Whooshy DV-New news

I m very interested to see whether this works and i am open minded.

However from all that I have read the one post that convinces me the most is still the Max-Torque post.

It will be interesting to hear what these big manufacturers have to say....

For anyone who hasn't read his post;-


When you fit a "leak" in the intake system (open circuit valve) the original calibration of the MAF sensor to manifold and cylinder filling modeling will not corespond. However due to the 20% allowance in the long term adaptive values the ECU will relearn your engine and "leak"

At idle the inlet model calculated airflow will exceed the MAF meters measured output, and depending on the state of your particular components - ie MAF ageing / contamination, throttle plate leakage, Fuel tank purge vapour concentration this may, or may not push the adaptive to it's 20% limit. If it hits the limit the ME unit will run in FMEM mode (Failure mode and effects management) causing reduced system efficiency. The Me unit will use the switching signal from the lambda sensor to return fuelling to lambda 1, storing the correction as a map against airflow. and add this correction to the fuelling calc when operating at non closed loop conditions, ie WOT, fuel injector reinstatment (after overrun shut off, traction control intervention etc.) Now depending on how you drive and how sensitive you are this may or may not be felt by the driver during certain manovevers. The throttle plate position will also learn the new airflow to maintain control of idle speed, but you may notice poor engine load rejection, ie turn on the aircon and the engine speed varries etc. or engine speed flares on starts or when operating PAS when parking.

However in all cases this will result in "incorrect" fueling. Now by "incorrect" i mean, not as the manufacturer intended. A post MAF leak will cause rich operation initially, but the adaptives will pull fuel out and become negative. This tends to cause a rich to lean spike on tip outs and other throttle transient. Now it is extremely diffucult for an untrained observer to spot these effects as they occur mainly on throttle transients, when the average drive may not notice. Therefore you could say "why do i care?". Well, any AFR excursion from the intended fuelling set by the manufacturer will result in non-standard engine operation. because of the adaptives this is unlikely to cause immediate engine problems, but over the course of time will change things like catalyst ageing, exhaust and turbo charger valve durability etc. Manufactures spend millions accruing miles on development fleets so hopefully the customers don't get landed with big bills as time goes on, and with most modern cars life'd at 150k miles (min design life) this is a big task.
It is unlikely that this will result in any performance loss, as at WOT the system is open loop, but you may see the result of an open circuit valve oas over fueling on gear changes etc. (a tell tail puff of black smoke is what you can see, a 1200 degC Catalyst is what you can't see, as excess fuel when injection reenstates and excess air from overrun shut off period combine in cat)

Now as you can see this is a seriously complicated subject and i haven't even mentioned the dreaded EOBD or OBDII words yet. Typically Bosch Me units have approximately 9000 calibratable parameters (constants, maps etc) and an engine calibration program will take a team of 8 calibration engineers 18 months to do the basic mapping and OBD validation. These days it's no problem to do the basic fuel and spark mapping, maybe 4 weeks on a midlimit engine on a dyno, but the diagnostics and emmisions devs takes years.

Moral or the story, before you start playing with something you don't understand, find someone who does!(And not just thinks they do!)

(for anyone thinking, "hey what makes me such an "expert" on this subject?" then i'd better mention the last 10 years i've spent as a senior calibration engineer at Cosworth and Prodrive!)

(sorry , another monster post!)

Why do people think 'whooshy' dump valves sound so great ? Whenever I hear one it makes me think something is broken on the car. To mess around with a closely tuned system just to get a strange whoosh noise coming from your car (so you can 'impress' people) seems a bit silly to me.

Edit: I agree with Steves post, look at what MaxTorque has to say on the subject - he is the most qualified to describe the problems you will have.

Bob

Scotty_b said:

Now im sure the engine wont last as long but what are we talking here a few thousand miles? As how many people (realistically that are going to do this mod) will keep there car to 150k+? Those that care about long term wear on the engine won’t use it. But don’t forget the likes of chipping, induction kits, performance zorsts will reduce you engine life too!

Ow and don’t shoot the messenger!

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I think your right, we know that a remap puts extra pressure on an engine, more boost etc, so it's not running as intended i.e, using up some of the built in safety margin.

Then we are talking about adding a DV to that engine to make it operate in a way it wasn't designed.

Now the ECU is clever and will adapt to suit so the engine will still run and all will appear fine.

The question is just how much life are we taking off these engines? and are we knackering expensive CAT's etc too.

Answer - no-one knows, so I for one am going to sit back and watch.......see what happens.

why not just fit a CAI rather than fork out £200 on a n other dual action, relocating, twin piston DV.

Scotty_b said:

Beacsue i cant have a CAI!

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Both the Dynatwist and BMC CDA provide a nice intake roar and DV echo, I had one and have listened to the other.

Why not get one of those electric dump valve (whoosh noise makers) to get the whoosh sound and leave the existing one to do it's job.
Never heard the electric ones so they may sound **** but atleast it won't mess with the car.

Sully

Scotty_b said:

Yeah but there not proper CAI's though.

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They have the sound you require, but agreed they suck in air from behind the n/s headlamp same as OE airbox. Still you get the induction roar and DV echo.

OMG this has been covered a thousand times and people still desperately want to fit something that will never work with the standard ECU.

Right forget the sound for a minute here...

The ECU in your car EXPECTS the extra air to be dumped into the inlet again. So the software compensates for this extra air by adding slightly more fuel for that split second. This isn't something that goes away when you put an amos valve on. So because the air is not there you run rich just after the gear change.

But the main reason the air is let back into the intake is to keep the turbo spinning. Ever wondered why you don't get much lag in a 20vt? Well it's because the pressurised air going back into the inlet helps keep it spooling just that little bit quicker. so when you get back on the power it's spinning faster so less spool up time.

As many know I tried just about every atmos BOV known to man at one point or another. On both the LCR and the LC I got a fault code but never once went into limp mode, and I never had the warning light come on. I just got a warning about a possible air leak - check faulty DV.

However I had a bad experience doing a quick 3 point turn with a truck hurtling towards me while my DV was held open by the ECU for whatever reason. So after nearly killing me through having less power than a hamster wheel I replaced the forge 004 I had on with the 007 recirc. Low and behold the car suddenly had no lag ( I'd been convincing myself I hadn't got any with the 004 ) and the car was 100% more responsive.

That was with the relocation kit as well, but I know why they're saying that makes a difference, but it doesn't I know that for sure.

Basically if you want a BOV then get an aftermarket ECU and have the car run that instead, then you can map the car without expecting the extra air and it'll work perfectly. But don't expect much change from £1k for the ecu, fitting, and mapping just to get the noise.

Pete

Oh I forgot that was out of character for the thread, I should have said....

t'is mint init m8, I gotz 1 ov dem blow offs an it sounds mint me m8 sez it's mint an i gotta ignor da light on da dash til he getz time 2 tak da bulb art...

They make your car sound like a bus anyway lol

Scotty_b said:

Yeah but there not proper CAI's though.

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bollox...

yes they are!

think of the downside of pipes with filters on the end of them and the serious dirt they get clogged with rapidly. Then ask which is the proper Cold Air Induction system. - I sell more than a few Large Green Filters for the likes of Carbonio, AEM, ABD induction kits cos their filters are blinded with shite and knackered. Good whennew, but degrade very fast in their low, inner wheel arch/wing locations.

Scotty_b said:

I must of missed where this became a free for all on slagging them off and not following the point of this thread!
ALL IM DOING IS TELLING PEOPLE WHAT THE MULTI MILLION POUND MANUFACTURES ARE BRINGING OUT AFTER TESTING AND APPROVING!

I give up i really do, its worse than being at work, no one will give anything chance.

Theres bene plenty of developent work done on the cars. Its all there in black and white.

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I found it interesting, please let me know if you hear anything more about it

Cheers

Scotty_b said:

I must of missed where this became a free for all on slagging them off and not following the point of this thread!
ALL IM DOING IS TELLING PEOPLE WHAT THE MULTI MILLION POUND MANUFACTURES ARE BRINGING OUT AFTER TESTING AND APPROVING!

I give up i really do, its worse than being at work, no one will give anything chance.

Theres bene plenty of developent work done on the cars. Its all there in black and white.

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Waiting with baited breath