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[algon]

 Can any of you steam experts give me some advice. Which of these two inline twins, the Saito T2DR or the  Graham TVR1A is more powerful? Can anyone tell me which is heavier?

[rhavrane]

Bonjour,
It is difficult to compare these two steam machines because the T2DR is a 5 cm3 and the TVR1A is a 8 cm3.
Furthermore, there are TVR1A and TVR1A BB (Ball Bearings), enhancement of the first version.
Saito is a living company as Graham is no retired.
Having a T3DR and a TVR1A BB, I personally find my T3DR very reliable, the BB "light"and difficult to adjust.   

To my opinion, power doesn't mean the same thing when you evoke steam or gas. Steam has a lot of torque at low RPM.

Based on my experience, the most important thing is to find the appropriate couple propeller / machine.
I have a large collection of boats with 5 an 8 cm3 different machines and for me 5 cm3 is 2.75 " (70 mm) 4 blades propellers and 8 cm3 is 4" (100 mm) and I specify that I operate at 2 bar / 30 PSI.

A small propeller with a large machine is steam consuming and the boat won't go faster.
I hope this will help you to make a choice, in France we have a manufacturer who offers a large choice of machines and I have all of them from 1 to 8,5 cm3:
https://www.jmc-vapeur.fr/
Example of a large boat with a small propeller and a 3 cm3 : https://youtu.be/nvadR7W78Xg
Example of a tug with a 3" peopeller and a 5 cm3 : https://youtu.be/9hN4i6FjPfw

[DBS88]

Both are good engines, do you have them or are you trying to decide which one?
The Saito T2DR is 675grams weight, it has a 12mm bore and 12mm stroke, its height is 100mm, width 70mm length 115mm
The TVR1A is 325 grams, it has a 1/2inch bore (12.5mm) 5/8 inch stroke (15.9mm), its height is 86mm width 47mm length 76mm.


The TVR1A is a larger capacity engine so needs more steam per revolution of the engine, it has a long stroke, so makes good use of the steam but is lower rpm. It has the Hackworth reversing mechanism. It is physically smaller than the T2DR and lighter, however it's no longer made and not sure about availability of spares should they be needed. You would have to buy a second hand one.


The Saito is excellent quality and is still made, it has a smaller capacity so uses less stem per revolution of the engine, it is a very powerful and reliable engine, it has the Stephenson Link reversing mechanism. It is physically bigger and heavier than the TVR1A, you can buy new or second hand.


I have both engines and both run really well, both are attractive well made engines, what is the project you wish to use the engine for?

[algon]

 Thank you both for you replies and opinions.  I am potentially looking for a new engine for a 50" Hartman fiberglass "Diana" steam launch.Currently fitting a Cheddar Puffin vertical boiler providing steam to a Krick / Wilesco Model II inline twin. The original boiler that came with that engine just cannot build enough steam. Propeller is a brass 2 1/2" 4 blade.

[rhavrane]

Bonjour,

Nice project for 2025 

If you wish keeping this propeller, and because this is a large hull, I would kindly suggest you a 5 cc more economical in steam in all cases 

[DBS88]

Nice project, I look forward to seeing the finished result on the water. In case you have not seen the TVR1A and the Saito running, here are links to both engines being run on the bench on air
TVR1A - [size=78%]https://youtu.be/w5-hT0efT4k?si=qcQmDiJ2ERoE3xAl[/size]
Saito T2DR - [/size][size=78%]https://youtube.com/shorts/tLaM3-Wr_A8?si=djypp-96eqR0OaWH[/size]
The videos show the engines running forwards and reverse on low air pressure

[rhavrane]

Bonjour,
The same ones on steam 
https://youtu.be/pydlP01QTm0
https://youtu.be/XklAjhQWbd4