Hello and Welcome to Hammer Down Dyno Service, home of
affordable dyno testing for the Briggs V-twin. Please take
some time to read our information. Feel free to e-mail us with
any questions or concerns. If you have never visited our
facility or are unfamiliar with Dyno Testing. Please read the
Frequently Asked Questions below.


How does it work?
Hammer Down uses a custom made dynamometer that utilizes
your current engine mounting plate and clutch setup. Your
engine is connected to a drive axle using the typical
clutch/sprocket setup found on the race car. Upon
engagement, the chain drives a heavy wheel to act as a load
resistance similar to how the car would be on the racetrack.
Because the engine has a load on it there is no additional
stress placed on the engine versus what it would experience
on just one straightaway of a track. In this wheel are sensors
which provide data in the form of acceleration vs. time
measurements. These ultimately tell us the horsepower of the
engine during a run. This form of dynamometer is widely
known as one of the most accurate and repeatable ever
produced which is very valuable when comparing tests and
Also attached to your engine are two cylinder head
temperature sensors and an rpm sensor to monitor
everything you could see if you were in a race and also to
keep test conditions similar.

What do I need?
In order to make serving you easier and to save you in
additional set-up costs your engine should be configured as
-The engine mounting plate should be attached (we may need
to adjust the bolts for chain alignment on the dyno).
-The L shaped throttle mechanism must be attached to the
engine along with the carburetor linkage and throttle return
spring you normally use.
-Your engine must be complete as it came from the racecar
(starter, carburetor, flywheel covers, full exhaust system
-A reliable and working clutch (with or without crank saver)
that can withstand the warm-up procedure and repeated
tests. A spare clutch is highly recommended to bring along as
we have encountered limited clutch problems in the past.
-Your own preferred fuel. The system uses its own fuel pump
that will draw fuel from any reasonably sized container
(Gallon jug-5 gallon can). BE SURE to bring enough with you
so you can use the same brand and grade of fuel throughout
all of your tests. KEEP IN MIND that average fuel
consumption is about 1 gallon for five pulls.
-Tools you would use to adjust, work on, or repair your
engine. We do not guarantee to have all tools necessary to
fully adjust your engine and would prefer to protect our
assets. You should have the tools you would need to build a
carburetor, remove manifolds, shrouding, spark plugs,
flywheels, clutch repair, tape for flywheel cover, change jets,
and other operations.

The dyno is equipped with the following:
-Breather lines to attach to your valve covers
-Its own battery with cables to connect to your “hi-tech”
starter (no solenoid is present so the “old style” starter can
not be used.
-Its own fuel system with a line to connect directly to your

Does it really work?
In a spec class it is common knowledge that any advantage is
critical. Everyone preaches about set-up and handling being
the key to speed. While this is true, having a horsepower
advantage will certainly help. Like most things, experience is
the key. Understanding how engines work is important to
gaining anything from your experience. If you don’t know
how to do anything to an engine besides change the oil and
gap the spark plugs, dyno testing is not for you. However,
dealing with a sealed engine still leaves a lot of variables to
adjust and configure. Without going into the list of
adjustments that are available one should also remember that
you can bring several sets of parts with you to see which
ones work best. Changing carburetors, manifolds, carburetor
spacers, spark plugs, exhausts, and air filters will certainly
affect power ratings. Isn’t this information you’d like to know
before hitting the track?

Will it damage my engine?
After reading the disclaimer you may be apprehensive about
trying this. Many people visualize dyno testing as an engine
with open headers sitting at redline in a room being put
through every torture test you can imagine. This is not the
case. A typical dyno pull lasts about 10 seconds. Max rpm can
be set wherever the customer wants. Theoretically, an engine
running a dyno test is under no more stress than one
accelerating from pace speed to the first turn of a racetrack.
Ensuring that the engine’s oil does not become milky and
monitoring head temperatures make test conditions the same
as a normal race.

Is it legal?
Certainly. No illegal parts or machine work are offered by
Hammer Down. We are simply a provider of a very expensive
and sophisticated tool for you to rent to measure your engine’
s performance. We are not affiliated with Speedway
Entertainment or any dealers, tracks, or manufacturers. We
will test any engine under 50 horsepower legal or not.
All rights reserved to
Hammer Down Inc..
Throttle Connection- Connects to bellcrank using allen bolt used for throttle cable heim