TRX250R.ORG
Workshop => The Mad Scientist => Topic started by: meathead on January 22, 2015, 05:51:06 PM
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Howdy guys Well I was just wondering about the air foils for the radiator
I mean there ugly It looks like you don't even need them It looks like you would get plenty of air without them Any body out there not using them ?
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you mean the shrouds? scoops? i think everyone uses them. Engine overheating is common so big radiators, scoops, engine ice, inline billet coolers all help.
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I'm building this thing to ride it not beat the crap out of it. I can see it overheating if your
racing or running the crap out of it. But for regular trail riding do you really think it would
overheat ? A big aluminum radiator I can see but those scoops really look redundant. I think
i'll give it a try and if it overheats i'll put them on. I've seen wheelers like this without them
For sale actually. I mean i'll open it up every chance I get I'm not gonna baby it either.
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Get one of those IR hand held temp guns & take a baseline on the exhaust side of the cylinder & than remove the shrouds & see how much difference there is. If it's extreme you have your answer as to weather or not there needed. Even at lower speeds I would think they help channel air through the radiator & I'd leave them on but thats just my opinion.
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I'd say you need them
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Must be there for good reason. Every sport quad has rad shrouds.
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Broken1 has a good idea with the hand held pyrometer. I just happen to have one of those.
I think i'll give it a try and re-post. It will be a while till I get this thing together.
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The majority of the shrouds on the market today for the 250r don't really do diddly squat. They leave a gap between the radiator and the shroud, so most of the scooped air is being lost. And they tend to terminate at the back of the radiator instead of at the front where the fins are. The best example of radiator shrouds were the ones that came with Walsh radiators. Check em out, you'll see what I'm talking about. But they have long been discontinued.
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Yeah I noticed that That and the way their shaped it looks like you really have to be moving to even get any at all air in there So I figure if you're really moving you don't need them anyhow I used to have a 86 atc 250r and I would go for a putt and just putt around and it never even got hot I could almost keep my hand on it for awhile sometimes I could. So I figure they are really aren't necessary. There just a pain in the ass.
The atc 250 r it looked like those shrouds really did something The way they are shaped
But the ones for the trx are almost in line to the air coming in so they don't really scoop anything It almost looks like they would cause a disruption of the air coming in actually
Make it swirl around instead of going through the rad freely I don't know really but it wouldn't surprise me if a temperature test like broken1 suggested yielded freaky results.
That's just an opinion So I'm gonna try that test. The problem is it wont be till summer
when I get it done Parts for this thing are expensive for the most part unless you can find a good deal on ebay which do come along once in a while. But anyways I figure a new possibly over sized rad is the way to go and leave it at that. But hey I will find out unless
someone else is real curious and wants to try that test sooner.
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i think the idea behind them isnt as much scooping more air, as it is making what air is in front of the radiator go through it, instead of the air going around it.
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imo They are very important for trail riding as well with less speed forced air going trough the radiator.
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I think that only so much air can go through the rad anyway so unless your using a blow
gun (without bending the fins) Your not gonna get any extra air through it at high speed
that can go through it And at low speed like I said And I mean really low speed Slow enough you want to rev it up once in a while so you make sure your keeping your cylinder and all the parts in there lubricated. Especially when decelerating with the clutch engaged. I think that the coolant circulates constantly. And I don't know for sure but in a car with
no thermostat it keeps the engine so cool that you will turn on your check engine light.
and it matters only slightly if you go real slow. So makes me think that even being a two stroke which naturally run cooler anyway due to the massive lubrication it gets, will be fine at low speed. Like I said I used to go super slow for long periods at a time almost like
trials riding And it never even came close to getting hot.
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i am confused by that last post of mostly run-on thoughts.
its really a simple model to understand. think of the radiator as a giant filter that lets air through. it has an amount of restriction to it like filters do, due to how close the fins are. its easier for the air to just go around it rather than go through without the funneling effect of the shrouds. of course some will go through, but some will also just push out and around to take the path of least resistance. with the funneling effect the shrouds create, instead of the air just pushing out around the radiator, the incoming air is already inside the shrouds and pushes the air in front of it through the radiator because it has no where else to go.
there is too many other factors that are going to determine the operating temp of your motor to be able to know on your setup, and the operating conditions how having them on your motor or not will effect your overall operating temp, but i think if you put a radiator in a flow tunnel with and without the shrouds, you would see more air going through and not around.
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Sorry about that last post. But I don't think that your going to be able to force air into it at high speed because only so much air can go through it. if you try forcing air through it all your going to do is create pressure in front of the radiator and actually impede your forward motion. in reality you might be able to go a little faster without them. Of course these are only opinions. Without proper testing you will not know for sure. But I'm very curious about what the results would be. I'm sure the scoops cause some air to be directed at the radiator and some goes through there. But at high speed you really don't
need them because it seems like your getting plenty. Unless the design of the wheeler
causes the air to breakup some how and deflect it away from the radiator. Who Knows
I just thought this was an interesting question to ask. Of course all opinions are greatly
appreciated. I'm going to try it with and without. And if they happen to turn out useless
I will permanently remove them because boy are they ugly.
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Op
If you already had your mind made up then why did you post the question? You obviously were fishing for the answer you wanted and that's not the answer you were given here by more than one person. If you want to run without them then run without them. Don't ask a question if you are not prepared to accept either of the possible answers.
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If your trail riding as slow as you are describing, with little to no air flow, you might as well get off and walk. You can't tell me your not cruzin in 2nd or 3rd gear. Moving even in the lower gears will create air flow. The shrouds are ment to direct the flow of air as little as it may be. Like I said every sport quad has shrouds. They are there for a reason. You like slow trails? Toss the shrouds install a fan and call it a day. Installing of fans have been covered on the forums also. Now your quad will be beautiful without the ugly shrouds. But then you'll have an ugly fan and some extra doodads to deal with.
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i am confused by that last post of mostly run-on thoughts.
its really a simple model to understand. think of the radiator as a giant filter that lets air through. it has an amount of restriction to it like filters do, due to how close the fins are. its easier for the air to just go around it rather than go through without the funneling effect of the shrouds. of course some will go through, but some will also just push out and around to take the path of least resistance. with the funneling effect the shrouds create, instead of the air just pushing out around the radiator, the incoming air is already inside the shrouds and pushes the air in front of it through the radiator because it has no where else to go.
there is too many other factors that are going to determine the operating temp of your motor to be able to know on your setup, and the operating conditions how having them on your motor or not will effect your overall operating temp, but i think if you put a radiator in a flow tunnel with and without the shrouds, you would see more air going through and not around.
You are on the right track, Jesse. Except that the air fins can handle a lot more air flow through them than we can achieve even with shrouds and going 85 mph down the highway. So having shrouds can be a good thing to add additional air, but only if they are forcing the air through the fins. Like you said, air takes the path of least resistance. So if you are trying to force more air through the fins and there is a gap between the shroud and the radiator, then your path of least resistance is the gap and not the air fins. The key is to give the air no place to go except through the fins.
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I'm not so sure Ryan. I could be totally off my chair, if I keep drinking! I believe the shrouds are designed to bring air to the side of the radiator. Enough air is flowing through the coils, with or without the shrouds. Angle the shrouds so air will be directed and pass by the sides. Cooling that area as well as the front. More surface area cooling, the cooler the contents. The gap between the shrouds and radiator, let's the air pass and not be trapped. Just thinking out loud. Next!
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Personally I think that we aren't getting 100% of the possible volume of air flowing through the radiator at any given time.
I'd want the shrouds with little to no gap whatsoever, to force as much air through the radiator as possible. I don't think there's any way we're getting 100% of the cooling capabilities of the OEM radiator without them
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I see what you are saying Fred, but the side tanks are not meant for cooling, just a little extra capacity and to incorporate inlets and outlets. Think about it compared to anywhere you see shrouds used, especially on vehicles. The shroud butts right up to the fins and typically don't cover the tanks. That's why the tanks are usually plastic on vehicles. Because the cooling takes place in the tube and fins.
I agree with what tbone said 100%. I designed the cooling package on the last 2 bulldozer designs that I worked on including the shroud and seals,and I can tell you with certainty that the shroud can play a big role in the cooling performance. And gaps in the shroud package also makes noticeable changes in performance.
I don't know personally, but I think someone one paid close attention to how the shroud was designed in the Walsh radiators. You'll notice the air scoops were aimed directly at the air fins and the shrouds were pushed up against the radiator and foam seals used, thus making sure all the air goes through the fins.
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I will add this, Fred. What you are saying is true. Air that passes over the tanks does cool them some, but only a very small amount compared to the air passing through the fins. My guess is the factory radiator was more than capable of cooling the stock engine without any assistance and at a very low speed, so the oem shrouds were used more as a deflector than an actual air guide. Now that we have more big bores floating around, we need as much airflow as possible.
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(http://forums.trx250r.org/vbulletin_imports/100_4407_2017-04-18_2411.jpg)(http://forums.trx250r.org/vbulletin_imports/100_4408_2017-04-18_2491.jpg)
Here's a couple pics of the Walsh shrouds. Notice how they butt up right to the side of the rad and the scoops point right into the air fins.
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^^^^^ show off :lol:
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I'm afraid the pics are not of my 250r, Mandom. Lol
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ok im sorry lol
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Thats one setup there that I've always wondered about. You seem to lose the straight forward airflow, and rely more on the deflected air from the side shroud.
I would think the angled screen part does a good job of protection from mud and roost though.
Nobody mentioned it just looks cool and is a good place to hang a couple of stickers. :p
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I'm totally on board. It would be hard to argue against Walsh engineering. :victorious::victorious:
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i was reading something the other day about airscoops. no scoop at all is a bad idea like you guys already mentioned. alot of the air just goes around the rad without going through. having the scoops pointed outward to much may be bad as well as some of the air may have a easier time being pushed back out and around the scoops. straight or slightly inward pointed scoops should be best as this would make it most difficult for air to come back out and around the scoops. i know it sounds opposite of what some people think but it makes perfect sense to me. i been around a ton of different mx bikes and most of them have outward pointed scoops. the only bike i ever seen with scoops facing straight ahead was ktm and i always wondered why but i think i know the reason why now
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OEM trx scoops are pretty much straight too.
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i never seen the oem scoops but ill take your word that theyre mostly straight on. mister honda was probly pretty smart. these little things like this is were alot of the aftermarket companies fail
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i never seen the oem scoops but ill take your word that theyre mostly straight on. mister honda was probly pretty smart. these little things like this is were alot of the aftermarket companies fail
Creating a negative pressure over the whole back surface of the radiator can usually do as much good as building a positive pressure on the front surface of the radiator. It is the pressure differential from the front to the rear of the radiator that causes the air to flow through the radiator. Preventing the air from spilling over the perimeter of the radiator can help build this low pressure on the back side of the radiator.
Angled scoops on the front or just adding a few inches or more of a straight flange around the perimeter of the radiator can help build a low pressure area behind the radiator
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i was reading something the other day about airscoops. no scoop at all is a bad idea like you guys already mentioned. alot of the air just goes around the rad without going through. having the scoops pointed outward to much may be bad as well as some of the air may have a easier time being pushed back out and around the scoops. straight or slightly inward pointed scoops should be best as this would make it most difficult for air to come back out and around the scoops. i know it sounds opposite of what some people think but it makes perfect sense to me. i been around a ton of different mx bikes and most of them have outward pointed scoops. the only bike i ever seen with scoops facing straight ahead was ktm and i always wondered why but i think i know the reason why now
Your thinking is correct. This is exactly what I spoke about earlier in this thread. Take a look at the pic I posted on post #22. That is why I used this example. It is the only shroud design that I have seen that guides the airflow towards the air fins and doesn't leave a gap for it to go beside the radiator.
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Lets be real, who cares how much more air the standard aluminum shrouds allow to flow through the radiator. Your quad would look goofy without any shrouds at all. :friendly_wink:
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Lets be real, who cares how much more air the standard aluminum shrouds allow to flow through the radiator. Your quad would look goofy without any shrouds at all. :friendly_wink:
Ryan does, I spent a whole month redesigning the stealth shrouds to fit up within an 1/8" and touching the radiator.
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Your thinking is correct. This is exactly what I spoke about earlier in this thread. Take a look at the pic I posted on post #22. That is why I used this example. It is the only shroud design that I have seen that guides the airflow towards the air fins and doesn't leave a gap for it to go beside the radiator.
those angled vertical fins across the frontal section of the radiator are old skool, dating back to the mid 80's from what i remember. i think there may be far better ways now days and we can learn from modern designs. every year ktm seems to be putting forth alot of effort to make their bikes the best and you can see theyre even adressing the little things like the fins across the front section of the radiator. by changing their shape they increased cooling efficiency 10% while mantaining the same coolant capacity and rad surface area. i have drawn red lines to represent what i believe is a close proximation of what their shape is but its hard to tell just from that one pic. it seems to me that rather than just a angled fin like whats been used for ages on nearly every mx bike, they have shaped the fins so the air turns back straight as it enters the cores. and those rad scoops that are angled outward at a rediculous angle, something tells me thats not the best idea. anyways heres a snippet from a article on these rad gaurds
KTM’s engineers put lots of thought into their radiator design. Rather than just put old-school plastic guards on the front of their radiators, KTM used wind tunnels to design a new radiator guard shape that flows more air (and is made from a stiffer plastic to help the flow and act as a radiator brace). The radiator shrouds also seal against the outer edge of the radiators to direct airflow into the radiator’s cores. There is a new filler cap and filler neck that seals better than last year’s design. The end result of all of this work is that the exact same capacity and surface area produces 10 percent better cooling efficiency