destroking and boosting for mpg

[user removed]

Shorter stroke engines generally are less efficient. The most efficient engine on the planet has a 3 foot bore and a 9 foot stroke, and runs at 92 RPM.

55% energy conversion efficiency, with a stroke to bore ratio of 3 to 1.

regards
Mech

[cabman73]

thought about going to a smaller bore sleeve but you could at most only go 2mm smaller. it had been awhile since i did the math on the smaller bore but i think it is only about 50 cc difference. that would be ideal though.

smokey, right now i am already getting 30% more mpg but i have no idea on power except to say it feels like more. ihave recently rebuilt my g10 in my convertible metro and am pushing 60mpg without any hypermiling drivimg techniques. i had the head milled enough to provide close to10:1 compression, cleaned up the bowl and ports on the head, installed a slightly larger undercut exhaust valve, and portmatched intake and exhaust. also running a slightly larger tire. if you want to write a novel, i will read it. the increase in mileage does take the larger tires in account.

[cabman73]

or smokey, if you just want to give me the cliff notes i will be fine with that.

[Frank Lee]

Originally Posted by ecomodded

...cut and weld the connecting rods...

I've never heard of that procedure.

[ERTW]

Turbo plus much taller gearing. Done. Polishing the ports and chamber also help. Hth

[ecomodded]

A Stroker kit increases the length of the stroke so,
a DE-Stroker kit would by definition, decrease the Stroke.
If one must , then get shorter connecting rods or shorten the ones you have.
I think increasing the Stroke to somewhere less then nine feet but more then it is currently would be more effective. Giving more bang per revolution.

[mechman600]

Originally Posted by ecomodded

De-tune it by shorting the stroke of the piston, cut and weld the connecting rods , shave both the head and the block for compression.

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.

[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.

[Frank Lee]

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.

Likewise with that 4-into-3 hacked up FrankenCrank.

Lotsa engine advice from people that have never touched an engine, I see.

[mechman600]

Like I said in a previous post: just get a smaller engine. You will be happier. We will ALL be happier for you....although slightly less entertained.