Turbo Lag?

[GandalfS6]

Lastly a pic of the exhaust side:

[sal_s2]

This sounds like how my car was like when the cam timing was out.
It would feel flat until 4500rpm and then a sudden burst of power.
The cam timing was out because the woodruff key on the cam pulley had sheared.

Make sure the cams are aligned correctly and the timing marks are spot on.

[Beetie]

This sounds like how my car was like when the cam timing was out.
It would feel flat until 4500rpm and then a sudden burst of power.
The cam timing was out because the woodruff key on the cam pulley had sheared.

Make sure the cams are aligned correctly and the timing marks are spot on.

This is related to what has happened to GandalfS6's car recently Sal, as i think its slipped the belt....

[GandalfS6]

This is related to what has happened to GandalfS6's car recently Sal, as i think its slipped the belt....

It looks as if the belt did not slip, the woodruff keyon the cam pulley broke off and the valve timing must have moved around. I was extremly fortunate that NONE of the valves were damaged.

I have a feeling Sal might be onto something - if the valve timing was out, it could also have resulted in lag. Maybe it is a real RS2 turbo, but the numbers are confusing me!

[Beetie]

I know the timing was an issue, but what had occured i didnt know. That was lucky that you haven't hit valves!
Theres been a few woodruff keys broke recently, I think now the pulleys ought to be a serviceable item....

[Mihnea]

@Gandalf: your turbo is an RS2 turbo.

Cheers,

Mihnea

[GandalfS6]

@Gandalf: your turbo is an RS2 turbo.

Cheers,

Mihnea

Thanks Mihnea - I was seriously worried there when I saw the different numbers - turbos are expensive. Anyway my quest to reduce lag continues! Maybe the valve timing was out - or maybe it is the software?

[audiman]

When you say lag..... when does the boost start coming in? I have the K26/27 #6 and the boost comes on hard at about 3500rpm, max torque was at 3997rpm

[APNess]

I have the same turbo as Tom, and it comes in at 2500rpm, hard on 3k, full on at 3.5k. Haven't got the stiffer wastegate spring in and that may improve things further still. I put it down to the downpipe and system, no doubts about it. Before I got it sorted out, on the RS2 chips there was nothing but wastegate pressure - 0.6 bar - below 3.5k. After, it started coming in at 2.5k and full boost (1.4 ish bar) from 3k rpm.

By 'fixing it' I mean sorting out a leak and getting rid of the 1-2-1 split where the two cats used to be. Downpipe will do some good too I reckon.

Just my 2 pennorth worth.

PJ

[GandalfS6]

Tom - by lag I mean very little below 4500 rpm - see the dyno plot attached:

I have about 0.5 bar boost at 3500 and at 4500 the car gets going with 1.8 bar boost.

APness - I have a turbo back 3" exhaust - no cats - no splits! The wastegate is standard - I get 0.4 bar boost with the WGFV disconnected.

I am starting to hope that the valve timing was out.

[bigvern]

i have a standard 95 s2 avant. it seems to loose turbo pressure at high revs (still does 165mph) would a heftier spring do the trick? anyone got the spring specification? as i can have them made! also what does the frequency valve do? i get a funny noise on the overrun from the air box!
to locate the cam shaft have a washer made with an offset lump on the back to fit in a corrosponding slot through the cam and pulley? like a mini flywheel?

[audiman]

Gandalf, with the WGFV un plugged, turn the boost up until you get about 1 bar peak. Then reconnect and try again, keep an eye on your gauge tho.

[GandalfS6]

Gandalf, with the WGFV un plugged, turn the boost up until you get about 1 bar peak. Then reconnect and try again, keep an eye on your gauge tho.

@Tom - I have a "standard" WG i.e. one without a nut on the top of it. Would I need to change the spring to achieve this?

[audiman]

Yes, cant beleive its still the std spring!! You will have to hack the tamper proof seal out of the top and below this is an allen key screw!! Put you will have to obtain a stiffer spring from Mihnea. Just PM him for a price

[Beetie]

Yes, cant beleive its still the std spring!! You will have to hack the tamper proof seal out of the top and below this is an allen key screw!! Put you will have to obtain a stiffer spring from Mihnea. Just PM him for a price

Surely a suspension spring will do?!