"snipped to death for reasons of health and sanity"

Post turbo pipe is the main restriction, pre turbo will restrict spool slightly with a VF22

Shit tune or driven hard...


1- Needs a bigger intake pipe: "Wont Hurt" do the post turbo hose first
2- Bigger intercooler: "Wont Hurt"
3- Injectors. The stock 440cc injectors are at 87%: Sard fuel reg and slight increase of fuel pressure will do
4- Split Fuel Rails: Just go Parallel when you do the sard

Take the shit East Coast tune you described, believe it or not, it can be improved on in Perth. Since we have had electricity connected they have done wonders in Perth See Lumpy at Hyperdrive or the Guys at the Wok, not to forget Tenagah, Leigh at RMS or Brett at PSI for a first class tune. Also see the Sticky Tuners thread this forum. Vote with you feet if any "Tuner" wants to lock your ECU, its your ecu.

What ever you do ensure the airfuel ratios/boost/IDC's are tested with reference to a calibrated meter and its should not have to end in tears
.....or you could just go straight to motec

I'm not a big believer in changing the configuration of the fuel rails - it's a hydraulic system under pretty big pressure (up to 70psi), and you're injecting only a few ccs of fuel each time, so it really doesnt make sense that cylinder lean outs are caused by the rails. What is much, much more likely is the setup of the fuel pressure regulator's vacuum/boost feed coming from an intake runner. Do a search for tuna's post with lots of detail about 6 months back.

I know of quite a few very high horsepower WRXs using the standard fuel rail config, and it doesnt seem to be causing any problems. Changing the fuel rails involves expensive custom fabrication, and that's always expensive!

The standard 440cc injectors were good for at least 300hp at the wheels when I was playing. Morgs has a point with the fuel reg, but don't wind it right up... a mild increase will get you some more margin without risking things. If you still want to do the injector upgrade after you've got a new fuel pressure regulator, wait until you're getting closer to 95% duty cycle at peak torque.

That's my thoughts!

spot on geoff,

i use a stock fuel system, stock fuel pressure regulator,
my only changes are decap injectors, walbro fuel pump and the fuel pressure regulator air line modification. i run over 30psi of boost and do not have any issues with lean cylinders or fuel pressure problems.

your biggest friend to the fuel system is an over spec'd fuel pump, make sure the pump has enough flow to maintain pressure in the return lines while under load, and you can be assured the stock 440cc yellow top injectors are good enough for over 300hp with stock fuel rail pressure.

another point is that there is a lot of speculation on injector duty cycles, 85% is not the limit of safe IDC's, the claims that the injectors do not have time to open and close is a lie, beyond 100% duty is when injectors are unable to close and open. with atmospheric conditions, your maximum safest duty should not exceed 95%, this will allow for cold nights and for the occasional air-filter removal.

- keep the factory fuel pressure reg
- keep the stock fuel rails
- keep the stock fuel lines
- keep the stock injectors (for under 300hp)
- UPGRADE THE PUMP!
- GET IT TUNED PROPERLY!

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Long live the WRC

Tuna unless you have a lambda and a temperature sensor in every cylinder how would you know if you had an imbalance? And this is not your original standard piston WRX bottom end is it?

the motec with high speed sampling and use of the wideband ueago lambda sensor shows no fluctuations in lambda, my AFR's never get above low 11's at WOT, even an imbalance at such rich AFR's would not cause a lean out of a singular piston without it being detected/corrected. (yes i have wideband enabled)

this is my stock unopened ej207 (not an ej205),

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Long live the WRC

Tuna, point is on a cast piston standard WRX having a balanced fuel setup is more critical than on your well tuned, forged piston/motec controlled setup.

Like an oil catch can a fuel reg and parallel fuel rail mod is just another level of safety. To save stealing this thread lets move further fuel disussions to OEM Fuel Regulators.

Bollocks, tuning with a clue is more saftey than either of those mods...

99% of catch cans are useless as all they do is take oil away from the motor, even if you shove it back into the intake pipe, its still pulling oil away from the motor, no one actually bothers to make a decent catch can that returns the removed oil to the motor after seperating the air from it..

as for the fuel rails, numerous BIG hp jappo rex's still run stockers, im talking 500+hp cars here, they just have the right reg and fuel pump setups..

where it all goes pear shaped is in the tune, 99% of failures are tuning related, the others are oil starvation due to not having enough in the motor, see catch can comment above, or from serious track work where the grip over takes the oil system, requiring a good baffle setup..

the proof is in the pudding, crack open any motor thats had a failure and you'll find out quick enough what has caused it, im pegging the fuel rail became a blame point because people couldn't be bothered spending the money in the right places to address the real issue,a nd just opted for the easy blame..

as for where to get it tuned, Race torque, Speedworks, HypermegaglobalnetDrive, or Xspeed are the only shosp id recomend for tuning, having seen these people in action, and seen the results..

Ive seen the results of other shops, and they wern't pretty

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Jesus Built my car, Its a love affair, Mainly Jesus and my hotrod

No bollocks Denver... agreed, your point about who tunes your car IS much more important. Mine is about having different (albeit lower) levels of safety built in. Question 4 of Gonadman 2 asked specifically about fuel rails.

I could still be using a Unichip, no Motec, no fuel rail mods, original fuel pump, no upgraded tmic, no cold air duct, no water spray, cheap shit oil, oem airfilter, etc etc. Would my car be as quick and would the original engine still be intact? I don't think so.

Its the 1-2% things that add up, if you don't want to do them fine. As for those who have payed thousands for expensive engine rebuilds ask them if they would have liked to have done a few simple mods along the way that may have prevented their meltdown. Like disposing of old catch can oil and trying fresh oil for a start.

I dun mean to hijack this thread BUT - does anyone out there have any experience to use the autotune method for a pnp MY99-00 Subaru Autronic ECU?

Need help!

Thanking you in advance!

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Soon to be driving a S204...

The Autotune feature requires a wideband analyser - such as the A/B type Autronic analyser.

Wideband analysers on most dynos will also do the trick

Once setup you select the cells/area requiring adjustment - select them with C for coarse or F for fine - then F6 to enable autotune - then take it through the rev range and try holding at each required point for a few seconds for it to do its business.

If you try to autotune with just the standard o2 sensor it wont be nice (lean).