Hi,

I have a 2009 hatch sti going forged and aiming for around 450bhp. It will only be used for road use maybe the odd track day.

Already have uprated fuel pump and going for 740cc injectors (future proof).

Are fuel rails and fpr really necessary?

Cheers Jamie

 

would suggest they are 'belt & braces' rather than required.......

 

I'm running just over 470 on standard reg and 650's with a meth mix...
JGM told me it wasn't necessary to change to an aftermarket FPR when I asked him, and whilst I could go parallel, unless I'm tracking it I felt it might be overkill.

Alyn, is there anything else you'd say should be considered, as I'm interested in your belt and braces comment.

 

Hi mate think there added for reliability soon as you go over certain power. Still undecided weather to get rails and fpr. Does yours run fine fuelling wise?

 

They're only needed if you're pushing the fuelling outside regular params (e. High boost) from what I understand. Mine runs absolutely fine, had it dyno'd several times and have it checked pretty regularly, normally at least every 6 or 7 months at SRR.
I also have a fuel pressure gauge in a pod as well to monitor it.
Got a larger fuel pump and injectors, on top feed rather than side feed they're supposedly more capable and we haven't seen the car run lean.
The only time it did was due to a knackered fuel pump, which was then replaced.
Not the rails or regulator. I think you need to be running higher boost (e.g 2 bar) before you have to start seriously worrying.

They make sure fuel goes to each cylinder at the same time; by default the passenger side goes first and then Tees off to the driver's I think.
I'm uncertain how much it REALLY helps though. There are several cars running big power on here that don't have parallel rails.

 

Cheers mate, clears it up abit better.. Yeah ive seen a few high spec cars with and with out!

Spose ill leave them then spend money elsewhere, if i get any problems can always just buy them and have them put on.

I have a uprate 290lph pump and going for 740's which are top feed so should be fine.

 

Hi Jamie

As above really depends on more factors,but if you going with build engine then I would at least think about this,doesn't cost too much and if its worth,yes and will looks bit better

About the fuel rails,I would speak with Alyn about the Carl Davey fuel rails and FPR I would choose only one and this one is Fuelab,we are run this one without the single issue,those latest one are methanol friendly and earlier ones hasn't been

Do you know what turbo and what other bits you will be running ?

Injector wise I would suggest Injector Dynamics or any Bosch EV14 based injectors,those have great spray pattern although higher idle(around 1000RPM),but I can recommend them

Hope this helps

Thanks,Jura

 

Thanks jura,

Yes im wanting to run a md321t

And what im currently going for

Forged pistons
Forged rods
Acl race bearings big and main
Cosworth stopper gaskets
11mm arp headstuds
11mm oil pump
Tgv delete air pump delete
3 port boost solenoid
290lph fuel pump
740cc injectors
3 inch revolution turbo back
AEM induction kit
Genuine subaru engine gaskets and seals
Water pump
Cambelt kit
Front mount intercooler

I have spoken to CDF regaurding there rails etc just undecided yet lol

Cheers

 

14mm head studs are a must on a 2.5 IMO ,, 12mm oil pump would also be better with avcs heads ,,,I have some tgv deletes I can sell and have already done a air pump delete if you need any help mate ,,, come find me at the next meet for a proper chat as i find typing hard so tend not to reply as much as I should lol
Also be worth thinking about a oil baffle plate aswell while its apart

 

I didn't realise this was for a UK and hence 2.5.
Unless you're going for CDB inserts won't you be right on the limit with a 321T? I thought those blocks were only capable of around 450 in reliable form, even built? If done right though it'll be a weapon for sure, but would be tempted to either use CDB inserts Alyn supplies or just go 2.35 if pockets are deep enough!

 

There's a 2.5 in the for sale section that was running an engine tuner built motor and it cracked the block around the 400 mark, maybe a one off but it does show yet again that they are vulnerable even when built by some of the best in the business, I'd go the belt and braces route if it were my build.