Comments on: Smaller and lighter is always better http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/ Specific mission-critical info for professionals Fri, 10 Feb 2012 13:32:17 +0000 http://wordpress.org/?v=2.7.1 hourly 1 By: Wayne Ward http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-8859 Wayne Ward Thu, 01 Sep 2011 19:13:07 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-8859 Ian, The point you make is correct; the best place to put the extra inertia is probably on the flywheel or the crankshaft. However, where this isn't possible, people have successfully turned to steel rods to increase inertia in an attempt to make power delivery more docile. Ian,

The point you make is correct; the best place to put the extra inertia is probably on the flywheel or the crankshaft. However, where this isn’t possible, people have successfully turned to steel rods to increase inertia in an attempt to make power delivery more docile.

]]> By: Harlton http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-8846 Harlton Wed, 31 Aug 2011 19:02:26 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-8846 Hi Wayne, I have been thinking about this subject lately as the type of engine I am building at the moment has tradionally been improved by fitting titianium rods. These are physically larger and do not allow the tight squish possible with the latest steel rods. If a coated titianium pin is then substituted instead of a coated steel one, it seems a win, win. I can no longer see any advantage in fitting titainium rods, but for the above reasons. I would not consider an increase in reciprocating mass as an advantage period, as I have spent large sums decreasing it to obtain smoother faster engines. If the rider could not handle the decreased mass, quicker spinning engine, then an increase in the dynamically balanced flywheel is where I would put it. Hope I am not missing something, pls correct me if I am. Best regards Ian Hi Wayne,
I have been thinking about this subject lately as the type of engine I am building at the moment has tradionally been improved by fitting titianium rods.
These are physically larger and do not allow the tight squish possible with the latest steel rods. If a coated titianium pin is then substituted instead of a coated steel one, it seems a win, win.
I can no longer see any advantage in fitting titainium rods, but for the above reasons. I would not consider an increase in reciprocating mass as an advantage period, as I have spent large sums decreasing it to obtain smoother faster engines.
If the rider could not handle the decreased mass, quicker spinning engine, then an increase in the dynamically balanced flywheel is where I would put it. Hope I am not missing something, pls correct me if I am.

Best regards Ian

]]> By: Jrobson http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-3099 Jrobson Wed, 24 Mar 2010 20:24:31 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-3099 Hi Wayne Would it not be better to match then a tungsten big end to a titanium rod? Alternative is to have more material on the crank, if possible. Hi Wayne

Would it not be better to match then a tungsten big end to a titanium rod? Alternative is to have more material on the crank, if possible.

]]> By: Wayne Ward http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-3044 Wayne Ward Thu, 18 Feb 2010 12:29:49 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-3044 In reply to Jim Wolf's post, I can't mention specific applications as I've been shown these parts in confidence. However, we can say that it is sensible to design the rod such that the extra mass is around the big end rather than the small end. This brings me to answer Basil van Rooyen's post. The mass around the big end of the rod is classed as being part of the rotating inertia of the engine and is treated as such in most calculations. I've not mentioned specific applications, but there are instances where it isn't possible to just fit a bigger flywheel etc, hence the reason why these parts have been designed and run, in race series up to international level. The teams are happy with the parts and because the lap time and, more importantly, consistency of lap-time is improved, they see this as a performance increase when judging vehicle performance. I agree that, given the choice, we would certainly look to add mass to the flywheel etc but, where this isn't possible, it seems that an approach such as the one described seems worthwhile. Best regards, Wayne Ward In reply to Jim Wolf’s post, I can’t mention specific applications as I’ve been shown these parts in confidence. However, we can say that it is sensible to design the rod such that the extra mass is around the big end rather than the small end.

This brings me to answer Basil van Rooyen’s post. The mass around the big end of the rod is classed as being part of the rotating inertia of the engine and is treated as such in most calculations. I’ve not mentioned specific applications, but there are instances where it isn’t possible to just fit a bigger flywheel etc, hence the reason why these parts have been designed and run, in race series up to international level. The teams are happy with the parts and because the lap time and, more importantly, consistency of lap-time is improved, they see this as a performance increase when judging vehicle performance.

I agree that, given the choice, we would certainly look to add mass to the flywheel etc but, where this isn’t possible, it seems that an approach such as the one described seems worthwhile.

Best regards,

Wayne Ward

]]> By: Basil van Rooyen http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-3038 Basil van Rooyen Thu, 18 Feb 2010 11:24:26 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-3038 I think Wayne Ward is plainly wrong, in asserting that a heavier rod may make for better performance because of a more drive-able throttle response - a result of greater or lesser inertia. Such rotational inertia, or damping, of throttle response is least appropriately sought in the reciprocating bits, as these are being accelerated and decelerated each stroke. Such drive-ability might be sought in the rotating bits, like the clutch and flywheel - but never the reciprocating parts. Before ANY power is transmitted to the crankshaft, the inertia of the rod must be overcome on every power stroke. At the end of each stroke there is no stored energy at the big end to assist the next stroke, but must begin again, unlike the rotating bits. I think Wayne Ward is plainly wrong, in asserting that a heavier rod may make for better performance because of a more drive-able throttle response - a result of greater or lesser inertia. Such rotational inertia, or damping, of throttle response is least appropriately sought in the reciprocating bits, as these are being accelerated and decelerated each stroke. Such drive-ability might be sought in the rotating bits, like the clutch and flywheel - but never the reciprocating parts. Before ANY power is transmitted to the crankshaft, the inertia of the rod must be overcome on every power stroke. At the end of each stroke there is no stored energy at the big end to assist the next stroke, but must begin again, unlike the rotating bits.

]]> By: Jim Wolf http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/comment-page-1/#comment-3030 Jim Wolf Wed, 17 Feb 2010 16:24:21 +0000 http://www.ret-monitor.com/articles/842/smaller-and-lighter-is-always-better/#comment-3030 >surprising number of motorsport situations >a number of applications where low inertia is actually a barrier to performance >In some of these applications >In some instances The article caught my attention with the tongue in cheek title, but disappointed with no specific, IE. why choose reciprocating vs. prime mass if strength isn't the problem or how increased mass on the rod equates to which attributes a driver can benefit from, etc. Please finish your thought in part 2, I am interested! >surprising number of motorsport situations
>a number of applications where low inertia is actually a barrier to performance
>In some of these applications
>In some instances

The article caught my attention with the tongue in cheek title, but disappointed with no specific, IE. why choose reciprocating vs. prime mass if strength isn’t the problem or how increased mass on the rod equates to which attributes a driver can benefit from, etc.
Please finish your thought in part 2, I am interested!

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