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Weight distribution with engine moved back


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Hi there,

 

New to this forum, but an active member over at Club Triumph. I've been trying to find out what effect on the weight distribution moving a 6-cylinder backwards in the chassis has on a GT6 or Spitfire. I've heard at least one person here's done that to avoid fitting a bonnet bulge, and I was wondering if anyone's measured the distribution.

 

Thanks :)

 

Simon

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The GT6 power bulge is only there because the cheapest/easiest way for Triumph to fit the 6-cylinder engine in to the Spitfire chassis meant a bulge was required.  It's not there because the engine position gave a 50:50 weight distribution or a front/mid layout, or anything else that's meant to be benificial to the handling of a car, and I think that's where BiTurbo228's coming from.

 

In general the less weight you have ahead of the front wheels the better turn-in should be but can you move it enough to make any noticable difference... No idea!

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Simon, Triumph had to raise the engine 1" (or was it 1.5"?) to get it over the chassis cross member & steering rack. Moving the engine back 6.5" also allows you to lower it to the 4-cylinder position, hence lowering (improving) the c-of-g. Weight distribution? haven't the foggiest! Not much help answering your question, I know.

 

Richard

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Hi

 

Can I ask why you don't want the GT6 power bulge?

It's less that I don't want the power bulge (I actually rather like how it looks), more that I'm trying to figure out the effect of moving weight behind the front axle. It's a bit late to be changing things on my current Spit6 project, but it'd be useful info to know for future reference (and comparison as I'm trying to get the same weight distribution using lightweight parts rather than moving the engine).

 

The GT6 power bulge is only there because the cheapest/easiest way for Triumph to fit the 6-cylinder engine in to the Spitfire chassis meant a bulge was required.  It's not there because the engine position gave a 50:50 weight distribution or a front/mid layout, or anything else that's meant to be benificial to the handling of a car, and I think that's where BiTurbo228's coming from.

 

In general the less weight you have ahead of the front wheels the better turn-in should be but can you move it enough to make any noticable difference... No idea!

Yeah that's it :) 

 

Simon, Triumph had to raise the engine 1" (or was it 1.5"?) to get it over the chassis cross member & steering rack. Moving the engine back 6.5" also allows you to lower it to the 4-cylinder position, hence lowering (improving) the c-of-g. Weight distribution? haven't the foggiest! Not much help answering your question, I know.

 

Richard

Now that's interesting. I didn't know they'd raised the engine as well. No wonder the Spitfire and the GT6 placed poles apart in this handling test: http://michaeljay.tripod.com/spitfires/cdtest/

 

Distribution's one story, but CoG height and moment of inertia are another...

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I know that late Spitfire turrets are slightly lower than earlier Herald ones, despite looking similar, but thought that was for bonnet clearance. I never knew they’d raised any of their engines; it’s always great to learn small details like this. Given the basic standard of engineering - advanced enough for its’ day, but not radical - I don’t think it was for any weight distribution or handling purpose. 

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