Up to £140m needs to be invested in the Welsh Ambulance Service over 10 years to achieve necessary reforms, says the organisation's new chief executive.
The current 999 system is "poorly designed" says Mr Murray
Alan Murray, the fourth person to take charge of the service since March, said the service's way of dealing with 999 calls was "poorly designed".
He added he was not expecting "a blank cheque" from the assembly government.
The assembly government said it had money available for reforms but changes would need to be fully evaluated.
A public inquiry into the service - described as "in crisis" by a previous chief executive - is ongoing and is due to report later this year.
Mr Murray, who said he did his "homework" before taking on the post, is seven weeks into the job. At the NHS trust's annual meeting on Tuesday he outlined how he thought the service could be put back on track.
He said parts of the organisation were poorly designed, leaving patients waiting for too long in emergencies and that the emergency response target of eight minutes was still not being met by enough crews.
Mr Murray said £20m needed to be invested in the service up front
"We're developing plans at the moment which look like something of the order of £140m over 10 years, with a lot of that up at the front end - over £20m," Mr Murray said.
"We need a lot of new ambulances, for example. We need new information and communication technology systems so that we know where our ambulances are when we need them, so we can get them quickly and so we can help them to navigate to where they are needed."
An assembly government spokeswoman said health minister Brian Gibbons was "looking forward" to seeing Mr Murray's draft modernisation plan, although further investment would have to be subject to a full business evaluation.
25 May: Roger Thayne quits as ambulance trust chief exec; deputy Dr Anton van Dellen remains
6 June: Mr Thayne warns service is in "crisis"
20 June: Welsh assembly votes for public inquiry
27 June: Dr van Dellen warns cuts in staff could put public at risk
28 June: Figures show worries over sickness levels in service
24 July: Dr van Dellen resigns as interim chief exec
7 August: Alan Murray appointed as chief executive
The statement read: "Improving the ambulance service's performance and response times needs both money and modernisation and extra funding would need to be phased over a number of years and be backed by a clear modernisation plan.
"Patients deserve the best possible service as quickly as possible, but they also need to know that any changes can be sustained for many years to come."
Jenny Randerson, the Welsh Lib Dems' spokesperson on health, said Mr Gibbons had "gone through several ambulance chiefs" because he had "demanded cuts to a beleaguered service".
She said Gibbons had, during questions last week in the assembly's Senedd debating chamber, agreed that the service needed more capital investment.
She said: "I welcome the minister changing his position. The ambulance service is underfunded and stretched to the limit.
Mr Murray's appointment in August came after months of turmoil for the service.
Acting chief executive Roger Thayne resigned in May after just two months in the post, claiming the organisation was in "crisis".
He wrote a damning report calling for £35m investment, cataloguing outdated equipment, a history of poor management and delays in getting ambulances to patients, which he said contributed to a "dangerous" service.
His successor Anton van Dellen also resigned as the service's interim chief executive after two months, saying he was unable to commit long-term to the role.