[Land-speed] Multiple Engines

Dave Dahlgren ddahlgren at snet.net
Tue Mar 23 15:05:17 MST 2010

Put a speed sensor with the same number of teeth on the front and rear of 
the crank and watch for degrees of separation change. that will read 
directly into degrees of twist and I have no idea what is acceptable to be 
honest. Possibly a crankshaft company could give some guidance there.. I 
would be tempted to but them with a tooth at 14 degress ATDC as that is when 
peak cylinder pressure should be or very close to it at least and the 
greatest twist.. I would not swaet 42 or 45 degrees close enough... much 
better than 3...
----- Original Message ----- 
From: "Skip Higginbotham" <saltrat at pahrump.com>
To: "Dave Dahlgren" <ddahlgren at snet.net>; <land-speed at autox.team.net>
Sent: Tuesday, March 23, 2010 5:42 PM
Subject: Re: [Land-speed] Multiple Engines

> Thank you and you are welcome!
> I will try to get to the 45 degree number.....coupler is made and it has 
> 20 teeth and 6 bolts so some combination of those should result in 42 
> degrees........or so. One bolt - one tooth...
> or 60 degrees minus 18 degrees. Dang!!! My head hurts already.......
> What can I do with my data logger to see how much the rear crank is 
> twisting?
> Skip
> At 02:04 PM 3/23/2010, Dave Dahlgren wrote:
>>Having never done done this but intuitively I would separate the firing 
>>points 45 degrees EX if engine 1 were to fire at 0 BTDC I would have 
>>engine 2 fire either 45 BTDC or 45 ATDC to fill in the time between firing 
>>any other choice would have them add to a higher torque level for the rear 
>>crankshaft. Obviously you need to add the ignition advance and only used 
>>those numbers for easy math..
>>BTW thanks for the racing related post!!!

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