rb25 boost creep issue

[ShaneO'F]

has anyone ever come across this?

just put on a hybrid turbo, actuator, new dual chamber stainless elbow, downpipe.. the car is boosting at 1.4 bar until you go flap out and at about 5k revs it creeps til about 2 bar and power cuts.. its definitely not an electrical misfire. all vacuums and IC pipes seem ok.. im wonderintg has anyone had issues where the bigger compressor housing and the elbow not big enough to blow put all the gasses and the back pressure causes the spiking? if I could get an actuator handy id try that but there not easy got Id say for this turbo.. standard ECU , injectors, car has 1.2mm cosworth head gasket and adjustable fuel pressure reg, full exhaust and induction kit is all the other engine mods..

thanks

[nicky h]

Is it a standard actuator or adjustable ?

[slithertooth]

What turbo?

[gem-s13]

Either the actuator is to tight or the turbo elbo is a china one and the wastegate flap cant open enough to cope with the boost corection at high rpm
and with the stock ecu you shouldnt be running any more than 0.8- 0.9 bar id say even after hitting 2ish and cutting you will be looking for pistons very soon ringlands dont like tgat

[ShaneO'F]

hybrid turbo with adjustible actuator.. the flat can open fullt in the elbow, i checked it while twas all out on the ground.. i planned on running it at a bar boost, iv an adjustoble fuel pressure reg, steel head gasket and just built head.. iv 11 bar compression in all 6 clyinders.. i only drove it over the road booted hard once so iv no damage done.. kinda scratching my head as to what to check now yano lads

[japstuff 2]

as gem said u will bust pistons without a map as a standart ecu can just about deal with 0.8-0.9 on a standart turbo
as for the boost i had a simular prob before due to the hole behind the penny/wastegate flap being to small welded it up went external wastegate and was 100% after that

[Tomas_s13]

Or bore out the westgate! Its enough for flap to overlap 1, 5-2mm over the hole, that should cure it! Its just not enough of a hole to drop the exhaust gas pressure

[ShaneO'F]

maybe a silly question now but would an elbow with a screamer pipe vent the gasses quicker to the atmosphere than it would through the exhaust giving the natural back pressure that wud already have?.

[gem-s13]

maybe a silly question now but would an elbow with a screamer pipe vent the gasses quicker to the atmosphere than it would through the exhaust giving the natural back pressure that wud already have?.

Not realy at that sort of boost. id be 90% sure that its just the actuater wound up to much if you say its not fouling the elbo. losen it off untill the wastegate arm is rattling then half a turn drive it if goes over 1bar if it does its something else. if doesnt over boost bring it back half turns until stays at .8 dont go over unless ur mapping it propperly

also get a new peice of pipe to run to the actuator so you nk there is no restrctors in it. and is it comeing from the turbos compressor housing to actuator or from an intercooler pipe?

[paulr5]

If its not fouling and your plumbing to and from is as direct as possible to the actuator controler I would say its a flow issue as in the waste gate port won't allow the flow trough. you will have to take off the ex housing and cnc or grind out the actuator port out that extra bit or go external gate.