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#196
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Originally Posted by heinrich
Thanks Victor. Now, if the problem is inertia at direction reversal, then wouldn't a piston that changes direction half as often, experience less strain over its life? Just asking, I don't know these things
This is unlike aluminum which theoretically has no fatigue limit, so even a small load will cause it to fail given enough cycles. In reality if the loads are kept low enough then it can last for enough cycles to have an esentially infinate life.
#197
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Originally Posted by heinrich
See Dave that's where you lose me. In order to turn that flywheel at 7,000 RPM, don't you have far greater stresses on the little short-throw rotating mass? To illustrate my thought, what if the crank throw were only 1mm. Wouldn't the piston have to work incredibly hard to push that crank? And conversely, if the throw is one foot, won't the piston have a relaxed time pushing and turning the crank? yes, I do see that there is greater distance covered per revolution, but is that distance not an easier one on the piston and rod and bearings, than the short throw scenario?
#198
My plan is to go as far as I can in bore, while knowing it will see boost. At least one bar above atmosphere, with respect to the CFM needs of the engine. 968 valves, and probably some 85/86 cams that may be built up a bit if needed.
The GTS crank is a great idea for me I know. I wasn't planning on the full stroker crank throw, but something in the middle, and I have the time to wait for the "crazY" people at moldex. I don't understand the crank throw thing PERFECTLY, but I do think I get it. I also need enough room on the piston below the crown for quite a bit of space before the top compression ring for more heat disipation.
I'm concerned about the cutting into the GTS crank for a bit more stroke. I was assured that it would work by taylor engine in Whittier, but I'm still concerned.
The GTS crank is a great idea for me I know. I wasn't planning on the full stroker crank throw, but something in the middle, and I have the time to wait for the "crazY" people at moldex. I don't understand the crank throw thing PERFECTLY, but I do think I get it. I also need enough room on the piston below the crown for quite a bit of space before the top compression ring for more heat disipation.
I'm concerned about the cutting into the GTS crank for a bit more stroke. I was assured that it would work by taylor engine in Whittier, but I'm still concerned.
#199
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Brendan the big problem is keeping the compression ratio down while going from moving the piston only 78.9 mm 3.11 inch to the 85.9 of the GTS or the "standard" stroker at 95.25. The GTS pistons were about 25 % shorter and the wrist pin 2 mm closer to the top .
#201
Originally Posted by Jim bailey - 928 International
Brendan the big problem is keeping the compression ratio down while going from moving the piston only 78.9 mm 3.11 inch to the 85.9 of the GTS or the "standard" stroker at 95.25. The GTS pistons were about 25 % shorter and the wrist pin 2 mm closer to the top .
Right Jim. Adding Bore will change this as well. A pretty big dish in the piston.
#203
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Brendan,
If you cut into the GTS crank to increase stroke are you decrease the journal diameter? When guys use the Moldex or Scat cranks that use Chevy connecting rods, does the big end journals have smaller diameter? I also think the thickness of the Chevy rod is thinner? Would it be better to weld up a S4 crank to increase the stroke and save that GTS crank? I would think it cheaper to weld a standard S4 crank to increase the stroke than buy a new Moldex/Scat crank even if you have to weld the journal shoulder for a Chevy rod. Aren’t the Chevy rods shorter too?
Carl
If you cut into the GTS crank to increase stroke are you decrease the journal diameter? When guys use the Moldex or Scat cranks that use Chevy connecting rods, does the big end journals have smaller diameter? I also think the thickness of the Chevy rod is thinner? Would it be better to weld up a S4 crank to increase the stroke and save that GTS crank? I would think it cheaper to weld a standard S4 crank to increase the stroke than buy a new Moldex/Scat crank even if you have to weld the journal shoulder for a Chevy rod. Aren’t the Chevy rods shorter too?
Carl
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I believe welding cranks was tested before the Moldex/Scat route was chosen for stroked cranks. Welded cranks resulted in too many failures, as I recall.
#206
Originally Posted by heinrich
Relax Brothers. Crank saved
#209
How far is Louis from you H? In which direction?