7 replies to this topic

[CH1EF]

Stage 4 Turbo setup, and I have serious compressor surge on part throttle.

 

Full throttle and driving under 2000rpm it drives as it should, but run with part throttle the car causes a load of compressor surge as its trying to pull 20psi. It can obviously be driven around as I find some threads saying its common on these engines, but this seems ridiculous, and when driving with anger, it makes the car so unsettled during corning when feathering the throttle.

 

I have bypassed the factory boost solenoids and this helps as it builds boost slower, but still causes the issue.

 

Any suggestions?

[CHILL Gone DUTCH]

have a word with sizetenboots he seems to made the delivery a lot better on his maps 

[chris_uk]

Have you tried a new recirc valve?

[Nev]

Have a "search" - this matter has been covered many time before.

Edited by Nev, 26 October 2017 - 08:20 PM.

[CH1EF]

Dont get me wrong, I have read plenty of past threads, and searched lots of times for surge on this forum with the same results of boost solenoids and recirc valves.

 

What does [color=rgb(40,40,40);font-family:helvetica, arial, sans-serif;]sizetenboots do to improve it with ECU mapping?[/color]

 

I also dont want to start a whole discussion after blow of valves etc, but my car is running with no blow off valve as I have on so many different motors and turbo's (I know the arguments on both sides, so we dont need to revisit that). So really i guess my question is, is the only solution most people go with is to bleed off boost via a recirc valve, which obviously has it downsides? Or have people solved it in other ways? If it is a case of this is just how this turbo and engine respond together when running this level of boost, then its tempting to put a larger turbo on and run more power and not have surge.

[siztenboots]

is there a rpm range where it happens a lot ?

[Nev]

its tempting to put a larger turbo on and run more power and not have surge.

This is the best (but most complex/costly) solution, as currently your titchy little K04 is simply being asked to do too much. When making 8 PSI on the OEM map there is no compressor surge and no torque spike at all, it's just that pushing the turbo to make another 100 odd HP is beyond what it's designed to do and I suspect the feedback system of the solonoid and bypass valve can't react fast enough to stop the force of 20+ PSI suddenly flowing backwards when you close the throttle.

Edited by Nev, 27 October 2017 - 11:04 AM.

[siztenboots]

This is the standard Courtenay CS4 boost limit map , overboost will exceed this for wide open throttle. Part throttle things are more complex.