whittlebeast
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| posted on 18/9/06 at 09:03 PM |
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see
http://www.scca.org/_FileLibrary/File/2006_solo_rules.pdf
starting at page 144 of 316
Its just the rules of the class. It is difficult to get anything to handle if it does not have about 60% rear weight and about 5 lbs/HP with
driver.
AW
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locostv8
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| posted on 20/9/06 at 05:38 AM |
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This would probably be a US only option but. Page 130 says EM, which includes Locost 7s, unlimited engine with weight of 1800. I know of a McSorley
+4 car with a 302/T5/8.8 that weighs 1250 with 50/50 weight (but it is too flexible). That would say that you would have to do some rather serious
balast. WHAT IF, the balast was in the form of a 460 (everything but block/crank/rods aluminum) with a big spline toploader, attach the toploader to
an aluminum 8.8 diff then build a 7 clone around it. The 460 can easily be 513 and grow to as much as 600 infact a worked but mostly stock 460 can be
gotten over 500 hp with ease. If you have to add balast anyhow why not in the form of unbreakable running gear?
http://wrangler.rutgers.edu/gallery2/v/7slotgrille/hssss/
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whittlebeast
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| posted on 20/9/06 at 10:22 AM |
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Part of this entire project is to build a test ride for my web site. See http://www.v8efi.com
I want to develope a bolt on MAF controled Megasquirt kit for LS1 motors for streetrod and dragrace applications. I have friends that have done back
to back testing with with removable 400 lb plates under the drivers set. His findings were that the car was just as fast with the added weight. The
issue is it is impossible to get a RWD 50% rear weight car to accelerate off corners. 40-60 just works better. Point one F1 car with 50-50. Veiw
http://www.ncs-stl.com/mike/Mike_Gateway_Spin.wmv to get a real feel for what these cars drive like. I am just trying to develope a road worthy,
non-winged, thumper version of an A-Mod car with all the drivability of a super-bike.
The goals are under 11.5 in the 1/4 mile at about 135MPH, 1.6 geez in a corner and 1.5 geez on the brakes and quiet. A passenger seat is optional and
my have to be left out.
AW
[Edited on 20/9/06 by whittlebeast]
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kb58
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| posted on 20/9/06 at 01:49 PM |
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quote:
Originally posted by locostv8
I know of a McSorley +4 car with a 302/T5/8.8 that weighs 1250 with 50/50 weight
This is a mystery to me how this can be. The engine and tranny weigh >500lbs, so where's the equal weight over the back axle? The
driver's pretty much at the CG, so he doesn't enter the equation. The gas tank is way out back but probably only 50lb half full...
My doubts come from Super-7 cars with 4-cylinder engines in them being 50/50. Then 6-cyl cars came out with the same spec, now 8-cyl cars are
claiming the same. Okay, some of those old 4-cyl are heavy, but the same as a V8?
Maybe these V8 cars have huge heavy rear axles to balance it out, but you said it weighs 1250lbs... How can a much larger heavier engine be added,
along with a heavier rear axle, and neither gain weight nor shift CG?
[Edited on 9/20/06 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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leto
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| posted on 20/9/06 at 03:36 PM |
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The driver in a seven at CG?  Only with a sever case of lead foot me thinks. With 50/50 ratio CG must be at half the wheel base, about the location
of the pedal stand.
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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kb58
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| posted on 20/9/06 at 08:26 PM |
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I thought about that later... okay, fair enough, though if the driver is same, and the wheelbase the same, the driver becomes unimportant.
Installing an engine literally twice as large, an axle twice as strong, and larger wheels and tires, and have it not only weigh the same, but not move
the CG... is pretty amazing.
Maybe I'm wrong on this... just how much does a "typical" (automotive) 4-cyl Locost weigh?
[Edited on 9/20/06 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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locostv8
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| posted on 21/9/06 at 07:20 AM |
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This sounds like a familiar discussion.
All I can talk to is what I'm doing. I keep refferencing Deman because his Wide 7 is closest to what I'm building.
http://www.deman-motorsport.com/widespecs.htm
with a Hyabusa 1300 his car weighs 985 lbs. He uses MN12 (89 to 92 Tbird) spindles and brakes and MN12 rear components with steel diff in what I
believe is a +4 width 93" wheelbase car. I would imagine the eng/reverse box/driveshaft would weigh about 250 lb so you would have an approx
rolling chassis weight of 735 lb
These are the same components I am using except. Front spindles/brakes are modded to remove caliper mount and rubbing blocks for pads and being
replaced with PBR aluminum calipers for a weight savings of 20 lb per side. Rear diff is aluminum 2000 Cobra R with Torsen probably 20 lb lighter.
The weight savings is nearly made up by heavier wheels and tires. The 351 weighs 525 lbs, I believe this is an early 351 with steel
heads/intake/waterpump/exhaust manifold/flywheel, The later blocks as with the 5.0 are a bit lighter and with aluminum heads/intake/waterpump/flywheel
and tube headers I would imagine that you could remove 75 lbs for a total of 450 lbs which is within a few lbs of a 302 or 2.3 turbo. A T5 weighs 85
lbs. I doubt I would add more than 75 lbs for steel floorpan and slightly bigger tubing. I will be adding power steering and brakes which probably
add 50 lb. Total 1355 lbs.
The car example above is a +4 with MII knuckles/brakes and an 8.8 but smaller tires/wheels and a chunk of foam for seats so I believe it is
concievable that he hit 1250 lbs and the engine is set as far back as possible.
http://www.strokerengine.com/EngineWeights.html
http://wrangler.rutgers.edu/gallery2/v/7slotgrille/hssss/
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leto
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| posted on 21/9/06 at 04:01 PM |
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kb58
Sorry could not resist 
It is easier to balance out a 7 than you might expect. Moving the engine back a few inches makes a big difference, increasing the wheel base is also
effective. With a longer chassis like a +244 it should be possible to get 50/50 even with a quite heavy engine.
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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whittlebeast
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| posted on 21/9/06 at 07:49 PM |
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The problem is that 50-50 is not the goal, 40-60 is. If 50-50 appears to work good, then you need more power, a lot more power.
AW
[Edited on 21/9/06 by whittlebeast]
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locostv8
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| posted on 21/9/06 at 08:08 PM |
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Back to the original point.
One of the current engine masters buildups, Livornious (SP) built a 509 ci 460 putting out 835 (within 1 or 2, going off memory) and the 460 can
easily go 557 so without thier major masaging figure more ci a7 800 hp with an original weight of 720 which used HEAVY heads/manifold even with
stroker should be able to get down to 650 (prolly a bit less). A car that over powered would be more easily handled with an automatic so throw in a
C6 for 200 lb. Throw in another 100 lb for reinforcement still comes out about 1685 with a bit for balast over the axle. conservativly that comes
out p/w of 2.3 lb/hp. An 800+ hp big block would be a challenge to megasquirt. How do you spell TIRES/TYRES.
[Edited on 21/9/06 by locostv8]
http://wrangler.rutgers.edu/gallery2/v/7slotgrille/hssss/
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Peteff
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| posted on 21/9/06 at 10:31 PM |
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Tyres....
Night John boy. 
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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locostv8
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| posted on 21/9/06 at 10:45 PM |
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OOPS!! Forgot myself. Them rubber thingys at each corner that keep wearing on the back corners.
http://wrangler.rutgers.edu/gallery2/v/7slotgrille/hssss/
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DIY Si
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| posted on 21/9/06 at 10:47 PM |
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And for that dirty great V8, he'll need some DAMN wide ones too!
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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cymtriks
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| posted on 24/9/06 at 12:30 PM |
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Re my mods-
2500 to 2700 ftlbs per degree isn't the most that can be achieved with the locost but it is probably the best that you can get AND-
get the original bodywork to fit.
get commonly used engines to fit
not fit a cage
fit the book suspension
still save weight overall
not increase complication greatly
etc...
Fitting a roll cage will have a big impact on stiffness but will cost you on weight.
I can't understand the reluctance to use stressed panels unless you mean riveted panels which are a bit dodgy as the rivets can work loose over
time. Welded thin gauge steel panels should be fine and may weigh less than a diagonal with an ally panel.
Re weight distribution-
I'm sceptical of the 40/60 weight distribution being optimum. Perhaps it was for the car tested with a 400lb weight bolted on (post earlier in
this thread) but many mass manufacturers try hard to get get closer to 50/50. BMW made an advert boasting of their nearly "perfect" weight
distribution of within 2% of 50/50 for every model. The advert stated how some of the cars had batteries in different position to get this figure. Why
bother if it wasn't a good thing? Also some supercars are described as twitchy, or at least needing great respect, on the limit precisely
because of their rear weight bias.
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kb58
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| posted on 24/9/06 at 03:41 PM |
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At the risk of hijacking the thread...
On a turn at constant speed, yes, I agree 50/50 is best, but how often are we in that situation? Coming into this turn we are on the brakes. Under
braking we want equal load on all the tires for maximum braking ability, and a rearward weight bias helps accomplish this.
After we make our turn we step on the gas. For maximum traction we want more weight on the driven wheels and a rear weight bias accomplishes this
too.
One other thing, it is very common to have larger rear tires. In that same corner, our 50/50 car will not have evenly loaded tires; the fronts having
a higher load/area than the rears. I'd expect understeer from this "perfectly balanced" car.
I know in the big picture all sports cars do pretty well, but I do feel 40/60 is a more optimum target than 50/50.
As far as manufacturers saying what's best, I think there's a fair bit of marketing BS thrown in. That is, with a typical front-engine
car, I don't think it's physically possible to get weight distribution to 40/60, so it's in their best interest to say 50/50 is
"best." About moving the battery, yes, it improves things, by moving the weight toward the rear, which is where the 40/60 already is.
[Edited on 9/24/06 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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C10CoryM
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| posted on 25/9/06 at 04:15 PM |
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From my experience weight bias front/rear is much less important than centering the mass to make a car stable and predictable. The polar moment of
inertia (PMOI) is far more important to me.
This is why when you are adding ballast to get up to minimum weight you add it to the center of the car, not the back.
Think of a stock, front engine rwd sedan. Weight bias of 60/40 or so. Can expect some understeer with easy/smooth throttle oversteer. Pretty
predictable and easy to drive at steady state cornering right? So lets try and make it better and get 50/50 bias by moving the engine back further.
So now you have the heaviest lump almost in the middle of the CG, no weight up front, and the same weight in back. Add a little throttle oversteer
and the mass in the back is going to pivot on the CG with no mass up front to counter balance it and it will try to come around much faster and be
much harder to get back. Think of a dumbbell on a pivot VS a bowling ball of the same weight. The dumbbell is harder to get turning, but once it
gets going its hard to stop.
Will this car put down faster lap times? Maybe due to the faster PMOI up front on entry but maybe not because the driver is too scared to push it
to the limits.
The point I am trying to make is that centralizing the mass is a better thing to worry about than weight bias. PMOI is what gets you through tight
corners faster and lets you feel more comfortable pushing the car to the edge. Yes, it makes the car easier to slip out, but it also makes it a lot
easier to get back and less likely to turn around on you.
I feel like I haven't explained that very well but Ive run out of time for now.
Maybe I can clarify later if it doesn't make sense.
Cheers.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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whittlebeast
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| posted on 3/10/06 at 12:05 PM |
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quote:
Originally posted by cymtriks
Re my mods-
2500 to 2700 ftlbs per degree isn't the most that can be achieved with the locost but it is probably the best that you can get AND-
get the original bodywork to fit.
get commonly used engines to fit
not fit a cage
fit the book suspension
still save weight overall
not increase complication greatly
etc...
Fitting a roll cage will have a big impact on stiffness but will cost you on weight.
I can't understand the reluctance to use stressed panels unless you mean riveted panels which are a bit dodgy as the rivets can work loose over
time. Welded thin gauge steel panels should be fine and may weigh less than a diagonal with an ally panel.
Re weight distribution-
I'm sceptical of the 40/60 weight distribution being optimum. Perhaps it was for the car tested with a 400lb weight bolted on (post earlier in
this thread) but many mass manufacturers try hard to get get closer to 50/50. BMW made an advert boasting of their nearly "perfect" weight
distribution of within 2% of 50/50 for every model. The advert stated how some of the cars had batteries in different position to get this figure. Why
bother if it wasn't a good thing? Also some supercars are described as twitchy, or at least needing great respect, on the limit precisely
because of their rear weight bias.
I have no intent to try to build one of these without a cage. Every sanctioning body that I know of will insist on one. My intent is to have the
fastest streetable autocross car in the country and still have a respectable e-mod car. I intend to have the ability to accelerate at about .9 g and
corner and brake at close to 1.5 g on Hoosier race tires. The goal is 1/4 mile in under 11 sec at about 135 MPH. Traction limited thru about 100
MPH. 40-60 may be a little aggressive but 43-57 is achievable. The motor will be capible of about 400 ft lbs thru a torque converter and about 1.8
first gear giving about 1500 ft-lbs of torque thru the driveshaft alone.
Re FEA numbers, Where are you appling the loads and the constraints? I am holding the right rear spindle XYZ, left rear spindle YZ and the front
center of the chassis in the z direction. 1200 lbs vertical on the front left spindle and -1200 lbs on the right front spindle. All shocks are
replaced with solid links. the front spindles are moving about .225" at this 5100 ft-lb torque for close to 10000 ft-lbs / degree. This is
about 66% of the strength a typical 3800 lb Nascar stock car.
AW
[Edited on 3/10/06 by whittlebeast]
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leto
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| posted on 8/10/06 at 05:59 AM |
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“the front center of the chassis in the z direction”
This one sounds a little suspicious, do you get any reaction here?
Try locking one of the front spindles in z and let the reaction force be one part of the force pair.
EDIT:
Sorry. Early Sunday morning z is “sideways” I guess, so let's forget about the force pair.
Still, if you get a reaction in that point something is fishy.
Cheers!
[Edited on 06-10-8 by leto]
“I'm gonna ride around in style
I'm gonna drive everybody wild
'Cause I'll have the only one there is a round”. (J. Cash)
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whittlebeast
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| posted on 9/10/06 at 02:10 AM |
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Restraining of the front center realy is in the Z (up/down) direction. Without that even with matching but opposite forces making a torque couple
without the vertical movement restrained you get a division by zero in the calcs. If I constrain one front spindle and apply the torque load to just
one front spindle I get the same chassis stiffness.
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whittlebeast
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| posted on 17/11/06 at 12:58 PM |
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The build begins 
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sb427f-car
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| posted on 19/12/06 at 06:04 PM |
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Any progress and how did you do the bearings on your AM cart?
-Aaron
2005 WRB WRX, stock and slow.
Researching a +442 or custom 7 project.
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turbo time
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| posted on 1/1/07 at 07:09 AM |
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Hey Andy,
I talked to you a little while back about the sucker car, thanks again for the info. I Didn't know you were on this forum, just wanted to say
the locost build looks good, should be fun... (I'm still designing and finding sponsors for the project.)
[Edited on 1/1/07 by turbo time]
The Projects: www.absurdcars.com
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