9:40 am
Stayt'ie ... now you mention it, I probably should be wondering why Harky is comparing my testicles to Almonds ...
Si, suck it and see.
Posted: Wed Dec 19, 2018 10:11 pm
OK, so I've just finished reading an EPIC article on cooling system setup. It had loads of theory, and coincidentally it used the LS to demonstrate what much of it meant in practice: https://www.pirate4x4.com/tech/billavista/Cooling/
Looks like I was misunderstanding a few things and underestimating a few others...
I had seen a couple of funny tubes emerging from the cylinder heads and wondered what they were, steam vents apparently. Will have to deal with those.
My initial reaction was to give the water tank idea away and go for a more conventional radiator setup ... bit overwhelmed actually ... but as I sit here thinking about it I think I had been over estimating the complexity of the heat exchanger setup; I thought it would have to be a series of tubes snaking through the tank all over the place ... but one key "myth" suggests that it might be best if I just fit a single long tube through the center of the tank from front to back ... that's this one from the article:
For those that cling tenaciously to myths, I am going to take one last crack at forever dispelling the Granddaddy of them all when it comes to cooling systems.
The myth is stated as either:
Coolant can be pumped too fast through the engine for it to absorb enough heat, or
Coolant can be pumped too fast through the radiator for it to cool properly, or
Cooling can be improved by slowing the flow of coolant through the radiator so it cools more completely.
NONE of these is true. The simple truth is that higher coolant flow will ALWAYS result in higher heat transfer and improved cooling system performance.
The reason the myth is so persistent, is that: a) without knowledge of fluid dynamics and laws of thermal conduction it does make a kind of intuitive sense and b) it is based on a tiny kernel of truth, but that kernel of truth does not explain the overall system behaviour and so, interpreted out of context, leads to a completely erroneous conclusion.
As long as I promote some turbulence in the tube so that the laminar flow doesn't mean that only the outside layers get cooled I might be onto a good thing. My first thought is to dent the outside of the tube a bit randomly along its length. Or put a few random bends in it ... yeah, that wouldn't decrease its cross sectional area ... probably better. My next Google search will be how to introduce turbulent flow into a tube ...
So on it goes.
Thanks Bones, a heat exchanger.
Posted: Thu Dec 20, 2018 8:04 am
Thanks for sharing your build Russell,I played around with a cooling tank idea a while ago, using Sumner's info listed somewhere on his "purple trading post", but I have no idea where the info was (yep, I'm loosing braincells rapidly)
These are links relating to engine cooling from landracing.com forum , which may help to confuse you more
http://www.landracing.com/forum/index.p ... 886.0.html
https://www.unitconverters.net/power/ho ... t-hour.htm
Edit:- I found Sumner's formula lurking in my PC
GPM = (C x HP) / delta T Where GPM = gal/min, C = constant which is 1.00 for water, delta T = Temp at end - Temp at start with Temp in degrees F.
Time = (Mh20 / Hpbtu) x delta T Where M = wt of water in lbs, Hp in BTUs and 1Hp = 42.44BTU/min, delta T as in formula previous.
Hint: cooling system heat load is about 1/3 of engine power at the flywheel in BTUs
Regards to All,
!7 bhp = 5.1 btu's ----- 5.1 btu's x 4 minutes = 20.4 BTU's generated
material cp (J/kg·K)
water, liquid, 80 °C 4196.3
water, liquid, 100 °C 4215.9
Btu joules 1,054.8 Btu kilogram-calories 0.2520 Btu kilogram-meters 107.5 Btu kilowatt-hrs 0.0002928
To Convert Into Multiply By
joules kg-calories 0.0002389
Amount of Heat Required to Rise Temperature
The amount of heat needed to heat a subject from one temperature level to an other can be expressed as:
Q = cp m dT (2)
Q = amount of heat (kJ)
cp = specific heat capacity (kJ/kg.K)
m = mass (kg)
dT = temperature difference between hot and cold side (K)
Example Heating Water
Consider the energy needed to heat 1.0 kg of water from 0 oC to 100 oC when the specific heat of water is 4.19 kJ/kg K:
Q = (4.19 kJ/kg.K) (1.0 kg) ((100 oC) - (0 oC))
= 419 (kJ)
136485btu needed to heat 1 gallon water from 80c to 100c
Posted: Thu Dec 20, 2018 10:05 pm
Heat exchanger in the tank works perfect on my bike. Norm from Aussie Desert Coolers did an awesome job making it up for me. I also use the tank water to cool the water to air intercooler and capacity of 25 litres works ok. That way I can use water wetter in the motor cooling system and dump the tank water after each run. We do shove two bags of ice as well though
Shit...times running out
Posted: Tue Dec 25, 2018 10:46 am
Look for Purple Sage Trading Post.
Sumner has loads of info on his site.
I want to do the heat exchanger deal on the new bike.
I will try for 20L ( much smaller engine) I was also thinking a pump to circulate the water within the tank. My tank will be under the bike.
What does the article say about some restriction on the outlet ( thermostat?) to make some pressure inside the engine?
I'll come up soon
Posted: Tue Dec 25, 2018 4:00 pm
Hey fellas, with these new constructions and if you plan to run FIM, be aware of the new ruleing limiting aerodynamic ground clearance to no further than below the "inside" diameter of your rims
Posted: Wed Dec 26, 2018 9:11 am
Stayt'ie, I have always been surprised that our rules allow us to run lower than the rim in both car and bikes.
Posted: Wed Dec 26, 2018 6:56 pm
Yes Chris, I wasent aware of the ruleing for cars,, with very low slung cars I would imagine thay would be a little more forgiving in the event of a flat tyre, in that thay would have a tendency to slide around on their guts,, however a little frightening if a bike bellies out, ya gunna be droped onya face pretty quick,,
Posted: Fri Dec 28, 2018 10:30 am
Thanks Tiny, Richard and Bones, loads of great info on those threads and from your experience ... very helpful. Especially when ... #timesrunningout!
I've put the water tank/heat exchanger on hold until I can get some aluminium tube. Been working on mounting the motor ... which I'm happy to say is now done!
Here she is from the motor mounts side; 100x50x3mm RHS tapered down to a 32mm solid steel "bush" which then bolts to the 6mm frame plates with an M12 bolt.
And from the motor plate side; 6mm steel plates with 2 x M10 bolts to 6mm plates welded to the frame. I think I'll bolt the scatter shield/chain guard to these plates rather than welding it to minimize distortion.
Next job is to mount the pillow blocks that hold the jack shaft bearings for the clutch and single gear. My initial idea was to have them adjustable to take up any slack in the primary chain ... but I think I'll go with a chain tensioner instead. Richard, I remember you having issues with your chain tensioner bearings, or maybe the primary chain itself, any tips?
I'm most of the way through modifying the LS3 electronic throttle pedal to hand operation, I'll show you all that later today.
Posted: Sun Dec 30, 2018 9:22 pm
These are from last night, I spent most of today trying to figure out how to mount the hydraulic clutch release bearing (actuator?) so don't have much to show.
(I had one of those moments where I figured out how I was going to do it, then when about gathering the measurements I needed and promptly forgot what I'd figured out previously ... 2hrs later I remembered, so I'll do that first thing tomorrow. This will seem like gibberish if you haven't been there ...)
Anyway, pictures are worth 10,000 of my words ...
And from above, where you can see how the components line up ... looks better here than on my bench aye!:
I'd love to put a thrust bearing between the sprocket carrier (which doesn't exist yet) and the green pillow block housing at the left; does anyone know if sealed thrust bearings exist?
If you all (Harky in particular) cast your mind back 15 pages or so, I was trying to figure out how to resist the thrust from the clutch release bearing because I hadn't taken it into account when I was designing the jack-shaft and its bearings etc (Richard spotted my oversight). Harky came up with an elegant solution of capping the ends of the shaft; which I went with and drilled the ends of the already hardened shaft. The thing is, this assumed the shaft itself was held by something ... it is, but only by the spherical ball bearings at each end. I've reread the discussion at that point, but can't quite figure out if it was generally felt acceptable to load the spherical bearings in this way i.e. axially.
So, now, with a few months in-between drinks ... does that seem ok?
I've got two bearings that can transfer the axial load from the clutch/sprocket to the jackshaft, so that's ok. From there though I have two options (to supplement/reduce/eliminate the axial loading on the spherical bearing):
1: Sandwich a thrust bearing between the sprocket and the pillow block. Out in the open.
2: Sandwich a thrust bearing in behind the pillow block and between the end of the shaft and the support plate (which has yet to be strengthened with some stiffening ribs at the top and bottom). There is only about 2mm clearance in there as it is, so I'd need to modify the end plate to make some room.
3: Employ the "Harky Solution" (TM) to transfer the thrust to the other end of the shaft where there is more room ...
Thoughts anyone? Like I said ... slower progress today because the stuff I'm building hasn't actually been designed yet... #notideal.
Posted: Sun Dec 30, 2018 10:57 pm