Devil's Refugee

Soon will be running a MY00 with VF28, larger TMIC, TEK3 remap, Dawes and full de-cat.

Will standard injectors cope and will I need an uprated fuel pump to help out ?

Have heard Mark Aigan does them but can't seem to get hold of him.

Theo

David_Wallis

mark@lateralperformance.co.uk

He replies to every email... but is a very busy man...

David

dowser

Fit the pump for safety. The remap will be done to ensure you don't run the injectors too hard

Richard

Devil's Refugee

Thanx guys

Adam M

mark can also be reached on 020 8420 5444.

Scott W

What will be achieved by the use of the Dawes and a TEK3?

I'm running a Tek 3 on a FMIC, Hybrid Turbo, Headers, uprated fuel pump, etc... and soon to be bigger injectors and TBH the TEK3 map I have is superb, and I honestly cannot see the benefit in having the Dawes attached?

I'm holding 1.3 bar and have a peak of 1.4 which is very rare. I used to use the Dawes previous to the mods, so I know what it is and how it should be used, but surely a proper map will provide everything you need?

JIM THEO

Hi mate
Similar setup with yours (VF29 +Magnex downpipe +Prodrive centre&tail pipe +PE exhaust manifold +Walbro 255HP fuel pump +John's TEK3 17psi boost).
Car really flies from 3100-3200 > 7000 rpm and according to John it's about 310-320 bhp regarding fuelling/boost/air flow.
I am going to put back my original manifold (ported) and uprated MRT TMIC in order to have more torque low down (<3000) and be safe as summer temp here are very high.
Let me know how is your car after all the mod you plan.
Cheers
JIM

dowser

Hi Jim,

How much do you want for the PE manifold?

And are you running using factory boost control?

Richard

john banks

Your injectors will be OK.

Reason for the Dawes - unless you have a 3 port solenoid, it controls boost better than the ECU. Very easy to adjust. Better performance in lower gears, fewer spikes, fewer environmental offsets.

Scott W

Admittedly I do have the 3 port solenoid now (MY00 as well) , but I still cannot see the point of in effect removing the boost control away from the ECU to the Dawes?

Would it not make sense that if you are spending that kind of money to spend an additional £150 and get improved boost control, and still have the ECU controlling everything?

dowser

Yup - don't get me wrong, I'm not knocking the Dawes. It has the best boost control I've experienced, but I want ecu to have control.

Richard

Turbo_Steve

Am I correct in my undertstanding that the older cars (pre 99) have a 3 port solenoid and the newer ones have a 2 port?

And that a 3 port solenoid car has NO restrictor?

And presumably if you are re-mapping the car you can tighten the wastegate and the remap+wastegate combo will provide 'snappier' control?

If Dawes is so good how come Subaru never adopted the design around something similar?

I kind of like the idea of the ECU remaining in charge of everything too. Maybe it's cos I am an IT dude?

I know Katana would disagree with me!
Perhaps it is a personal preference thing?

Scott W

John the spikes have only happened twice in all the time I've been driving the car which is some 1000 miles or so, and that is throughout all the gears. One of these was actually with Bob whilst he was mapping it aswell.

john banks

I'll let you off then

Bob Rawle

John the car is mapped like that ... benefits of a three port, nice bit of "extra". Dawes is a bleed which is why I don't "like" it but if it works for a car then that's fine ... I've mapped cars with and without, its especially useful when mapping automatics (eh Gavin?)

I actually set it up to overboost 0.1 bar (1.5psi) if the turbo sweet spot was hit.

The early cars have a 2 mm restictor fitted with their three ports but its in a different position.

Pavlo

the stock 3 port setup on mine uses a restrictor in the line to the vacumm side of the turbo. It's quite large, probably 1.5mm or so, but might help smooth out the spikes.

Paul

Bob Rawle

John, yes its possible to map using a three port with no "spikes" BUT ... why would you want to, a mapped and programmed controled overboost is superb at "kicking" a car off on the road. You need to map from the "sweet spot" which vary's car to car and setup to setup. The car spec (including engine) will determine wether thats advisable or possible of course.

Dawes bleed ... having bought and stripped one its a bleed with a pressure relief valve to control the point of bleed ... you can do the same thing with a std bleed valve it just won't spool the turbo quite as quickly.

john banks

OK I'll give one a go then. Still don't like overboost as I always end up compromising on ignition timing when I do so - coudl argue that it is rate of boost ramp, but also the actual peak itself gives a slug of charge temperature and exhaust backpressure - would rather run a safe level of held boost perfectly damped, although many would argue that optimum boost control is slightly underdamped for response. If there is a method to hit target without compromising spool up rate then that is ideal for me. My suspicion is that unless you let it overboost slightly it won't spool up as quick as a Dawes, but I'll have to suck it and see... these VF based turbos need all the help I can get.

The point with querying the bleed was the stigma attached to such a device although I have no shame in proudly using one Still don't see how it is "bleeding" (diverting airflow from one path to another rather than obstructing it) though... just a pressure controlled restrictor, so active in function hence the quicker spool up compared to a bleed which is passive in function? Certainly this is how I understand they can be classified from only a rudimentary knowlegde of pneumatics.

Andy.F

A 3 port solenoid is just an electrically operated bleed valve

Andy.F

Bob

The Dawes is actually a variable volume bleed too, it is also operating in a closed loop system all be it on a purely proportional control basis......unlike a classic, open loop fixed orifice, bleed valve.
IMO the only good reason for an electrically operated boost control is to retain the ECU safety features.
If the solenoid valve was a superior or more reliable control then it would no doubt be used to control a more important parameter - Fuel pressure !!! but no, a pneumatic proportional control valve does this (a bleed valve )

Andy

R19KET

Andy,

"IMO the only good reason for an electrically operated boost control is to retain the ECU safety features"

Well IMO, that's a pretty good reason

Mark.

T-uk

as all the clever folk are on this thread could someone answer me this.

could a dawes not be used with no bleed what-so-ever,with the boost solenoid still connected and the ecu/ecutek mapped to allow the bleed to still be controlled by the ecu?.

john banks

As I said before T-uk, yes it can, BUT you lose most of the benefits of the Dawes in doing so - you have to set the Dawes to open at low pressure otherwise you have two closed loop processes fighting for control. You might save a tiny bit of wastegate creep, but there isn't much with even a 2 port solenoid anyway. For me the benefit of the Dawes at least over a 2 port is to control peak and held boost. With a solenoid also bleeding off with a boost target it would not do this properly. You could use it to taper off boost by using fixed duty cycles in the ECU map for different engine speeds, but usually I have the opposite problem of getting enough boost at high RPM.

The only reason for the bleed hole being bigger than the tiny 0.5mm standard one is to stop part throttle full boost on frisky little TD04s. The bigger turbos don't need it. I have run the standard bleed hole without issue. This is just big enough to stop boost trapping between gears.

So I can't see the point of what you are suggesting - makes it more complicated to setup, with less good boost control and you recover no real safety benefits. It is fine as it is I reckon. 2 port solenoids suck though.

john banks

The problem is that to allow the ECU to intervene to reduce boost it has to be contributing to boost control in the first place so it has a duty cycle of any significance to cut. If you are running a significant duty cycle you dilute the Dawes and start making it into a bleed valve and suffer more offsets/peaks etc.

If you want to allow the ECU to cut boost to 8 PSI you need a Dawes that is set for 8 PSI - the ECU can only drop the boost as low as the Dawes is set for. So the other 8 to 14 PSI (to run 16 to 22 PSI like most of us do) come from... the solenoid which gives you the issues you started with (crap 2 port boost control).

Bob Rawle

Sorry guys but in my book dawes is as I described ... as i mentioned I am not going to change what I call things just to be topical .. I am not knocking it ... its a good band aid if you can't get the electronics to work as you want. Part of the challenge of mapping a car is to get the ecu you are using to do exactly what you want .. whether it be boost control, idle or what ever.

John, in your case you are quite right to feel nervous at 1.5 bar ...

[Edited by Bob Rawle - 10/13/2002 12:06:04 AM]

Andy.F

Bob

I find it a bit arrogant of you to suggest someone is using this as a 'band-aid' when you clearly do not even understand that it functions in closed loop !

You stated And then which is also incorrect as the valve does not 'crack open and bleed pressure away' from the actuator. It actually continually SUPPLYS air to the actuator at a VARIABLE not fixed rate, dependant upon boost pressure. The vent will also bleed air away at a variable rate dependant on the actual control pressure present behind the diaphragm/piston.

Bob Rawle

Dear Andy ... no arrogance about it ... the term is a loose one just as some people define water injection as such ... I have already said its a useful device ... as a valve moves off its seat it "cracks" and opens, as it opens it varies flow with the pressure drop achieved of course ... I think the terminology thing has sort of taken over this thread, I only stuck my nose in cos it looked as though it could develop into another good techy one but as I'm now "accused" I will leave it alone.

I enjoy discussing and debating the different facets of tuning with people, a bbs (or should I say this bbs ? .. perhaps not)is clearly not the right place to do it as things can be taken the wrong way, I look forward to discussing this and other subject's with yourself (and John) as and when we meet up some time.

cheers and have a good weekend (rest of)

R19KET

Andy,

Whist you may not be using it as a "band aid", others certainly are.

No one is questioning if it works, or not, but if it's being used in conjunction with a re-mappable ECU, it's because either they can't get the ECU's boost controls set correctly, the over all set up isn't ideal (2/3 port solenoid) or they are just too lazy to spend the time sorting it out properly.

There are issues with the two port solenoid, and even the 3 port is hopeless when used with a Motec.

IMO, it doesn't really matter what method is used, so long as it works, and it's safe.

This started off as a good thread, and now, it's just degenerating into "splitting hairs", over how a flippin valve works !!!

Get a grip guys

Mark.

john banks

Can we progress this in another direction technically without mine or anyone else's ego getting in the way...

1.5 bar - is the objection the P18 housing, no water injection, retarded timing, non-STi internals or something else before I scamper off and turn it down to 1.3 bar and sulk and think how I will get all that torque back? I still have the crappy OEM inlet pipe, but apart from that it is breathing reasonably well now. Bob are you running about 1.45 bar? Apart from the inlet pipe, bigger turbo and STi internals what enables this to be safer? Or is is those three things?

It is not detting, the EGTs and inlet temps are OK. The AFRs will soon be checked with wideband and the injectors changed. Anyway, it can't be that quick because the clutch still isn't noticeably slipping

Andy.F

My apologies to all if differentiating between open and closed loop control is deemed to be 'splitting hairs'