Good morning , Now you can see the dilemma I'm faced with. The H&F G-series dyno is unidirectional directional of rotation. Direction of rotation 'A' is capable of holding more torque where direction of rotation "B' is less torque and suits smaller engines ( less cylinders application, four cylinders and less ) . 

- Maximum power absorption of the dynamometer is in direction of rotation 'A'

- Minimum power absorption of the dynamometer is in direction of rotation 'B' 

Here is a Heenan & Froude GB4-2 Hydraulic water brake engine dynamometer - power curve graph , do have another better graph but need to find it amongst my great office filing system, NOT!

As in all hydraulic water brake engine dynamometers water temperature is very crucial for proper operation the GB4-2 can handle 1000BHp(746Kw) effortless and room for more. Water outlet temperature is very important as is inlet depending on how one is feeding the dyno either with fresh new cold water or recycling from a tank setup and other factors.

Interesting. Huge power difference with only 10 C temp difference. Better have a good heat exchanger if you use a tank setup!

Is 70C max it can handle, you think? Of course you need to stay below 100C with some margin, but you probably don't need a margin of 30C?

Ok , just studied some H&F dyno drawings as sure enough the water control orifice port is triangular as can be seen in the drawings.

Ordered the yourdyno kit with weather station , speed sensor and a 5oo kilogram load cell.

Toying with the idea of getting a  ST-12: Engine Data Acquisition System from  http://www.innovatemotorsports.com/products/st12.php to start replacing some of my old analog gauges. 

hI Jostein , Thank you, my purchased of YOURDYNO kit has just arrived at work less than 15 minutes ago at 12-23pm and thank you,  now just waiting for the stepper motor ,stepper motor controller and power supply to arrive. 

I'm excited and nervous at the same time. Here comes a huge learning curve.

I'm hoping to setup three (3) large TV/ monitor , one for the Yourdyno interface details , one for the    Innovate Motor Sports ST-12: Engine Data Acquisition System and the third reserved for HP_tuner and SCT flash tuning and data logging on one large TV/ monitor display setup.

The dynamometer test room isn't going to know what hit it with all the changes I'm planning for it.

Bye

This is probably too late .  Anyway an option that might be worth thinking about . The megasquirt ms3 pro ecu could be used instead of the innovate platform. If you use the ecu instead, you can add so many more features . Best to search yourself so I'm not pushing a product, I have no connection with them other than buying from them. But you could run 8 egt , 8 wideband and heaps of gauges all configurable to different curves . Down to even injector information and heaps more. just run the ecu with the free datalog software or upgrade if needed to pay software , but mostly that's for auto tuning.

Hi , Thank you Pumpngo , Yes Megasquirt MS3 Pro ECU would be a nice ad on for a fulltime fixed data engine dyno logger.  

Ok , was hoping to utilise the existing H&F GB4 RPM Sensor Trigger Wheel which isn't going to happen , it has very fine teeth and to many to count, didn't even bother plus its tucked in a confined space to affix the one I bought from Your Dyno Kit which is a lot bulkier in size.

Upon looking at the dyno I'm just going to fabricate a NEW RPM Sensor Trigger Wheel and brackets to mount the sensor.

The H&F GB4 mounting flange is 150mm in diameter so i will finish the RPM Sensor Trigger Wheel  between 170mm to 180mm in diamter so the teeth are very proud of the flange and no interference with the sensor

Studying Jostein specification on his website   http://yourdyno.com/the-trigger-wheel/  

1 - Tooth height minimum = 5.06mm  ( 0.200 inches )

2 - Slot Width minimum = 10.16mm  ( 0.400 inches )

3 - Tooth Width minimum = 2.54mm  ( 0.100 inches )

4 - Target Thickness  minimum = 6.35mm  ( 0.250 inches )

I'm going to make a 8mm thick steel plate with 36 teeth trigger wheel . I did some drawinsg with a 60 , 36  and a 24 tooth wheel and all depends what i  endup spacing the teeth and Tooth Width minimum. Due to my wheel diameter being between 170mm to 180mm finished diameter. 

Found a rusty 10mm plate of steel today and quickly cut it up and started machining it up.

Hopefully will have the trigger wheel finished tomorrow and mounted on the H&F GB4 engine dynamometer.

I'm sure somewhere i read on this forum you only need two teeth for load bearing , and more only needed for inertia. Could be wrong though. Pretty easy to get two.

Posted by: pumpngo

I'm sure somewhere i read on this forum you only need two teeth for load bearing , and more only needed for inertia. Could be wrong though. Pretty easy to get two.

Hi , My interpretation and understanding of Jostein specification for a  RPM trigger wheel on his website link here 

http://yourdyno.com/the-trigger-wheel/ is some what different to what you have suggest pumpngo ???

Quoting "  How many teeth do you need -

As a general recommendation, choose a trigger wheel with enough teeth to give at least 200 pulses per second at the RPM you care about. This is because YourDyno needs 2 pulses to produce 1 result, so unless you have at least 200 pulses per second you will not get 100 updates per second. All calculations will work at lower rates, so it is up to you if you want 100Hz updates or not. Brake control performance is reduced when the update rate is below 20 pulses per second. 

More teeth is better up to a certain point. If you have say 2000 pulses per second, YourDyno will make an average of 10 samples per calculation, which automatically filters noise without any downside to accuracy.

There is no hard limit to the maximum number of pulses per second, but it is recommended to stay below 6000. " .

Thanks.

Yes, go with 200 teeth per second minimum is the recommendation. If you don't use MOI compensation for brake dynos, 2 teeth is strictly enough, but for averaging reasons, 200 minimum is recommended in any case. 

Hi , my RPM trigger wheel is finally round and sitting on 9.5mm thick and 180mm in diameter hopefully will cut the teeth tomorrow if work permits and mount it on the backside flange of the dyno.

Hi  Jostein , I do have the MOI for my dyno from the manufacturer H&F consine , but will still make a few adjustments cause I have added more rotational weight and gone to a bigger tailshaft diameter and larger universal joint arrangement. Will use you software to overlay the ramp_up and ramp_down and correct accordingly 

Hi pumpngo , this is how i calculated the requirements to suit my dyno application. The engine dyno is rated at maximum 10,000 RPM.

Revs Per Minute (RPM) = 10,000

One (1) minute =  sixty (60) seconds

Revs  Per Second = 10,000÷60 = 166.6667

Therefore a 36 tooth trigger wheel will produce 36×166.6667 = 5999.99 pulses per second at maximum dyno speed.

I did calculation for other trigger wheel teeth ( 24,36 and 60 teeth) combination so i think I'm within YourDyno recommend limits. 

At sixty ( 60 ) tooth trigger wheel that equals nice and easy 9999.99999996 pulses per second. Even 10,000 pulses per second.

If my maths is wrong please correct me.

Here is a picture of the original rpm trigger wheel on the driven side of my dyno , will count how many teeth on it tomorrow, it's a pity I couldn't utilise it but all is good.

Thanks