T-uk

I think we need a Dawes forum .

just wondering how much boost people are seeing higher up the revs, at say 6000rpm and what held boost in the mid-range,in the higher gears.I set one up at the weekend(standard MY00) and saw 15psi in third and 16.5psi in forth,but never noticed what was happening higher up in either gear.

from dyno scoobynet,(Powerstation) for Jase Cooper and Ian Gratton, at 6000rpm they have about 0.8bar,this is 11.8psi (I think),how much more does a Dawes or EBC give you?I also looked at Paul Walker's PPP car and see it has about 0.85bar(12.5psi,it is 14.7psi to a bar isn't it?) at 6000rpm,do Prodrive think scoobs need standard ish boost higher up.

I will be fitting my Dawes soon but want to see about 12psi at 6000rpm.

T-uk

anyone else?

john,
you have removed the Dawes haven't you,what sort of boost are you seeing at 6000rpm with the PPP+solenoid etc?

john banks

No John I removed the Dawes for about 10mins and couldn't stand to be without it! PPP boost control was crap in comparison - consdierably lower at 6000rpm but I can't remember what figures exactly.

Cosie Convert

Not sure how usefull this is as I have a TD05 on my 95 WRX RA but I have just recently fitted a home made Dawes type ball valve and bleed and it now holds the set boost (16psi) right up to the red line which is 7500 on this model.

The only other adjustment I made was to adjust the rod on the wastegate actuator slightly to increase the spring tension.
The car is standard apart from a magnex twin dump downpipe and back box.

The difference is incredible, this car allegedly has 260 BHP from the factory. This mod feels like it's added 50 HP !!

Timed acceleration runs below (average of 3) Remember RA has close gears and short diff ratio. (RA 4th gear is same as a UK 3rd gear)

30 - 50 2nd gear 1.4 sec (3800 - 6400)
50 - 70 3rd gear 1.8 sec (4800 - 6700)
70 - 90 4th gear 2.1 sec (5200 - 6700)

Overboost brick wall still active at approx 17.5 psi Boiiiinnnnng !

cc

Bitten Hero

Erm... and how long before this goes bang?

WRX and STi's are prone to detting on normal UK fuel anyway at higher revs - this is why the boost is tailed off by all standard Subaru and Prodrive ECUs (UK and import). If you're holding 16psi to the red line, it's probably running incredibly lean above around 6000rpm and detting like a mad thing. If you want to run this I would strongly suggest you take a quick trip to a rolling road where they can check for detting (pre-detonation due to fuel mixture being to lean) - say PowerStation, Power Engineering, ScoobySport, etc.

Don't want to scare you, but equally don't want to see a post about your car going BOOM in a few weeks time And your insurers wouldn't pay a penny either as they wouldn't take kindly to a home-made engine mod!!

I notice you're a Cossie convert. Bear in mind the Scooby block is nowhere near as tough as the solid iron Cossie ones, and won't take tuning above about 290bhp without some serious mods (STi head for a start).

Take it easy mate and be safe! Good luck...

Cheers
Richard

Bitten Hero

Heh heh! John, you read my mind and posted at the same time

Richard

john banks

It really does sound too good performance to last long. From what I have heard your internals are basically the same as a UK engine given that it is not an STi. I guess your TD05 and intercooler are the same as Phase I cars.

Most of us Phase II guys with TD04 just cannot flow much over 0.9 bar at 6500rpm. You have 1.1 bar at 7500rpm with a less efficient intercooler. We are using 97 RON fuel on cars mapped for 95RON. You I suspect are using 97 RON + booster = 99RON on a car mapped for 100RON.

I am very jealous of your performance figures and am certainly not knocking what you have achieved, but I am really VERY concerned indeed! No offence at all intended. At this sort of boost you must be monitoring everything and be running an engine rebuild in my opinion. Goodness, some people think I push a TD04 on PPP ECU by running 18PSI midrange and 13.5PSI at 6500rpm! I am actually very glad the tiny TD04 does drop off so much high up for safety. If it didn't I could not run an MBC.

I just don't think you can trust a big turbo/small intercooler on a 100RON map at high revs. Injector size on earlier cars may also be an issue. Get a remap m8 and monitor to the hilt. I say remap rather than RPM based boost controller as mapping on our fuel will give you much better results.

IMHO, boost controllers should be left to UK cars only and running only moderate extra boost. We should also pay attention to where the extra boost is. I would be way more worried about you running 16 PSI at 7500rpm than I would someone with a UK car running say 20 PSI at 4000rpm.

Your ECU can only retard the ignition so far to compensate for increased intake temperatures, excessive injector duty cycle, hot spots etc. I really think it is only a matter of a short time before you would have a serious engine failure.

[Edited by john banks - 1/11/2002 11:14:16 PM]

Cosie Convert

Calm guys !

I said it feels like +50 don't know what it really is.(maybe 60 tee hee)

I don't think a RR would prove much as it's sure to Det and pull timing due to the lack of cool air to the I/C.

I also forgot !! to mention that I run 20% Toluene and 10% Xylene which helps just a tad by increasing octane to approx 102 RON (It's cheaper than SUL + OB)

Oh, and the standard water spray has been altered to increase it's efficiency, the I/C was "scooshed" prior to the high RPM runs.

Alcohol/Water direct injection next !!

ps I'm not completely mad, I monitor EGT , I/C temp and AFR.


CC

john banks

I'm sure it probably is 60!

You have reassurred me a bit

Still strongly recommend a Knock Link or equivalent, and check injector duty cycle and timing - Select Monitor can show the latter two, and turn the boost down until you know it is not knocking. AWD motorsport in Perth have one. Well worth a visit.

What EGTs and charge temps are you getting and is it staying rich over 7000rpm?

john banks

Toluene and Xylene - where do you source it? Presumably you need about 10 litres of one and 5 litres of the other every time you fill up? Could I store it in my shed or would it blow me up and be illegal?

Would love a ride (before it blows up ) (last bit tongue in cheek and forgive our concern please we only care and you obviously know the risks).

Cosie Convert

John

I agree that continued running may cause problems but, I only blast it through the gears and under controlled conditions.
I would never dream of holding it WOT in 5th or putting it on a RRoad with a top mount ! I think you are the brave one !!

cc

Cosie Convert

My cossie was a bag of nails on the rollers but ran sooo sweet on the track. Falklands cossie couldn't look at it and they had a P.E. engine I believe. In fact it was so good they bought it from me !! (Kevins current 3 door Cosy)
My set ups have always been done "on the road"
Have you ever thought what effect the G force of acceleration has on a 3 metre column of fuel trying to get forward from the tank ?
RR set ups can get you in the ball park but fine tune on the road I say !

PS Toluene and Xylene from Auto Paint Supplies.

PPS Charge T 42 C was most I seen on 30 - 70 run through gears.
EGT hits 700 but is still rising when I lift.

Must go to bed, Up at 0400 to go to Autosport show at NEC Yaaaawn.

Cosie Convert

John

Search "Toluene" on i-club mucho info !

Also for excellent reading on ECU timing and Dynos generally try
Factory Forced Induction > got data?

(don't know how to do thread IDs but it's No 40852)

Andy

john banks

http://www.i-club.com/forums/showthr...&highlight=mbc

is the data thread and it is a very good one. Looks like they are managing to hold around 14 PSI at 6500rpm - similar to a UK car and the setting of the MBC makes little difference at the top end as it is flow limited as we have discussed before. It seems for their car that the optimum shift point is over 6500rpm with an MBC if you look at the points where the power curves cross.



also this thread illustrates nicely the difference with MBC and how flat the POWER not just the torque curve is if you bump up the mid by a long way and the top end by a bit.

Fact is T-uk I don't think you will be able to limit to 12 PSI @6000rpm and you don't need to from the looks of these advance curves and if the results on my car are anything to go by.

If you set your MBC to x PSI the boost will be x PSI as high as the turbo can flow it. So to limit to 12PSI at 6000rpm you would need to set the MBC to 12 PSI or buy one of the more sophisticated EBCs. But you would have a slow car by doing so

[Edited by john banks - 1/12/2002 10:30:10 AM]

T-uk

john,

I am desperate to fit the Dawes,especially with the r/r day next weekend,but am trying to resist until the knock and lambda monitoring is here and fitted.things are looking doubtful anyway for my car running , as I gave my Dawes to a m8 to try and was supposed to get it last night,but did not have time and he is away abroad today.I was going to fit it for the day at 15psi so that I could get some figures to post,the car has been run twice at Star now and has been very consistent both times.PAW has never changed,torque has hardly moved only flywheel power changed with me getting Jim to rev the car 500rpm more the second day.I was going to fit it now at lower boost and crank it up before I left to go to Star that morning.will still be going up to see how your car does against the P1 and Linked cars .

do you think that the company you got the bleed valve from in Glenrothes would have something similar to a Dawes?

Cosie Convert,

where did you get the parts from to make up yours?

john banks

They didn't do anything quite like the Dawes.

If you want an interesting comparison we could set your car up with a different restrictor and your solenoid disconnected. Give me a ring if you want to discuss this - it is different to what we did before and should drive very smoothly.

T-uk

thanks john,

I have posted on another thread to try and get a MY99 ECU to run at Star but I may take you up on the offer if I cannot get it.

Cosie Convert

T

I used a Ball relief valve sourced from the RS catalogue, it was fairly straightforward although I have access to pneumatic fittings etc. For a "plug n play" I would still recommend the Dawes valve.

John

On the topic of holding boost pressure, the reason the TD04 drops off is, as you are aware, due to it's size. Exhaust back pressure (before the turbine) increases rapidly as the Dawes (or any MBC) closes the wastegate as it tries to maintain boost set point.
This high back pressure contaminates the next filling of the cylinder, weakens the effective AFR and raises combustion temperature and pressure. All very bad things which = Knock Knock.

A bigger turbo runs more efficiently at the higher flows, the wastegate doesn't need to close to maintain the increased flow, hence less exhaust back pressure = lower cylinder pressure and temperature.
This equals higher boost and power before onset of detonation.

BH

It's my understanding that it's cylinder pressure that kills pistons, gaskets, blocks etc not RPM , within the design RPM of the engine of course. Therefore I conclude that holding boost to higher RPM with a bigger turbo only serves to extend the torque curve and hence increase power.
If the fuel flow can be maintained and the charge temperature controlled, I see no increased risk.

Indeed I would consider that 18 PSI at 3000 RPM is harder on an engine. You only need look at the timing graphs to see how much retard has to be dialled in under these conditions.

cc

john banks

CC do you think the setup I am running at high rpm is dangerous because of the closed wastegate? If it was your car would you want to see lower boost on a TD04 than 13.5 @ 6500 or are you just explaining why you can safely run so much more boost at the top end with a larger turbo?

I am making an EBC and will be able to set boost targets at different engine speeds - what would you recommend at 6500 rpm if you could choose?

Cosie Convert

John

As long as you monitor for AFR, Injector duty and Detonation (which I believe you do) I don't think there is any danger in finding your safe limit by means of an E or MBC.
It's just the smaller turbo starts to work against you, that's all.

Do you think your wastegate is remaining open as your boost falls off at higher RPM ? Or is the turbo just choking ? I don't know, if it's the former then there may be scope for improvement via EBC.

cc

john banks

Yeah I do monitor all that just wondered what you were saying about in-cylinder pressures which scared me a bit. But I do have a nice twin dump downpipe which I am sure helps a bit

"It's just the smaller turbo starts to work against you, that's all."

Indeed!

I think it is just the turbo running out of flow. From results from EBCs I think I have just found its flow limits.

Boost controller code is coming on. I was wondering if I was going to use PID, RPM boost targets and have to program in duty cycles. But in modelling it I think I can do PI, start with a single target of 18PSI and let it find its own duty cycle. I will have to set the constant for P to get it about right, then add in I to sort offsets for different weather and gears. It is getting there. If that works then I will make a map for RPM based targets and a scaling factor for TPS. I have code in to stop the integrator winding up if it can't hit target boost, and limits set so that duty cycle is 0 if boost is below 2 PSI or peaks above 19PSI to give an overboost cut. The main limitation is 128 bytes of RAM in which to manipulate several floating point variables. Code so far is using only 20% of available space, and I have not delved into using the EEPROM yet, but I expect this will just hold user defined data that could be modified with a terminal program through the serial port if I get round to it.

Initially I will use variable resistors through the chips ADC to set the variables when testing. Later it will be a laptop thingie, and if on here I am sure someone will come up with a little bit of code to run an interface.

Lets hope it works.

Cosie Convert

Sounds promising ! I think you may need the 'D' In your PID control loop in order to catch the boost as it shoots up to target rather quickly ??
P+I will need/allow an overshoot to gain control of the loop.

I think ??

Richard Curtis

Funny - i was just trying to work out the max boost band on the way home from work tonight

My UK97 (with std. downpipe cat + std. filter) gets to 15psi at 2800rpm and holds it until around 5500 (in 4th), seems to run out of puff from then on, gradually dropping boost.

Not too bothered about dropping off at high rpm (seems much lower than yours thou)- i don't like revving the nuts of it anyway

Probably the TD04 limiting - who knows?

Edited: after a run from Tescos

Since your measurements are at 6K I done another run on the way home from tescos just to check like 4 like.

Getting between 13-13.5 PSI @ 6000rpm, still pulling well
Not sure how accurate gauge is, should be under +/- 1 PSI.

Can also confirm shopping goes everywhere in boot when pushing it @ 6K in 4th on a mild bend

Rich

[Edited by Richard Curtis - 1/10/2002 11:17:35 PM]

john banks

I get 13-13.5PSI at 6500rpm in 3rd gear, can't remember what at 6000rpm. It rarely goes that high is regular use.

Can't think a PPP ECU would make any difference - it would be turbo and volumetric efficiency and environmental conditions.

My held boost in 2nd is about 17PSI, rising up to 18PSI in 5th (0 deg C) - when a bit warmer the other day (8 deg C) it was about 17.75PSI.

[Edited by john banks - 1/11/2002 8:24:36 AM]

john banks

Those are some nutterish times! Must be great fun.

But a non STi RA does not have forged pistons IIRC and I would be ever so slightly concerned about running so 16 PSI so high up!

At that sort of boost level you are running more boost at the top end than some guys do with front mounted intercoolers and totally remapped ECUs.

Would hate it to go pop. If it was my car I would want lambda, knock, EGT and intake temps, as well as injector duty cycle and ignition advance. You are braver with your engine than I would be with a Subaru.

And I would be absolutely flabbergasted if you don't get dodgy readings. Subarus are not as easy to push up the boost as Cossies from what I hear about Cossies.

[Edited by john banks - 1/11/2002 10:58:23 PM]

john banks

Do you think I am at danger when I put my car on the RR from detting due to intercooler inefficiency? YOU have worried ME now!

However, I know a lot of people with 280bhp modded UK scoobs with TMIC have done it and escaped. I don't expect mine will show that much at Star - maybe at PE it would. Maybe 260bhp at Star? Forgot to say I am over 9% CO at the top end.

[Edited by john banks - 1/11/2002 11:27:30 PM]

john banks

Have played with a simulation and been looking into it quite a bit. I don't fancy tuning three variables if possible. If I need D I can add it without TOO much hassle, but from what I hear most of the commercial ones don't use D. I tried simulating it with PD, and it worked OK, but various folk put me off saying D is a pain in the ***. With 2 out of the three I can get pretty good control, and may even want to engineer in a small boost spike. We'll see. I'll forward you an email I sent to Stephen Done with links and code in if you want. Presumably you already saw my recent thread in drivetrain and links to the webpage?

Mail me your address if you want it. Old code is here http://www.jcsbanks.btinternet.co.uk...controller.htm and has changed substantially.

[Edited by john banks - 1/12/2002 11:21:34 PM]