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  1. #1
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Functional hood scoop design UPDATED AS I GO

    Im trying to help control heat under the hood of my Rally... after advice from Dadx2mj and many others i have decided that opening up a vent in the body is probably the best way. I have a motor fan so my motor heat is in pretty good shape, but even on 2S after 2 packs my ESC can go up to 160 which im not comfortable with. I didnt want to just chop a hole in the windshield as I think it looks cobby... I wanted something unique and custom. So I used the plastic packaging from a Venom lipo I just got to make a functional hood scoop with interior ducting. This is my first version, the install will look similar with my final version, and the way its mounted will stay the same, but ive used a second plastic piece and for version 2 and painted it black to match the car. The paint is drying now and ill post up the final instal when its done.



    I know the scoop is big... but I honestly wanted it to be big... I wanted it to look oversized. I think once its black it will actually fit pretty well on the car and I think it will actually function well... it directs the air straight onto the motor and the final version I may try to duct further toward the ESC.
    Last edited by ksb51rl; 11-18-2010 at 12:14 PM.

  2. #2
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    hmm this is interesting!! it looks way oversized in the pics!!
    rustler vxl 2.4

  3. #3
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Oh, it is... its not the pics. Its just huge. This body is my runner body... more for function than looks. Though I do like it in a weird way. Im going to buy a 2nd stock body to have on the car when its sitting on the shelf.

  4. #4
    RC Turnbuckle Jr. Dadx2mj's Avatar
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    If you cut that almost in half you would have an opening about the size of the one in the Slipstream body for the MERV I mentioned in a different thread. In half it still might be bigger than the opening in the Slipstream body.
    BlindMan Racing
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  5. #5
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    Pretty huge scoop

    I grabbed my reamer and made five or six holes where the grill is.

  6. #6
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    You beat me to it. I was thinking of doing something very similar. I still might, but I have another option I'm looking into before sticking a scoop on mine By the way, you do know there is a company that sells hood scoop kits right? It comes in 2 pieces, a top scoop, and a piece for inside the body to duct the air where you need it. I saw it a few weeks ago, can't remember the name of them(of course) Maybe you could use the inside piece they offer, with your scoop. I'll let you know if I stumble on it again.
    Traxxas Rally Car
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  7. #7
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    You can get them here
    http://www.oocrcracing.com/
    Drive it, Break it, Upgrade it

  8. #8
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    make a small one but fit a tube going from it to the motor and esc. it works wonders.

  9. #9
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Those OOC scoops are cool. They do pretty much what mine is doing but without looking so HUGE...
    Heres some crappy pics of it painted and installed: All I need to do now it cut out the opening in the nose.

    Last edited by ksb51rl; 11-18-2010 at 12:14 PM.

  10. #10
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    well it does look better painted, looks like a pro stock car, i think!!
    rustler vxl 2.4

  11. #11
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    Keep in mind besides an entry point for air, you should also create an exit point on the rear of the car. Otherwise you will be creating a parachute type of effect. Typically you would want the exit to be larger than the entry. This also allows the hot air a quicker exit. I learned the importance of this while racing 1/18th scale with 9600kb motors which offer lots of speed and lots of heat !

  12. #12
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    I was thinking about cutting the rear window out. That way it wont look like ive hacked more holes in the body. My other idea was to remove both smaller rear side windows. But I think that will look more hacked than taking the rear window out all together.
    Heres the final version pics of the hood scoop with the beak cut out:




    My reasoning for going with such a big air intake is that with a typical onroad car your moving forward most of the time so your usually getting great head on air flow... therefore the opening doesnt need to be quite as big. But, with the rally (at least the way I seem to be driving it) its rarely going in a straight line at higher speeds so having a larger opening will allow more air at lower speeds. Hopefully. Its 0 degrees here right now and ill hopefully be able to get out tonight to test... the last time I ran it at 0 degrees the motor and ESC both ended up at 145... so if they are any lower today, it will be a success.
    Last edited by ksb51rl; 11-18-2010 at 12:14 PM.

  13. #13
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    ZERO ! I hope you mean Celsius... I can't imagine with those temp that you would have any thermal issues !

  14. #14
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Oh yeah, celsius. But it was -14 last night and its supposed to snow 3 inches here this weekend. All the running I did with this car stock, was in cooler weather and I was still dealing with heat. Which is why I want to get it sorted out now, so next summer its not an issue.

  15. #15
    RC Turnbuckle Jr. rag6's Avatar
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    Pave, have you thought of increasing the speed of the air as it approaches the esc, by a funnel duct, that captures the air and reduces the inside diameter of the duct?
    Having a large intake/small exhaust that isolates the collected air and funnels it directly to the esc would be the perfect cap to this project.
    I cant believe how "mean" and perfect that humongous intake looks!
    Again, you have outdone yourself.
    Ya can't polish fertilizer...

  16. #16
    RC Turnbuckle Jr. rag6's Avatar
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    Cool

    Pave, have you thought of increasing the speed of the air as it approaches the esc, by a funnel duct, that captures the air and reduces the inside diameter of the duct?
    Having a large intake/small exhaust that isolates the collected air and funnels it directly to the esc would be the perfect cap to this project.
    I cant believe how "mean" and perfect that humongous intake looks!
    Again, you have outdone yourself
    Ya can't polish fertilizer...

  17. #17
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    Great idea... ive got a few thoughts on narrowing down the size of the intake track as it goes toward the back. I also had an idea to close off the bottom of the duct so it literally directs the air straight to the motor/ESC... I want to try it just like this first, just to see how it effects heat... then make more changes as needed. But thats for the ideas and nice comments.

  18. #18
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    nice job man...heres mine i made from a old hotel key card and screen...
    Last edited by ksb51rl; 11-26-2010 at 12:44 AM.
    hmmm what did i break now

  19. #19
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Sorry guys, that last comment from Purple_pede_girl was actually from me... thats my wifes account name and for some reason the forum glitched and automatically signed me in under her account... weird...

    NICE looking scoop havoc... really, thats a clean install... id like to see it from the front. Did you heat the card to get the rounded edges? How did you fasten it?

  20. #20
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    Quote Originally Posted by pavmentsurfer View Post
    Sorry guys, that last comment from Purple_pede_girl was actually from me... thats my wifes account name and for some reason the forum glitched and automatically signed me in under her account... weird...

    NICE looking scoop havoc... really, thats a clean install... id like to see it from the front. Did you heat the card to get the rounded edges? How did you fasten it?


    Yes, I would also like to know more about that scoop.

  21. #21
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    So I just came back from running the rally with the new scoop and man, does this ever make a HUGE difference in heat. Its 2 degrees out right now, the last time I ran it, air temp was 3 degrees... so almost exactly the same. Its been cold here the past few days so id guess the pavement temps are cooler and they definitely has an effect on tire grip, but probably only has a tiny effect on the temps under the hood.
    The last time I ran, I had exactly the same setup, stock tires, (2) 2S Duratrax 1600mah lipos in parallel, geared 25/45 with an integy heat sink and fan on the motor. NO holes in the body at all and I ran both packs to LVC without stopping. My temps after that run were 145 on the motor and 160 on the ESC... today after installing the scoop, everything else including HOW I ran the car being exactly the same the motor was 85 degrees and the ESC was 106... thats over 50 degrees cooler. Now I will say the ambient temps being cool MAY have had a small effect on this, but the whole car is cooler now too... everything under the hood is cool to the touch whereas before everything under the hood was warm. The body was not only preventing airflow over the motor and ESC but I believe it was also trapping all the heat inside and causing a heat soaking effect on the whole car.

    I think im going to charge up my 3S lipos and try them out again. Ill only run one of them at a time (which was causing overheating with my previous setup) but I think I could run a full 1600mah 3S pack and still be in safe temps with this new air management system.

  22. #22
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    for the scoop i took a old hotel key card..first took a piece of paper to the hood and rubed a pencil to the edges of the indent,to get the width/length.. of the scoop. then made the lines on the card of where it would need to be bent to fit the edges of the hood...heat it with a lighter( very little at a time or youll melt it...trimed it alil,then made the hole in the hood alil bit smaller then the scoopis so the scoop with have something to be glued to..(i used a hot glue gun, and scuffed the hood where the glue will be used so it gets a real good bite to the plastic..plus the hot glue is a good kind for plastic),added alil screen mesh to the front..and bam..



    Please keep all images to a size of 640 x 480 pixels or smaller.
    -ksb51rl
    Last edited by ksb51rl; 11-19-2010 at 11:01 PM.
    hmmm what did i break now

  23. #23
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Cool man, it looks really good. At first I couldnt see how you bent it but now I can see how you got it to work. Love the mesh also... maybe my monster scoop needs mesh or something...
    Have you done any tests to see how it helps cooling?

  24. #24
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    Why do some Rally's have masked windows?

  25. #25
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    I took it out with the scoop , and it seems to be doing pretty good so far, I didnt have my temp gauge with me, but I could feel by hand a difference , and today was the first time I actualy got to go full throttle and the temp felt a descent amount cooler the when just ripping in front of my house, but I may add a type of wind director in the inside of the body to push the air straight on to the motor
    hmmm what did i break now

  26. #26
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    thanks well i am 30 sooo i guess that makes me some what of an adult lol
    hmmm what did i break now

  27. #27
    RC Turnbuckle Jr. rag6's Avatar
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    Pave, excited to see the temps dropped so much. Do you have an indoor area to test the temp drops? Also check them without the body...
    Ya can't polish fertilizer...

  28. #28
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Good idea on the without body tests... ill try that next time. I could also do a test with one 2S and cover the scoop up, then do the 2nd 2S pack with the scoop uncovered on the same day to see the difference. I may actually try that with my 3S packs as they create more heat so the effects would be more drastic.

    Ill post results when I can get out and drive again.

  29. #29
    RC Turnbuckle Jr. rag6's Avatar
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    I guess if you want to get really crazy, you could set up the scoop like a blower, with it opening and closing with throttle input using a micro servo. I know it would be less flow, but what a wow factor.
    Ya can't polish fertilizer...

  30. #30
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    I have a sneaky suspicion that the way you and I in particular get along is not conducive to forum happiness... I tend to agree and dont really miss what was deleted.

  31. #31
    RC Turnbuckle Jr. Dadx2mj's Avatar
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    Pavmentsurfer is right and if the bickering does not stop the thread will be closed.

    rpe-Rally if you dont have something good to say it is best not to say it. Your know it all my way or no way attitude is wearing on a lot of people and I suggest you give it a rest.
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  32. #32
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    Quote Originally Posted by BAC5.2 View Post
    Why do some Rally's have masked windows?
    Why do some rally's have masked widows I noticed that as well.
    http://www.youtube.com/profile.php?do=editpassword/Revoman859

  33. #33
    RC Turnbuckle Jr.
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    Quote Originally Posted by havok View Post
    nice job man...heres mine i made from a old hotel key card and screen...
    Nice...Like it a lot !!!

  34. #34
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    So Pave and others, heres the idea. I would love to try i tmyself but i don't own a rally. take a castle cooling fan unit for the castle mamba monster. Dremmel/cut it down to just the top part. cut a square hole in hood, install in hood with CA. Voila, functional, blowing fan, almost like ram air. Check my pic for example.

    I will be doing this to my DF03RA rally car that i am building, but someone please try this in a rally VXL, it looks like it would work awesome. When I do my rally car I am only going to cut a hole for the small covered/ducted part of the fan, and install it on the roof of the subaru, possible ductine it internally toward the esc. Whats neat about the castle unit is that shroud around the fan, draws in air like a scoop!

    Actually, this mod might be better in the roof of the rally too!



    This mod will be know as Tim's fan mod. because I am vain. and I want something named after me. Maybe i should get a dog.
    Last edited by Frostbite; 12-11-2010 at 08:04 PM.

  35. #35
    RC Turnbuckle Jr. rag6's Avatar
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    Your right. It would look awesome.
    Ya can't polish fertilizer...

  36. #36
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Kindof like the Rag6 chassis extension or "paved" body mounts on a pede? Sweet.

  37. #37
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    Cooling duct

    Here is my solution for cooling. very little mod to the body, ducting stays on chassis and easily removes for service, not interaction with suspension. With very small fan there is ample amount of air over esc and motor so should work great. it is minus 20 c here right now so overheating no problem but will work great when warms up or in doors.http://i608.photobucket.com/albums/tt165/odieser/Traxxas%20Rally/TraxxasRallyCooling003.jpg
    Last edited by odieser; 02-16-2011 at 12:08 PM.
    1/16 Rally and 1/16 Summit

  38. #38
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    That is wild, I want to see more pics. Post up a top view and some views of how you mounted it, with the body mods etc... I think its pretty sweet.

  39. #39
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    Body mods are minor just removed the plastic that would be the grill section. mounting is just 2 quick ties (plastic) one around bulk in front where bumper mounts and one thru hole on motor mount so exit is right at the esc cooling fins.
    1/16 Rally and 1/16 Summit

  40. #40
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    Great pics, thanks. Id be tempted to open up more of the nose... but I always go too far...

    Very clean when the bodies on, almost invisible.

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