MY01-05 WRX and mods

[DRIFTIN]

Hi

I'm interested to see if there is any truth in a statement made by Brett Middleton on the MRT forums regarding risk of leaning out with minor mods on recent model WRXs.

This is what he said in one of his threads advertising their power-upgrade kits.

If you already have a cat back system, why are you worried about doing the XB kit.

More so you should be worried why you have NOT done it yet as your car will for sure be overboosting and risking damage to your engine.

Is there any truth in the statement in bold? I'm interested in doing some minor mods shortly but am not interested in being reamed on a ECU re-flash out of fear of leaning out. Will do the ECU when I've done sufficient mods to warrant it.

Adam

[maddy]

yes because the turbo spools faster due to reduced backpressure, causing spikes and lean conditions in the newer ECU's. Pre 00 didnt have such issues as the computer was more 'free' and made better allowances for this.

[DRIFTIN]

I've read this also, but never from a reputable source who has seen the said boost spikes happening. Have you seen this occur?

[TheRealGarvs]

I've read this also, but never from a reputable source who has seen the said boost spikes happening. Have you seen this occur?

I'll second what the bloke above your post said!!!

Even the old shapes with their outdated ecu's would spike a fair bit....however the newer versions- a lot of people suffer shocking performance problems upon fitting anything to the exhaust in hopes of gains.

That said- ther are a few people who have done it and SWEAR they never suffered a problem. I know one person in town with an my02 that did just the exhaust and had it like that for a fair while (might still- think it's chipped tho) and he reckons he's never had a single problem.

[trent from punchy]

bah, if i did spike, it would be one micropoofteenth and not do any damage.

they have a boost cut for a reason.

[maddy]

yes the standard BOV will stop the party at 15 psi, but most zorst owners will have some sort of bleed valve.

it's lack of retuning that kills them

[old baggins]

The BOV will stop the party? Explain?

[DRIFTIN]

this is why i have asked the question..

none of the explanations as to why this occurs are technical - the bov has nothing to do with the factory boost cut whatsoever

[maddy]

standard BOV will leak above 15psi.... and the wastegate would start to let go in the same situation unless you have a bleed valve.

Boost cut is cutting ignition which may cause backfiring due to unburnt fuel going through to a hot manifold, damaging turbos and cats

[DRIFTIN]

given that standard boost is 14.2psi, they'd be cutting it pretty fine to use a standard BOV that leaks at 15psi. on all the cars i've seen running 17-20psi, most have had the standard bov with no ill effects.

[old baggins]

standard BOV will leak above 15psi.... and the wastegate would start to let go in the same situation unless you have a bleed valve.

That is absolute bollocks.

[DRIFTIN]

well, i reckon i'll do the cat-back shortly and get a dyno graph showing the original power curve and the after power curve. hopefully the after curve is not erratic as many suggest. i'll install a boost gauge first as well.

[nui]

mine was running 21psi and peaked to over 23psi on a cold night with the standard plastic bosch BOV.

[maddy]

ive got an 01 BOV on my GT and it leaks once boost hits 14psi (comapared to the 99 valve which was a dual chamber jobby and gradually leaked up to 8psi)

we have tested this with a boost guage - are we doing something wrong or is it broken?

[old baggins]

who is "we"