Mi16 Injector Flow Rate

[TheLarneMan 4]

Does anybody know what the flow rate is for a standard Mi16 injector?

 

I did a search and found a figure of 214 cc/min. Is this correct?

 

Cheers.

[Ryan 99]

214cc is correct.

[TheLarneMan 4]

214cc is correct.

 

Thanks Ryan.

[smckeown 1]

@3bar

[stux 0]

213,9 cc/min

[VisaGTi16v 1]

For the uneducated such as myself, is it true that the injectors in an Mi16 are only good to 180bhp or is that an old wifes tale? Wondering if thats why my power curve goes flat over 6600 or perhaps its due to a lack of fuel pressure and is running lean.

[Ryan 99]

A good rule of thumb is 5cc per 1bhp.

 

So 214cc x 4 injectors = 856cc

 

856cc / 5cc per bhp = 171bhp.

 

That's only a rough general estimate so 180bhp sounds about right.

[stux 0]

It depends on injectors duty cycle and fuel pressure.

80% injectors duty cycle and 3bar - approx 148bhp – standard

85% and 3bar - approx 158bhp

85% and 4bar - approx 183bhp

95% and 3bar – approx 177bhp

95% and 4bar – approx 204bhp

85% and 4,5bar – approx 194bhp

 

So it’s possible if you raise fuel pressure and injector duty cycle. I do not recommend duty cycle greater then 85% and fuel pressure over 5bar.

Edited April 5, 2007 by stux

[VisaGTi16v 1]

Any idea what the standard fuel pressure is?

 

Next question, suitable upgraded injectors...? All ive read when searching on here is use cossie ones but they are £100+ on ebay, I did read about some Saab ones mentioned but apparently its critical to get ones which use the same spray pattern but I forget if Mi16 ones use a single squirt in the middle or spray it out wide etc.

[stux 0]

As smckeown wrote 3bar !

 

For example you can use Citroen Xantia TCT injectors – 240,2 cc/min – they are cheep and easy to buy.

 

80% & 4bar - 193bhp

85% & 4bar - 205bhp

 

But in the first place you should buy adjustable fuel pressure regulator and try with standard injectors.

[Mandic 0]

It depends on injectors duty cycle and fuel pressure.

80% injectors duty cycle and 3bar - approx 148bhp standard

85% and 3bar - approx 158bhp

85% and 4bar - approx 183bhp

95% and 3bar approx 177bhp

95% and 4bar approx 204bhp

85% and 4,5bar approx 194bhp

 

So its possible if you raise fuel pressure and injector duty cycle. I do not recommend duty cycle greater then 85% and fuel pressure over 5bar.

 

Going over 4 bar (on injectros where manufactor quotes them at 2.5-3.0 bar) is pointless, as if You look closely, You will see that the solenoid is unable to raise the pintle as rapidly when fuel pressure is raised past certain point. This effect can be noticed from 3.0 bar onwards, and even significanty past 4.0 bar. And even their life-span shortens dramatically after 4.0 bar.

 

Cheers

 

Ziga

[VisaGTi16v 1]

oops missed that, I read your first line of 80% 3 bar = 148bhp standard so got confused as the engines 160 standard. I will be buying an adjustable regulator which hopefully will help. Ta for the advice of the Xantia ones, not heard of TCT though, was that a trim/model? Which engine did the come with? The 150bhp 8v turbo or the v6 perhaps?

 

cheers

[stux 0]

Going over 4 bar (on injectros where manufactor quotes them at 2.5-3.0 bar) is pointless

You must be joking Pressure limit for these injectors is 5bar!

 

TCT = turbo constant torque. XU10J2TE engine, 147bhp. You will find them in Xantia, XM, 406, 605 (turbo)

[Mandic 0]

Yes, pressure limit is one thing, but pressure to flow ratio gets worse with increased pressure + life-span is shortened.

 

Going from 3 bar to 4 bar might show cca 16% increase in flow, but going from 4 to 5 will only show in 2% increase in flow.

 

Cheers

 

Ziga

[VisaGTi16v 1]

ta

[stux 0]

oops missed that, I read your first line of 80% 3 bar = 148bhp standard so got confused as the engines 160 standard.

 

Perhaps the standard duty cycle (at max power) is something between (80-85%), and I wrote „approx” not „exact” so I think that 10bhp more is possible.

 

All I wrote (esp. calculations) is based on “modern engine tuning” – A. Graham Bell, Hayens Publishing.

I agree with Mandic that exceeding 4 bar can be pointless because of poor increase in flow but as far as I know only too long duty cycle can overheat or even burn the injectors. Higher fuel pressure will not do any harm however over 5 bar injectors control can be lost.

 

I’m sure that 4bar is good/safe pressure and with standard injectors (213.9cc/min) one can get 20bhp more without changing injectors duty cycle (if air flow is not the limit). That is why I recommend buying a proper fuel pressure regulator instead of buying bigger injectors in the first place.

 

With standard pressure and duty cycle and with bigger injectors (from 2.0 8v turbo - XU10J2TE) one can get also 20bhp more but without adjusting fuel pressure, air/fuel mixture can be even too rich.

 

As I wrote before 80-85% duty cycle, 4bar and bigger injectors(240.2 cc/min) is enough for 200bhp.

 

 

Wondering if thats why my power curve goes flat over 6600 or perhaps its due to a lack of fuel pressure and is running lean.

 

Don’t You have AFR curve plotted together wit power and torque, for example like this: http://forum.205gtidrivers.com/index.php?a...ost&id=1325 ?

Edited April 6, 2007 by stux

[VisaGTi16v 1]

Nope, only gave me a wheel power output. A friend has one of those gas analyser things I need to put up the exhaust to test when I have put all the wiring back together