Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Other Technical Questions... => Topic started by: kurt cave sikk 27 on September 25, 2007, 09:19:12 pm

Title: twin petrol inline help needed
Post by: kurt cave sikk 27 on September 25, 2007, 09:19:12 pm

 O0 does anyone know if you have to run twin inline engines both at top dead center or one at top dead center and the other at a 180 degrees.any info will be greatfully received,these are 2 27 cc petrol engines O0  kurt

Title: Re: twin petrol inline help needed
Post by: tobyker on September 25, 2007, 10:20:51 pm

If these are two separate engines are you going to link them together, and are they 2 or 4 stroke?

Title: Re: twin petrol inline help needed
Post by: kurt cave sikk 27 on September 25, 2007, 10:43:08 pm

Quote from: tobyker on September 25, 2007, 10:20:51 pm

If these are two separate engines are you going to link them together, and are they 2 or 4 stroke?

hi.they are 2 stroke engines and they are going to be linked together inline, O0

Title: Re: twin petrol inline help needed
Post by: Martin (Admin) on September 25, 2007, 11:21:29 pm

I'm sure I've read somewhere you set them up like a steam engines pistons (train) i.e. 90^o which smooths out the  running a bit and should make starting a bit easier..... but what do I know!?!  :)

Title: Re: twin petrol inline help needed
Post by: kurt cave sikk 27 on September 25, 2007, 11:32:14 pm

Quote from: Forum Admin  (Martin) on September 25, 2007, 11:21:29 pm

I'm sure I've read somewhere you set them up like a steam engines pistons (train) i.e. 90^o which smooths out the  running a bit and should make starting a bit easier..... but what do I know!?!  :)

thankyou  O0

Title: Re: twin petrol inline help needed
Post by: tobyker on September 28, 2007, 12:08:59 am

With respect, I've not heard of the 90 degree link theory, unless of course you put the cylinders at 90 to each other and run it as a vee twin. If you do that you can cut down the flywheels, as you only have to balance the weight of one piston and rod. If you're going to have them strictly in line, I'd go for 180 degrees to smooth out the power impulses. What does the Taplin twin do?

Title: Re: twin petrol inline help needed
Post by: Telstar on September 28, 2007, 11:52:33 am

Hi

Quote

I've read somewhere you set them up like a steam engines pistons (train) i.e. 90o

I am pretty sure that 90^o setting was to cure starting problems ( with 180^o settings both pistons could stop at the end of their travel and wouldn't move when steam was reintroduced ) with petrol engines this is not a problem (you need to turn them over to get them to start).
I would go for 180^o cranks the same as some of the Japanese motorcycles. The dynamic balance is supposed to be better. Something about the force of one piston changing direction on the up stroke being countered by the second piston changing direction on the down stroke. :-\
Cheers Tom

Title: Re: twin petrol inline help needed
Post by: tobyker on September 29, 2007, 12:14:39 am

Indeed 90 degree setting makes a twin steam engine self-starting - so long as the cylinders are double-acting. This is a bit tricky to achieve with i.c. engines.

Title: Re: twin petrol inline help needed
Post by: HS93 (RIP) on September 29, 2007, 12:34:48 am

As self starting is not needed 180 deg would seem the one to go to as most car (full size) are configured that way and boxerengines are as well ( yes I know they will prob be upright ) but it would seem like the Way to go.

Peter