It would be fantastic if we could all refer to a definitive guide on cooling of our engines, as the majority of users on this Forum must surely have subjected theirs to some modification.
Perhaps there may eventually be a test conducted by a respected body, such as a magazine, but it would undoubtedly mean a thorough, methodical process as we were able to read recently, as was the case with the comparison of the proliferation of 'Clubman' exhausts.
Let me say now, that whatever modifications are performed, unless the profiles of the piston & 'head are correct & concentric with the squish @ it's optimum (for which opinion varies, but 1.0 mm has never let me down) then you are compromising the ability of any 'head to perform it's function.Personally, I have a number of modified kart & motorcycle engine cylinder heads as well as Lambretta specific 'heads that were produced with the remit of higher heat transfer in mind, but these were often used with no actual scientific proof of them being better than the standard generic OEM heads, other than when direct air cooling was employed. Principally, such heads are used because the finning is North/South & they are less likely to distort, though their surface area is probably no greater than an OEM 'head, despite some having a larger size & mass, as in the case of the MBD item.
Undoubtedly, some of us follow a different path to reach an objective, & if you consider heat sinks that are employed on a PC, those that are proven to give better results rely upon upgraded fans to enable their superiority.
Like Fast&Furious, (who has teased us with his very sound ideas upon the principle of improving the basic 'head cowling design
) my belief is that there are substantial improvements to be gained by modifying the standard tinware employed to reduce any losses.
For instance, for those of us that use the Smallframe flywheels, whether points based or the AF type, simply adding a ring to the flywheel cover to match the fan's smaller intake diameter & reduce the gap, really does reduce any chance of cavitation & increase flow through the system. To augment the quantity of air, one easy modification that was employed years ago (when Group Four were still using iron barrels with fan cooling), was to effectively make the LH floorboard an air scoop by adding a thin (aluminium) plate to force air through a cutout that matched the fan intake. For my own engines, this simple modification enabled down jetting & the consequent increase in power, so it was definitely worth doing in that scenario.
I apologise if this response is somewhat 'off target' to the original Post, but sometimes the best cure to an anticipated problem is not necessarily what tends to be the norm & gets selected, but to consider other components within the chain & if that makes me the Devil's Advocate, so be it.......
Posted: Wed Nov 14, 2018 9:01 am
