Well, Fossa’s engine has been removed and stripped.
Fossa’s sump with parts of big end bearings
Well, what was different to our previous setup? When removing the sump after the valve broke and destroyed the cylinder head and piston, I found marks of the oil pickup on the bottom of the sump. The train of thought was, it is too close and could not draw oil from the entire pickup surface. With a bit of effort, the pickup pipe was bent to give a little more clearance. Probably not a bad decision ….. but, I suspect that in corners the available hot oil in the sump moved away from the pickup and left the pickup to suck air. Not cool.
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The conclusion, other than going dry sump, either move the pickup back down to touch, or / and, add a horizontal taper baffle plate or two, to the existing vertical baffle plate. And, that’s not all folks, a high volume, high pressure pump being imported from the UK with the assistance of Barry Scott. Lets see how it goes!
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Posting information on facebook can result in a lot of “help”. Sometimes help way out of your budget. Quite often conflicting. When the information is needed the conflicting can result in a headache, how to siphon the useful from the not current valid and the useless. I can write a book on all the info given and the relativity of the info with reference the challenge.
1. Recent comments with reference to Fossa running her big end bearings, advised to reduce piston and conrod weight, also to reduce rpms. Considering Fossa has been reliable with our “heavy” pistons and conrods since our spate with big end problems early last year, were is the connection. Fossa was also raced during her reliable period at 7500 – 8000 rpms. At our last two races Fossa was only capable of 6000 ……. This failure started on her rebuild after her valve broke off on 1 February ….
2. Then reference is made to Fossa burning too lean, that was resolved in May 2013.
3. It is then mentioned that we could be pre igniting due to ignition timing. When I advise that we are running 27° @ 5000rpm which is beyond Fossa’s maximum timing movement due to centrifugal and vacuum. Then I am advised I can run her at 34°. True, I am aware of this, the 27°decision is a safety margin.
4. I advise that we have ordered a high pressure, high volume oil pump from the UK. Then told in short it is used for higher clearance engines in racing. Track side, post the failure last weekend, I was told by three racers, to firstly get this pump. Somehow due to their being active in the sport with very good race results, I do tend to believe them.
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We made the decision to use our recently acquired AX block in its current 40″ oversize form. Coming from the metrology field, I am often very critical and checked every water and oil way. I found the water way at the waterpump so blocked that I had to drill it out! That tells me one thing, over heating! After running the cylinder hone, a clear short vertical line. I have found a crack. That is the AX block out of the question for now.
Enough chatting, back to work, cheers