Ignition timing vs engine torque
Ignition timing vs engine torque
(OP)
Hi all,
I am currently testing a ford escort 1100 cc petrol engine through a water break dynamometer. I carried out steady state tests for 0, 4 and 12 BTDC through an RPM range of 1500 to 4000, in steps of 500. the total torque for O degree timing was low compared to 4 and 12 degrees. I was thinking that the reason for this may have been due to misfiring and knocking.
Am I right?
and another question. I noticed that for 4 and 12 degrees the torque readings were very similar to each other (almost on the same line on the graph).
Is this normal? I mean I would have expected greater power developed at 12 BTDC.
Thanks :)
I am currently testing a ford escort 1100 cc petrol engine through a water break dynamometer. I carried out steady state tests for 0, 4 and 12 BTDC through an RPM range of 1500 to 4000, in steps of 500. the total torque for O degree timing was low compared to 4 and 12 degrees. I was thinking that the reason for this may have been due to misfiring and knocking.
Am I right?
and another question. I noticed that for 4 and 12 degrees the torque readings were very similar to each other (almost on the same line on the graph).
Is this normal? I mean I would have expected greater power developed at 12 BTDC.
Thanks :)





RE: Ignition timing vs engine torque
Cheers
Greg Locock
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RE: Ignition timing vs engine torque
Regards
Pat
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RE: Ignition timing vs engine torque
Cheers
tbug
RE: Ignition timing vs engine torque
RE: Ignition timing vs engine torque
Thanks
RE: Ignition timing vs engine torque
That is what I was wondering - 12 degrees is not much advance for 4000RPM - 30 or so would be more appropriate.
Maybe when you don't have enough advance it doesn't matter much whether it is 4 or 12 degrees?
RE: Ignition timing vs engine torque
Thanks for the data. The difference 0 to 4 looks far too great, and difference 4 to 12 looks suspiciously non existent.
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Ignition timing vs engine torque
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Ignition timing vs engine torque
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Ignition timing vs engine torque
Rod
RE: Ignition timing vs engine torque
Greg, thanks for that chart, I found some good examples in heywood.
Rod, I wasn't actually testing the engine. it was used for commissioning a new water brake dynamometer. However, I was surprised with the results. I wasn't expecting the optimum timing to be at 4 btdc.
Thanks
tbug
RE: Ignition timing vs engine torque
With the almost bizarre results I was wondering if you had constant load and a computer was controlling the throttle or something equally ridiculous.
4 deg seems unbelievable. I really wonder about your timing marks or if the spark is strong enough to fire under load or you have an ignition system that retards as you think it advances.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Ignition timing vs engine torque
Engineering is the art of creating things you need, from things you can get.