23 replies to this topic

[mini13]

they will certainly sort you out!

[MIGLIACARS]

decking a block you'll normall remove about 30 thou about 3/4mm

 

the BK450 wont make much difference to the C/R,

 

those pistons and that head are going to give a pretty low compression, about 7.3 maybe lower, I'd be aiming for high 7's with a charger, and at 8 psi boost probably mid 8's to 9:1

 

those injectors are known as "pico's" meaning they are shorter than normal ones, a look on ebay for fiat injectors might prove worth while.

 

if its maxing out at 6k all you'll do my running it higher is run the engine lean and risk melting somthing, in fact woth some ecu's when you reach 100% injector duty the fueling can go haywire!

 

 

 

 

With these pistons.

 

http://www.med-engin...istons-020-18cc

 

what is the highest compression ratio you could achieve??

 

Is 10-1 possible???

[mini13]

Hmmm,

 

with 18cc pistons 10-1 would be a struggle, you would need to get the chambers down to about 14cc, if the head is taken out to 26cc then I can imagine being able to skim it enough, especially being a 7 port.

[MIGLIACARS]

what psi should I be seeing of the fuel pressure.

 

my reg is this one, with no gauge,

 

http://www.demon-twe...ssure-regulator

 

not sure which one i have as there are 3 to choose from but at best it produces 49 psi thats the 3.5 bar version

 

 

id have thought that with my car being supercharged  id need to see at least 60 psi ??????????????

my car produces about 9 psi on the supercharger so fuel pressure will need to increase by this to.

 

im thinking the injectors are not getting the pressure they need????? and thats why they are maxing out early, 

am I talking sh t????

 

 

i gonna get this one

 

http://www.ebay.co.u...=item1e7f0cb352

Edited by MIGLIACARS, 03 September 2013 - 06:19 PM.

[evoderby]

My 340BHP integrale ran with IAW 058 injectors, rated at 384cc @ 3 Bar. These racing injectors are able to withstand 90% duty cycle (most normal injectors cope with 80%) and can see fuel pressures up to 5 Bar. I ran 3.2Bar base pressure with 1.3 Bar boost added on max power Rpm, and up to 1.7 bar boost in mid range.

When interpolating these figures to a 80% duty cycle 285cc set up this should be good for 215-225Bhp given the right fuel pressure, so the question is where do you expect to end up?? by the way injector flow vs. Fuel pressure isn't a linear relationship i.e. double the pressure does not equal twice the flow. It is a square root function, if your injector flows 285cc @ 3 bar it flows (6/3)^1/2 = 41% more @ 6 Bar or 403cc.

My advise would be to first hook up a fuel pressure gauge to your system to check your base pressure AND whether your fuel pump is able to sustain the required pressure higher up in the rev range. From here you can make informed decisions on how to best proceed.

Good luck!

Edited by evoderby, 06 September 2013 - 04:33 PM.

[MIGLIACARS]

ive checked the base pressure and is 52psi with the engine off. and 52psi at tick over, when its revved the pressure increases upto 60psi at red line and at 8.5 psi. 

[evoderby]

Excellent, fuel pressure/pump capacity doesn't seem to be a problem then. Which injectors are you running, do you have a data sheet that specifies their flow rate and max fuel pressure??

Some modern injectors are able to take 7 bar fuel pressure, this would give 32% added flow / HP potential.....setting your FPR up for 5 bar / 73psi (which most injectors are able to take) gives 12% added flow. The latter seems a bit thin with your current setup maxing out....

[MIGLIACARS]

these are my injectors now

 

http://www.ebay.co.u...984.m1438.l2649

 

 

going for these

 

 

http://www.ebay.co.u...984.m1438.l2649

 

 

 

thing is the car always felt so good and crisp

 

 

 

this was before the gearbox blew and destroyed the engine.

 

ive since rebuilt the engine myself using the exact same parts.

except using a cooper s gearbox instead of a dogbox. 

 

it went to the rollers at rdt and they showed me the injectors maxing out at 6000 rpm.

 

and the engine didnt produce the power i was told it had pre blow up.

 

im hoping that if i replace the injectors ill have more power .

peak power should be at 7500rpm which is redline. as this is max boost.

[evoderby]

Ok, so you're currently running weber style 240cc injectors that can handle up to 5 bar fuel pressure. These would be good up to 180-190 bhp, running them on 4 bar as you are makes this around 165 bhp which altogether seems a bit more logical maxing out in your application.

On the maxing out part, what did the RR guy exactly show you? Did the mixture go lean with injectors near 100% dutycycle? It all seems a bit odd that a gearbox change effect a previously perfectly running engine/ well functioning injection system. A gearbox change on the other hand very well can effect power seen at the wheels....

Anyway, I'm trying to help you make an informed decision based on data/facts not assumption. The 490cc injectors you're planning on fitting will support you well into 400bhp territory and are complete overkill accordingly and also run a risk of proving difficult to tune in the lower rev range. Base-Mapping them is very easy however, since they're almost exactly twice the size of your current injectors just devide your current map in half, go back to the rollers and have them concentrate on the 6000rpm+ mapping.

Edited by evoderby, 07 September 2013 - 07:02 AM.