Injector capacity of a 3.2?

[911st]

Anyone know what the HP limit is for the stock Carrera 3.2 injectors when running stock fuel pressures?

Will they support 300 fwhp?

Thx!

[911st]

Will they support 350fwhp?

[Rot 911]

I am curious how you plan to get 300 hp out of a 3.2 without turbocharging or supercharging.

Oh and a stock 3.2 injector flows 240cc/min @ 45 PSI, 2.5 Bar pressure

[stlrj]

Originally Posted by Kurt V

I am curious how you plan to get 300 hp out of a 3.2 without turbocharging or supercharging.

Oh and a stock 3.2 injector flows 240cc/min @ 45 PSI, 2.5 Bar pressure

1 bar = 14.503 773 801 pound/square inch
http://www.onlineconversion.com/pressure.htm

So 2.5 Bar must be 2.5 X 14.50 psi or 36.25 psi.

Stock Carrera fuel pressure is set at 2 Bar or 29 psi.

[Steve W]

Originally Posted by stlrj

Stock Carrera fuel pressure is set at 2 Bar or 29 psi.

Correction, the stock fuel pressure is supposed to be 2.5 bar, but typically measure about 40 psi, vacuum line disconnected.

The injector capacity is similar to those used on the 964, with the 964s running 3.8 bar fuel pressure. 964 injectors at 3.8 bar run fine up to about 300 hp, but their control starts loosing linearity and gets sketchy as you approach 310-320 hp. On a 3.2 at 40 psi, about 270 hp is the max practical limit.

[stlrj]

Originally Posted by Steve W

Correction, the stock fuel pressure is supposed to be 2.5 bar, but typically measure about 40 psi, vacuum line disconnected.

I was quoting "testing pressure at idle speed...approx. 2 bar" per Spec book, pg. 66, 84-87 911 Carrera, 911 Turbo Technical Specifications.

This is with the vacuum lines connected as a normally running 3.2 would be.

[911st]

So to do 300 may require new injectors (944T) or a 964 fuel pressure reg.

Current 3.2 HP w chip and cat bypass, 217rwhp or 255fwhp at 6200rpm.

Bore and stroke to a 3.8 (102 nickies w stroked 76.4 3.2 crank) w proper mods to support. Could approach 300fwhp ((255hp/3.2)x3.8).

Second reference point, factory RS 3.8 makes 300 hp at 6500rpm.

Still very much at the dream / research stage. (I do have the car though.)

[911st]

Oh, thanks Steve!

Love the chip!

[cgarr]

Steve, Would you start to see a lean condition as the injector reached its peak?

[Steve W]

Originally Posted by cgarr

Steve, Would you start to see a lean condition as the injector reached its peak?

Pretty much. Either you'd see lean spikes if there loss of injector control, but you can tell when you keep increasing fuel map values and there's no change in the AFRs. On a 3.2 type motor, this has only happened on a highly prepped 3.2 race motor with a $4000 custom exhaust, in which case I needed to bump up the pressure by about 5 psi, or on a 3.2 to 3.7l street conversion, again where had to bump up the pressure.

[911st]

How are you bumping the fuel pressure please?

What would be do without 911Chips.com to make our work!

[911st]

Sorry.

What would we do without 911chips.com to make our mods work!!!

[Steve W]

Originally Posted by 911st

How are you bumping the fuel pressure please?

What would be do without 911Chips.com to make our work!

LOLs. There are adjustable fuel pressure regulators that you can buy special for the 3.2. The other way is to press the body of the regulator in a vice to place the internal spring under greater compression, which increases the diaphragm release pressure.