2si

{{Short description|Defunct American engine manufacturer}}

{{Use dmy dates|date=January 2022}}

{{Use American English|date=January 2022}}

{{Infobox company

| name = 2si

| logo = 2si Logo.jpg

| type = Private company

| genre =

| fate = Out of business 2014

| foundation =

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| location_city = Beaufort, South Carolina

| location_country = United States

| location =

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| key_people =

| industry = Manufacturing

| products = Two-stroke engines

| services =

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| parent = AMW Cuyuna Engine Company

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| homepage = [http://www.2si.com/ www.2si.com]

| footnotes =

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}}

2si was an American engine manufacturer located in Beaufort, South Carolina. The company was a wholly owned subsidiary of the AMW Cuyuna Engine Company, formerly known as the Cuyuna Development Company.Cliche, Andre: Ultralight Aircraft Shopper's Guide 8th Edition, page G-2 Cybair Limited Publishing, 2001. {{ISBN|0-9680628-1-4}}{{cite web|url = http://www.2si.com/2si_company_profile.htm|title = 2si Company Profile|accessdate = 2010-02-16|last = Two Stroke International|date = n.d.|archiveurl = https://web.archive.org/web/20100115032358/http://www.2si.com/2si_company_profile.htm|archivedate = 2010-01-15|url-status = dead}}Purdy, Don: AeroCrafter - Homebuilt Aircraft Sourcebook, page 69. BAI Communications. {{ISBN|0-9636409-4-1}}Cuyuna Development Company: Cuyuna Engines, Cuyuna Development Company, undated

The company acquired a line of two-stroke engines that were originally designed and produced by JLO of Germany and marketed them under the Cuyuna brand name for snowmobile and later ultralight aircraft use. Later Cuyuna formed a subsidiary Two Stroke International, commonly known as 2si, to produce and market the engine line. Cuyuna ended selling engines for aircraft use, but instead switched to marketing them only for industrial, marine, auto racing, kart and all-terrain vehicle applications.{{cite web|url = http://www.2si.com/2si_applications.htm|title = Applications|accessdate = 2010-02-16|last = Two Stroke International|date = n.d.|archiveurl = https://web.archive.org/web/20100317034839/http://www.2si.com/2si_applications.htm|archivedate = 2010-03-17|url-status = dead}}

The company seems to have gone out of business in 2014.