550cc and 400hp

[campbellju]

Yes I have done a search and I do know that in theory 550cc will support up to 420hp.

I also know they wil be 95% load at my taget hp (Previous target was 380 but slight change of plan en route)

This was the same load I used to run the 444's at delivering 320hp with no fueling problem.

The turbo is oversized so will not be increasing charge temps over my old setup. I might have bought 600cc injectors before now but still don't see a great problem.

So here is my question, why does everyone seem to be installing 660cc or 700cc when "most" people don't go past 400hp?

Jim

 

[Odin]

I agree mate , I went for 740cc injectors but these seem to be over kill and will proberly swop them for some 600's in the future .

But you never know I might end up with 500bhp which was my plan in the first place.


rob

 

[campbellju]

What would be your target for 600cc?

Just trying to work out whether I'm being reckless or whether other people are being over cautious?

 

[Rishi]

Because the rating stated for the injectors is at more than 3bar fuel pressure...

Also you don't want to be running the injectors near their max... 85% is about right...

Also if you have the multi-hole injectors like myself and Rob, mapping for normal rpm and idle is far easier and smoother over the normal single hole types...

Although running 1000cc injecotors on a 300bhp car would just be silly as fueling would be minimul and so at that capacity the injector spray would be poor and would adversely affecty the running of the car...
Extreme example i know...

Hope that helps though...



Rishi

 

[campbellju]

Because the rating stated for the injectors is at more than 3bar fuel pressure...

Also you don't want to be running the injectors near their max... 85% is about right...

Also if you have the multi-hole injectors like myself and Rob, mapping for normal rpm and idle is far easier and smoother over the normal single hole types...

Although running 1000cc injecotors on a 300bhp car would just be silly as fueling would be minimul and so at that capacity the injector spray would be poor and would adversely affecty the running of the car...
Extreme example i know...

Thanks Rishi. extreme examples a side, picking up on the first point, what pressure are injectors normally rated at then? I thought 3Bar was normal. I'l have to check the test results tonight on the injectors I've got, I'm sure it will say.

I understand the 85% rule too and yet many people (including myself) have run the car at 90-95% with out any noticable problems?

Don't get me wrong, for 400hp I would feel happier with a 600cc rather than a 550cc, just trying to work out if I need to panic because theoretically it seems okay.

 

[zia]

chossing injector depend's basically on

1..boost you wish to run
2..flow need to achieve power level
3..reserve capacity once desired duty cycle has been reached.
at 93% you worn,t have any reserve capacity in injector incase ambient temp's drop and your car run's lean due to max duty achieved earlier than expected/or your boost spike and no additionall fuel inj due to same senario. yes you can run 93% duty but then the injector could overheat and remain open/or close which leave's you with either overfueled engine or underfueled,in both case not good for engine.
inj are rated at minimum fuel pressure which on turbo'd car would 2.5 bar max would be 4 bar. obviously flow will increase with rise in pressure.

zia

 

[Rishi]

chossing injector depend's basically on


inj are rated at minimum fuel pressure which on turbo'd car would 2.5 bar max would be 4 bar. obviously flow will increase with rise in pressure.

zia

I always thought they were rated at higher presures... Or at least 3bar...

I would say that its dependant on the manufacture...


Rishi