destroking and boosting for mpg

[Frank Lee]

Originally Posted by baldlobo

first of all most cranks are cast iron(with steel cranks coming in a close second); anything cast, shouldn't be welded, it will fail.

second most engine blocks and cylinder heads won't/can't be cut down inches(0.050 or less)

you'd have better luck sleeving the block down.

Yes, or maybe leaving some of the cylinders empty.

A smaller engine BUILT as a smaller engine is the best bet.

[baldlobo]

yup along with removing the rocker arms for cylinder 2(this is me guessing 2 is the one not 180 out of phase)

[orangustang]

None of the cylinders on a Metro are 180° out of phase. They're all 120° apart and counterweighted. If they were as you describe, the engine would always be out of balance and would never run well at all. That's why there's all this business about cutting and welding the crankshaft. You would have to do that (or have a new one forged if you wanted it to last more than a few seconds) to get an engine with any sort of balance at all.

[ecomodded]

Two key characteristics differentiate stroker kits from OEM rotating assemblies.

First, and most important, the crankshaft's rod journals are physically farther from the main journals than on the original equipment. A given extension in the distance between the rod and main journals results in twice that distance in increase of piston travel. For example, in a Chrysler LA (1971-1992) 360 cubic inch (5.9 l) V8, the rod journal centerline is 1.79 in (4.55 cm) from the main journal centerline. The piston travels 3.58 in (9.1 cm) in this configuration. When this engine is modified with a 402 cubic inch (6.6 l) stroker kit, the distance between the main journal centerline and the rod journal centerline is increased to 2.00 in (5.08 cm), which results in the piston travelling 4.00 in (10.16 cm). So, the modified crankshaft with 0.21 in (0.53 cm) further distance between the main and rod journals results in 42 cubic inches (.7 ) of displacement greater than the engine had before.

The second key characteristic of a stroker kit versus OEM is the required changes to allow a stroked crank to 'fit'. This is accomplished in one of three ways:

▪ Location of the piston pin (and the top of the rod) within the piston, or the compression height is shortened.
▪ Length of the rod is shortened.
▪ Height of the cylinder is lengthened.


Stroker kit - Wikipedia, the free encyclopedia

[baldlobo]

well you learn something new everyday(i've never played with a 3 pot before); was using a 4 cylinder analogy. but from what you just said i'd never remove a piston in that configuration

[baldlobo]

Originally Posted by ecomodded

The second key characteristic of a stroker kit versus OEM is the required changes to allow a stroked crank to 'fit'. This is accomplished in one of three ways:

▪ Location of the piston pin (and the top of the rod) within the piston, or the compression height is shortened.
▪ Length of the rod is shortened.
▪ Height of the cylinder is lengthened.

In case you missed that - Length of the rod is shortened-

Stroker kit - Wikipedia, the free encyclopedia

1.yup, not done by dicing up a piston and welding it back together

2.yup, not done by dicing up con-rods and welding back together

3.haven't seen it done(most commonly by sleeving)

incase you missed it cast metal shouldn't be welded

besides off-set grinding cranks need smaller internal diameter bearing surfaces(which would be best accomplished by different rods); then you have to think about oiling passages,etc...

[ecomodded]

Originally Posted by mechman600

A) Good luck on cutting and welding connecting rods. Please take a video of the first time you start the engine so we can all enjoy watching the carnage that ensues.

B) Shortening connecting rods does not change the stroke. Changing the length of the crankshaft throw changes the stroke.

I was attempting to figure out a way to decrease the cylinder size without lining them or disabling
a cylinder.
A shorter travel distance for the piston would give the piston less cc to travel in.
It is a experiment on paper,I never said it was a conventional method.

[Frank Lee]

An easier non-conventional method would be whittling the new bits out of wood.

[ecomodded]

Come on Frank, you must have an idea to offer the op?
No ? just in pest mode?

[baldlobo]

frank already gave his idea; get a different engine getting a flywheel adapter and bell housing adapter, along with the engine; might be the cheaper way.