Q&A Forum
I have a Crosley engine in a 1960 H-modified racecar. I am trying to size things to build a dyno for the motor. It makes somewhere above 55HP. I have a "big block" Crosley engine that people say can produce 95-100 HP. What size of hydraulic pump will I need to load the motor? It turns 7500 RPM so I will probably have to reduce the shaft speed by at least half.
Hi,
There is a calculator here: http://yourdyno.com/choosing-the-right-hydraulic-pump/
You need somewhere around 50cc/revolution, but it depends on a few things like max pressure and max RPM, and at which RPM (after gearing) your engine has max power.
And correct, you need to reduce the shaft speed, check max speed on the pump spec. Normally it is not higher than around 3500, although some pumps will tolerate somewhat higher revs.
Here are a few examples of pumps that at first glance look ok:
https://www.ebay.com/itm/Hydraulic-Gear-Pump-Group-3-4-Bolt-Flange-1-8-Taper-Shaft-25-to-55cc-250-Bar/232480792632
https://www.ebay.com/itm/HYDRAULIC-GEAR-PUMP-GRH-GROUP-3-DIN-MOUNT-TAPERED-SHAFT-VARIOUS-CCs/322843150441
or maybe one from this series:
https://www.alibaba.com/product-detail/SETTIMA-GR47-45CC-GEAR-PUMP-GR47_60532411027.html
Make sure to double check all specs!
Regards,
Jostein