Underpowered N52 2.5i - upgraded to 2.5Si

[Street]

[ref]Zedebee[/ref], thanks, well hopefully I may be able to pick up Streets then.
Cheers I hadn’t realised the existing disa …114 can be reused and I would only need disa 11617560538.
Just seen that on realoem.
And sorry I just re read the thread and saw you sourced yours from a breaker not street.
Looking forward to hearing about the drive.

Still here if you want to drop me a line.

 

[Zedebee]

All back together now, fired up fine and running with no codes. Reassembly was significantly easier than disassembly, the main problems being a couple of hard to access screws but mostly those horrible pipe fittings that you have to squeeze and pull. 10 electrical connectors and 5 pipe connections - I had to count them out and count them back in.

Only managed a five minute test drive before it started raining, but it certainly feels like it has a stronger pull and felt more peppy. I won’t be taking it to the dyno and it may just be my imagination, but that’s enough for me. A real world result!

 

[RMB]

Thanks Street, pm sent.
[ref]Zedebee[/ref], great work, did you flash it or code to Si?

 

[Zedebee]

It should be possible then, to release power in the 2.5i by simply swapping out the manifold for one with 2 x DISAs from the 2.5Si or 3.0Si. Online sources suggest 15-20bhp, with an ECU tune required to release full 2.5Si power.

[ref]RMB[/ref] - The above from my opening post. I just changed the manifold. I suspect the ECU tune is more to do with the top end (raising the rev limit etc), which I’m less interested in.

There’s an interesting, if incomprehensible, explanation of how the DISA works in NewTIS, if you have that.

 

[Zedebee]

Plugged in INPA last night and ran the DISA test. I was concerned that the second DISA might just be dormant (open) and not do anything, but both DISAs open and close as they should.

 

[RMB]

That’s good to know. I havent attempted my install yet.
I assume one opens at lower rpm, then perhaps both midrange and then the other at the top.
1, 1&2, 2 sequence.

 

[Zedebee]

Just tested, definitely working.
The default state (engine off) is both DISAs open.
At idle, both DISAs are closed
At c. 2850 rpm, DISA2 opens
At c. 3800 rpm, DISA1 opens (i.e. both open)
Hence, three stage intake.
This is surprising, as it suggests the gains from DISA2 are in the mid range.

 

[Zedebee]

Good deal on a suitable manifold if anybody is thinking of this “upgrade”
https://ebay.us/m/CFB19x
Both DISAs and cover included.

 

[RMB]

Damn, should have waited, that’s a great deal!

 

[pvr]

Damn, should have waited, that’s a great deal!

30 days buyers remorse :wink:

 

[RMB]

I got a good price, just not that good!

 

[Zedebee]

Rain stopped play on the OEM 10-speaker Hi-Fi install today, so I decided to flash the 2.5Si tune. To be honest it was a bit worrying listening to my car whirr and click for almost an hour, but eventually the RSAdelete and flash tune did its thing and I was able to fire up the car with no warning lights.

In theory I should now have the full bhp available to a 2.5Si, but that will have to wait until tomorrow for a test drive.

+39bhp for £60 has to be a bargain, right?

 

[Mr Tidy]

That is a bargain - it should feel much perkier.

 

[pvr]

Rain??? Where did you manage to find that :lol:

 

[RMB]

Looking forward to the test drive report and wonder if the programming will have increased the red line.
The 2.5 has a lower limit than both si motors.

 

[Zedebee]

It works :trampoline: Much stronger acceleration throughout the rev range. I didn’t test the rev limit though, as limited to automatic gears only at the moment. Idle was a lumpy on first couple of startups, but now back to normal, I guess as a result of adaptations resetting themselves. Unless you are determined to stick with stock, this upgrade is a no-brainier for the “underpowered” 2.5i owner, and it’s virtually invisible too (unless you know where to look for that second DISA valve).