Dynomometer low cost ?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
Rep732 said:
clutch engagement is only relevant to the rig being on the ground . On the dyno a clutches only purpose is to put the power down reliably and hold it
Click to expand...
Ya BUT if the rpm is to low the motor is OFF the PIPE , in a 2 stroke this is everything ! all the power is ON the PIPE.
 
Yea but on a dyno you have endless room for the engine to get back on the pipe. The engine will pass by that rpm regardless where the clutch will engage
 
So with a clutch at a higher engagement your going to miss out on a pipe that comes on off idle. From what I understand short cones higher in the band and longer cones more torque ?
 
Rep732 said:
So with a clutch at a higher engagement your going to miss out on a pipe that comes on off idle. From what I understand short cones higher in the band and longer cones more torque ?
Click to expand...
BASICALLY Yes on the smaller vs bigger displacement , theres a bunch of calc's you have to do to figure it out , on a dyno you can measure it , I don't know for sure what I will see ???? this is fairly new to me , Ive dyno'd race cars like RX7 etc. but they were inertia dynos not brake like this one.
 
Seandonato73 said:
You shouldnt really have load on the engine till its hit max rpm. Then you drag it down. Then go back up again.
View attachment 68188
Click to expand...
I have read articles that say static load is the best test so ?? I need to read up on this more , but for now it will be off the clutch so whatever spring RPM is in there will be the setpoint, I don't trust my setup to do 15,000 Rpm at the brake disk !
 
buzzkill said:
I have read articles that say static load is the best test so ?? I need to read up on this more , but for now it will be off the clutch so whatever spring RPM is in there will be the setpoint, I don't trust my setup to do 15,000 Rpm at the brake disk !
Click to expand...
How they are saying to do it is how I was taught to do it. Now diesels don't spin fast, and neither do most gas engines, but it was more or less the same for either. Matt them out then start the pull.

I would think if your bearings are up to it, the rpm isnt going to be much of an issue. Your set up is light so vibration should be minimal. the only downside to your set up is managing heat build up in the braking system, which could cause inconsistent brake loads. However I don't think this will be a major issue unless your doing sustained pulled, or multiple pulls consecutively.
 
this setup is not balanced enough to run those speeds trust me ! at 3k rpm it is already shaking

Seandonato73 said:
How they are saying to do it is how I was taught to do it. Now diesels don't spin fast, and neither do most gas engines, but it was more or less the same for either. Matt them out then start the pull.

I would think if your bearings are up to it, the rpm isnt going to be much of an issue. Your set up is light so vibration should be minimal. the only downside to your set up is managing heat build up in the braking system, which could cause inconsistent brake loads. However I don't think this will be a major issue unless your doing sustained pulled, or multiple pulls consecu
Click to expand...
 
IMG_20210111_124203334_HDR.jpg

here is the setup now , the load cell is on the end of the bar , just ran 2 tests , got some mixed detailed results BUT I think I am getting real numbers now , peak was about 4 HP on a Rovan stock head and pipe with ESP piston ( I did not see any mods to the piston BUT there might be some ??) anyhow look at the Xcel files to get the numbers.
 

Attachments

Z.hb71 said:
4hp is pretty realistic. Rovan rates it at 3.4hp on their site, so 4hp with the nicer dominator pipe seems realistic. Curious what the esp will read
Click to expand...
that was stock Rovan pipe ! I have about 1/2 " of offset on my load arm , gotta fix it , that's only 4% wrong . I have some fine tuning to do to the setup the load cell is bouncing all over the place , noticed some neg. load #'s
Ok I changed the clutch spring to 8k rpm and there was a BIG difference , It is on the PIPE now , I have a 9500 rpm spring coming to test soon. 5.4 HP peak , Rovan motor ROvan Pipe ESP piston FYI .

crank test 8k spring.webp
 
Last edited:
Ok so I made a new EGT setup it uses the stock exhaust spacer with a smaller thermocouple that reacts MUCH faster , th eMAX temp was 950 deg F ! , also I am getting consistent readings all the time now , this setup is MUCH cheaper and more accurate .
I should have the CAN muffler here today.
Baja 5 RPM.webp
Baja 5 HP.webp
 
dougstar said:
Ok so to date, what has it cost??‍♂️
Click to expand...
Well this is R&D so MY COSTS are about ??$450 , the point was to design and make a low cost DYNO for you idiots LMFAO ! , my last design is IT , simple cheap and easy to run.

it will have to be tried on different Models of cars/bajas/trucks etc. to make the STOP bar ( where the load bar hits ) that is attached to the chassis , It has also spawned a RPM monitor and EGT monitor setup that I MIGHT add WIFI to for real time monitoring of temps + RPM's .

Your WELCOME
 
I think with the new design that will go down to about $200 !! ,

Heres a run using a stock CAN muffler NO PIPE.

It is about 2 HP lower than with a DDM V1 Pipe , max @ 3.2 HP , V1 Pipe was 5.44 HP ! so 2.2 hp more with a decent pipe. Also the EGT temp was about 100 deg higher ! ??



Baja 6 CAN HP.webp
 
Back
Top