What Dyno? Water Brake, Inertia.....

I’d like to acquire a dyno so I’d be interested in comments, feedback, suggestions, from those who own or are familiar with them. I would primarily be using it for 4 stroke but would want the capability to also use it for 2 stroke Rotax, Rok, IAME, etc. as well. I’ve looked online at the Hewit and Land and Sea dyno’s but it’s not easy to compare as not much technical data is shared online. Accuracy and repeatability would be the key items in my decision making.

Thx
 

alvin l nunley

Site Supporter
In 1985, I purchased a Go Power water break dyno absorption unit. This was the dark ages of karting dyno's. lol. I built everything else, everything!! A friend of mine, a computer geek to the 10th order, wrote the acquisition software. In 1985, at the IKF Nationals, I showed the people from Yamaha of America a dyno sheet from my software, and they agreed, their dyno sheet looked pretty much like mine. Not definitive, I know, but encouraging.
The water break came with a graph showing at what RPM, at what horsepower, and RPM, the absorption unit could work. This gave me an idea of what RPM I would have to spin the absorption unit. My main concern was to spin the absorption unit as slow as possible, this would give me much more definition. My water supply came right out of the faucet and the hot water coming out of the absorption unit went straight into the drain.
The strain gauge, that was supplied with the absorption unit, is very sensitive to the ambient temperature. Everything worked very well. My acquisition hardware, analog to digital converter, was slow, that was the only negative thing that I ever experienced. Modern acquisition software so much faster. You're right about the dyno makers being very closed mouth, I have some experience with that.
Inertia dyno's, I believe, have their own problems with accuracy.
Call me, I'm home most of the time, I'll give you more details.
 

flattop1

Dawg 89
The inertia is accurate , as would be a land ans sea .
The water brake may be able to brake in engines and do a longer load analysis .
 

knighty

Member
I have an inertia dyno and I'm quite happy with it. A water brake dyno has potential health issues associated with the cooling system, associated with legionella bacteria, just tread carefully there, an eddy current dyno is far more posh, but reflected in the price.

The reason I like my inertia dyno is because it has a 25Kg flywheel, and that never changes, therefore testing between engines is far more consistent, the water brake and eddy current have many more factors that can sway the results between engines. Others will disagree for sure.

If it comes down to cost, the inertia dyno is far cheaper, the best thing I did with my dyno was to update the software in order that it records average power and spin time between 2 points. If you are looking at just a power curve and torque curve let me assure you are working blind to your engines actual performance. I see some engines make fantastic power, but the spin time is awful, as a guide 0.05 seconds of spin time gain on my dyno equals 0.3 seconds gain in lap time on the track. Spin-time is the most important parameter on my dyno by far. Heres a sample dyno plot at the bottom of this link. Its a SportDevices dyno.

https://www.knightorque.co.uk/services
heres the SportDevices website

https://www.sportdevices.com/
I have the Sp1-V4 control unit. You can just buy this unit and hook it up to any inertia dyno, very cost effective.

https://www.sportdevices.com/sp1.php
The software is free to download from the site.
 

DynoDon

Moderator
I like my water brake. I have control over holding a certain rpm to view changes. Be aware that if you purchase a land and sea that the software that goes with the dyno will not transfer to you unless you buy it. Many are already outdated and land and sea has no support for it. So they say. Land and sea informed me that they could have me arrested for using the software issued with the dyno I purchased. In order for me to set up the dyno correctly I needed to invest another $1700 worth of software from them. Also their bedside manners on the phone are less than to be desired. Not just once but two times. I got the impression that if you weren't a drag team or a nascar team that spent thousands of dollars with them you weren't important. That was speaking with the head honcho. Once I got an opportunity to speak with the technician he was exceptionally helpful. Still doesn't erase the fact that I need to spend another $ 1700 to get my dyno up and running. If I purchase software, I will get it from performance trends who has the software to work with land and sea brake. When the dyno is sold to a buyer the software is in the name of the buyer. There is a clause in the contract that says no one else has rights to use the software.
 

Don K

Member
We used On Trak software on our low budget inertia dyno for cost. Did OK for our needs. The Performance Trends offered a lot more features and was probably worth the added investment.

The inertia dyno we built immediately became the best tool in our garage. Not only did it allow us to fine tune our motors it allowed us to fine tune our clutches. Results were all positive.

DK

http://performancetrends.com/CustomerDynos.htm
 
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CarlsonMotorsports

Site Supporter
Performance Trends is awesome - can't go wrong with them for service and their data acquisition.

I have a brand new (circa 2000 or so) Prototype hydraulic dyno that I purchased a load cell and parts to take it digital (same as the Davenport dyno that I regularly use here in the shop.) I had purchased this dyno with the intent of renting it out to other builders/DIY'ers to use in our shop and the idea got squashed when I realized how easy it is to wreck a dyno (load cell, etc) for an untrained person. Anyhow, that dyno (just as I got it) is available if anyone is real serious and wants to put the Perf. Trends system on it. Not looking to just unload it -- Heaven forbid anything happen to our primary, this would be my back-up.

Personally, I like the constant load dynos and being able to pull down rpm rather than just seeing how quickly an engine can accelerate.
Both types of dynos have their advantages and drawbacks.

I LOVE our dyno because it is repeatable - that's the very most important thing to me.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
 

alvin l nunley

Site Supporter
I have a dyno spreadsheet, it's free. You have to put the torque numbers in manually, but if you enter the correct temperature and barometric pressure, it will do the math to give you a correction factor. Use metric or decimal. It also has an Excel dyno chart. See the picture.
27 dyno chart.jpg
 
I like my water brake. I have control over holding a certain rpm to view changes. Be aware that if you purchase a land and sea that the software that goes with the dyno will not transfer to you unless you buy it. Many are already outdated and land and sea has no support for it. So they say. Land and sea informed me that they could have me arrested for using the software issued with the dyno I purchased. In order for me to set up the dyno correctly I needed to invest another $1700 worth of software from them. Also their bedside manners on the phone are less than to be desired. Not just once but two times. I got the impression that if you weren't a drag team or a nascar team that spent thousands of dollars with them you weren't important. That was speaking with the head honcho. Once I got an opportunity to speak with the technician he was exceptionally helpful. Still doesn't erase the fact that I need to spend another $ 1700 to get my dyno up and running. If I purchase software, I will get it from performance trends who has the software to work with land and sea brake. When the dyno is sold to a buyer the software is in the name of the buyer. There is a clause in the contract that says no one else has rights to use the software.
Thanks and your impression of the Land and Sea customer service is exactly what I have experienced. I have no idea why they bother spending so much effort building products specifically for the small engine (kart) market and then treat you like sh*t on the phone.
 

bpoirier

Site Supporter
I bought a Hewitt inertia dyno last year. It was totally worth the investment. It uses Performance Trends software. It makes tuning motors very easy. It's repeatable and consistent. I've made over 120 runs on it from stock predators to open billet motors. Stan Hewitt builds a great product and has always been available and helpful with any questions I've had.
 
Performance Trends is awesome - can't go wrong with them for service and their data acquisition.

I have a brand new (circa 2000 or so) Prototype hydraulic dyno that I purchased a load cell and parts to take it digital (same as the Davenport dyno that I regularly use here in the shop.) I had purchased this dyno with the intent of renting it out to other builders/DIY'ers to use in our shop and the idea got squashed when I realized how easy it is to wreck a dyno (load cell, etc) for an untrained person. Anyhow, that dyno (just as I got it) is available if anyone is real serious and wants to put the Perf. Trends system on it. Not looking to just unload it -- Heaven forbid anything happen to our primary, this would be my back-up.

Personally, I like the constant load dynos and being able to pull down rpm rather than just seeing how quickly an engine can accelerate.
Both types of dynos have their advantages and drawbacks.

I LOVE our dyno because it is repeatable - that's the very most important thing to me.


-----
🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
www.CarlsonMotorsports.com
Carlson Motorsports on Facebook
30 years of service to the karting industry
Linden, IN
765-339-4407
bcarlson@CarlsonMotorsports.com
repeatability is huge when you are looking for .1-.2 hp
 

CarlsonMotorsports

Site Supporter
repeatability is huge when you are looking for .1-.2 hp
Absoltely!
I'd say it's equally important when you're looking for 5 hp on a 500 hp engine.
Dynos are merely a comparison tool. Really not much different than your stop watch.
Like your dyno, if your stop watch stopped being repeatable, it wouldn't be of much value.
 

triton03

Member
Ihave data trends on my inertia dyno and I have a local ( within 20 miles) weather station and I am linked to it so it automatically corrects everything but I think one of the most important part especially in the winter is to have it in a climate controlled environment I’m getting ready to try to change my bearings to oil bath instead of grease
 

alvin l nunley

Site Supporter
Alvin, In case you haven't ever explored the many great things available in a dyno print out sheet I would really recommend that you spend some time on this web site. http://performancetrends.com/
Just looked at the dyno print out sheet on the site you listed. There's a correction factor number but no barometric pressure or temperature information. And they use the old SAE standard reference 29.92 and 60°. SAE changed that, I think, in 1999.
The sheet that they show has a correction factor of 1.2. They must be using uncorrected barometric pressure. The only numbers I have found to be readily available are corrected to sealevel. I've been tracking weather conditions for 3 years and have never seen a 1.2 correction factor. That's part of the reason I was asking about a dyno sheet with barometric pressure and temperature listed.
 

alvin l nunley

Site Supporter
To follow up on that 1.2 correction factor, on my dyno sheet the barometric pressure has to be at 25.00 and 77° F. Where in the United States can you get that low of a barometric pressure?
 
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