"Last year and this year has continued with rates of return on various exchanges in Sub-Saharan Africa ranging from 15 percent (in Mauritius) to 65 percent in Ghana," McLaughlin said at the event hosted by the New York Society of Security Analysts. "So in U.S.dollar terms, somewhere between 10 percent and 20 percent is where a lot of Sub-Saharan funds are at."
Development Capital expects its performance in the same double-digit range this year.
Successful frontier mutual funds with African investments include T. Rowe Price Africa & Middle East (up 18.77 percent this year); Harding Loevner Frontier Emerging Markets Portfolio (up 15.48 percent); Wasatch Frontier Emerging Small Countries Fund (up 14.02 percent); Templeton FrontierMarkets (up 10.64 percent); and Nile Pan Africa (up 9.48 percent).
(Read more: Private equity's growing play: Africa)
Another Africa bull is Tim Drinkall, the portfolio manager for Morgan Stanley Investment Management's frontier emerging markets strategy.
Drinkall said at the same event that investors in Sub-Saharan Africa can expect a return of between 15 percent and 20 percent this year—even if finding large and liquid enough Africa investments means going offshore.
"There are all these companies that if you slice and dice them properly you can actually find that they have significant exposure to Sub-Saharan Africa. But you really have to go out and see where those are and find those opportunities," Drinkall said of stocks outside of South Africa, Kenya and Nigeria—by far the largest continental equity markets.
Drinkall mentioned internationally listed companies like retailer Shoprite, bank Barclays Africa Group and telecommunications company MTN Group on the South African stock exchange. He also noted Bombay-listed telecom company Bharti Airtel (which owns Africa focused Zain) and energy businesses like Tullow (London-listed) and Total (Paris-listed).
It seems to be working.
Drinkall's fund, the Morgan Stanley Institutional Frontier Emerging Markets Portfolio mutual fund is up 25.19 percent through Oct. 20 with nearly 27 percent of the fund invested in Africa-focused companies like Lagos-listed beer maker Nigerian Breweries and London-listed oil and gas company Afren.
(Read more: The big winners in Kenya's oil debut)
Drinkall recommended investors look at the power sector in Africa.
"I think power is interesting. The entire continent is very low on electrification. There's massive amounts of power that has to be installed and distribution has to be put in," Drinkall said. "None of that is really listed with the exception of Kenya. So I think that would be an interesting opportunity."
Jamie Odell, deputy global portfolio manager at frontier-focused private fund manager Caravel Management, said the next wave of investing would be in three areas: Infrastructure, agriculture and manufacturing.
"Maybe it's wishful thinking, but those are the areas we feel Africa really needs in order to drive the next leg of growth on the continent," Odell said. Caravel manages $630 million, up from $241 million in April.
Private equity firms are also increasingly bullish on Africa. Top American PE shops Carlyle Group, Blackstone, KKR and PineBridge Investments have invested in projects on the continent recently.
And while cheap money makes it easier for U.S.-focused private equity firms to juice returns, investors in African companies can receive three or four times their money without leverage.
"The interesting thing about Africa and emerging markets is you can make a lot of return just with equity—you don't need to use leverage to generate return. We typically don't use any," Abraaj Group senior partner Tom Speechley said at the NYSSA event. "We just put in equity and hope the business grows three or four times over three or four years and you make three or four times your money."
Abraaj manages about $7.5 billion globally today and has invested about $2 billion in Africa since inception in 2002.
Speechley warned that investment success is driven by local partners and other micro factors despite Africa's positive growth story.
"You can be in the hottest sector, in the hottest country, and still lose all your money," he said.
(Read more: Nigeria's property boom: only for the brave)
Interest in the continent is growing despite inherent risks of frontier market investing,
"We've seen interest grow in frontier and Sub-Saharan Africa markets," said Ashley Bendell, an Africa capital markets specialist who was recently head African equities at Russian investment bank Renaissance Capital.
"Performance has obviously been key to that. The Sub-Saharan markets are up 50 to 100 percent over the last couple years and have performed well year to date. That in itself has driven inflows and we've seen a lot of launches in the Sub-Saharan, frontier, emerging market small-cap universe."
—By CNBC's Lawrence Delevingne. Follow him on Twitter