Engine hours until refresh

I use track time (hrs) from the data logger. My calculation is it is about 20% more than load time. 

According to the Radical dealer that did my engine overhaul (who I trust very much) they recommend that 1500 engines get overhauled every 40 hours of "Engine Run Time".  This is supported by the wording in the Radical engine warranty which says "Warranty is valid up to a maximum of 40 hours of total running time".

This seams a little un-intuitive because if you warmed up your engine for 35 hours and and only ran it on the track for 5 hours it would have much less wear then if you warmed it up for 5 hours and were on track for 35 hours... but, this is what Radical recommends.

It also is important to consider how hard you are pushing the Engine.  Engine longevity is highly dependent on how much of their life is spent at high RPM.   In the SR3 Operators manual it says: " Under race conditions, the engine should run for no more that 40 hours before being returned to the factory for a rebuild.  Engines which are not raced, regularly cover 90 hours without requiring attention".

Hopefully Dan (@rlm-dan) will comment because he is in the Radical engine overhaul business so he could give a much more detailed explanation.

Charley

@charleyhradicalsportscarregistry-com Thanks Charley, that's pretty interesting, and yes I'm curious as to what Dan would have to say on this...  Thx! Jon

This total engine hours metric is why there is a lot of interest in oil warming techniques for engines with dry sumps, since the greater oil volume takes longer to get to a minimum safe temperature for high-rpm use on track.  

In other words, it seems like a lot of the 40 hours is consumed with warming up in the paddock.

One would have to assume that 40 hours is a conservative estimate on Radicals' part such that they can offer a warranty.  They will also keep a database of failures so that they know what to look for when refreshing.  If anyone has any insight into that database I for one one would love to see it.  Moving on, I'm pretty sure a Radical refresh does not include a blanket replacement of parts and does consist of an inspection, crack testing and replacement of parts that they have experienced failures on.  I have heard, and am inclined to believe, that cranks, pistons, rods, bottom end bearings etc are more like 200 hour parts and rings and valve clearances are wearable and serviceable parts that benefit from more frequent checking and replacing.  I think the main suspect parts that just plain old break are things like valve train components such as cam chains and cam chain tensioners; mainly chains.  I would suspect you can do a lot for the longevity of the engine by keeping it in fresh oil, properly warmed and engine heat soaked before entering the track, watching any over revs, and, changing the cam chain(s) on a regular basis.  The reason the cam chains are a somewhat weak link is that on a bike there is a cush drive to dampen shocks from down-changes but cars to not have the same cushioning.  A car designed engine of this nature would likely have gear driven overhead cams. My preference for the chains are the hardened chains all the Hayabusa shops fit - Vance and Hines. I would bet Radicals' replacement policy is steered by over-revs recorded in the ECU, crack testing and their database of known failures.

I don't think anyone here would argue that 40 hours comprising light use and warm up is easier on the engine than a life of full throttle rev limiter gear changes.

Hope that helps when deciding your refresh policy.

-Andy

I agree with you Andy.  For the 4 cylinder engines the transmissions are an area that usually needs the most attention.  Also, as you mentioned, Radical keeps track of weak points and continually develops engine updates.  For example they have a clutch basket update, motor mount update, Quaife coupler update, billet shift lever update, etc.

Charley