S2 Injector Flow

[T2Andy]

Does any one know how much bhp the standard S2 injectors are good for
or when when would it be advisable to change them ,would you need a larger
fuel pump then and fpr too thanks
The engine i will be running is rated at 350hp with a ported \flowed head.

[S2central.net]

I'll spare you all the math, but on an S2 - the max bhp you can get is the same number as the injector flow rating - assuming nominal overheads on duty cycle.

Stock injectors run at 320cc per minute ==> 320bhp
RS2 injectors get you into 360cc per minute ==> 360bhp territory
Bosch Greensare 440cc per minute ==> 440bhp country

Seeing the trend here ?

Its one of those anomolies and rules of thumb that is a good reckoner - you can squeeze a little higher than those ratings as we run higher fuel pressure than the 3bar (43.5psi) that injectors are tested at - traded off with knowledge that you shouldn't drive them much harder than 85-90% duty... So this is not an exact science.

For your target then RS2 injectors should do just fine. FPR of 4bar is fine for that. Adjustable FPR is nice quick easy way to trim out best mixture at WOT if its found to drift off with fuel quality an aging pump or whatever - or playing with E85/95 fuel and other ECU tweaks.

[T2Andy]

Thanks paul i did read one of your other posts on this topic which makes things clear
i was wondering because the MTM set up i will have is rated at 350bhp but it does run standard injectors plus i also have the supersprint down pipe rs2 airbox which is over and above what you get in the conversion so it might run alittle more ? if this is the case then the standard injectors will be past there limit no.Or the set up doesnt make that figure in the first place ,confused i am

[T2Andy]

ps .if i was to add larger injectors would the MTM chipset not be compatible with the new flow caperbilities .phew

[S2central.net]

The highest figure I have seen from stock injectors is 330-340bhp on the Nothelle ABY setup... I've always wondered if they ran a slightly higher fuel pressure for that, but I've been told this is not the case. When you do the math you find that a 320cc (at 3bar) injector runs to 370cc at 4bar so with a 95% duty you get 350cc ==> 350bhp. IMHO this is really on the ragged limit.

And to answer your question - changing to different spec injectors without ECU mods will throw off your fuelling big style.

[shark_90]

It was one of my concerns when I was looking at buying that engine.. 350bhp on standard injectors just doesn't compute. As Paul says (who knows much more about it than me), if you changed the injectors you'd need to change the chips/map to suit.

[ericd]

much over 340/350 and the std injectors will go static, somebody on here was selling a set of "green" ones for £200, bargain

[S2central.net]

I stand by my rule of thumb for 320bhp being the ceiling for any sort of headroom on the factory injectors (at 4bar)... Nothelle went to the max at 340 - anymore than that is just dreaming.

[ericd]

I stand by my rule of thumb for 320bhp being the ceiling for any sort of headroom on the factory injectors (at 4bar)... Nothelle went to the max at 340 - anymore than that is just dreaming.

agreed, n300 was supposed to have parity with rs2 performance /power levels quoted
at 315.

[T2Andy]

so what your saying is ive bought an engine that can not produce its claimed
350bhp ,i am still optimistic and it will be on the RR at the end of next month
so fingers crossed .

[S2central.net]

Well - throw some toluene in the tank - that'll pep things up...

I personaly think the 350bhp claim is hyped - but possible on the rollers with an operator who knows how to sway the numbers that way.
Its what you get at the wheels is the most important thing so make sure to get those readings and you can compare with S2, RS2 in stock and chipped form to see where the truth really is.

Don't get me wrong here - not saying MTM setup you have is rubbish - just the 350bhp claim seems to be a bit hyped. Assume its on a small hyrid K24/26 of some kind ?

[GazzaG60]

guys. it depends on where you get the power too.

if you have a bigger turbo you will see you cant hit the samer levels as a smaller (stock) item. feeding the engine at 6k is not the same as at 3500.

i did 321 and 325lbsft at 5k. at 4k the injectors went 100%dc. after that it hit 10:1 and then rose at a rate similar to the hp curve to 5200 where i terminated the run. 1.35bar boost. with a standard turbo the power drops away just after 5k or so so its not about holding the rpm the same.

[GazzaG60]

if you see 350hp then id be surprised Andy. maybe if they fitted a better pump it can hold on a little more.

think im on the same RR day as you too. i gotta get the juice going in yet though.

[Jamo]

I refuse to comment.........

[GazzaG60]

you just did lol