destroking and boosting for mpg

[cabman73]

hi all. first post here although i have been lurking for quite a while. i have a 92 geo metro and was wondering what you all thought the benifits would be (if any) of destroking the g10 to somewhere around 650cc's and boosting it enough to get back up to 60hp. think ford 3.5 ecoboost compared to fords large v8. the only two ideas for the crank that i have are to offset grind the crank or if suzukis 4 cylinder g10 has the same bore centers have a machime shop chop a throw of that crank and use the four cylinders rods. whatcha think?

[mechman600]

It might work, but it would be cheaper and easier just to get a 650cc engine and adapt it to your Geo. Probably cheaper and easier to buy a brand new EcoBoost for that matter.

[MPGranger]

like the 1.0L inline three ecoboost slated for next year

[Duffman]

You cant chop a throw off a 4 to make a 3 cyl crank, the throws need to be spaced differently from each other in each configuration.

[ksa8907]

there my be some gains in efficiency, but the cost of doing the proposed work may not be worth it. if you really want a smaller engine, use a motorcycle engine. im sure you could find a machine shop that can make you an adapter to your trans.

[cabman73]

i have considered one of the japanese ki (sp) engines. they are 600 cc or under but the few i have looked at were dohc turbo motors making around 100hp. i will have to check out the 1.0 ecoboost though i would guess that it would also make over 100hp. the crank shop i was talkimg to was sayimg they would have to cut and weld the crank in several places in order to get the 4 cylinder crank to work. i do realize that the return on the investment might not be the best but if i could verify that the four cylinder crank had the same bore spacing as the 3 cylinder g10 and if i could find one reasonably priced it might not be terrible.

[MPGranger]

123hp for the 1.0L ecoboost with talks of a performance variant with 177hp and considerably less FE

[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.

[smokey442]

If you can live with a 30% gain in fuel economy and a 10% gain in power stick with the engine you have without altering the stroke. Mathematically compression ratio and expansion ratio are the same. Its the gain in expansion ratio that gives greater return in FE and power output. Custom pistons with thin compression rings and a one peice oil control ring reduce internal friction with good oil control. I'm a big fan of total seal rings. Conventional rings cannot match gapless rings sealing ability during part throttle operaton. Much more to recomend that would make this post into a novel.

[cabman73]

177 reliable hp in a package small enough to fit in a 1600lb metro. hmmmm