TJ brass bedplate expansion

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coaster
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Joined: Sat Jun 30, 2012 4:10 am

TJ brass bedplate expansion

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The TJ V10 had an experimental brass bedplate clamped to an aluminium upper cylinder block.
The 2 different materials have expansion rates that dont match up ideal.
Does anybody have experience with such a difficult design problem, insights?
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Tommy Cookers
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Joined: Fri Feb 17, 2012 3:55 pm

Re: TJ brass bedplate expansion

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brass ?

not bronze then ?
bronze is a proper engineering material - brass isn't
the right bronze will have almost the same expansion coeff as brass but a higher elastic modulus and strength
manganese bronze seems best - it has higher expansion coeff than any brass

others might not be called bronze eg copper beryllium formerly known as beryllium bronze
(bear in mind dimensional changes on heat treatment - similarly with high expansion steels eg maraging steel)
Last edited by Tommy Cookers on Thu Feb 06, 2020 4:41 pm, edited 2 times in total.

Maritimer
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Re: TJ brass bedplate expansion

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Could be naval brass, which is bronze

Tommy Cookers
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Re: TJ brass bedplate expansion

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well ..... Google tells me that ....
Naval brass and Admiralty brass are tin brasses ie tin is added to prevent dezincification

bronze doesn't have zinc so presumably doesn't dezincify itself

Maritimer
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Re: TJ brass bedplate expansion

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Could very well be, we always refer to it as bronze at my old job and in school but I dont know what its strength is like compared to true bronzes.

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Mudflap
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Re: TJ brass bedplate expansion

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coaster wrote:
Thu Feb 06, 2020 1:46 pm
The TJ V10 had an experimental brass bedplate clamped to an aluminium upper cylinder block.
The 2 different materials have expansion rates that dont match up ideal.
Does anybody have experience with such a difficult design problem, insights?
Not much of a problem.
Look at all the engines with aluminium heads on cast iron block running around with no trouble.

The bottom end is cooler and has less of a thermal gradient than the block/head joint.

In fact there are many examples of mating components in engines that have very different coefficients of thermal expansion: head/valve seats , head/valve guides, head/exhaust manifolds, any aluminium component bolted with a steel bolt, carbon fibre brackets bolted to aluminium (probably the most extreme combination).

As long as the components are designed to cope with the induced thermal stresses it shouldn't be a problem.
How much TQ does it make though?

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humble sabot
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Joined: Sat Feb 17, 2007 9:33 am

Re: TJ brass bedplate expansion

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It's also a question of geometry. Higher aspect ratio objects have more apparent dimensional change. Hence the whole "coefficient" thing.
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static balance
dynamic balance
static imbalance
dynamic imbalance