Boost control

[Evodelta]

Ok, after a recent thread where we veered off a bit onto boost control, I've dug out some articles for you to read, pour yourself a drink and get stuck in. :smile:

Steve: If you have any problem with the articles then let me know and I'll pull them, maybe after some of the guys have had the time to copy them?

Guys, you might be able to view them yourselves here:

http://www.autospeed.com/cms/search/index.html?keywords=boost+control&x=18&y=5

I'm not sure, because I am a member, some articles are public, some aren't. Sadly the pics and graphs won't copy onto here. The intercooler waterspray articles are well worth a look at too as are many others.
If not, it's well worth joining as there is a lot to read on there, the fee lasts forever, it's not yearly.



Boost Control Considerations
Let?s assume you?ve decided to push some more boost through your turbo car. Congratulations ? you?ve settled on one of the most cost-effective ways to improve performance. But let?s take a moment to consider things in detail.

The first question is how much boost your car can safely withstand. This is a difficult question to answer but there are two main factors that limit the amount of boost you can run ? the point at which the engine starts to detonate and the point at which the fuel system can no longer maintain a suitably rich mixture. Detonation is most widely be detected by ear as a ?tink-tink? noise while mixtures are best monitored using an air-fuel ratio meter. Do an AutoSpeed site search under ?detonation? and ?air fuel ratio meter? and you?ll find plenty to read.

Within these limits, you can now think about the boost characteristics you?re after. How quickly do you want boost to rise and do you want to hold max boost to the redline? The shape of the boost curve (ie how much boost there is across the rev range) has a major effect on the on-road feel of a car ? for example, a car that comes onto boost quickly can be very exciting to drive on the road (especially in the wet!). Note that the rate of boost rise is sometimes referred to as wastegate creep ? by reducing wastegate creep, boost pressure will build faster.

A characteristic of many boost controllers is boost pressure fall off at high revs. This is often the case where the turbocharger is being pushed near its output limit and, as a result, the wastegate opeing must be reduced to hold steady boost pressure. In other words, when the engine is running at high revs and full throttle, the turbo may need to be run almost flat-out to provide constant boost pressure. It's most people?s aim to maintain constant boost pressure to the redline but be aware that running the turbocharger near flat-out will likely reduce its lifespan. It?s also not necessary to maintain constant boost in engines that provide ample mid-range torque ? there?s no need to spin the engine to high revs.

Also be aware that certain types of boost controllers are more susceptible to pressure variations than others. A system that is set to provide 14 psi in normal temperature conditions might allow 18 psi in unusually cold conditions ? a scenario that can easy cause a lean-out and one dead engine. For maximum safety it?s advisable to go for a controller that offers good consistency.

Finally, you should consider the price and installation difficulty of each boost controller. Obviously, the cheapest controllers are the most appealing but if you?re not confident installing and tuning such a device, it might be worthwhile to spend extra on an easy-to-use controller. You might also want to invest in professional installation and tuning.


DIY Boost Controller #1
One of the most tried-and-proven systems is the in-cabin boost controller discussed at Project EXA - Part 3 - DIY Boost Control. This system is suited to all turbo cars and is easy to install and calibrate.

The system uses two brass valves ? a quarter inch needle valve (which becomes the in-cabin controller) and a quarter inch ball valve (which should be mounted under the bonnet and gives coarse boost control for set-up purposes). You?ll also need a quarter inch T-piece and a couple of metres of quarter inch hose. Total cost should be less than around AUD$75. Installation and calibration is discussed in our original article (Project EXA - Part 3 - DIY Boost Control)

So what are the characteristics of this system?

Well, the rate of boost rise is very fast but it's possible to achieve an even faster rise with other systems. Boost pressure stability also varies depending on the combination of turbocharger and engine. In some instances your newly set boost value will be held all the way to the redline ? however, in some cars (particularly those with a relatively small turbocharger), it will fall off at high rpm. Note that this system is also susceptible to variations in ambient temperature and across different gears.

So, in summary, this system is reliable, easy to configure and cheap ? but it doesn?t necessarily give the fastest rate of boost rise (if that?s what you want), it may allow boost to fall off near redline and it can?t compensate for changes in ambient temperature and across different gears. It may seem flawed but this system can work well ? especially if you have an in-cabin boost gauge to keep an eye on.

DIY Boost Controller #2
One of the most discussed boost controllers is the system outlined in The Audi's DIY Boost Control - Part 1 and The Audi's DIY Boost Control - Part 2

This is the first Do-It-Yourself boost controller we?ve seen that incorporates adjustable wastegate creep ? you can have a relatively progressive rate of boost rise or you can have it shoot up as quickly as possible. And, in contrast to the previous system, boost pressure is controlled using a pressure regulator rather than a bleed.

The Audi DIY Boost Control comprises two main components ? a pressure relief valve (which allows adjustment of wastegate creep) and a pressure regulator (which allows adjustment of boost pressure). The pressure relief valve is fitted in the wastegate hose and the regulator is connected downstream (towards the wastegate actuator). The pressure relief valve can be set to open at, say 10 psi, so absolutely no pressure will reach the regulator or the wastegate actuator at boost pressures lower than this. This means boost can build as quickly as possible. Then, once the relief valve opens, the pressure regulator steps into action to control the amount of pressure applied to the wastegate actuator - and therefore control boost pressure.

In addition to these two main components you may also need a large diameter one-way valve which serves to improve boost response after gear-changes (by ensuring there is no residual pressure trapped against the wastegate actuator). The one-way valve is plumbed so that it connects the outlet end of the pressure regulator to the inlet end of the pressure relief valve. The valve is orientated so air can flow from the wastegate line to the input end of the pressure relief valve.

The biggest advantage of this system is the adjustment it gives over the rate of boost increase ? you can have it exactly how you want. In terms of boost pressure consistency, the pressure regulator ensures the wastegate opens the same amount regardless of any other conditions. This might seem ideal, but in very cold conditions (where the engine can produce more power and, therefore, more exhaust gas than usual) we?ve seen this system allow over-boosting. Again, this is a good system to use in conjunction with an permanent in-cabin boost gauge.

At around AUD$100, the Audi Boost Control has been widely put into service with success. Its adjustability is the major drawcard, but be aware that ? like a bleed - the pressure regulator does not ensure consistent boost pressure. Compared to the previous controller, it?s also slightly more difficult to install and tune.

DIY Boost Controller #3
The final Do-It-Yourself system we?ve devised is exclusively for use in cars with open loop factory electronic boost control - see Brilliant Boost and Bumped Up Boost. This is probably the trickiest Do-It-Yourself approach because, unlike the previous systems, the logic of the factory boost control system is retained. You?ll enjoy a ?bumped up? version of the factory boost curve along with all of the manufacturer?s safety strategies.

Extremely easy to set-up, this system involves installing a quarter inch flow control valve in the factory hose between the compressor outlet and the OE boost control solenoid. Start with the flow control valve fully open and adjust it so that the desired boost pressure is reached. It couldn?t be easier.

So what boost characteristics can you expect from this system?


Well, you?ll be able to set your maximum boost pressure but you can?t alter the factory boost curve ? if the factory system brings boost up gradually and drops off toward the redline, then that?s what you?ll get. However, as a result of inserting the flow control valve in the wastegate hose, you can expect boost to rise slightly faster than standard. In addition, you?ll have the protection of OE failsafe strategies which, for example, might involve a reduction of boost pressure when the airflow meter signal is detected faulty.

For under AUD$50, this is an easy to install, safe and well integrated approach to boost control and should appeal to anyone not wanting to ?throw the baby out with the bath water?.

Stick around for the second and final part of the series ? we look at off-the-shelf aftermarket boost controllers...

[Evodelta]

PART TWO:



In the first part of this series (see Boost Controller Roundup - Part One) we looked at the considerations surrounding boost controllers and detailed some Do-It-Yourself type systems. Now, in the final part, we delve into the off-the-shelf aftermarket controllers we’ve tested – everything from around AUD$30 to AUD$750!

Off-the-Shelf Aftermarket Boost Controllers
Turbotech Controller

The cheapest off-the-shelf aftermarket boost controller we’ve seen is the Turbotech unit, which sells for around AUD$30 on eBay.

Sceptical? Don’t be!

As covered in the article Thirty Dollar Boost Control, the Turbotech boost valve is not a run-of-the-mill bleed valve that vents pressure from the wastegate hose. Instead, it contains a steel ball that is forced down onto a seat by a coil spring. Boost pressure enters through the bottom port of the controller and tries to push the ball off its seat. When there’s enough boost pressure for this to occur, air passes through the top port and reaches the wastegate actuator. Boost pressure is then controlled.

The advantages of this approach might not be obvious at first. But compared to a bleed, the Turbotech controller offers potentially superior boost consistency across a range of ambient temperatures and in different gears. You see, unlike a bleed, the Turbotech unit has some inbuilt intelligence – for example, in extremely hot conditions or in a low gear (where the engine will produce a relatively small volume of exhaust gas) the steel ball inside the valve body will stay closed as long as necessary until enough boost pressure is developed to lift it off its seat. And, of course, the opposite also applies – in extremely cold conditions or in a high gear (where the engine will produce a relatively large volume of exhaust gas) the steel ball will lift off its seat as soon as there’s enough pressure to do so.

In addition, the Turbotech controller gives a very quick rate of boost rise due to the spring preload applied on the internal steel ball – its impossible for any pressure to reach the wastegate actuator until there’s enough boost to lift the ball off its seat.

Installation is very straightforward. Simply remove any existing boost control system and install the Turbotech (in its specified orientation) between the compressor outlet and wastegate actuator. Turn the bolt on top of the controller to achieve your desired boost setting and secure it in position using the locking nut.

As we said in our evaluation of the Turbotech controller, anything that allows you to control boost pressure for around AUD$30 is a winning product. But let’s not sell it short. It gives a very fast rate of boost rise and, across different driving conditions, it has the potential to give better control than a conventional bleed.

PowerUp MBC
In 2002, the Powerup MBC (Manual Boost Controller) was released as a cheap off-the-shelf boost controller with a RRP of AUD$99. These days, it’s not especially cheap but it is representative of entry-level bleed valves.


Like the AutoSpeed Boost Controller #1, the Powerup MBC shares the concept of bleeding pressure from the wastegate hose to increase boost. But, unlike Boost Controller #1, there is only one valve required – it incorporates a tiny opening in the intake port which restricts airflow through the valve to allow the necessary amount of air to be bled. There’s only one point of adjustment – the dial on top of the valve body.


When we fitted the MBC to a Holden VL Turbo we saw improved rate of boost increase and an elevated boost value. But, like many bleed valves, there was a there was a boost drop off toward the redline and a substantial gear-to-gear boost pressure variation – in fact, of all the controllers covered in this series, the MBC gave the least consistent boost pressure across different gears.

Pros and cons? Well, it’s one of the easiest boost controllers to install and calibrate, it’s modest in price and looks sexier than a pair of brass valves. Unfortunately, boost pressure consistency is not a strong point – at least, as far as our testing goes.

For the full article see Low Buck Boost

Digital Pulse Adjuster (DPA)
The Silicon Chip DPA is a universal electronics kit that can be successfully used to increase boost pressure in most cars running factory electronic boost control.

The Digital Pulse Adjuster is configured to intercept the variable duty cycle signal that the vehicle’s ECU sends to the boost control solenoid. The duty cycles sent from the factory ECU are spread across 128 ‘load sites’ onboard the DPA unit; this means when the factory computer is outputting a duty cycle of 50 per cent, the DPA assigns load site 64. Boost is increased by programming the DPA to send a greater duty cycle signal to the boost solenoid any combination of load sites. The shape of the boost curve can be tailored by individual adjustment of each load site.

Fitted to a ’94 Subaru WRX with intake and exhaust mods, we were easily able to tune the DPA to hold a steady 14 psi boost to the redline. We were also able to dial out a previously existing boost spike without reducing the rate of boost pressure increase. In addition, the factory ECU retains the ability to pull back boost as a safety measure (although it can’t pull it back as far as originally).

The DPA retails for AUD$79.95 and is programmed with a separately available Hand Controller which costs AUD$59.95 - both kits supplied requiring electronic assembly. Alternatively, the Hand Controller can be bought pre-assembled and tested for AUD$139.

See Digital Pulse Adjuster, Part 1and Digital Pulse Adjuster, Part 2for more details on the DPA.

Independent Electronic Boost Control (IEBC)
Another release from Silicon Chip is the IEBC – a standalone boost controller that can be used on any EFI turbo car.

The IEBC is a trick bit of gear that receives information on injector duty cycle (which is closely related to engine load) and allows you to program a corresponding duty cycle output to drive a boost control solenoid. The output frequency from the IEBC is 10Hz, which allows you to use pretty well any garden variety OE boost solenoid. And, interestingly, the solenoid is not intended to be configured as a bleed – instead, it is placed in-line between the compressor outlet and wastegate actuator. When the solenoid is un-powered it is closed and no pressure can reach the wastegate actuator and, conversely, when the solenoid is pulsed it allows pressure to reach the actuator and boost pressure is controlled.

This graph shows the IEBC map used to control boost pressure on a Japanese import Nissan Maxima Turbo. The map shows that at light engine loads (up load site 28), the IEBC outputs nothing so the wastegate is kept closed. Then, as the turbo spools up, the IEBC sends up to a 44 percent duty cycle to the solenoid to achieve a maximum desired boost level of 11 psi. Near the engine’s maximum output, the efficiency of the factory turbocharger begins to drop off and the wastegate is almost closed to maintain steady boost pressure. This map achieved a steady 11 psi boost to redline.

The IEBC retails for AUD$79.95 unassembled (or AUD$279.99 pre-built) and you’ll need to pay another AUD$59.95 (or AUD$139 pre-built) for the associated Hand Controller. This means an all-up price ranging from AUD$139.90 and AUD$418.99.

Note that this is not a system for beginners – we suggest it only if you have experience tuning other boost control systems and understand how easy it is to accidentally over-boost an engine.

For more on the IEBC, check out The Independent Electronic Boost Control, Part 1and The Independent Electronic Boost Control, Part 2.

TurboSmart e-Boost
The most sophisticated boost controller we’ve tested – and by far the most expensive – is the TurboSmart e-Boost.

The e-Boost is a stand-alone electronic boost controller which constantly monitors manifold pressure to ensure rock-steady boost all the way to the redline. This is known as a closed-loop boost controller – it monitors manifold pressure for feedback and adjusts the wastegate accordingly.

In addition to controlling boost pressure, the e-Boost incorporates a boost gauge (with a peak recall function), an overboost alarm, overboost shutdown and an auxiliary output which can be used to trigger intercooler water sprays at whatever you chose. You can also program three different boost pressures.

Installation is pretty detailed but anyone with a good knowledge of turbo systems should be able to get through it using care. First, the e-Boost unit should be mounted inside the cabin - preferably somewhere where it’s not an attraction for thieves. Next, you’ll need to run a hose through to the engine bay and connect it to a supplied boost solenoid. Note - if your car is equipped with factory electronic boost control, this circuit should now be disabled. Now use the supplied hoses to connect the new boost solenoid between the compressor outlet and wastegate actuator. That’s the plumbing completed. Wiring involves connection to a switched 12V power supply, earth, two connections to the new solenoid and a connection for night-time illumination.

To achieve your desired boost pressure you need to program a ‘set point’ between 99 and 0 - start off with a low number to ensure the engine doesn’t over-boost. The set point should then be incrementally raised until you arrive at your desired boost level. Next, you need to program the so-called ‘gate pressure’ – the boost pressure at which the wastegate begins to open and, therefore, the rate of boost rise. Following this, you can enter the e-Boost’s various alarm and shut-down values and, if required, an axillary output.

[Evodelta]

Part two Cont:

Currently selling for around AUD$750, we’ve proven that the TurboSmart e-Boost does a spot-on job of maintaining constant boost pressure regardless of temperature and gear position. It also has the benefit of user-definable wastegate creep, though we think the head unit is a tad fiddly to operate and too large for easy mounting.


See e-Boost Evaluation for our test of the e-Boost. Note that an updated e-Boost2 (seen here) has recently been released boasting a tacho, shift light, a two-dimensional programmable output and more. Price remains similar to the first generation unit.

Warning!

In an article like this we must emphasise that increasing turbo boost pressure is an easy way to destroy an engine.

If you are unsure about any aspect of installing and tuning a boost control system – which includes listening for detonation and monitoring air-fuel ratios – we suggest that you enlist a performance workshop to do the job for you.


So there you have it – everything from the cheapest and easiest Do-It-Yourself boost controllers to the most sophisticated and expensive. If you chose wisely, you should be able to achieve exactly what you want for minimum $ and effort. So get boosting!

[Evodelta]

This is it. The cheapest aftermarket boost control valve we’ve ever seen. Selling for around AUD$30 on eBay, the Turbotech boost controller sets a new standard in bang-for-buck.

So how good – or bad – is an AUD$30 boost controller?

Let’s find out!

The Turbotech Boost Controller
The Turbotech boost controller works differently to most other cheapie aftermarket boost valves. This is not a bleed valve which vents pressure from the wastegate hose.


The Turbotech controller contains a steel ball that is forced down onto a seat by a coil spring. Boost pressure enters through the bottom port of the controller and tries to push the ball off its seat. When there’s enough boost pressure for this to occur, air passes through the top port and reaches the wastegate actuator. Boost pressure is now controlled.

Peak boost pressure can be varied using an adjustment bolt and locking nut. Turning the bolt clockwise increases preload on the spring which means greater boost pressure is required to lift the ball off its seat.


A small hole in the valve body (called an "excess pressure valve") allows pressurised air to escape from between the controller and wastegate actuator following a boost event. This pressurised air would otherwise be trapped against the wastegate actuator and cause poor boost response.

The valve is also equipped with a pair of ? inch barbed brass fittings to allow easy fitment.

Installation
If you own a turbo car that has factory electronic boost control (such as a Nissan Skyline, Subaru WRX or Mitsubishi Galant VR4) you’ll need to disable the existing control system before installing the Turbotech unit. This ensures you’ll consistently get the boost pressure that you set.


The easiest way to disable the factory electronic boost control system is to remove the hoses at the boost solenoid (as seen here). We recommend that you then remove all of the existing boost pressure control hoses – everything from the boost pressure source (typically the turbo compressor outlet) to the wastegate actuator. This eliminates problems with unseen hose restrictions and lets you keep the hose route as short as possible – this improves boost control accuracy.


Starting from scratch, you can now connect a new length of hose between the pressure source and wastegate actuator. Cut this hose and fit the Turbotech controller in the correct orientation – the bottom port should connect to the pressure source and the top port should connect to the wastegate actuator. Unfortunately, the direction of flow is not marked on the controller body and there are no mounting provisions – the controller simply dangles in space.

Job done.

If you own an old-school turbo car that doesn’t have electronic boost control (such as a Holden VL Turbo, Daihatsu Charade or Nissan Pulsar ET) the installation process is even easier. Simply cut the existing hose between the pressure source and wastegate actuator and install the controller in the correct orientation.

Tip! When installing the Turbotech controller it’s a good idea to turn the adjustment bolt so that you j-u-s-t blow air through the valve. This gives you a good base for calibration – you’ll be close to the adjustment range that gives your desired result.

Calibration and Testing
Warning! An accurate boost gauge is essential when calibrating a boost control system. It’s also important to use an air-fuel ratio monitoring device to ensure mixtures don’t run dangerously lean. You should also listen carefully for detonation at increased boost pressure.

Failure to take these precautions can result in engine destruction.


Before installation of the Turbotech controller, we established a baseline boost curve for our Galant VR4 through second gear and fifth gear. It’s always a good idea to test boost pressure in different gears – in some instances, the extra engine load in high gears will cause the turbo to overboost compared to in low gears.


As seen in this graph, our lightly modified Galant VR4 spikes to 1 Bar boost (14.7 psi) in second gear and levels off to around 0.75 Bar (11 psi) toward 7000 rpm. This mid-range boost spike is quite common when a high-flow exhaust is fitted to a turbo car that employs a conventional (open-loop) electronic boost control system.


This graph shows the VR4’s boost curve in fifth gear running to a maximum of 4000 rpm (with the car travelling as fast as conditions would allow). As you can see, boost pressure builds much faster in fifth gear compared to second gear. By 2000 rpm you’ve got 0.2 Bar (3 psi), compared to around 0.06 Bar (less than 1 psi) at the same revs in second gear. Peak boost is reached by 4000 rpm and, in this particular car, the maximum boost pressure is 1 Bar (14.7 psi) regardless whether you’re in a low or high gear.

Now it’s time we calibrate the Turbotech boost controller.


Fitted to the car (with the adjustment bolt set so we could just blow through the valve), the Turbotech controller gave a peak boost pressure of around 0.7 Bar (10 psi). A safe starting point - but not enough for us. We then loosened the locking nut and turned the adjustment bolt clockwise one full turn. This increased peak boost pressure to 0.9 Bar (13 psi). One additional full turn gave us the peak boost pressure we wanted. Our aim was to reach a maximum of 1 Bar (14.7 psi) and hold it there.


Adjusted to give a maximum of 1 Bar (14.7 psi), the Turbotech controller gives a similar shape boost curve in second gear compared to the standard control system. This graph shows the Turbotech-equipped boost curve (in pink) against the standard boost curve (in blue). Boost pressure is oh-so-slightly improved at around 3000 rpm and, more importantly, top-end boost pressure doesn’t fall away as much as standard. Boost does fall away but we imagine this is a characteristic of the VR4’s relatively small turbocharger which becomes inefficient at high revs – the wastegate probably needs to be shut to hold 1 Bar (14.7 psi) through to 7000 rpm. Incidentally, any closed-loop electronic boost controller or the Silicon Chip IEBC can achieve this.

In fifth gear up to 4000 rpm, the adjusted Turbotech controller provides exactly the same boost pressure curve.

How Quick to Boost?
One of the most important aspects of an aftermarket boost controller is the rate of boost rise. It’s likely that you want to get up to maximum boost as quickly as possible.


We decided to temporarily remove and seal our VR4’s wastegate actuator hose and (carefully!) measure the fastest possible rate of boost rise. This is a very dangerous process that requires an eagle-eye on the boost gauge.

So what did we discover?

Well, with no wastegate control we saw 1 Bar (14.7 psi) of boost arrive at 4300 rpm in second gear. This is the absolute quickest that the engine can build boost. Interestingly, we reached 1 Bar (14.7 psi) at damn-near the same revs using the Turbotech controller and with standard electronic control.

In this case, it’s impossible to improve on the standard set-up. But at least the Turbotech unit doesn’t reduce the rate of boost rise.


Verdict
Anything that allows you to control boost pressure for around AUD$30 is a winning product.


Fitted to our Galant VR4, the Turbotech controller was successful in providing adjustable peak boost pressure and giving the fastest possible rate of boost rise. Unfortunately, it wasn’t able to hold high boost through the top-end. This is likely to occur in all cars with a relatively small turbocharger.

At the time of writing, the Turbotech controller can be purchased through eBay Australia www.ebay.com.au with a "Buy it Now" price of AUD$29.90 (plus postage). With more than 160 units sold, it seems the allure of an AUD$30-odd boost controller is too much to resist.

And, yes, an AUD$30 boost controller can perform well. We’ve proved it!

[AlfaJack]

Bloodyell, going to have to print that out and using as reading material for the train to work!

Thanks for posting it up :)

[jimnielsen]

I also printed out this article so that I could read it more comfortably! Its a good article, thanks for posting it for us EVO2.

I would make the following observations:

1. boost valve solutions are inexpensive and effective but don't give you any control over the AFR. So it would be nice to see what the AFR's are as you increase boost. Here is a solution to seeing what the AFR's are: http://www.moates.net/index.php?cPath=57 it claims to be the cheapest way on earth to see you AFR's - I can't attest to that but its a cheap solution that I use and it works.

2. Electronic boost control systems are more complicated than boost valve solutions. As it happens the Q4 has an ECU that its easy to exercise control over, so if you are going to the trouble of messing with an electronic system you may as well mess with the Q4 own first. It does let you configure fueling too. But I still think that you need this: http://www.moates.net/index.php?cPath=57


jimn~

[wrinx]

Interesting, many thanks for posting.

I was looking at one of the Turbotech controllers on ebay the other night....couldn't see what the problem was and this article kinda backs that up :D

Pierberg loses too much power for my taste :D

wrinx

[Evodelta]

Can you guys find these articles on Autospeed yourselves? They are laid out a lot a lot better on there with diagrams and pics etc. If you can't and do want the full versions then send me your email addresses and I'll send them on.

Just a note regarding manual boost controllers (MBC) over the Pierburg (PV):

The PV is (as we know) linked to the ECU, now if there is an issue with the engine and it's picked up by one of the sensors then it will cut the boost using the PV, you don't have this of course with a MBC.

The other guys (Whizz and Jim) idea of re-writing the chip is of course a better and more refined way of doing it - if they can get it to work and I hope they do.

[AlfaJack]

I think I now understand boost control/ Some great info there, brilliant site, I expect it can help me out on understanding the effects of detention when I get a chance. Thanks again.

[Evodelta]

I expect it can help me out on understanding the effects of detention when I get a chance. Thanks again.

I learned all about the effects of detention when I was at school, it usually made me an hour or so late home. :rolleyes:

The site is very good for understanding intercooler waterspray too, not a lot of people do.

You never know, I might even have you guys reading some useful books by the end of the year. :tasty:

[Evodelta]

Boost controller sale:

http://store.autospeed.com/Boost%20Controllers/Turbosmart/Boost%20Controllers/

[AlfaJack]

I have bought one of ebay, should be here by tomorrow and tested at the weekend.

[wrinx]

Which one did you buy?

wrinx

[AlfaJack]

This one: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=270243483380&ssPageName=STRK:MEWN:IT&ih=017

[Evodelta]

This looks ok and for ?16 too. Let us know what you think when it's set up.

[wrinx]

Any news Jack?

wrinx

[AlfaJack]

Sorry, not a lot.

I have fitted it (simple enough job), by default it is set to 0.6. It is surprising how normal it feels to drive, just shows how often I really get to boot it when doing my normal journeys :(

I plan to start raising the boost this weekend. Need to buy some insurance before I go anywhere though.
:(

[AlfaJack]

Is it likely that fitting this controller has changed the characteristics of the boost from 0 0.6 Bar?

I ask as when coming on boost it feels a bit more lively and the back end twitched tonight on a roundabout which it rarely does. Or maybe the roads are greasy as there had been a little rain....

[wrinx]

My brief experience of running without the PV gave the impression that it's more like my JTD...i.e. instant strong boost.

Feels like the PV makes the boost gentler so removing it and fitting one of the controllers means you just get all the boost (for your setting) much more rapidly.

I loved running without the PV until the water pump made me put it back in the garage :cry::tapedshut:

wrinx

[wrinx]

Any updates Jack?

wrinx

[AlfaJack]

Sorry, iv not driven it anywhere meaningful to do a test :( I am going to the essex meet on Wed night so will have a go then :) Will take a spanner for adjustments on the way back :)

[AlfaJack]

Some testing has been done and every setting I try (up to 0.8-0.9 now) is giving a good whack of boost (power is really there in an instant) but it is slowly tailing off to 0.5-0.6 and sticks there, the car is still going pretty quick but I wonder what is causing this.

I suspect I have a boost leak somewhere along the line (I will check all connections in the induction soon), or can this be caused by bad manual boost controllers?

[wrinx]

Mmm, could be the system doesn't hold pressure, these boost controllers are supposed to stop leakage from the wastegate.

Wonder if once the pressure setting is reached you then lose some boost for a while???

Dunno...just guessing.

Try setting it to 1.2-1.4 and see what happens ;)

wrinx

[axaQ42]

Can be there a faulty MBC(not the bleed valve type)?Becouse on my friends Q4 when you screw it in to the max there is no more then 0.8 bar of boost!As far as i know the problem could be only in weakness of the spring that pushes the ball down.

Boost leaks are not an option we tryed that by blocking the hose from the turbo(so the WG stays closed!) and the boost quickly raised to 1.5 bar(my friend tryed that a few times just for fun and guess what...he blew the intercooler :D :D )

[AlfaJack]

I guess there could be, perhaps some oil or dirt in it? Have you taken it apart?

Perhaps a split in the pipe from the turbo to the MBC has a leak?

[axaQ42]

No the pipe is brand new also we blocked that pipe for testing and the boost went skyhigh...so that proved that there is no boost leak.I have taken it apart and as it supposed to be ...evertyhing was nice and clean and ok.For me the only logical expalantion is the spring which is too weak.We are going to try to change it for a stronger one or just stratch this one for a a few mm.

[axaQ42]

Problem solved...as we thought the original MBC spring needed a nice stratch and a few "rings" cut off to get the right setting for the controller :).

[#84]

Many interesting devices! The relief valve principle is really brilliant, so that no pressure at all reaches the wastegate actuator below a certain boost pressure.
However, I am very sceptic to all these devices which have as purpose to maintain the boost pressure even at higher engine speeds. A closed loop control would be fantastic, but as I understand it all these aftermarket electronic boost conrolers are excellent at keeping the boost at a certain level, but they have no functionality to adjsut boost v.s. speed. With the Q4 as an example; it boosts about 1,1-1,2 bar in the midrange with standard chip+turbo. If that boost could be held up to 6500 rpm, there would be no chance to supply it with enough fuel...

Anyway, I can see a few other strategies to a) have better boost build up b) have better boost control:

* Do not run the Pierburg Valve at primary boost build up - you will just re-circulate air through the PV to the compressor inlet.

* Use a two-way waste-gaste acuator. Put pressure on the closing side to help keeping the waste-gate closed during boost build up and on the opening side when controling boost at higher speeds. They do excist, but where do I find them?

* Use so called air injectors with inverted logic instead of Pierburg Valve.

* Run closed loop boost control within the ECU - RP-lab offers it now and I will order it soon :)

[Evodelta]

QU: "With the Q4 as an example; it boosts about 1,1-1,2 bar in the midrange with standard chip+turbo."

Is it really as high as that??

Your theory about the injectors not being able to produce enough fuel at higher rpm/higher boost is ok, but in practice most aftermarket chips overfuel anyhow, so the increased boost may even things out a bit - only an AFR test will tell the truth.

One-size-fits-all chips are crap anyhow, no two engines or conditions are alike, mappable ECUs are the only way to get it right.

[jimnielsen]

I have found that you can keep the AFR at about 12:1 with boost @ 1.1bar to 7000 rpm using the standard injectors, turbo, ecu. Properly mappable ECU's like autronic/motec - where you are not left to guess/experiment with the table values - would make it simpler.

[#84]

Evodelta:1.1-1.2 bar is with modified air filter and exhaust system, but that is pretty normal upgrades.

Jim: The exhaust back-pressure will be very high at 7000 rpm and 1.1 bar, so it is reasonable that there will be fuel enough. However, my point is that it is around this boost pressure you find the upper limit at top speed, but if you tune your engine you probably want to raise the boost pressure in the midrange and then a flat boost curve is not very suitable.

/A