There was not much detailed information on how to make a small engine dyno, so I put together a couple step by step videos on a budget hydraulic build.

I put together a homemade small engine Dyno for a DIY build, to tune some kart and mini bike engines. Subscribe to see how I’m breaking it in with futures videos and doing calculation for HP ratings! I’ve been discussing many things with DIY dyno groups and people with similar machines to get the most accurate break in and test procedure as can find! I will be making minor adjustments as listed in the video, based on what I find to be best! I’m going to be tuning engines for go karts, race kart engine tuning and mini bikes. I wanted to have a home made dyno that could do about 20 HP.

Subscribe and check back to see how I use it and check horsepower gains for performance engine tuning!

Want to calculate horsepower? I made a second video showing how to use it after it’s built. This may give better detail of what you get as an end result so you can see how to tune your engines and get the best learning experience!

I’ve still got my Tillotson 212r race engine video to compare to the Predator 212 non hemi engine. Check it out on my YouTube Channel “Me Going Fast”!

Total cost for this Small Engine Dyno was $500 plus tax and shipping. I called a few other places, their dynos cost anywhere from $5000 for a base model without computer graph, to $15,000 with computer print out and all the bels and whistles. I have seen used dyno cost $4,000 for inertia dynos to $8,000 used. Some water brake and hydraulic dynamometers cost $3,000 to $8,000 used.

So basically I’m cheap, and want to tune engines.

Parts for instructions for my DIY Dyno seen in video — Parts coming from Hydraulics Direct in Colorado USA: 5/8″ ORB (SAE 10) Male x 1/2″ NPTF Female – (Note: can use swivel female adapter here instead for ease) 3/4″ ORB (SAE 12) Male x 3/4″ NPTF Female – (Note: can use swivel female adapter here instead for ease) 1/2″ NPTF Male x 1/2″ NPTF Male (*QTY 2*) Extender – 1/2″ NPTF Male x 1/2″ NPTF Female Union Tee – 1/2″ NPSM Swivel x 1/2″ NPSM Swivel x 1/2″ NPSM Swivel 90 degree Elbow – 1/2″ NPTF Male x 1/2″ NPSM Swivel 90 degree Elbow – 1/2″ NPTF Male x 1/4″ NPSM Swivel 90 degree Elbow – 3/4″ NPTF Male to 1/2″ NPSM Swivel 90 degree Elbow – 3/4″ NPTF Male to 3/4″ NPSM Swivel (*QTY 2*) Note: extra mentioned “ease of assembly parts” – I recommend getting as you’ll see in my next video 1/2″ NPTF Male x 1/2″ NPSM Swivel [$2.69 each] 3/4″ NPTF Male x 3/4″ NPSM Swivel (*QTY 3*) [$3.24 each] Note: I used discount code “new20″ to save money. It may still work. Part coming from BMI Karts: Fully Adjustable Motor Mount Plate with bolt kit Parts coming from Amazon, but can come from other sources: Dynamic Fluid Components hydraulic pump with 3/4″ shaft and key (CLOCKWISE direction – NOTE that most CLONE engines run counter clockwise) GP-F20-20-PL-C Hydraulic Hose 3/4″ x 48″ 2-wire Male to Male Hydraulic Hose 1/2″ x 48″ 2-wire Male to Male 5 Gallon Field Tuff Hydraulic Fluid Reservoir 2 1/2″ pressure gauge, liquid filled 0-2000 PSI 1/4″ mount NPT (Note: I upgraded to this 3,000 PSI since video was made) In-Line Variable Control Valve 1/2″ NPT connections Thread reducer bushing 1 1/2″ Male to 3/4″ Female NPT Teflon thread tape Digital tachometer (Note: not the best option for high RPMs AND needs to be mounted directionally for the magnet if used) 10′ #40 chain with 2 master links 3/4″ centrifugal clutch 10 tooth, 420 chain sprocket #40 size 36 tooth sprocket 3/4″ bore Coming from Tractor Supply: 5 gallons hydraulic fluid Coming from hardware store: 1 1/4″ x 3/8″ carriage bolts with metal locking nuts (*QTY 2*) 2 1/2″ x 1/4″ bolts with washers and nuts (*QTY 4*) 5/8″ x 1/4” bolts with metal locking nuts (*QTY 4*) Can save money by using propane or other tank, if have an older tach. if already have clutch, if already have mounting plate, if anything goes on sale.

homemade dyno
homemade dyno

Early on

This build is the most cost productive way to get into accelerating your learning for small engine builds. It can help tune on load. Although it’s not a certified Dyno, the best use for it is comparative before after results on engines to see gains with real time tuning.


Additional measures can be added and the dyno can be adapted for things such as fuel/air meter and as needed load cell to arduino/RP board. This, however is a simple setup for HP, Torque measures, and tuning your kart engines, mini bike engines, or whatever else your needs would be.