B8.5 S4 crank pulley change

[youngsyp]

Hi,

I've managed to convince myself to go the 'stage 2' route with the car now and fit a larger diameter crank pulley. Originally, I thought I'd go down the remap only route and maybe change the pulley and tweak the map at a later date.

Anyway, I'll fit the pulley myself (possibly MRC's 'high torque' pulley) and have been looking around the web for experiences. I've found a good guide over on Audizine, but I'm just trying to understand it a bit better. So any first hand experiences you might have would be good to hear (read).

Things like the acc serpentine belt route. In the image I've seen, there's a 'servo' pulley but I think that's only applicable to the B8, with hydraulic steering?!
Also the tools you used. I think a low profile rachet is going on the shopping list...

Paul

 

[Cerbera9]

Which tune are you going for as most of them are developed using their own specific pulley’s? If you going for MRC’a pulley then it’s probably best to go with their tune rather than one developed for a smaller SC pulley.

 

[jdp1962]

Not sure but I think a crank pulley change might be the route @Dippy used for his S5.

 

[youngsyp]

Which tune are you going for as most of them are developed using their own specific pulley’s? If you going for MRC’a pulley then it’s probably best to go with their tune rather than one developed for a smaller SC pulley.

I'll be using Unicorn for the mapping. I wouldn't put 'off the shelf' code on the car, when there's true bespoke mapping solutions out there.

Not sure but I think a crank pulley change might be the route @Dippy used for his S5.

Yes he did, the Fluidampr/ iABED Industries pulley. However, MRC fitted it when he went in to have it mapped by them I believe.

Paul

 

[Cerbera9]

What mods do you have?
Very few cars on this platform have bespoke mapping unless you have the likes of ultra charged, porter blower, running Meth, headers etc etc. Most cars with just an intake, exhaust and pulley swap up to stage 2 will have an off the shelf base map loaded up to get them about 95% there and then the last 5% fine tuned.

 

[forty3]

For how much the pulley removal tool costs would it not be just as cost effective to get the mapper to do it when they do the tune?

 

[youngsyp]

What mods do you have?
Very few cars on this platform have bespoke mapping unless you have the likes of ultra charged, porter blower, running Meth, headers etc etc. Most cars with just an intake, exhaust and pulley swap up to stage 2 will have an off the shelf base map loaded up to get them about 95% there and then the last 5% fine tuned.

Well of course, all established tuners will have a base map for the respective car and base hardware combination as a starting point. It wouldn't be cost effective for them to approach it any other way. It's the tailoring of the map for the particular engine and mods that's bespoke. That's why I chose Unicorn.

Every engine is different, as evidenced by the power/ torque outputs reported on these pages, so they should all be treated that way when mapped. Hence my comment on 'off the shelf' code, like Revo as an example, and I've had first hand issues with that one particularly.

As for my car, it'll have a little more done on the intake side than most as well as some light porting of the supercharger by the time it's mapped.

For how much the pulley removal tool costs would it not be just as cost effective to get the mapper to do it when they do the tune?

There's no special tool required for the removal of the crank pulley.

Paul

 

[Dippy]

@youngsyp - that Audizine post is the only one I have come across. I may be wrong, but I don't think that any B8 owner currently active on ASnet has done their own pulley change.

 

[Cerbera9]

Well of course, all established tuners will have a base map for the respective car and base hardware combination as a starting point. It wouldn't be cost effective for them to approach it any other way. It's the tailoring of the map for the particular engine and mods that's bespoke. That's why I chose Unicorn.

Every engine is different, as evidenced by the power/ torque outputs reported on these pages, so they should all be treated that way when mapped. Hence my comment on 'off the shelf' code, like Revo as an example, and I've had first hand issues with that one particularly.

As for my car, it'll have a little more done on the intake side than most as well as some light porting of the supercharger by the time it's mapped.

There's no special tool required for the removal of the crank pulley.

Paul

I've been up Unicorn a couple of times when a mate had his B5 S4 mapped with great results, really knowledgeable guy. Would be goo to see your before and after results and dyno graph.

 

[youngsyp]

@youngsyp - that Audizine post is the only one I have come across. I may be wrong, but I don't think that any B8 owner currently active on ASnet has done their own pulley change.

Thanks, I think you could be right.

It's no biggy, as I was just after any tool recommendations and pointers from a UK owner.
I've found a low profile rachet easily enough, which seems to be the only 'special' tool that's required.
I've got an engine oil and gearbox oil change coming up in the next month, so will have a poke around then.

Paul

 

[youngsyp]

I've been up Unicorn a couple of times when a mate had his B5 S4 mapped with great results, really knowledgeable guy. Would be goo to see your before and after results and dyno graph.

I'm based in Silverstone, so MRC are right on my doorstep but, I just like what I've read about Unicorn. The drive back from Manc will give me a better run to assess the changes too.
I think I'm more interested to see what the car does before the remap than after as the changes I've made, translate into a tangible feeling of improvement on the road. Not something I've felt on any other car with similar changes.
Having said that, if they make a decent enough difference before the re-calibration, they should also make a decent increase after too, of course. Or I could be kidding myself, there's no hiding in the dyno.

Paul

 

[youngsyp]

I've not had a chance to do this yet but that's because I'm waiting on a pulley to be delivered. I've ordered a 189mm Kustom Imports pulley and am now having second thoughts on whether I should go with the 194mm pulley instead. The 189mm will give a drive ratio of 2.99 and the 194mm 3.07, the thing that's playing on my mind is the extra heat more boost will generate, as I have no intention of upgrading the charge cooler main core.

Rationally thinking, the engine won't spend much time at all at 7200 rpm, and I'll gain more at every rpm point up to there with the larger pulley, maning I won't need as many rpms for the same result. Hmmm.

Any thoughts?

Paul

 

[Dippy]

I played safe and chose 189mm because that's what MRC use for their "most popular" tune with stock cooling. My engine can easily cope with it, but we have reason to believe that there is improved intercooling in the CREC's supercharger so it may not be a good reference point. I also do not drive much at high revs but unless I am wrong, it is not that end of the revs that generate the heat. The heat comes from peak boost which is the mid revs range.

Also there is the question of how much heat is too much? Certainly the ECU will reduce torque when the IAT is too high and improved charge cooling will help, but it does nothing to address EGT. Certainly in the UK most tuned B8s have MRC's 189mm crank pulley or someone else's 57mm supercharger pulley, both of which give a drive ratio of less than 3.0. I have seen very few if any reports of cat failure from UK owners. Whereas in the US there are plenty of owners running ratios over 3.0, and plenty of reports of cat failure.

 

[youngsyp]

I played safe and chose 189mm because that's what MRC use for their "most popular" tune with stock cooling. My engine can easily cope with it, but we have reason to believe that there is improved intercooling in the CREC's supercharger so it may not be a good reference point.

I'd like to do some more research on this as from the little I've done, there doesn't seem to be any substantial change to the TVS 1320 SC since it's release. I suspect they only change the front cover assembly for the CREC engined cars, giving the facility for a bolt on pulley. That aside, if they did change the IC cores, logically, with the size of the integrated coolers, how much more efficient could they be?

I also do not drive much at high revs but unless I am wrong, it is not that end of the revs that generate the heat. The heat comes from peak boost which is the mid revs range.

I'm not sure that's true. My understanding is that in simple terms the greater the engine/ SC RPM, the greater the volume of air being compressed and so the greater the heat generated by the SC. In essence heat produced and compressor velocity are direct related.

It reads like you're referring to peak torque there, not peak boost?!

Also there is the question of how much heat is too much? Certainly the ECU will reduce torque when the IAT is too high and improved charge cooling will help, but it does nothing to address EGT. Certainly in the UK most tuned B8s have MRC's 189mm crank pulley or someone else's 57mm supercharger pulley, both of which give a drive ratio of less than 3.0. I have seen very few if any reports of cat failure from UK owners. Whereas in the US there are plenty of owners running ratios over 3.0, and plenty of reports of cat failure.

The ECU will reduce torque by bleeding off boost and possibly increasing the fuelling. Both will reduce EGTs immediately.

I see you're point about the US guys and I think they largely use 'off the shelf' maps. As part of a true custom map, the boost could be bled off if EGTs are getting too high. More fuel could also be added at specific load points to manage cylinder temps along with tweaks to ignition advance.

But that's a separate issue from the SC producing too much heat from being spun too fast, which is only influenced by the manipulating the drive ratio.

I'm leaning much more to playing it safe...

Paul

 

[Cerbera9]

These engines run hot even at stock so upgrading the cooling should always be a consideration at any level as it will be a benefit.

 

[youngsyp]

These engines run hot even at stock so upgrading the cooling should always be a consideration at any level as it will be a benefit.

I've not read of anyone upgrading the cooling systems on this platform, after tuning. Are there many option for that? Or did you mean the charge cooling system? If that was what you meant, doing so is more likely to increase the heat produced by the engine, than reduce it.

As it turns out, my question was a moot point anyway as the 189mm pulley was sent out on the 27th. It's not an issue though as I'd decided to stick with the 189mm pulley anyway. In the unlikely event it doesn't give me enough power/ torque, I'll investigate other means to extract it, without manipulating SC drive ratios.

Paul

 

[Dippy]

I'd like to do some more research on this as from the little I've done, there doesn't seem to be any substantial change to the TVS 1320 SC since it's release. I suspect they only change the front cover assembly for the CREC engined cars, giving the facility for a bolt on pulley. That aside, if they did change the IC cores, logically, with the size of the integrated coolers, how much more efficient could they be?

I don't know. I had read a few opinions on the matter that's all. As for the TVS 1320, I can note that @arad85 contacted Eaton to ask about the clutch and they directed him to ask Audi. I suspect that Eaton don't actually make the whole S/C on our cars, rather they licensed the design to Audi and supply some of the components.

I'm not sure that's true. My understanding is that in simple terms the greater the engine/ SC RPM, the greater the volume of air being compressed and so the greater the heat generated by the SC. In essence heat produced and compressor velocity are direct related.

It reads like you're referring to peak torque there, not peak boost?!

Torque is directly proportional to boost. The volume of air being compressed in a cylinder is fixed, however the overall compression is highest at peak boost. As the revs increase and boost falls, that peak compression will too. If anything the higher rate of cold air flowing into the engine at higher revs will help to reduce temperatures slightly. So I will maintain that heat generation is highest in the mid revs. But we can agree to disagree.


As you know, I am an MRC customer so I'll refer to their figures. Their standard 189mm package does not require uprated charge cooling and achieves around 470-480 PS at the crank (on their dyno). They also offer a "big" pulley (I don't know the dimensions) solution which "needs" uprated cooling and can break the 500 PS mark. That't not really much of an increase is it?

 

[youngsyp]

But we can agree to disagree.

Agreed. All opinions are welcome, I wouldn't have posted up otherwise. It's also fair to say that you did influence my decision to stay with the 189mm pulley.

As you know, I am an MRC customer so I'll refer to their figures. Their standard 189mm package does not require uprated charge cooling and achieves around 470-480 PS at the crank (on their dyno). They also offer a "big" pulley (I don't know the dimensions) solution which "needs" uprated cooling and can break the 500 PS mark. That't not really much of an increase is it?

That's where using power figures turns it into an abritrary stipulation. They shouldn't dumb it down and simply state that, in their experience, when a pulley greater than X size is used, to counter the SC's operation becoming less efficient as engine speeds increase, an uprated charge cooler is recommended.
It has to be said that's the very reason why I didn't initially plan on going the larger pulley route. So momentary blip of getting carried away aside, the 189mm pulley is just this side of the right choice for me.

Paul

 

[Dippy]

My plan had always been to start with the 189/no cooling and see how the car fared. I imagined that if it got hot then I'd get the bigger rad and go for a bigger pulley at the same time. But my car does not overheat, and then we had the CREC clutch problems and also I read about cat failures. Living as I do in an area where I rarely get a chance to "use" my tune as it is, my motivation to go further is limited. However I'm keen to read about other people taking their cars further and it might spark some enthusiasm to go to the next stage anyway.

 

[Cerbera9]

I’m also MRC stage2 and was happy for about 12months then decided to add an additional charge cooler and immediately realised the benefits. I’ve since swapped that cooler set up for a larger Merc Racing HX and now added Meth Injection just for cooling via a small nozzle in the intake pipe before the throttle body which helps raise the boost by a couple of psi. I’ve now just purchased a smaller Forge Motorsport SC pulleywhich I will fit in due course then gut the CATs before going back to MRC got a nap tweak. I’ve also decided that an additional DSG cooler would be a good idea in the near future.

 

[RyanJonS4]

I did my usual and went all in from the get go.

I’m MRC stage 2 silly pully with their recommended ams alpha cooler and pump upgrade.

I’ve no idea how the different stages of tune feel but I know the difference between stock and how it feels now is night and day. I’ve also never really felt the power reduce due to heat soak.

MRC where working on a bigger throttle body design a year or so ago which seems to have all gone quiet now.

Plans for the future are to get my charger ported and a carbon clean carried out at the same time. If the throttle body ever comes to market I’ll probably jump on that as well.

 

[arad85]

Well... I now have a FIS-Control MMI installed and since yesterday have been monitoring my intake temps. In the 60 miles I have done (whilst I'm concentrating on the road at the same time) I can tell that:

• Intake temps today (7deg ambient this morning, 15 deg ambient this evening) fluctuated between low 30's and mid 40's.
  
• Intake temps were highest (~45 deg) when stop start had kicked in (not surprising really as no air is flowing through the system)
• Intake temps were highest when moving when the supercharger was spinning idly. That is, with the CREC engine, the supercharger ratio is dependent on whether the clutch is engaged. When it is disengaged, the supercharger is spinning at ~0.5x crank and temps were about 40ish.
• When the clutch was engaged, temps fell to 35ish. I didn't check rigorously, but stepping on it and temps fell. Didn't really have a big pull, but seems to make sense.

I have uprated cooling (the APR radiator) but given lower air temps mean denser air, I would expect more power from lower temps. I may be 100% incorrect about this though...

 

[youngsyp]

My plan had always been to start with the 189/no cooling and see how the car fared. I imagined that if it got hot then I'd get the bigger rad and go for a bigger pulley at the same time. But my car does not overheat, and then we had the CREC clutch problems and also I read about cat failures. Living as I do in an area where I rarely get a chance to "use" my tune as it is, my motivation to go further is limited. However I'm keen to read about other people taking their cars further and it might spark some enthusiasm to go to the next stage anyway.

Being able to monitor what's happening with the engine/ SC/ transmission is a key factor for me so the FIS-Control is at the top if my list as far as supporting mods go.
I've already performed some mild porting on the SC and some not so mild porting on the inlet to it, so that and porting the throttle body is where my interests lie. I have a buddy who's an engineer and has access to CNC and machining equipment so I'd talk to him about putting the throttle body on a lathe to smooth/ enlarge the throat.
I've no interests in exhaust mods and they seem pointless for power gain anyway. If I did a charge cooler upgrade it would be via a Merc Racing core, as they see to be the best solution. By then, I'd have fitted some form of brake upgrade, as the standard stoppers are not up to hauling up 1750Kg from high speed repeatedly without wilting.
However, in a similar way to you, although the roads in my area would support using the car in it's enhanced state, the traffic at 90% of the time I use the car would not. I also don't tend to drive flat out all the time as already mentioned. So I suspect the pulley (and TCU) tune will sustain my want for more power and anything else I do, will come through having time on my hands and the curiosity to do it. As that's what usually happens!

Paul

 

[youngsyp]

Well... I now have a FIS-Control MMI installed and since yesterday have been monitoring my intake temps. In the 60 miles I have done (whilst I'm concentrating on the road at the same time) I can tell that:

• Intake temps today (7deg ambient this morning, 15 deg ambient this evening) fluctuated between low 30's and mid 40's.
  
• Intake temps were highest (~45 deg) when stop start had kicked in (not surprising really as no air is flowing through the system)
• Intake temps were highest when moving when the supercharger was spinning idly. That is, with the CREC engine, the supercharger ratio is dependent on whether the clutch is engaged. When it is disengaged, the supercharger is spinning at ~0.5x crank and temps were about 40ish.
• When the clutch was engaged, temps fell to 35ish. I didn't check rigorously, but stepping on it and temps fell. Didn't really have a big pull, but seems to make sense.

I have uprated cooling (the APR radiator) but given lower air temps mean denser air, I would expect more power from lower temps. I may be 100% incorrect about this though...

This is interesting and is why the FIS-Control is on my list of things to do.

My results would differ slightly however. Mine missed the CREC engine change by about 6 months so the SC will always be spinning at circa 3 x that of the crank (with the upgraded pulley)
I've also disabled stop/ start, so again, the air will always be pushed though the SC outlet.

You're right of course when you say cooler air is denser (it contains more O2 molecules), so power should increase as the IAT gets lower however, it's relative. I'd not class 35 degree air as cool but, it's certainly cooler than 45 degree air. It would be good to understand at what air temp you'll see the benefits of it being 'cooler'.
That doesn't diminish the benefit of the uprated cooler though as it will also vastly improve the recovery time of the charge cooling system and it's overall efficiency.

Paul

 

[Cerbera9]

Well... I now have a FIS-Control MMI installed and since yesterday have been monitoring my intake temps. In the 60 miles I have done (whilst I'm concentrating on the road at the same time) I can tell that:

• Intake temps today (7deg ambient this morning, 15 deg ambient this evening) fluctuated between low 30's and mid 40's.
  
• Intake temps were highest (~45 deg) when stop start had kicked in (not surprising really as no air is flowing through the system)
• Intake temps were highest when moving when the supercharger was spinning idly. That is, with the CREC engine, the supercharger ratio is dependent on whether the clutch is engaged. When it is disengaged, the supercharger is spinning at ~0.5x crank and temps were about 40ish.
• When the clutch was engaged, temps fell to 35ish. I didn't check rigorously, but stepping on it and temps fell. Didn't really have a big pull, but seems to make sense.

I have uprated cooling (the APR radiator) but given lower air temps mean denser air, I would expect more power from lower temps. I may be 100% incorrect about this though...

Interesteding, do you know which of the intake sensors you are monitoring as I understand there are three?

 

[arad85]

Interesteding, do you know which of the intake sensors you are monitoring as I understand there are three?

Nope. But was the only one that jumped out when I looked in VCDS. I'll take another look next time I'm hooked up.

EDIT: I am using the sensors @Dippy asked to be included. When I scanned VCDS with thge car not running at all, I found these:

IDE04000 Intake air temperature sensor IAT 11:20 C
IDE04003 Charge air temperature sensor B1S1:17 C / B2S1:17 C
ENG101741 Intake air temperature 17.3 C

I believe the one I am looking at is ENG101741 (would need Dippy to confirm) which looks like it could be calculated from the two IDE04003 temps. which look like they are on the engine side of the supercharger.

 

[Cerbera9]

Sorry I’m not sure which sensor is which.

 

[youngsyp]

This arrived today. Very quick turnaround from Kustom Imports in Canada, they shipped it on Thursday!

Paul

 

[arad85]

Whilst I am not 100% on this, I think

IDE04000 Intake air temperature sensor IAT 11:20 C

Is the Temperatur und Druksensor

IDE04003 Charge air temperature sensor B1S1:17 C / B2S1:17 C

Is Temperatur und Ladedruksensor (and I think there are two of them, one for each bank, hence why I have two values - B1S1 = Bank 1 sensor 1).

and

ENG101741 Intake air temperature 17.3 C

I think is a calculated value from the two IDE04003 sensors (and I think is what I am displaying). The reason I think that is because the values I qoute on these lines were from a VCDS scan when the engine had been sat idle for 24 hours so they are captured simultaneously. The value I am measuring cannot be the ambient temperature, so has to be after compression. Also, given the way it fluctuates, it appears consistent.

Another couple of points on the temperature. On the way to work, I have a long (mile or so long) pull up a hill. At 2k rpm, 17 deg external temp and the supercharger at ~6k rpm, IAT = 30 deg. C more than half way up the hill so had already stabilised. That is the lowest value I've seen. Also cruising on the motorway, I've seen it reach 50 deg. C with the supercharger at ~3x rpm. Can't remember the speed I was doing at the time.

 

[Dippy]

@arad85 - the choice is much simpler than you think! As Stefan told me, IDE4000 and IDE4003 are text, not numerical, so FCM cannot handle them. ENG101741 is numerical so is the one and only possibility for this ECU. I also monitor IDE09983 which I expect to show less than 100% in the event that the ECU decides that IAT is too high to allow full torque.

 

[Dippy]

Based on what I have read here and on AZ, it does seem that the Merc Racing rad is a popular choice.