was just wondering if ity's really worth doing the parallel fuel rail mod? simple as that really

 

only if you use parallel fuel

 

very good

 

the offset in cylinder fuelling is not caused by serial fuel feeds, so unless you are going for big power figures, therefore high fuel flow rates, i dont see it making any diference.

 

what sort of high power are you talking about john? was planning about 350 eventually anyway.

 

The best people to ask are engine mappers like Bob, i personally dont think at that level it makes any diference. You will need a high flow fuel pump/reg more than parallel feeds to achieve a safe 350BHP.

 

yeah. going for a walboro pump and some sort of reg. i asked in general about the reg's. was talking to branko about the rail mod and he said not to bother as he had over 350bhp in his sti6 without it and no problems.

 

I think it's one of those things that would be 'nice', but probably have no noticeable improvement on fuelling as the main fuelling irregularity is likely to come from air flow from the inlet manifold - someone had this measured once, and IIRC the flow varied by about 4% - far more than the additional consistency you are likely to get from the parallel fuel rail.
Hope that helps the decision a little?

 

so what would i be as well to do to improve the air flow bit?

 

I think it was even more than 4% nom

The fuel rail mod is not absolutely necessary but everything you can do to balance the air/fuel ratio across the cylinders will bring gains in specific output by allowing you to reliably run a leaner 'average' AFR. Without the mod you will need to run a richer (less powerful) AFR to account for the leanest cylinder.

This is one of the reasons some cars make more power than other 'apparently identical' models running the same boost

Andy

 

cheers for clearin it up for me there m8. round about 350 be alright for me car then?

 

Yes it will be fine Dave, the Phase 2 fuel rails are better than the Phase 1 anyway. Twin feed is only really necessary when you are chasing 1/4 mile times or big numbers on the rolling roads

Andy

 

Will the left hand phase 1 rail go straight on the righthand bank?



JGM

 

Yes it will.... i now have two left hand rails on the manifold sat in the garage (thanks to Jase Mac after Tweenie decided to ignore all e-mails ).

Tony.

 

Tony,

Do you need to remove the manifold to do this?

I thought you had phase 2 inlet manifold in your garage?

I might replace righthand fuel rail and have a metal T made to run from my FSE FPR.. and the T the returns in I guess..

I know we discussed this before Tony but I never thought I would need to do it as only aiming for 350bhp max.. but if it is more efficent and you get more power for the same fuel then it might be worth me looking at it.. better mpg and more power.. lol

Sorry to hijack btw.. but along the same direction.

Simon

 

It is only a small difference Simon but all these small tweeks add up to something measureable in the end.
I know I would rather have 401 bhp than 399

 

 

The inlet manifold runner flow difference was 13% before the porting work....and still 3 or 4% after

Not sure how much difference it makes in the real world; you have a relatively small opening (2 inlet valves cracked how many mm's?) and over 1 bar of pressure waiting to force mixture in. Is a 4% difference in flow going to be noticeable?

Lets just say I'm still trying to get my injectors flow tested so I can match them to the runner performance

I figure if you're going to do something, do it right - as mentioned, if you could ensure that every combustion event in every chamber was exactly the same, then you're no longer mapping fuel/timing to the weakest cylinder.

My current engine is detting badly - I guess something mechanical. 99.5% it's only affecting 1 cylinder, but I'm running lower boost and 5 degrees less timing to try and nurse it until the ej25 is finished (and it's still doing it.... )....car is as flat as a pancake and down 40-50ps from the same time (ie; temps ) last year.

Sorry, back on topic - if you're going to to be fitting a (presumably 'off rail') regulator anyway, then why not convert to parallel feed anyway. Good Karma

Richard

 

The difference between inlet tracts 3 & 4 (MY99) was around 15% measured @ 28" pressure iirc.

 

my first idea was to leave changing things like the fuel rail mod and/or injectors, till i HAD to as i just don't trust changing things like that enough. i know that if something went wrong with a mod like that, i don't want to be sitting in the car at the same time, if you know what i mean? the reg is sort of similar, don't get me wrong, but in a way, i HAVE to do it, more so than the rail mod anyway. if i can get away without having to do it i will. thats all. or so i believe