I get that a short wheelbase generally gives you a better turn radius but how short is to short and how long is to long? Would hp be a factor. Meaning in a higher hp car could you use the power to rotate the car at better?
I get that a short wheelbase generally gives you a better turn radius but how short is to short and how long is to long? Would hp be a factor. Meaning in a higher hp car could you use the power to rotate the car at better?
My experience is that the duster (108 wheelbase) is much easier to drive sideways than the miata, or the old extended cab longbed i had. So, medium length wheelbase better than the extremes.
All i got.
wheelbase to track width would also play a role, see the ill handling of the smart car.
Not to mention weight distribution, center of gravity, etc.
In my uneducated opinion, medium-short would be ideal for tight courses. Medium-long for courses with more fast sweepers. *shrug*
Very timely topic. For the past few days I've been mulling this same question in my head. Thought about asking it but glad Stampie beat me to it. Not talking extremes, like the Smart Car. More reasonable wheelbases.
What made me think of this question is there is a guy on a book of faces Opel page that is doing a body swap of a GT onto a Miata chassis. He had to lengthen the GT body 6-7 inches to fit the Miata chassis. I've heard about others doing also and they all lengthened the GT body. I was wondering about just transplanting the Miata suspension onto the GT unibody and adding box flares to make up the width difference. GT engine is already inset into the firewall and behind the front wheels but naturally the cast iron no power GT engine would also be swapped out for something more powerful but not too heavy. How would it affect handling? In my head, this is an easier swap than the body to chassis. All this being hypothetical. Don't have the space, equipment, time or dollars to make it happen. Just bench building.
Just consider a somewhat normal/regular small car. Like Spridget being about the smallest.
wlkelley3 said:. I was wondering about just transplanting the Miata suspension onto the GT unibody and adding box flares to make up the width difference.
with just the body swap you dont have to deal with suspension pickup points changing in regard to the chassis and you can run off the shelf parts for spares like the driveshaft,
width has way more effect on autocross course than wheelbase, since shorter wheelbase cars tend to be narrower also they tend to be faster. The slalom equation only ask for width and grip. simply put a smaller car runs a shorter course.
slalom equation:
(π/8)√(W+1/G)= Time in seconds between cones
*W is width(feet) of vehicle, G is total lateral grip(Gs)
echoechoecho said:width has way more effect on autocross course than wheelbase, since shorter wheelbase cars tend to be narrower also they tend to be faster. The slalom equation only ask for width and grip. simply put a smaller car runs a shorter course.
slalom equation:
(π/8)√(W+1/G)= Time in seconds between cones
*W is width(feet) of vehicle, G is total lateral grip(Gs)
But I was told online that the extra width of a BR-Z relative to, say, a Miata was irrelevant.
(I don't like wide cars for this reason. You can't cut as close)
I think you are asking about just a couple of variables of a much larger and more complex equation.
I would guess there is an "ideal" track to wheelbase ratio. I would look up this ratio for some top handling cars (F1 car, Miata, BRZ, M3, 911) and see if you find any harmony in the data points.
Auto manufacturers spend millions figuring this stuff out. Derive the anwser from implemented solutions.
In reply to echoechoecho :
Well thank you. Now to go see what the track width is on small Toyotas.
In reply to Stampie :
Wheelbase affects straight line stability but by itself won’t seriously effect your times.
Track width on the other hand will seriously affect times. A wider car has to travel further than a narrow car.
MG’s while their suspension is seriously dated with zero camber gain front and straight axle rear are both short and narrow. Track width is something like 50”
NordicSaab said:I think you are asking about just a couple of variables of a much larger and more complex equation.
I would guess there is an "ideal" track to wheelbase ratio. I would look up this ratio for some top handling cars (F1 car, Miata, BRZ, M3, 911) and see if you find any harmony in the data points.
Auto manufacturers spend millions figuring this stuff out. Derive the anwser from implemented solutions.
Toyota increased the track width for the ST205, and it was slower in stage rally than the ST185 as a result.
Wider track means worse handling if you are using differentials that do not like unlocking. The more "square" the footprint is, the more sensitive handling is to the differentials.
Wider track and longer wheelbase also mean more weight to carry around, all else being the same.
frenchyd said:In reply to Stampie :
Wheelbase affects straight line stability but by itself won’t seriously effect your times.
While this is true, remember that back In the days spirits were brave, the stakes were high, men were real men, women were real women and small furry creatures from Alpha Centauri were real small furry creatures from Alpha Centauri. The Porsche 935 was doing well over 220 mph down the original Mulsan straight on an 89” wheelbase......with a spool diff!!!
Adrian_Thompson said:frenchyd said:In reply to Stampie :
Wheelbase affects straight line stability but by itself won’t seriously effect your times.
While this is true, remember that back In the days spirits were brave, the stakes were high, men were real men, women were real women and small furry creatures from Alpha Centauri were real small furry creatures from Alpha Centauri. The Porsche 935 was doing well over 220 mph down the original Mulsan straight on an 89” wheelbase......with a spool diff!!!
It also had a giant whale tail spoiler that stuck out a meter past the end of the car so that the center of aerodynamic pressure was behind the center of force.
Arrows fly straight because we make the noses heavy and put feathers on the back to increase drag back there.
The national level data points to the shortest possible/allowed wheelbase generally being an advantage for autocross.
I drive an almost-stock 500 Abarth and I enjoy the short wheelbase for autocross. A little extra stability (and power) would be nice for track work, but on a tight cone course it’s quick and fun.
In reply to Knurled. :
Aero in autocross is far less important than weight. At the slower speeds of autocross compared to LeMans or Elkhart Lake, I’m not sure the added weight of aero can be justified.
Knurled. said:NordicSaab said:I think you are asking about just a couple of variables of a much larger and more complex equation.
I would guess there is an "ideal" track to wheelbase ratio. I would look up this ratio for some top handling cars (F1 car, Miata, BRZ, M3, 911) and see if you find any harmony in the data points.
Auto manufacturers spend millions figuring this stuff out. Derive the anwser from implemented solutions.
Toyota increased the track width for the ST205, and it was slower in stage rally than the ST185 as a result.
Wider track means worse handling if you are using differentials that do not like unlocking. The more "square" the footprint is, the more sensitive handling is to the differentials.
Why is a autocross car wide across the rear? If you’ve seen the new Morgan 3 wheeler do doughnuts and watch it whip around an autocross track it seems to me that there might be something to a Narrow rear track.
We know that a tear drop has the least aerodynamic drag. While wings, and spoilers add significant drag.
Perhaps we don’t need to go to a single rear wheel but a more narrow rear track would aid in getting a teardrop shape. Reduced drag ( and weight )
In reply to Knurled. :
Don’t spoil one of my favorite WRF facts with physics!!!! 
Adrian_Thompson said:In reply to Knurled. :
Don’t spoil one of my favorite WRF facts with physics!!!!
I see the 935 as a triumph of engineering over physics.
Or, straight from the mouth of a Porsche engineer during their Formula 1 days, Porsche excellence is the truimph of superior Porsche engineering over incredible Teutonic refusal to admit that they were wrong (air cooling, rear engine).
I can make a very strong argument that When it came to racing, up until the 911 GT1, Porsche were an engine team who won in spite of their chassis.
Adrian_Thompson said:I can make a very strong argument that When it came to racing, up until the 911 GT1, Porsche were an engine team who won in spite of their chassis.
They also had some very good chassis engineers who forced good handling out of an inherently flawed chassis layout, because it could not be altered because it had been handed down from Ferdinand on High.
This is the reason why the 928 was always treated as a bastard child despite being superior in every way to the 911 that it was intended to supercede, why the 924 and 944 were never given the attention they deserved, and why to this day the Boxster/Cayman must play second fiddle to the almighty 911.
My F500 autocross car has a 73" wheelbase and per the rules maximum width is 55". I'm not sure of the actual track width but my gues is around 50"
In reply to Knurled. :
I call BS on this. Unless you can't see where the car is going (some cars have ridiculous overhangs, poor sightlines, misplaced fender ridges, etc.) you can cut EXACTLY as close with a Miata as you can a Corvette.
Miata might be the answer, but Corvette has the highest rankings in autocross finishes across almost EVERY category.
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