john banks

As title, MY00, 2.33 with flowed STi heads, mostly sorted breathing, 20G, target 450 BHP 400 lbft at less than 1.5 bar.

Heard mixed opinions, but all it has been has been opinion. Anyone got any results before/after?

john banks

Oh, just heard the inlet manifold is back on now Not to worry, later project maybe. I'll see how the individual cylinder timing is and if there is one aberrant cyl I will think again.

Adam M

why mixed opinions?

can you explain the downsides!

By converting to parallel, there is only ever one injector inbetween the injector and the fuel supply, why is this a bad thing?

I converted all 8 injectors on mine to parallel feed, despite the engine builder preferring to run series to all 8 injectors because he wasn't keen on the pipework!

caz1562

I'd like to hear any1's views on this as my engine is currently out and I could carry this mod out

john banks

Downsides - being ar$ed to do it, also you still end up with a gradient front to rear.

Adam M

a shallower gradient!

you can always convert to individual feeds!

effectively have a fuel supply bar with an individual take off to each cylinder, and a return from, the bar to the tank.

David_Wallis

John..

Its not worth possibly running leaner on one cylinder than the rest..

unless you have w/band / egt per port..

David

caz1562

So is it worthwhile ??

VinnyP!

Rang up an old university PAL re this, (Fluid Dynamics) now working outside the field but did work for British aerospace. Says it's snake oil. Pressure to injectors won't be affected provided the pipes can flow enough and the pumps up to it, even then all will be affected equally.

David_Wallis

still not convinced..

surely as the injectors are restricting the flow.. unlike top feeds?

David

john banks

Tomorrow I think Andy. I will be having dreams about engine noises tonight

Andy.F

I hope they're not loud enough to keep you awake

Bob Rawle

Pressure at the start of the rail (adjacent filter) can be significantly greater than pressure at the end of the rail under constant conditions, there are other variables as well which add up to a v large discrepancy.

Parallel rails help but do not solve.

nom

In a theoretical dreamworld, serial should work just as well. Out here in the real world, where pipes have bends in them - inconsistent diameter ones at that - there is always going to be a pressure drop across them.
I don't think it can ever be perfect - but may as well make every effort to get as close as possible?

MorayMackenzie

"I say go for a separate feed and regulator per injector"

The WRC car certainly used to run two FPRs. In fact, IIRC, they used to run a pair of the LH fuel rail. Great as long as you can guarantee that you have either closed loop fuel control on each bank or you are very sure the two FPR's are exactly matched in flow/pressure characteristics. I think the WRC used this setup for: parallel fuel feed, the higher fuel flow capacity through the pair of regs and a degree of fault tolerance (one fpr screws up and you may still have a small chance of getting to service)

Moray

Andy.F

Phase 2 rails are better than Phase 1.
My Ph1 rails had some tight bends that decreased in diameter.
I measured the pressure at the filter outlet and it was 3-4 psi higher than at the pressure regulator. This was at idle which would give the biggest differential. When on full load the pressure drop would be less, due to less fuel having to make the full trip round the rails IYSWIM !
A bigger concern is the unequal flow characteristic of the std intake manifold It was either Harvey or Dowser that had theirs flow tested and there was over 10% difference between runners !!

Andy

PS Is it running yet JB ?

[Edited by Andy.F - 9/11/2003 10:27:02 PM]

dowser

Maximum of 14% airflow difference at 1 bar on the manifold originally...not anymore Still don't know what effect it will have....still waiting for the engine to put it on...may yet bolt it to the ej20.

Why would you even consider taking the manifold off and *not* doing this? Basic physics says there will be a difference, however small. My mechanic will still use the stock phase 2 rails, but will modify input/output pounts for better flow.

The Perrin design I'm not sure about - it's said to smooth the flow being available at the injector for a more consistent feed...I reckon the 1st injector firing will still upset the flow to the second one. And their whole design is restricted by their Y-piece being closer to one bank than the other.

I say go for a separate feed and regulator per injector

Richard

[Edited by dowser - 9/12/2003 11:00:19 AM]

MorayMackenzie

The rails on the 97 models flow differently on each side (bank). I asscertained which side flowed best with the least restriction and set the car up with parallel feed to a modified pair of the better flowing rail.

This could/should also be applicable to other model years.

Moray

[Edited by MorayMackenzie - 9/12/2003 11:13:05 AM]