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Old 06-11-2007, 07:27 PM   #76
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Originally Posted by vtl1180ny View Post
This post... He already tore up a tire bench testing it... You stated a known fact...
It's allright, I think RCSteve93 meant once I start running the car on the ground, the tires will wear fast.

But yes, I already decimated one tire from free wheeling the tire on the bench:


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Old 06-12-2007, 12:34 PM   #77
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Your right! It does look american!! LOL
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Old 06-12-2007, 12:50 PM   #78
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This is how far I'v got. I should have the rest together tomorrow. The exhausts were just to see if they fit (they dont but it looks real cool!)
what up ziggy! I wonder how hard will it be to have all those 2 speeds shift at the ame time?? Looks good!!
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Old 06-12-2007, 01:01 PM   #79
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what up ziggy! I wonder how hard will it be to have all those 2 speeds shift at the ame time?? Looks good!!
....looks good Ziggy,........ but won't having 3 different engines in 1 car with different power characteristics actually put a bind between the different engines since 1 engine could be producing more torque at a given RPM than the other 2? ie. the other 2 engines holding back the power of a third engine. seems to me they would "fight" each other. wouldn't 3 IDENTICAL engines be a better setup. not trying to rain on your parade, just trying to help you figure the beast out.........
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Old 06-12-2007, 01:03 PM   #80
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I'll try to set them the same but I dont think it will matter that much. When the first 2nd speed kicks in it will accelerate the car and this will kick in the 2nd engine then the 3rd. I think it will happen so quick you wont notice it.

... thats the theory anyway....

The problem comes when I put the high gear ratio on. Its set so the 2nd speed comes in around 108mph. I need to have a very heavy clutch to top it slipping but this means it comes in really early
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Old 06-12-2007, 01:05 PM   #81
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I'll try to set them the same but I dont think it will matter that much. When the first 2nd speed kicks in it will accelerate the car and this will kick in the 2nd engine then the 3rd. I think it will happen so quick you wont notice it.

... thats the theory anyway....

The problem comes when I put the high gear ratio on. Its set so the 2nd speed comes in around 108mph. I need to have a very heavy clutch to top it slipping but this means it comes in really early
very cool, would love to see it run!!
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Old 06-12-2007, 01:07 PM   #82
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....looks good Ziggy,........ but won't having 3 different engines in 1 car with different power characteristics actually put a bind between the different engines since 1 engine could be producing more torque at a given RPM than the other 2? ie. the other 2 engines holding back the power of a third engine. seems to me they would "fight" each other. wouldn't 3 IDENTICAL engines be a better setup. not trying to rain on your parade, just trying to help you figure the beast out.........
Its worse than that as they all have different gearing as well... LOL I am waiting for the parts so am just getting the bugs worked out.

The plan is to use these three engines then get three of these

http://murnanmodified.com/product_in...roducts_id=108

I still havent figured out the exhaust yet. I know tuned pipes give more power but I dont have room for them

Cheers
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Old 06-12-2007, 03:46 PM   #83
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I got maybe a dumb question, but when I looked at the little video and the pics of the prototype car something I see disturbs me...

CHASSIS height.

It appears that you have less than 3/16 of an inch clearence to the ground...and you've also got a pic of how distorted a BODY can become under downforce load... So what happens when you put 200 LBS of downforce on those front tires...how much clearence will you have then?

I would guess, unless you are using NO suspension that can move, you'd want to be able to count on the chassis dropping 1/2 - 3/4 inch under full speed loads. The more evenly the better...

The pics look to have way too much frontal downforce...which should in my mind make it very steerinng sensitive too, needing more rear downforce.

I always kind of liked this type of shape and thought it should be pretty neutral at higher speeds...maybe even a blunter front nose yet.

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Old 06-12-2007, 04:10 PM   #84
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I can aswer a couple of those questions. The stock Associated pan car front suspension is being used. There is .3 inch or so of space under the front. The stock suspension will bottom long before this space is used up. It will then become a flexure type of suspension and rely on the lower arm flex to carry the load. Only a test will tell if its actually going to work or not. A test is forthcoming. This flexure suspension may or may not be intended, but this post is based on my knowlege of the suspension. It would be easy to increase the front ride height to whatever creates no new scratches on the bottom of the chassis. I have a backup fully dampened front suspension that Nick can use in case this one does not work. Things are being eliminated by experiement. This is probably a sensible approach. Now a couple of us are thinking the body will lift so maybe 200 lbs is a number that is too large. There is more to the body than meets the eye at this point.

Pics Dampened front end on left. Middle, Murdoch long travel Mod, Far right short travel stock suspension. Bottom arms are bolted directly to the chassis, but they have some flex to them when the suspension bottoms on the two at the right. The first suspension on the left has dual dynamic A-arms.

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Old 06-12-2007, 04:22 PM   #85
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John,

We are running 4 cell b/l motors on a bicycle velodrome at close to 70 MPH, and most run over 1/2" of ground clearence and our bodies have a lot less frontal downforce (Stock Car Bodies)

Nic Case also currently holds the single lap 4 cell record (8.4 seconds on the approx. 860 ft. track (which I calculate at about 69.8 mph) I think coming up this July we'll see that time drop into the high 7's, and near 75 MPH on a OVAL track.
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Old 06-12-2007, 04:49 PM   #86
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Its good to have that kind of hard data. Thanks. You guys probably have extended wheel travel on the front (see the Murdoch picture in my previous post). I think that Nick does not at this point. On my car the rear is the problem at those speeds (now that I have a dampened front end). What I have done is put uptravel limiters on my rear shocks (bump stops) This keeps the chassis off the ground without having to go so high. I understand that on an oval car, hitting bumpstops on a curve would be a big upset. Not so much on my straight though. Nick's short front wheel travel will create bump stops as the spring goes into coil bind and the bottom arms start flexing. I have already suggested fairly stiff coil springs so this happens gently.

Bottoming the front chassis completely on a bump is generally disasterous. We will just have to see. He can move it up a bit if he gets scratches on the bottom or the top.
John

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Old 06-13-2007, 08:43 AM   #87
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Default down force

I'll have to agree with joe on the down force of the body.

I still think that a stock car superspeedway body, or a blunt nosed body resembling the body Joe diagramed. That would be the best choice for hi speed runs. all that down force of the LMP shaped body is needed for road racing but will only slow you down for hi speed runs. Shakey Dave and I have tried using a hi down force stock car body at the velo and it slowed the car drastically,. to much down force is not good at over 50 mph.

Mccallister racing makes a Dodge Charger hi speed body. it has a blunt nose. Mccallister has experience in velo racing since the very first race at the encino velodrome 20 years ago. yes I use this one, but there are others.

as far as bottoming, it can be disasterous at speed in excess of 100 mph.
watch out for polly seeds. lol with the hi downforce body they will be flat polly seeds.

keep the shiney side up!

Wayne
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Old 06-13-2007, 10:42 AM   #88
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Originally Posted by SWTour View Post
I got maybe a dumb question, but when I looked at the little video and the pics of the prototype car something I see disturbs me...

CHASSIS height.

It appears that you have less than 3/16 of an inch clearence to the ground...and you've also got a pic of how distorted a BODY can become under downforce load... So what happens when you put 200 LBS of downforce on those front tires...how much clearence will you have then?

I would guess, unless you are using NO suspension that can move, you'd want to be able to count on the chassis dropping 1/2 - 3/4 inch under full speed loads. The more evenly the better...

The pics look to have way too much frontal downforce...which should in my mind make it very steerinng sensitive too, needing more rear downforce.

I always kind of liked this type of shape and thought it should be pretty neutral at higher speeds...maybe even a blunter front nose yet.

The body will not become that distorted at high speeds. I made sure to say that the image was EXAGGERATED about 90,000 times more than what is actually happening. The computer diagram is done that way to more easily see how the body will deform. If the computer simulation showed the actual deformation, the actual deformation is so small, you wouldn't be able to see any difference from the original body from the deformed body. I made the body from fiberglass and is much more rigid than a 0.060" lexan material. A number of people have mention to me that the body is deforming way too much. It doesn't seem like people are paying attention to what I wrote underneath the picture about the deformation being exaggerated 90,000 times. Look in the upper left hand corner of this picture, it says DEFORMATION SCALE: 91368.7



I'm not sure where your 200lbs of downforce is coming from. If anything, the way the body is configured now, it will create lift. That is, if you don't take into account the ground effects I have designed on the bottom of the car. I haven't been able to test that yet.
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Old 06-13-2007, 11:00 AM   #89
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Why do you guys keep concentrating on Cup Car , and gtp bodies.

Look around on the internet, unless its an oval race like SWTOUR promotes run anything you want. Look around on the internet. Heck there are European, and Japanese manufactures outthere that produce som killer shells with the characteristics your looking for.

Keep in mind that the Japanese hold speed trial events and even though they are held on velos its not just a Cup body., They run some wicked looking stuff.

Take a look at Hpi, Ride they also have an acura nsx body that would work well. Blunt nose yet slight slop( ala gtp ) and a long tail with a wing mounted up between side finns. There are bodies out there that may work with added wings and side damns.

Just trying to help!!



Also is this speed challenge on a velo or straightaway ( drag strip) ?
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Old 06-13-2007, 11:17 AM   #90
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The body is made except for the back. The intended body shape is in B4maz's Avatar in green. It is neither cup nor GTP. It does look like it is very low drag. The run will be in a straight line on a dragstrip. Now that I can mention the ground effects, that is what will keep this body, which may have some lift without ground effects planted to the ground. The ground effects should kick in strongly at 100 mph plus. It will be concentrated to the back of the car. A front diffuser could be added as well though. The actual shape of the top surface of the tail may change from testing. I don't believe any bodies that you can purchase will withstand the high speed. That is why this one is in fiberglass. I realize other bodies could be used as a form for the fiberglass. We discussed a collapsible wing for speeds below 100 mph. I get trermendous traction gains on my pan car when the rear wing kicks in after only about 15 feet out of a corner. Nicks bare chassis had good forward traction when I drove it. There is considerable weight compared to my pan car which is at 40 ounces.
John

Last edited by John Stranahan; 06-13-2007 at 11:29 AM.
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