MB BIG HEAD
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Joe Swoonara
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ive finally finished repairing (long story i wont bore you with at present) my TS 240 fitted it with a MB big head and finless flywheel question is what egt temps are people getting ??
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Warkton Tornado No.1
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I am sure you know your stuff & have made your decision about cooling the cylinder assembly rationally.
The fact that racing Lambrettas in Group Four are only air scoop cooled is because of several factors. Apart from their time sitting in the holding bay, where the sensible riders just keep their engines running @ a fast tick over with the occasional blip, the machine is constantly having air blasted over the cylinder assembly with sufficient volume. That air is also able to escape via adequate routes. Having very little under the panels apart from a fuel tank & some electronics helps matters, though often panels will have 'bigger than necessary' cutouts for carbs, rear sets etc to aid flow through.
The exhaust bleed will be of adequate size to prevent head build up.
However, the fundamental ingredient to help sustain a cooler running engine from the inside is the use of Avgas. It is a very stable fuel & allows lower temperature burn. The trade off is that petrol can create more power, but when finishing a race is the priority, Avgas is the natural choice.
I mention this as I wouldn't fancy sitting in crawling or 'stop-start' traffic with no other means of cooling than an air scoop......
The fact that racing Lambrettas in Group Four are only air scoop cooled is because of several factors. Apart from their time sitting in the holding bay, where the sensible riders just keep their engines running @ a fast tick over with the occasional blip, the machine is constantly having air blasted over the cylinder assembly with sufficient volume. That air is also able to escape via adequate routes. Having very little under the panels apart from a fuel tank & some electronics helps matters, though often panels will have 'bigger than necessary' cutouts for carbs, rear sets etc to aid flow through.
The exhaust bleed will be of adequate size to prevent head build up.
However, the fundamental ingredient to help sustain a cooler running engine from the inside is the use of Avgas. It is a very stable fuel & allows lower temperature burn. The trade off is that petrol can create more power, but when finishing a race is the priority, Avgas is the natural choice.
I mention this as I wouldn't fancy sitting in crawling or 'stop-start' traffic with no other means of cooling than an air scoop......
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gaz_powell
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Great heading..... was expecting a different topic!!???
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Warkton Tornado No.1
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I had hoped that I was not the only reader that thought that!
What with it being a Sunday, should we bow down & say three "Hail Mary"s whilst shuffling backwards?
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gaz_powell
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Naaahhh!
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Warkton Tornado No.1
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- Joined: Mon Oct 17, 2011 6:16 pm
- Main scooter: Lambretta SX200
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Warkton Tornado No.1
- registered user
- Posts: 296
- Joined: Mon Oct 17, 2011 6:16 pm
- Main scooter: Lambretta SX200
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Much depends on air flow but also the engine itself in addition to the way it is ridden.
An alloy barrel with a good, tight squish running with an exhaust with a large enough bleed will tend to lose power if it gets hot, rather than seize as a cast iron barrel would, it will expand but lose power.
However, it's swings & roundabouts.
It used to be mandatory to try to gain every ounce of power by omitting the fan for sprinting, say.
That's no longer the case, as Eric Cope has proven, no doubt the fan contributing to consistency enabling a greater state of tune......
An alloy barrel with a good, tight squish running with an exhaust with a large enough bleed will tend to lose power if it gets hot, rather than seize as a cast iron barrel would, it will expand but lose power.
However, it's swings & roundabouts.
It used to be mandatory to try to gain every ounce of power by omitting the fan for sprinting, say.
That's no longer the case, as Eric Cope has proven, no doubt the fan contributing to consistency enabling a greater state of tune......