ChristianR

iTrader: (1)

Can you really compare them? Dawes is just like a bleed valve, and a link is a fully programmable ecu.

john banks

I suppose you are comparing original ECU with boost to an aftermarket ECU and deciding if the aftermarket ECU is worth the extra?

The bleed valve is functionally a passive device and the Dawes is functionally an active device. Bleed valves are rightly viewed as a crude device, the Dawes actually produces better boost control than the standard ECU in many situations, and better than some EBCs and aftermarket ECUs too. It is not unheard of to use a Dawes instead of the Link boost controller. It certainly spools up very well.

C h a z

thanks JB

Deep Singh

"It is not unheard of to use a Dawes rather than a Link boost controller".Not quite sure what you mean John.No such thing as a Link boost controller is there? Boost control is one of its functions as a fully mappable ECU.The boost will be tailored to provide a smooth torque curve and protect the engine at higher revs.
Also the opinion that a Link could give slightly more power than a Dawes? Any fully mappable ECU will be able to take most advantage of exhaust/better fuel/fmic etc.So I presume its lead would be significant.Please let me know if I am misunderstanding the Dawes,you could save me a lot of money!!

jonny concrete

John, if your getting comparitive performance with ppp+dawes compared to link, then the link has to be the better performance per pound upgrade. The ppp alone surpasses the cost of the link.

Deep Singh

John Banks,thanks for that.I was'nt trying to criticise just very curious.A very informative reply.Time for me to read a bit more about the Dawes before I right it off!!

BugEyed

Hi Guys

This is a debate I've been having for a while.

The map on the standard cars appears to be fairly good in terms of fueling and ignition advance, with a few caveats. For example, the fueling is generally rich on a standard car, and the ignition retards itself significantly if excessive (15.5 psi +) is used on the MY01+ WRX. No doubt the limits on these can be pushed by using a good quality aftermarket ECU (eg the Link mentioned in the title of this thread), but the gains will not be that huge.

If I am correct, the biggest gains being made at present are to raise the boost used and to prevent the ECU "protecting" the engine against this boost.

Both the old model and the MY01+ PPP ECUs run higher than standard boost, and the effect of this can be achieved by other means of raising the boost (eg the Dawes device). I am slightly concerned about the use of a Dawes as the standard ECUs do not set a linear boost target, but instead vary it to smooth power delivery across the rev range, and also vary it to lower the targets in 1st and 2nd gears to reduce the strain on the gearbox. People in the Australia and the USA running high boost in the lower gears are sufferring gearbox failures on a fairly regular basis and are resorting to dog boxes or Sti 6 speeders for the WRX. Some aftermarket boost controllers (eg Apex-i AVC-R) can be used to set different boosts across the rev range and for each gears), but cost a lot more than a Dawes.

The ECU can be prevented from "protecting" the car against excessive boost by the use of a "fuel cut defender". The device being made elsewhere by John Banks can be used not just to prevent the "fuel cut", but also to protect against the excessive fuelling and retard used on the MY01+ WRX.

Duncan

john banks

If the MY01 retards a lot above 15.5 PSI I wonder why? Is it because of the MAP or MAF inputs or both? Why do Prodrive cars which only change the MAP by RPM not suffer? Some argue they do. AFAIK the main input to the fuelling and ignition maps is the MAF sensor. Some Dawes users in the US and here seem to be wondering about the MY01 retarding a lot leading to loss of performance. This does not happen on the MY00. People that have tried changing the MAF voltages seem to get problems on the MY01 - the ECU seems to resist the change a heck of a lot and is often richer than 10% CO at high boost - off the scale of many analysers.

Whatever, on the MY01 running 15.5 PSI will still give you a lot more power at the top end.

It would be nice if you could map the part throttle and also base it on RPM, but a bleed hole stops more than about 10PSI at very small throttle openings.

Some guys in the state have made a very simple circuit using a couple of 555 timers to give a PWM signal to the solenoid which only goes to about 70% duty cycle after a certain throttle position, but I don't believe it spools up as quick as an MBC, and is not as good as a full closed loop PID EBC, but obviously a lot simpler. It is effectively an electronically controlled bleed valve that opens over a certain throttle position.

I thought limiting boost in low gears was for traction? Whatever, if you don't go silly with the boost and drive sympathetically I suspect the gearbox is OK at this sort of level of power. It is the new turbo boys that track the car many times a year that seem to eat gearboxes.

BugEyed

John

My belief is that the excessive fuelling and retard exhibited by the MY01+ are MAP related as they occur on the standard ECU at boost levels below that run by the PPP. My guess is that the "amended MAP" signal in the PPP version prevents the problem, hence the desire to use a "fuel cut defender" to achieve the same effect.

The failure mode of the WRX gearbox is to strip 1st and 2nd gears, caused by either poor gears or flex of the shafts (likely to be the latter if you comare the 5 speed and 6 speed gearbox designs). I have come across this problem in my previous existence - the MT75 in the 4x4 Cosworth Sierra was weak in a similar way. Rather than re-engineer the box (or use the Borg Warner T5 as in the RWD cars) we chose to re-map the boost to remove the peak boost in the lower gears. Even more embarrassing than admiting doing it is where I got the idea from - the MG Metro Turbo that used exactly the same idea for the same reasons.

Duncan

dowser

John

With the Dawes I get a massive push in the back with a 4k rpm launch that was never there with just the PPP - it has me worried about a lunched gearbox.

Not sure whether it's because with the dawes the boost comes in quicker, or the PPP is capping boost in lower gears....I'm always a little preoccupied until I'm into 2nd, and by then it's gone

Roll on the diagnostics software!

Richard

john banks

How will the diagnostics software save your gearbox? Or have I missed something?

Yes it does launch well, but thankfully I don't drop the clutch at 4K very often.

dowser

Nope, won't help g'box - but will let me compare with/without....safely....! I guess the Dawes is just hitting max boost much quicker on a launch whereas by the time solenoid control hits target you're already changing into 2nd?

Richard

C h a z

What would be your recomendations guys and gals. With the DIY FCD and dawes your lookin' at spending less than a ton. Link ECU is alot more, what are the pros and cons of each set up. Thanks in advance for any information.
Car in question is an MY97 with induction kit and full decat

[Edited by C h a z - 3/11/2002 6:56:24 PM]

john banks

The Link allows you to custom map the fuelling and timing to your application which may help if you have an induction kit. You can also map your boost by RPM.

As a result the Link should be slightly more powerful for the same boost by running more ignition advance where possible and leaner fuelling at the top end at least.

Overall the Link will be better, but also about 15 times more expensive.

Dawes £35, AFR £50, Fuel cut lifter £5. Knocklink would be a good idea as well if you are lifting fuel cut. Also you need to be prepared to fiddle with this setup to get the best out of it, but the same may be true of the Link.

The Link would obviously be beneficial if you want to change anything else.

In terms of safety, both depend on how they are set up. Either have the potential to kill your engine if misused. It is not unheard of for a remapped car to det on the rollers and a Dawes car running more power with the same turbo and intercooler not doing. It proves nothing except that it is how it is set up.

Also consider the Ecutek reprogram which may well come out for your model year.

[Edited by john banks - 3/11/2002 7:19:20 PM]

john banks

GavinP uses the Dawes for boost control rather than the function on the Link ECU because it works better in his individual application (auto box).

From boost plots I have seen, the Dawes spools up earlier than most Link cars. I understand some people with Links have trouble getting the right compromise of wastegate sensitivity and duty cycle.

Depends on what you mean by slight. I believe 270-280 BHP has been seen at PE from an exhaust and boost controller on the original or PPP ECU. This isn't really on a different planet to a lot of Link cars on the original ECU and turbo? In fact on the Scottish rolling road at Star my car with a PPP decat and Dawes seems to be holding its own so far against the Link cars. If you run the same boost you gain on the Link by leaning out the fuelling and advancing the ignition, and gain about 10 BHP from the looks of it.

You may also note that 260bhp has been seen at Powerstation on several Dutch cars from a fuel cut lifter and restrictor change, which is right up there with the remaps. It occurs to me that often a remap is not necessary for safety or performance. If you increase the boost on the standard car and it fuels sensibly (maybe 9% CO but some tune for that) and the timing is fine with lots of reserve then what is the issue? If it ran lean then fine, but it is quite the opposite. Running rich and less advance could be one reason why my car does not det on the rolling road with a crap TMIC fan, and a remapped car was detting audibly - mapped with a Link (it did not do this on the road, but all I am illustrating is the the remapped car could easily be nearer to knock than a crude cheap tuning method).

Also note that the PPP on the MY01 is a MAP remap, yet with a decat has seen 285+ BHP at PE. Again up there with the properly remapped cars.

I believe I painted a rounded picture above and already referred to the benefits of a remap for other modifications.

Am I really being that contentious or misinformed?

I am presently working on both boost and fuel controllers which will work with the fuel cut lifter and not require the Dawes. These will allow RPM and load mapping of boost and MAF sensor. They will not allow independent alteration of the ignition timing. So I think the results will be nearer to a remap. It will almost be along the lines of a Unichip but control MAF and boost rather then MAF and crank position sensor. The original ECU will look after the ignition advance, and granted it won't be as aggressive as an aftermarket ECU could be.

I think remaps are great, but personally I would save it for significant mods like FMIC or turbo.

[Edited by john banks - 3/11/2002 10:19:34 PM]

john banks

Agree. But knowing what I know now I would not have bought the PPP - I may yet sell it and go back to the original ECU. But even then: £1763 + £250 for downpipe + £25 for Dawes. Would a Link with a full exhaust be any different? £1430 at BRD + exhuast £600? Sounds about the same to me. What about resale value of a PPP car compared with taking all the bits off and selling them separately? Compare similar results when you spend £25-35 on a Dawes, £10-20 on electronics for DIY AFR and lifter, and then £600 on exhaust. The latter option is tempting? Can it be shown it is less safe?

I looked up the results: up to 262BHP at Powerstation from decat and boost increase (these are not on the dyno page). 278BHP at PE with 17.6PSI (boost controller) with Exhaust, induction - incidentally the same or better than the Link ECU cars on the same page. Both of these examples are within safe parameters running 17-18PSI on std ECU.

[Edited by john banks - 3/11/2002 10:40:47 PM]

john banks

Nothing wrong with MG type turbos, a Maestro turbo was giving me some sport off a roundabout the other day until I dropped two gears


I don't think the Link, or the PPP or the original ECU are mapped for different boost in different gears. Like you the only product I have heard of it on is the AVC-R. Of course you do get a bit less boost in lower gears anyway. But if the PPP runs 17 then can we assume that is OK for the gearbox??

I don't think the torque from a Dawes car is any higher than the PPP, and probably less if you don't lift the fuel cut. So at this level are we really threatening the longevity of our gearboxes?

[Edited by john banks - 3/12/2002 1:31:08 PM]