When I can't sleep my mind drifts and I think of things.
One of the things I thought about was building a 188cid engine with off the shelf parts; no specially made crank, rods, or pistons.
These are the parts I came up with:
Stock 200cid seven main block - 3.68" bore, milled 0.020" leaving a 0.018" piston recess
170cid seven main crank (they do exist) 2.94" stroke
255 V8 flat top pistons - 3.68" diameter, 1.585" compression height
200 rods - 4.715" length
The bore and stroke gives me the 188 cubic inches I want and the compression ratio with a 0.053" head gasket and 53cc head is 8.8:1.
I would like to have the CR up around 9.5:1. In order to accomplish that the head would have to be milled so the combustion chamber displaces around 48cc.
My mind drifted some more.
So then I placed all of the variables in a spread sheet and started playing with the different stock pistons, rods and cranks, and came up with this combination:
Stock 200cid seven main block - 3.68" bore, no milling. Centerline of crank to top of block - 7.808"
170cid seven main crank - 2.94" stroke
200 flat top pistons - 3.68" diameter, 1.511" compression height
144cid rods - 4.855" length.
Now with this combination the displacement is still 188, but the compression ratio with the same 0.053" head gasket and a 56cc head jumps to 9.47:1. MUCH BETTER!
An additional plus with this combination is that the Rod to Stroke ratio is 1.65, which is in the ideal range of 1.65-1.80. This should result in less side loading of the piston
(less cylinder wear) and allow the engine to rev higher.
The downside is that the piston sticks out of the block 0.028", but with a 0.053" head gasket, it would be the same as a zero decked 200 with a stock steel 0.025" head gasket.
What I'm wanting to know is whether the piston sticking out of the head that much is a concern? Can this engine be built with these components and not have a piston hit a valve?
If it can be built, what are my cam limitations in regard to lift and duration?
Here is my calculation. See if I missed something.
Centerline of crank to top of block, stock 200cid block - 7.808"
170 stroke - 2.94"
CH 200 piston - 1.511"
144 rod - 4.855"
7.808 - 1/2(Stroke) - CH - Rod Length = Piston Recess (+), or stickup out of deck (-)
7.808" - 1.47" - 1.511" - 4.855" = -0.028"
Some of you may be asking why I would want to do this. My answer is the same that I tell people why I have a 6 cylinder instead of a V8, because everyone does that and I want to be different.
All input is appreciated.
One of the things I thought about was building a 188cid engine with off the shelf parts; no specially made crank, rods, or pistons.
These are the parts I came up with:
Stock 200cid seven main block - 3.68" bore, milled 0.020" leaving a 0.018" piston recess
170cid seven main crank (they do exist) 2.94" stroke
255 V8 flat top pistons - 3.68" diameter, 1.585" compression height
200 rods - 4.715" length
The bore and stroke gives me the 188 cubic inches I want and the compression ratio with a 0.053" head gasket and 53cc head is 8.8:1.
I would like to have the CR up around 9.5:1. In order to accomplish that the head would have to be milled so the combustion chamber displaces around 48cc.
My mind drifted some more.
So then I placed all of the variables in a spread sheet and started playing with the different stock pistons, rods and cranks, and came up with this combination:
Stock 200cid seven main block - 3.68" bore, no milling. Centerline of crank to top of block - 7.808"
170cid seven main crank - 2.94" stroke
200 flat top pistons - 3.68" diameter, 1.511" compression height
144cid rods - 4.855" length.
Now with this combination the displacement is still 188, but the compression ratio with the same 0.053" head gasket and a 56cc head jumps to 9.47:1. MUCH BETTER!
An additional plus with this combination is that the Rod to Stroke ratio is 1.65, which is in the ideal range of 1.65-1.80. This should result in less side loading of the piston
(less cylinder wear) and allow the engine to rev higher.
The downside is that the piston sticks out of the block 0.028", but with a 0.053" head gasket, it would be the same as a zero decked 200 with a stock steel 0.025" head gasket.
What I'm wanting to know is whether the piston sticking out of the head that much is a concern? Can this engine be built with these components and not have a piston hit a valve?
If it can be built, what are my cam limitations in regard to lift and duration?
Here is my calculation. See if I missed something.
Centerline of crank to top of block, stock 200cid block - 7.808"
170 stroke - 2.94"
CH 200 piston - 1.511"
144 rod - 4.855"
7.808 - 1/2(Stroke) - CH - Rod Length = Piston Recess (+), or stickup out of deck (-)
7.808" - 1.47" - 1.511" - 4.855" = -0.028"
Some of you may be asking why I would want to do this. My answer is the same that I tell people why I have a 6 cylinder instead of a V8, because everyone does that and I want to be different.
All input is appreciated.