RS2 Factory Boost pressure

[wowow]

I have a stock 95 RS2 and have been dealing with a worn out shaft issue. I replace the shaft with a new one, and the boost pressure I get is only around 1.1-1.2 bar, instead of the factory boost pressure of 1.4. I read from a few articles saying that the RS2 turbo is an upgrade from S2 with a boost pressure raising from 1.1 to 1.4 bar, hence I believe the stock pressure should be 1.4bar. Is this piece of info correct ? If so, what could be my problem? There is no more boost leak after I replaced all hosts with uprated ones.

Is it possible that I got the wrong shaft ? I ordered my shaft from Turbo Dynamics and quoted the correct turbo number (5324 988 7200 KKK turbo).

[UrS4boy]

I would say 1.4 Bar (20.3 psi) relative boost is low(ish) for a stock RS2 with a 3.0 Bar MAP sensor in the ECU. Stock ABY and AAN is about 17 psi (1.19 Bar) peak boost (relative, 2.2 Bar absolute). RS2 should probably be closer to 22 psi (1.5 Bar). You might have small boost leak.

Regardless, you might want to sort out the boost leak and then consider chipping your RS2 ECU with a good aftermarket chip set. I run a chipped ECU (MRC Stage 3) with a 3.0 Bar MAP and RS2 turbo, RS2 exhaust manifold, RS2 exhaust cam, RS2 injectors and RS2 MAF, and regularly get 27 psi (1.86 Bar) relative boost. This equates to about 360 crank HP (289 wheel HP).

[Avantus]

Iirc it is 1.4bar max and 0.9bar at 7000?

[wowow]

Boost leak ? I have a tester and tried up at 1.5bar with no problem.

When you say you have rs2 injector and stuff, you mean "stock" injector ? So your car is relatively stock and only a remap bring it up to 1.8bar ?

[wowow]

Iirc it is 1.4bar max and 0.9bar at 7000? What does this mean ?

Does it mean getting 1.4bar for a short while ( a few sec ) and then drop back down to 0.9 ?

[Nik0las]

Iirc it is 1.4bar max and 0.9bar at 7000? What does this mean ?

Does it mean getting 1.4bar for a short while ( a few sec ) and then drop back down to 0.9 ?

correct

[popdemonic]

boost taper off from 1.4 to 0.9 bar.

[veneto rs2]

Sotck RS2 Motronic gives a 1.4 bar (real not absolute) boost just on overboost.
Overboost it's active from 2000rpm to approx 4000rpm on wot.
After 4000rpm it should dropping to 1.1/1.2 bar.

[wowow]

So I should see a sudden surge from 0 to 1.4 bar, up until 4k rpm, then tappering off to 0.9bar if keeping at 5k rpm ? I used to have an electronic boost gauge that can record peak boost and it showed only 1.2 bar. Now that I have a VDO match gauge, it will be harder to see the peak. But still, I don't recall seeing 1.4 even at low rpm.

Urs$Boy, does yours peak at 1.8 or does it tapper off to 1.8 ?

I have little knowledge on turbo so thank you for being patient on me:-)

[Rusty]

Only way to get a good boost profile is to use 3rd or 4th upwards and give it WOT from 2k rpm or lower, preferably uphill rather than down...

[dobbin]

to test boost you should drive in 3rd or 4th gear at 3000rpm then floor it on a rs2 you should see 1.4 max boost and then after 4000 rpm going down to 0.9 bar and holding.
if not you probably have a boost leak check all rear hoses off the back of inlet manifold as these will cause small boost leaks.

[driftin jo]

[wowow]

will try and revert

[UrS4boy]

..When you say you have rs2 injector and stuff, you mean "stock" injector ? So your car is relatively stock and only a remap bring it up to 1.8bar ?

If you are talking to me Wowow, my car is a 93 C4 S4 which came with a 227 hp AAN. However, I have upgraded it with all the external hardware that a 315 hp RS2 ADU engine has (as listed in my previous post). With a set of Stage 3 fuel and boost chips from MRC, the engine now makes 289 wheel hp (about 360 crank hp). A set of chips from a reputable supplier could get you into the same 360 to 380 hp range.

[UrS4boy]

I stand corrected. 1.4 Bar peak is apparently correct and 1.5 is too high.

Thanks for finding and posting that info from the now ever absent Paul N. (Hope he is doing fine).