Tuning Little and large
- Thread starter Toshi 975
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Tuning Little and large
Interesting construction on the big piston. They were made by ASSO No 7059 inside they have four small steel plates set into the piston wall covering four holes that are drilled in line with the gudgeon pin. I can’t imagine what these features do?
Are plates baffles, with an indirect connection between the external hole and the inside of the piston? If so, could it be to cause an induction of oil on the down-strolke to help lubricate the cylinder.
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If they are baffles, I agree with @fiat500, I suspect those holes allow oil mist from the crank case to be blown on to the cylinder walls on the down stroke of the crank to aid cylinder wall oiling. Conversely you often find small holes or slots inside the oil control ring groove, those are to channel oil that the control ring has collected away from the cylinder walls.
Alternatively if the steel plates are blocking the holes completely, then it could mean this is essentially an 'off the shelf' piston that has been repurposed by Alquati and blocking those holes off was part of the modification. Holes like that to allow oiling are common on 2 stroke pistons to aid cylinder wall oiling as mentioned above.
Alternatively if the steel plates are blocking the holes completely, then it could mean this is essentially an 'off the shelf' piston that has been repurposed by Alquati and blocking those holes off was part of the modification. Holes like that to allow oiling are common on 2 stroke pistons to aid cylinder wall oiling as mentioned above.
The pistons were an integral part of the big bore kit sold by Alquati from the early 70’s which also required extensive cylinder head work. You hardly ever hear about Alquati these days but if you look at their original brochures they produced a huge range of tuning components for a range of cars. They are possibly more remembered for tuning the Fiat twin cam engines, also Lancia engines.
I discovered a car sporting an Alquati badge whilst in New Zealand, a rare Heron sports car fitted with the Fiat twin cam engine, tuned with Alquati cams.
I discovered a car sporting an Alquati badge whilst in New Zealand, a rare Heron sports car fitted with the Fiat twin cam engine, tuned with Alquati cams.
@Toshi 975
I know this is an old post, but I've just come across it while searching for something else.
This piston seems to be either an "Invar Strut" piston or possibly an "Autothermic" piston.
For further info, see the webpage below, scroll to Types of piston, then see #2 Invar Strut pistons and #3 Autothermic pistons for explanation on these types. Internet searches using these terms will give lots of other info.
Piston: Parts, Types of Pistons and Working Principle (PDF)
In this article, you'll learn about the piston, types of pistons, piston clearance, Piston head or shape and high performing pistons.
www.theengineerspost.com
Incidentally, Invar struts were incorporated in various standard application pistons, not just on applications for tuned or high-performance engines.
