S3 Dv

[S2_Dave]

I'm guessing I've broke the diaphram again in my DV, as boost has dropped from 2.1 to 1.5bar after a slight 'pop' sound on my journey home. The same thing happened two weeks ago. Is it likely that the local Birmingham or Shirley stealer would keep S3 DVs in stock and does anyone have the p/n handy to make sure I get the right one? I've done a search, but can't find the p/n. I did read the thread containing the link to the ARP R1, but I want to fix it tomorrow and £171 inc. delivery is also a bit steep. I will give it a go if this next S3 DV doesn't last though.

Apart from the DV problems, the engine now pulls very well (and a 911 Turbo driver got a bit of a shock last weekend, even with me having a 17st passenger and a full tank). I still think the 5 speed gearbox is quicker and 3rd gear is nice with a lot of torque, but the 6 speed is more involving so it has its plus-side.

[Knight Rider S4]

2.1bar what you running?

[S2central.net]

That'll be ABSOLUTE pressure - calm down dear

[S2central.net]

Part number for S3 DV/TBV ends in 710N

[avants2turbo]

That'll be ABSOLUTE pressure - calm down dear

hold on surely 2.1bar is still high?! ive got an MTM remap on my avant and thats .4bar (presumably thats 1.4bar absolute?)

or am i just talking She-it now?

[4WheelDrifter]

06A 145 710 N is the S3 DV. That's one part number I have in my head.
2.1 bar boost isn't that high these days. Now 3 bar would be interesting.

[S2_Dave]

Thanks Paul. I have just tracked down an invoice with it on. For anyone searching in the future, the part number for the S3 DV is 06A145710N.

2.1bar is relative to atmospheric pressure, using a GT3071.

[S2central.net]

Your MTM will be 1.4bar boost - which is 2.4bar absolute. You nominally add 1bar for atmospheric pressure on the boost value. The MAP device inside the ECU only measures absolute pressure - so its setup for a scale of 250kPa - which is 2.5bar... The RS2 MAP scales to 3bar absolute.

3bar BOOST would require a good supply of clean underwear (and tyres - oh and money).

[S2_Dave]

Beaten to it.

My understanding is that when we talk about "boost", that's relative to atmospheric pressure of 1bar. Absolute measurement includes this bar, hence needing a 250kPa map sensor when remapping a 3B beyond 1bar of boost.

[S2_Dave]

Beaten to it again!

[S2central.net]

Yes Dave - sorry I didn't know you had a 3071 beastie under the bonnet - though I was a bit perplexed about the surprised Porker - with maybe 1.1 bar boost on a K24 !

How wide on the revs are you running 2.1bar with 3071 ? Seems a bit excessive to me but I don't have comp maps in front of me here.

[S2_Dave]

Yeah, I don't think going back to a K24 I would get past even a Carrera 2.

There's more than a bar from 3krpm but after that it rises so fast I'm concentrating so much on the road and not crapping my pants I can't tell you how early it hits 2.1bar. To be honest, I'm usually short-shifting everywhere, as it's still more than powerful enough for me. I'm hoping to get back to Western Performance after my disappointing first visit to have it plotted and check the AFR. I certainly wouldn't want boost any higher as I still ocassionally get a misfire and, not being coil per cylinder, even higher boost would just make it worse. 2bar max was the original intention and I have now got thinking about whether my 3bar map sensor has been changed or recalibrated . What are the implications if it's still 300kPa? Running lean?

[Jon441cc]

Sorry to hijack Dave, but are you still running with the original 3B ignition coil ?

[S2central.net]

@Dave - I think you are taking a chance at 2.1bar on a 3B... I'd have thought 1.9 - 2.0 bar is plenty enough on that - especially so with single coil. The higher your boost pressure - the bigger chance of spark hop inside the dizzy so make sure it is in tiptop condition. An uprated coil can help. Definitely get the AFR checked on a WOT run or few.

You might also find that a piston based TBV (Bailey, Forge, Turbosmart etc) is better for the very high boost levels you have - versus splitting the diaphragm on an S3 one every month !

[Ross]

Yeah, I don't think going back to a K24 I would get past even a Carrera 2.

From personal experience, when pushed to it's absolute limits a K24 can do pretty well against a Carrera 4S Really fecked one off once - he could just abouts get level with me, he would have had me if we'd been going into triple figures though. Geez I miss my 3B

I'd uprate the S3 DV, went through 2 of them in the first 3 months of S2 ownership - and that was only at 1.5bar. Regarding the 2.1bar pressure, depending on who mapped the car, you will probably find that the ECU is not being used to control boost, so it won't matter what MAP sensor is in there. With my 3B i had slight hesitation in the midrange, cleaning up all the contacts and dizzy made a good difference. I was seeing 1.9-2.0 bar (backing off to 1.7 at 7400RPM) and making 428HP.