spence7

Having read a fair bit about the Dawes MBC and found out a few problems with the early WRXs I'm now very cautious as to whether I can safely fit a Dawes MBC.

OK, I can get an AFR to confirm that a safe rich mixture is maintained during open loop and the newly increased boost levels

OK, I have a factory boost gauge to check pre/post boost levels and ensure I'm not running at silly levels

BUT, I can't ensure that the timing can adjust to compensate for the extra charge pressures. Apparently extra charge pressure would demand a retarded ignition timing relative to normal to maintain the correct timing. And apparently just the need for the ECU to retard ignition timing for UK fuels and whether it can do this is already is in question. I run 98 with no pinking noises ever or any other evidence of problems but who knows.

SO, I was wondering if anyone has fitted the Dawes to a 93WRX and hasd it all running sweetly with no major probs ?

Cheers
Alex

Markus

Kinda interested too as the BB is a MY94 WRX Wagon, and I'd quite like to join in the dawes related fun hell it's another mod so why not!

IainCam

DOn't know the in's and out's of it all but it works fine and has made an improvement on MY94 UK turbo and I know Ken's running it on his MY95 STi without any problems, he helped fit mine (I held the torch - he burnt his hands ;-)

john banks

I previously posted this in a thread in the Dawes FAQ http://www.scoobynet.co.uk/bbs/threa...d=75220&Page=2 half way down this page in this thread http://www.scoobynet.co.uk/bbs/threa...threadid=69382

I am not an expert on Japanese imports. However I know seven things:

1. They tend to run lower boost (more so earlier models) and have lower fuel cuts.
2. They are mapped for 100 octane fuel and can even det as standard on 98 octane, whereas as standard UK car should be nowhere near detting on 95 octane.
3. They tend to have bigger turbos (TD05 I believe in your case) which removes the need for any extra bleed hole.
4. The MAF sensor sometimes saturate and therefore do no fuel adequately at higher boost.
5. Fuel cut is not always much or any higher than your peak boost. On late models at least it is timer based - so I could happily peak at 20 PSI but hold it for 4 seconds and fuel cut.
6. The intercoolers are small for running big boost.
7. The fuel injectors can be smaller than later models.


For reasons 2,4,5,(7 sometimes) I have advised import or P1 owners to get remaps instead. But if you understand the limitations it could be tried, but do not underestimate the effect of a Dawes on performance and possibly engine safety by even running at standard boost as it will hold that as long as your turbo/actuator setup will allow.

To keep it safe you would (IMHO) need to monitor:

1. Boost
2. Air fuel ratio from lambda sensor
3. Exhaust gas temperature
4. Knock
5. Ignition advance

.. on a Jap import at least during setting up. UK cars are very different (esp late models) and you can get away with just 1 & 2 and I recommend a check of 5 on a select monitor after setting up to be sure.

Hope this helps.

IainCam

I've a boost gauge to check what it's actually boosting to but no AFR at the moment, although it is something I planned on doing later on (esp once I fit the decatted downpipe).

Other than when I've had the AFM go in the past I've never had the engine check light come on which surely it would if there was anything to be found on a select monitor or will it log other problems without it showing anything from the drivers point of view?

It's definitely the TD05 on the UK94 and on Kens MY95 STi, when we were checking out the two engine bays there was very little differences between them that we could see (I even have the Alloy bonnet on mine).

john banks

AFR and knocklink would do the job.

The standard ECU has the capacity to go into limp home mode and limit boost to about 8 PSI. It can also reduce boost if it detects knock which is not removed from retardin the ignition.

The Select Monitor tells you far more than the check engine light trouble codes. I don't think the car produces a CEL with a knock signal.

To offset the effects of a damaged knock sensor (presumably) most cars have a limit as to how much they can retard. Picture an STi mapped for 100 RON run on a dodgy tank of UK fuel, with a decat exhaust - it COULD if you are unlucky det in these circumstances. Then add a whack load of more boost - which as I say even running at standard boost in the midrange it will hold more up top and you could have trouble. With earlier models having smaller injectors how do you know what pulse width you are running? Intake temps because of the small intercoolers? Too many ifs to run a Dawes on just a boost gauge.

Perhaps the best question to ask is not whether anyone has done it, but have several done it, with appropriate monitoring and proved it is safe over extended running periods?

Caution means you keep your engine, sorry if it sounds like I am a wet lettuce.

IainCam

It's better to be safe than sorry, I know that the car pulls more up top than it did before. IIRC it used to get to around the 5500/6000rpm and feel like it was running out of puff whereas it now pulls into the redline.

Most of the time it's the wife driving it so it probably only gets to about 0.5bar and about 4000rpm anyway ;-)

Was looking at pods and AFR's to fit when I do the decat pipe, although being a UK car I shouldn't (hopefully) have the same type of problems imports do.

spence7

No I wish to err on the side of caution for all the reasons you give about the STi John. It's not worth engine going bye-bye for the sake of 30 odd bhp or whatever. I know it's more than just 30 bhp but you know what I mean.

Anyway, maybe I should post PE an email and ask some specific quesitons re: my model year, 98 ron, my mods (perf rear BB decat DP and ITG), dawes, timing, etc. because like you say the bottom line is.....the ignition timing and detting needs to be known about with my car.

One question though, will detting or knocking or similar timing issues, cause check engine light to come on? If so then maybe I can use this as a guide instead of having to actually check the values of the timing?

OR like you say an AFR and knocklink...? Forgive my ignorance here, but will a knock link tell me that it can't retard to safe levels, indirectly by telling me that it's knocking?

Cheers
Alex

john banks

Det/knock is the final common pathway for many adverse conditions inside the engine. It occurs when the fuel spontaneously ignites before the spark. With the piston in the wrong position this puts a massive load on the conrods, and liberates tremendous piston melting heat. It can occur because of high intake temperatures, excessive pressure, poor quality fuel, overadvanced ignition, lean fuelling. The imports seem to have when you turn up the boost with a Dawes the POTENTIAL for every single one of these factors for the reasons outlined in my earlier post. Go for a remap - Unichip is possibly a good solution? The Check engine light is certainly not a reliable means of detecting knock.

You could try SUL/Optimax PLUS octane booster, and then run a lambda and knocklink if you want to fit a Dawes. That would be safer.

Edit to say the balance to all that is it can be done - Cosie Convert was/is running 23-29 PSI on a 1995 WRX RA with effectively a Dawes. He measures EGT, Knock, boost, intake temperature, has intercooler water spray, water/methanol injection, 5th injector, fuel pump modifications and takes the risk that it all might go pear shaped. He disconnects the knock sensor so it can't retard and then controls det with water injection. The fuel injectors run wide open and fuelling is controlled mechanically by the fuel pressure. It is right on/considerably over the edge of safety depending on your opinion and making better 1/4 mile times than any other UK Scoob I have heard of.

[Edited by john banks - 4/24/2002 6:06:21 PM]

john banks

top for johnny gav.

spence7

Nice one....this modding lark I dunno - fun though when it works

Cosie Convert's car sounds like a terrific beast ! OK, so it's not impossible to use Dawes type device and but it sounds like Cosie C is overriding normal systems to ensure correct timing. I mean the timing can't be that far out if it's running as well as it is though

Hmmm well I dunno, bottom line is I won't be modding that much I just kind of want a cheap Dawes style upgrade

I mean if a knock link tells me that the timing is not retarded enough, then that's probably good enough for me if it works. Then I'll have AFR & boost gauges tell me safe mixture and boost, and the knock to warn of serious hardcore damage. If I tweak boost progressively then maybe this sounds like a safe ish plan, short of getting it mapped for UK fuel first that is.

Al

spence7

just checked out the unichip sites they seem pretty good. No mention of prices or fitting to an old 93 wrx though unfortunately will wait for the UK website to come back online I reckon.

Cheers
Alex

john banks

All sounds sensible enough Alex re the Knocklink etc.

spence7

Nice one and thanks for the advice by the way

I'll post results when it all eventually happens, maybe there's some other 93wrx owners who are thinking the same things...!

cheers
Alex

Tone Loc

iTrader: (1)

Hi'

I've got a MY93 WRX and am just waitin' for the Dawes to arrive from Jamie, think that they're stuck in customs! The only thing i've gto at the moment is a boost gauge, but will be gettin' an AFR and knock link. At first im goin' to run it 14.7 (i bar)psi and see how that goes then possibly up it (with the help of an HKS FCD) to 16 psi witha rolling road setup. The main reason i bought the Dawes was not to get real high maximum power gains but to hopefully get some more low down power (i.e get round the lag from the big turbo).

I'll let you know how it goes when the Dawes arrives.

Tony.

spence7

Tony, nice one much appreciate any info you find out !

By the way HKS FCD ? What's that then?

Which AFR gauge did you go for by the way? And one last question, how much was the knocklink as it doesn't seem to mention this on the site !

Cheers
Spence

Tone Loc

iTrader: (1)

Just got an e-mail from Jamie to say my Dawes has been sent out, so should have it up and running next week. The AFR is an autometer one (scoobymania, jap innovations etc sell them). Knocklinks i've seen for £85, but some i've seen are £135, i think that they probably come with a new sensor???? Try http://www.brdevelopments.com .

The fuel cut on our cars is at about 15.5psi, so if you want to run 16psi you have to raise the fuel cut. HKS do one for about £110 (the FCD) and you can then alter the fuel cut level.

Hope that helps a bit.

Tony.

[Edited by Tone Loc - 4/25/2002 3:39:22 PM]

pmr147

i have fitted a dawes device on my 94wrx boost running at 1.0 bar on optimax dont seem to have any troubles

spence7

thanks for info Tone...good luck with the installation !

pmr147 - no problems eh? Nice, nice...

Katana

Buahahahahahaha! I've just got my Dawes today. I'll wait till Sunday to hook it up.



[Edited by Katana - 4/26/2002 3:56:04 PM]

Katana

OMG OMG! Even at low PSI setting (I'm sticking it at 7 for test purposes) this thing pulled better than it did before I had it on. Turbo seems to be spooling much quicker. Dunno if my boost guage is right though, It seems to go from -10 to 7 at full boost. I'm going to take it a notch(turn) up tommorrow and see how far it'll go.

This is probably the bets 30 quid that I've spent on this car. Jamie, I'll e-mail you tommorrow afternoon once I've got it at the right boost after Uni. Cheers again.