Rb25 Feeling Unresponsive

[Fryters]

Hey guys,

I recently installed a HKS 2835 GT-pro on my s1 rb25det.

I have a fmic, z32 afm, with apexi pfc and splitfire coilpacks.

I was given the impression after speaking with many people and threads on here that this turbo would feel amazing and come on very quick. After taking it out on track, it was better then the ebay turbo I had before but still didnt have an exciting power curve where it "snapped on" like i was told it would. Didnt really feel like it was coming onto boost propery until well after about 4000rpm.

On actuator pressure (1bar) it made 290hp. the power curve looked like it creeped on (linear), rather then having a steep curve which I am after.

Would running a boost controller fix this problem? or could it be another underlying issue? It was extremely hot on the day 38deg + when testing the car on track

Any help appreciated

[hypergear]

Assume if no cold side leaks.

Make sure the actuator is preloaded and tightly shut.

Test if the VCT is working.

Lastly the ECU would deduct timing depending on whats been programmed to reacting on how hot the air temp is. So on a 38+ degrees day, under the bonnet it would be very hot. See if there are any noticeably differences driving on a cold day.

[Blackkers]

Assume if no cold side leaks.

Make sure the actuator is preloaded and tightly shut.

Test if the VCT is working.

Lastly the ECU would deduct timing depending on whats been programmed to reacting on how hot the air temp is. So on a 38+ degrees day, under the bonnet it would be very hot. See if there are any noticeably differences driving on a cold day.

Pretty much exactly what he said;

Test for boost leaks.

Test preload on the actuator, maybe even tighten it up 1-2mm.

This may be a dumb question but since you didn't mention I have to ask, have you had it properly tuned since installing the new turbo? Also what is your fuel set up? 1bar isn't a lot, I'd go for a few more psi if your fuel system is up to it

[75coupe]

You realise the 2835 wont light switch onto power, its a controllable linear power delivery, but definitely need preload on wastegate.

who did your tune?

[Chris32]

Those HKS turbos need a good amount of boost to really show what they are capable of.

On my old R32, the difference in power delivery from 1bar to 1.5bar was immense running a 2510

As long as you've got suitable injectors and a good tune, 18-20psi would transform how that turbo performs

[KiwiRS4T]

More boost! Yes boost controller will help. Have you replaced your stock injectors? Is the fmic doing the job? Got a good tuner?

[75coupe]

16psi felt ok, 21psi is a different power on the 2835, it does like boost

[Fryters]

Ak ok more boost sounds the way to go haha might look at 18-20psi

Yes had the car tuned, car has 440cc gtr injectors and walbro 500l intank fuel pump. I will have a suss for boost leaks and give it a drive on a cold day. hopefully it was just the heat making her feel sluggish haha

[wolverine]

More boost and more tuning required.