What is the difference between dynamax and ramtec fans. Also, how can one tell the difference between the two. Also, I have a OS 91, in a sport jet, which fan between the two would be better.

These fan units do look somewhat the same. The quickest way to tell the difference is the Dynamax has an 11 blade impeller and the RamTec has 9 blades. The Ramtec is usually $10 or so less than the Dynamax. The Dynamax also has aluminum angle fan shroud mounts. The Dynamax is made by Jet Model Products in Missouri and the Ramtec hails from Australia. Both are quality units.

Generally, the Ramtec requires a bit more airflow through the intakes for top performance than the Dynamax does. I have used both and I liked both. I used the O.S. .91 on both of these fan units. I believe the Ramtec does not allow the O.S. .91 to rev up quite as high as the Dynamax does so one could reason that that is a benefit of the one over the other. Both units produce lots of power and a strong running fans.

To best answer which would be best on your sport jet, could you please share with us what sport jet you are speaking of.

Yeah, I have a C.S. model X-terminator. I just counted the blades, they are 11 of them.

Here is a pic.

APTAR is absolutely correct in what he said.

The basic difference is the pitch of the blades. The Ramtech is higher pitch, therefore it will probably have a little less static thrust, but will produce higher velocity(speed)

Kinda like a 3.23:1 rear end gear(Ramtech) compared to a 4.11:1 (Dynamax)

I'm sure others can elaborate on this subject.

Regards, Johnny

BTW Either fan should work very well in your airframe.

Thanks guys. I plan on flying jet for awile, then re-paint. How close should the intake (where the two intakes come together and the spinner goes through the hole) spinner hole be to the spinner on the fan?

Hi Gents

Just want to clarify some info on the Ramtec Fan unit:

- The Ramtec fan is designed around the OS 91 and uses all the available power from the engine to produce max thrust at a lower rpm.
- The Ramtec fan works extemely well with intake areas down to 85% of the swept fan area.
- The Ramtec comes with anti-vibration mounts built-in to isolate the fan from the air frame. Important to the longevity of the air frame and reduction of aircraft noise.
- The Ramtec fan produces approximately 12 lbs of thrust at 21000 rpm.
- Our price on the Ramtec is much lower than the Dynamax.

Enjoy,
Ed

JMP's Tom Cook designed the Dynamax unit with the help of some engineers that were air flow engineers at GE.
The unit was acually running in an under performance state till the OS 91 came about with the additional horspower.
The unit does run a little more RPM than the ramtech, but it is at the design RPM of the OS91.
The Dynamax puts out 15lbs of static thrust in the 21,000 to 24,000 RPM range.
I think the Dynamx will give better performance both on the low end and Top end power.

Hope that helps
Marty O

I see that this is an old thread but it's exactly what I'm trying to determine. Is the hex bolt on the cone the same size on both? And if so is there any difference between starter wands for each?

Thanks

Dave

Starter wands will work with either one. Same size.

Thanks

[]DYNAMAX, WISHES, IT PUT OUT 15LBS!!! 11 LBS IS REAL WORLD EARTH SPECS.. RD

In no way Dynamax produces 15 lbs. More like 10lbs, but feels like 7.

I have used both units on the same airframe (YA F-16). Dynamax flies it a lot better, specially when it comes to takeoff performance. On the top end side, I could not notice any difference in speed at all.

Both run pretty good on OS .91's.