rossyboy

iTrader: (8)

Have had my car on the same rollers a few times as follows:

MY94 WRX, standard apart from H&S Backbox 240 bhp, 226 lb/ft
As above with Decat downpipe 247 bhp, 240 lb/ft
As above with Z4 ECU 252 bhp, 248 lb/ft

12 bhp doesnt seem that much to me with decat and Z4?

Would a stainless centre section and uprated panel filter make much difference?
Anything else fairly minor likely to improve matters apart from ScoobyECU?

Cheers.

WUZ

iTrader: (14)

Who to say the car was not running lean when you first went on the RR and got 240?

Z4 ECU seems to be running OK considering only a B/B and Decat D/P is on the car. Really need to get a Panel Filter and centre section in car and get the AFR checked using a WideBand Lambda to see if the fuelling is OK on boost.

Remember wrx is 240 ps as standard (Z4 gives 260ps) which is (+/-)236 bhp BUT that is on 100 ron. So, to account for inaccuracy in R/R due to a number of factors, and Optimax fuel and Millers used (I assume?) giving 99 ron, 252 and 248 on a Z4 is not bad!

You need to factor engine condition into this as well. An older, tired engine will not put out as much power as a newer or rebuilt engine!


Russell

rossyboy

iTrader: (8)

Thanks Russell, to be fair have never used OB. Getting on for 2 years now and no problems. That would obviously make a difference.

Wouldnt have thought my engine would be that tired, she's just run in at 50k miles surely

Think I will get the centre section and Panel filter, get it RR'd again and as you suggested get the fueling checked.

Is it possible to fit an AFR guage on my car and is it a big job? dont really fancy forking out for one of those LM1 gadgets!

Ross.

blacky555uk

I would say that unless you get a chip/ raise the boost you will not see too much more bhp/torque.

I have a 95 WRX with the Z4 as standard....its been on the same dyno 3 times.

1. Cat back 3" exhaust and STI panel filter 251 bhp 239 lbs/ft
2. De-cat downpipe 3" + above mods. 253bhp 239 lbs/ft

I was dissapointed with No 2 as everyone had said that the de-cat make a massive difference......and it had in turbo spool up and midrange but not peak (which is not the most important ) The RR operator said that the boost was oscillating as it was wanting to make more boost due to the much better gas flow but the ECU was pulling it back to the normal 13 ish psi.

3. ScoobyECU 16.5 psi Map + K&N Induction + above 285bhp 260 lbs/ft

The max torque was also down the rev range 1200 rpm and it pulls soo well now all the way to the redline.

IHMO the only way to see more power is to get it mapped or up the boost via a MBC or an electronic jobbie. Obvisiouly the savest way to do this is by getting a chip.

And as said above you NEED to get the car checked with a Wide Band lambda before using the full power

rossyboy

iTrader: (8)

Its interesting that quite a few people aren't getting the expected gains from their de-cats.

I know very little about engines, but what you're saying makes sense to me. Like you say, the standard ECU maybe doesn't allow the full gains of a de-cat to be released due to its limits.

I would love a scoobyECU, but the chances of getting one are pretty slim. I know Jon at customscoobies does the chips, but I dont know how these are attached to the standard ECU. Think I'd need to send mine away and get it done somewhere if there is somene that would do it!

Failing that, would an Apexi ECU get me to 280 bhp safely without anymore mods? Think I'd be prepared to stretch to the £750 if it would.

On the plus side, I did see a nice flame out of the exhaust on the rollers
At least one of the benefits of a de-cat has actually happened.

WUZ

iTrader: (14)

AFR gauges are available from Autometer for about £45 (AFAIK) and fitting is about 1 hour.

Russell