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 karmannghia60
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Karmann Ghia Sucker
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| posted on June 17th, 2003 at 08:43 PM |
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What gives more torque, bore or stroke?
I am guessing longer stroke will give more torque than bigger bore, right?
What needs to be done for a longer stroke engine? No machining? Replacement of crank, rods and barrells? Anything else?
Raf
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karmannghia60
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| posted on June 17th, 2003 at 08:43 PM |
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Ahh, what about exhaust & tin for a stroked engine?
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OvalGlen
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| posted on June 17th, 2003 at 09:23 PM |
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If exhaust is type with slip joins across back of engine then will probably not be any problems with existing.
The use of stroker type pistons (where the Crown to Gudgeon pin length is smaller) usually results in little or no increase in engine width.
Small increases in stroke dont need Huge clearancing, but you should see the case when clearanced for Big Strokes.
Use of smaller big end connecting rods like Chevy , certainly help ,
I had to de-compress my engine for Boost.
I put in 2.4 mm spacers under the barrels, and I had to cut exhaust and re- weld section to join up again. Also had to custom cut Push rods for
correct rocker Geometry. As an extra bonus... every engine removal / install is especially difficult as the tin ware scrapes sides of engine bay seal
(more so due to 1600 style in Oval ).
Regards,Glenn>
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 Bizarre
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| posted on June 17th, 2003 at 09:45 PM |
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Firstly and simply i will say STROKE gives torque.
BUT
mot design MUST have somethng to do with it cause a T4 motor has heaps more torque and it has a 71mm crank Vs a T1 69'er.
But a 78x90.5 will torque all over a 69x94 - yet the difference is less than 100cc's
ALthough people say "build a stroker - it only costs a couple $100 more" this is where true engine builders come into ther own.
It is not a simple job
rocker geometry
pisto speed
rod lenght
skirt clearancing
let alone width and fitting
Nah - my next motor will either be a 1916 or a little 2007 baby stroker
Futue te ipsum!!!
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Phil74Camper
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| posted on June 19th, 2003 at 11:11 PM |
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Strokers work well if done properly, but they ARE more work to do properly!
Torque is force x distance (in the sense of from the rotation centre). You can apply the same force to a short spanner or a long spanner. But the
extra length of a long spanner multiplies your force and results in more torque (leverage).
Same with a stroker engine. The force of the combustion downstoke acts over a longer distance, so it increases the raw turning effort on the
crankshaft.
To make one fit is a bit of work. The case needs to be clearanced for the bigger crank and rods. The deck height of of the piston at TDC needs to be
checked, and the C/R determined as a result. You will probably have to fit spacers under the cylinders. This widens the finished engine.
Which means you have to re-engineer the valve train as your pushrods need to be longer. Your whole engine might be 10mm wider than a stock engine,
which then affects your tinware, exhaust and carb linkage. Not to mention how it fits in your engine bay.
But the work is always worth it.
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