taken from k-series.com
King Motorsports sent us this useful info.
Why does wheel hop occur on a front wheel drive car?
There are a number of variables, from a number of independent systems on the
vehicle, that, under the right conditions cause wheel hop to occur.
Primarily the drivetrain and suspension are the two systems that cause most
of the problem. From the factory the RSX and Civic have the suspension and
drivetrain connected to the vehicle by means of rubber bushings. Rubber is
an elastic material - that is an important fact.
When the vehicle is accelerated quickly a few things happen. Frist, the
increase in torque from the engine make the engine want to twist in the
opposite direction that power is being applied. The engine mounts are in
there to resist this motion, and the result is the engine tilts back towards
the fire wall. This is very evident when you have a car on the dyno. This
movement puts a good deal of downward force on the subframe once the engine
mount travel is used up.... again, the purpose of the engine mount is to
take up some of this force and control the speed of this movement.
At the same time, the force being applied through the drivetrain is
transferred to the suspension via the driveshafts, hubs, wheel, tire, and
then (hopefully) to the road surface. These forces act on the suspension
components and weight is transferred from the front of the vehicle to the
rear. In other words, the front suspension "unloads" and the rear suspension
is "compressed"
You now have two systems (drivetrain and suspension) interacting with each
other - one trying to push the front of the car down and one trying to lift
the front of the car. As the wheels spin they are constantly gaining and
losing traction which in turn is constantly adding and removing the
upward/downward force on the front of the car -> the forces from the
suspension (weight transfer to the rear) and engine are both impacted by
this gain and loss of force (traction) in the system.
The result is something like a harmonic, an "oscillatory mechanical system"
that develops. Forces are transferred causing traction to be gained and lost
causing forces to be transferred.... and so on until it gets so bad that the
front wheels literally bounce on and off of the road surface. Large
irregularities in the road surface is an outside variable that can also
worsen the situation, but that is a variable that is not necessarily in our
control.
There are a number of things you can do to improve the situation:
1)Change the suspension to minimize the weight transfer front to rear and
also to improve the up and down motion of the front wheels when wheel hop
does start.
2)Change the engine mount system to minimize the amount of travel, time of
travel, and resultant forces that occur when the engine applies large torque
loads.
3)Improve the traction in the system.
In my humble professional opinion, the biggest impacts will come from
changes made numbers 1 & 3. Increase compression damping in the rear shocks
and both compression/rebound damping in the front shocks. To better the
traction a good set of sticky tires and a limited slip diff will go a long
long way.
As for the engine mounts, yes they do help, but at the expense of vehicle
comfort. Also, by eliminating the movement in the engine mount set you risk
damage to the drivetrain components - the forces have to go somewhere...
To answer the question at hand... all other things being equal the ES motor
inserts will reduce wheel hop more than the Mugen set because they pretty
much completely eliminate the movement of the engine. But, remember the
reduced wheel hop will come at the expense of increased drivetrain wear and
potentially failure. Bottom line is that drag style launches are hard on a
car. Your best bet is to increase traction and have the suspension set up to
handle your specific application.
You, or those in the peanut gallery, may be wondering why Mugen even made an
engine mount set if they don't really a lot to reduce wheel hop... In
spirited road/track driving and road racing controlling the engine movement
is important for a different reason. Same technical stuff applies with
weight transfer, however controlling engine movement and resultant forces is
needed to keep the car settled during hard, fast, down and upshifts. When
you are "on the edge" in the middle of a high speed turn and you go to grab
the next gear (upshift) you want controlled movement from the engine because
any slight change in weight can disrupt the balance of the car and send you
spinning into the grass. The same goes for downshifts under hard braking.
That's my $0.02 on the subject.
Clayton
King Motorsports
Jason Christopherson
Store Manager
tintmasters motorsports
Fargo, ND
(701)239-8468
www.tintmasters.net
