VRS 220 Boost Pressure

[rich_hodgetts]

Being a bit geeky on the way home from work today I was monitoring the inlet manifold pressure via the OBDII port and a smartphone (mounted in a holder of course!).

Interestingly (maybe) it seems that the maximum boost pressure varies according to gear:

 

Numbers are approximate:

 

1st - 19 PSI

2nd and 3rd - 23 PSI

4th+ - 28 PSI

Does anyone know if this is normal? I assume this has been done to limit power and torque in the lower gears to reduce wheelspin?

 

Rich

[StealthRS245]

Nah that doesn't sound quite right, the boost pressure channel on OBD eleven is Charge Pressure, Actual - should be similar on other OBD readers. It's in bar then you need to take ambient air pressure off that as well. My Stage 2 245 peaks at about 23psi, I believe stock is somewhere around 17 and the same for all gears.

Edited 22 November, 2019 by StealthRS245

[shyVRS245]

My stage 2 Octavia 245 is set up for maximum boost of 2 bar or 28psi.

[SC03OTT]

How does that help the OP? 

[Stoofa]

3 hours ago, SC03OTT said:

How does that help the OP? 

Internet points init?

[Auric Goldfinger]

7 hours ago, shyVRS245 said:

My stage 2 Octavia 245 is set up for maximum boost of 2 bar or 28psi.

 

5 hours ago, SC03OTT said:

How does that help the OP? 

 

1 hour ago, Stoofa said:

Internet points init?

 

I Suspect a case of willy waving.    

[shyVRS245]

Just demonstrating my drivetrain is under more strain in gears 1, 2 and 3 compared to the OP and I drive the car accordingly in the lower gears but I do forget on occasion and get dramatic axle tramp in 1st or 2nd gear if I floor it. Not bragging just comparing boost pressures. Nothing blown up or broken yet as sympathy is the key with such upgrades. If you haven't experienced this type of performance upgrade it's hard to describe unless you've sat in the passenger seat and only 2 Briskoda members have had that pleasure in my car. Hard to explain how 350lb/ft at 2,000rpm feels in a 1,370kg hatch.

[rich_hodgetts]

StealthRS245 - I was using Torque Pro to monitor the inlet manifold pressure - as you say, boost is manifold minus static pressure (14psi typically). I think what I said was misleading - the max boost pressure would have been about 14psi. If the data read by Torque Pro was accurate, the inlet manifold pressure was definitely maxing out at a lower value in lower gears. I think these engines have a turbocharger with an electronically controlled wastegate (IHI IS20 turbocharger?) and so differing max pressures in different gears is not implausible.

[shyVRS245]

Just read on a VW Forum that the EA888 Gen 3 engine has boost from factory at 1.2bar (17.4psi) and most people recommend not going higher than 29psi with 35psi or 2.5bar and hard driving likely to lead to turbo failure.

[StealthRS245]

12 hours ago, rich_hodgetts said:

StealthRS245 - I was using Torque Pro to monitor the inlet manifold pressure - as you say, boost is manifold minus static pressure (14psi typically). I think what I said was misleading - the max boost pressure would have been about 14psi. If the data read by Torque Pro was accurate, the inlet manifold pressure was definitely maxing out at a lower value in lower gears. I think these engines have a turbocharger with an electronically controlled wastegate (IHI IS20 turbocharger?) and so differing max pressures in different gears is not implausible.

You may very well be right, it's probably a case of the tuner removing those boost limits when remapping. I went out today and did a number of logs starting in 1st and going WOT through to 4th gear and the boost doesn't vary much, I think it peaked at 22 in 1st, 22.9 in second and 23.5 gears 3 and 4. Would be interested to see some logs from a stock car. I know for a fact that boost by gear is a feature of some tuning solutions over in the US so the ECU and turbo must be capable of it.

[TheClient]

On 22/11/2019 at 20:55, rich_hodgetts said:

StealthRS245 - I was using Torque Pro to monitor the inlet manifold pressure - as you say, boost is manifold minus static pressure (14psi typically). I think what I said was misleading - the max boost pressure would have been about 14psi. If the data read by Torque Pro was accurate, the inlet manifold pressure was definitely maxing out at a lower value in lower gears. I think these engines have a turbocharger with an electronically controlled wastegate (IHI IS20 turbocharger?) and so differing max pressures in different gears is not implausible.

I have seen other reports of circa  1.0 bar, 14 Psi real life and using torque.  Torque will use the onboard pressure sensors so I don't think it would be a specific torque issue of under reporting. Maybe theoretical turbo on bench vs real life in car.

 

I'm not sure about control in the earlier gears, could be ECM regulated if regulating wheels spin, axle tramp in lower gears or a lag in the data stream that doesn't allow the torque display to catch up in time in the earlier gears?  

 

Would need someone with a standard set up with VCDS to do some logging to fully answer perhaps.