[OCD_Performance]

Robert,

A real conundrum. A larger WG didnt solve anything. But I kinda knew that since the pressure ratio was too low. However I have some new info and a choice to make and I wouldnt mind some help.

Placing the T72 with a 68 Ex and a 69 AR saw regulation return to normal. So I borrowed 2 more billet turbos.

The HPC 64 with a 68 Ex and a 69 AR saw the return of regulation problems. The 9 psi spring saw regulation at 17 Psi of boost. Too High. The Pressure ratio was about 1.25:1. Which is just too low for decent boost regulation on the street.

The next Turbo tried was a HPC 64 with a 65 Ex and a 69 AR. This generates proper regulation around 10 psi of boost. The pressure ratio balanced out at 1.5:1, which is where it should be. However the 69 AR is too restrictive for my application so I have to choose another Turbo. I must now buy as im out of borrowing options.

So I'd like to stay with the billet wheel, so i think my choices would be narrowed to two options.

1) HPC 64 with a 62 Ex and a 91 AR

Or

2) HPC 69 with a 62 Ex and a 81 AR


So you can see my dilemma. Can you offer any clear advice in make this choice? There are no compressor maps for these unit so Im flying by the seat of my pants and not enjoying it.

[OCD_Performance]

Fyi,


I thought the Evolution WG was 38. You thought it was 35. In actual fact, its less than 32.

Thats the valve seat passage being measured. The entire bore is 31.60.

[Robert]

Originally Posted by OCD_Performance

Robert,

A real conundrum. A larger WG didnt solve anything. But I kinda knew that since the pressure ratio was too low. However I have some new info and a choice to make and I wouldnt mind some help.

Placing the T72 with a 68 Ex and a 69 AR saw regulation return to normal. So I borrowed 2 more billet turbos.

The HPC 64 with a 68 Ex and a 69 AR saw the return of regulation problems. The 9 psi spring saw regulation at 17 Psi of boost. Too High. The Pressure ratio was about 1.25:1. Which is just too low for decent boost regulation on the street.

The next Turbo tried was a HPC 64 with a 65 Ex and a 69 AR. This generates proper regulation around 10 psi of boost. The pressure ratio balanced out at 1.5:1, which is where it should be. However the 69 AR is too restrictive for my application so I have to choose another Turbo. I must now buy as im out of borrowing options.

So I'd like to stay with the billet wheel, so i think my choices would be narrowed to two options.

1) HPC 64 with a 62 Ex and a 91 AR

Or

2) HPC 69 with a 62 Ex and a 81 AR


So you can see my dilemma. Can you offer any clear advice in make this choice? There are no compressor maps for these unit so Im flying by the seat of my pants and not enjoying it.

It sounds like the 64mm unit worked well for you so id go that route. As for the evolution the valve itself is 35mm but the outlet is 32mm I believe

Sent from my MB860 using Tapatalk

[OCD_Performance]

So,

Which is better and why?

a) Stay with the 64 with a 65 Ex and a 69 AR.

or

b) Go to a 64 with a 62 Ex and a 91 AR.


Which flows better? How will this effect spool? Top end differences?

Cheers

[Robert]

The F1-65 turbine is physically larger and capable of flowing more air in the future if needed. Going with either one is going to get you what you want but only the 65 would have room to grow for the future.