D5 tuning box

[XC90Mk1]

Originally Posted by Quacker

I'm all for being educated by those that know better, so please do explain the basics as you see them.
Perhaps you think it blows constantly? I do look forward to your explanation and I'm sure there are plenty of on-line references you can quote.

the System has a compressor that provides air flow into a reservoir which stores a volume of air under pressure. There is then a solenoid valve which opens under low rpm and an increased throttle position. This airflow does not increase the peak performance and depletes in a few seconds.

The systems job is not to increase power but to lower the Rev range at which the forced induction may operate for the few seconds that the exhaust gasses are insufficient to spin the turbo vanes.

[XC90Mk1]

Originally Posted by XC90Mk1

the System has a compressor that provides air flow into a reservoir which stores a volume of air under pressure. There is then a solenoid valve which opens under low rpm and an increased throttle position. This airflow does not increase the peak performance and depletes in a few seconds.

The systems job is not to increase power but to lower the Rev range at which the forced induction may operate for the few seconds that the exhaust gasses are insufficient to spin the turbo vanes.

Given the choice between a power pulse and non power pulse engine I would probably chose the power pulse but it would be no deal breaker. The complexity and additional parts for small gain are not of massive advantage.

[Quacker]

Originally Posted by Berkshirebob

I was surprised to read the D4 also has two turbos..

The Powerpulse only works in the lower gears so the extra 40ish bhp must come from different components/bigger turbos as when mapped the D4/D5 still achieve different outputs.

I’d love more ‘go’ in my D4 but this is the first car I’ve had that I’ve not tuned at the first opportunity.. something about the lazy, relaxed feeling of the car that makes me think the benefit from tuning will be lessened.

Plus it’s not even mine - it’s leased, and I’m scared something will go horribly wrong!!

If it does happen it will be mapped. Just my opinion, but I wouldn’t touch a tuning box if it was given to me. The prices they now charge are comical, probably because there’s a growing market of people being fooled that you can fit one of these and simply remove it if it all goes pear shaped.

I have seen no reference to the Powerpulse only working in lower gears, only at low engine revs. Of course if you do floor it from idle, a low or lowish gear will be engaged by default.

The issue with D4 that makes the Powerpulse system on the D5 worthwhile is that even though the D4 has twin turbos and the smaller, more responsive one defaults at low revs, when accelerating from idle the management system must limit the fuel injected to balance the amount of air available for soot free combustion. As load increases, gas flow increases, so spinning the turbo faster, but as I said, in that initial phase where turbo is not up to speed and compressing the air, fuel and therefore acceleration is limited to minimise excess soot which would block the DPF quite quickly.

The D5 avoids this by spinning the turbo up instantly to speed with a strong but very brief pulse of compressed air, allowing more fuel to be injected sooner and therefore a near zero lag time upon acceleration.

However there is an expert here with a completely alternative view of how powerpulse works and why, apparently. I for one look forward with great interest his alternative theory of how it works, because I am apparently ignorant and mistaken. We shall see.

EDIT
In the time I took to compose this, he has posted and I fail to see where he differs substantially from my explanation of the system, despite him a accusing me of some ignorance of the subject. Very puzzling character.

[Quacker]

Originally Posted by XC90Mk1

the System has a compressor that provides air flow into a reservoir which stores a volume of air under pressure. There is then a solenoid valve which opens under low rpm and an increased throttle position. This airflow does not increase the peak performance and depletes in a few seconds.

The systems job is not to increase power but to lower the Rev range at which the forced induction may operate for the few seconds that the exhaust gasses are insufficient to spin the turbo vanes.

So how is that different to my detailed explanation both before and composed during your composition of this post? What have I missed? More to the point, how is it that you missed an accurate interpretation of what I wrote in quite clear terms?

[XC90Mk1]

Originally Posted by Quacker

So how is that different to my detailed explanation both before and composed during your composition of this post? What have I missed? More to the point, how is it that you missed an accurate interpretation of what I wrote in quite clear terms?

You described it as a compressor that shoots a pulse of air. It’s actually a compressor, reservoir, solenoid, dp sensor, control ecu, air separator, it’s not a simple system.

It also provides a large volume flow rate for several seconds.

[Quacker]

Originally Posted by XC90Mk1

You described it as a compressor that shoots a pulse of air. It’s actually a compressor, reservoir, solenoid, dp sensor, control ecu, air separator, it’s not a simple system.

It also provides a large volume flow rate for several seconds.

You forgot to list the pipes, connectors, fasteners and electrical cables.

[225]

Originally Posted by VO11VLO

Does your car have polestar?
No it doesn't.

Did you fit the box yourself, and if so how difficult was it?
Yes took all of 5 minutes, very easy all you do is plug it in 5 places and secure it.
Did you go for the bluetooth app control or not?
I did with this one yes and is very useful.
thanks

Answers above

As for the powerpulse... My understanding is what's been said, it basically has a reservoir of air that is used to squirt air into the turbos to reduce lag. Maybe the d5 has a bigger turbos for more power? Must be something as remaped or tuning boxes on a d4 still produce less power.