Dyno Results And Over Boosting Issue

[PM-R33]

With the gate fully opened (ie the actuator disconnected so the flap moves freely) both of our cars still make near 1.3bar of boost so it definetely isn't the actuator and i have changed dump pipes so it aint the dump pipe. For my car the only thing i think it could be is in the stock ECU retarding the timing so much. In Simon-R32's case i have no clue what it could be, and if my microtech being tuned doesn't fix the problem then im going to be in the same boat as him

[MBS206]

it sounds like simon and PM-R33 have two different problems

Simon sounds like his just can't get enough air around the turbo. So it boosts up some more.

PM-R33 just sounds like pure boost creep.

[RNS-11Z]

cam timing has alot to do with it... when my cam timing was out, i couldnt hold less then 20psi

[PM-R33]

cam timing has alot to do with it... when my cam timing was out, i couldnt hold less then 20psi

Really? Well i hope thats what mine is then. So when it got tuned and the timing was corrected it held boost perfectly?

[Haines]

Phil stop being soft mate

run 25psi

[PM-R33]

Phil stop being soft mate

run 25psi

Hahahah! If you promise to buy me the forgies and rebuild the head and block, sure i will

[Dale FZ1]

it deffinately has something to do with ur wastegate actuator,

also make sure u have a 1bar actuator on there not a 1.5bar

This is something I agree with - double check the spec of your actuator.

Secondly, while the pics of your turbine housing show the wastegate arm moved through a big arc, have you checked to see how widely a wastegate normally opens? Basically it moves enough to unseat the valve, and then enough to vent excess gas. Probably 8-10mm or so, but no more from the observations I've made.

Which makes me ask - how/where is the actuator mounted on the turbo? Main point of interest here is the angle that the actuator rod has to work on. If it is a dicky angle, then the actuator might push to its maximum extent but not really enough to vent the main turbine flow and control boost effectively. I did read your comment about disconnecting the wastegate and getting 17psi, but you're getting 20psi. A revision of the actuator mounting bracket and actuator rod position might be in order? If it gets a fairly straight push onto the bell crank then you're getting the valve moved through the maximum available travel. Hope that makes sense.

[STATUS]

^^^ Simon its common knowledge even the melb garret distributor knows the int gate is too small to work correctley.... he was the one who recommended a reah housing swap.

as for PM-R33 with the HKS GT-RS issues i havent had any dramas so im sorry i cant help there.

[PM-R33]

This is something I agree with - double check the spec of your actuator.

Secondly, while the pics of your turbine housing show the wastegate arm moved through a big arc, have you checked to see how widely a wastegate normally opens? Basically it moves enough to unseat the valve, and then enough to vent excess gas. Probably 8-10mm or so, but no more from the observations I've made.

Which makes me ask - how/where is the actuator mounted on the turbo? Main point of interest here is the angle that the actuator rod has to work on. If it is a dicky angle, then the actuator might push to its maximum extent but not really enough to vent the main turbine flow and control boost effectively. I did read your comment about disconnecting the wastegate and getting 17psi, but you're getting 20psi. A revision of the actuator mounting bracket and actuator rod position might be in order? If it gets a fairly straight push onto the bell crank then you're getting the valve moved through the maximum available travel. Hope that makes sense.

Actuator is definetely 1bar, its a genuine HKS GTRS kit for an RB25. Lots of people use this turbo with no problems so i seriously doubt that the rear housing is too small because im pretty sure garret and HKS would have found this out, afterall, HKS get the exhaust housing built to their specification.

Secondly, the actuator came mounted on the turbo when it was brand new and i have never removed it, other then taking the circlip of the end of the rod. The flap opens freely and doesn't hit on anything and the actuator is in perfect working condition, it opens over 90 degrees when the flap is disconnected, if exhaust gas cant flow properly through that then i dont know what can. I am nearly 100% sure it is not an issue with the actuator, nor is it an issue for the dump pipe as i have 2 completely different dump pipes and both do the exact thing.

The car will be tuned in January and hopefully it is due to the timing being so retarded that unburnt fuel is going straight through the exhaust manifold and igniting creating a sudden rush of exhaust gas, which in turn is spinning the exhaust turbine and creating boost that cannot be controlled by the wastegate. (Atleast that is my understanding of how timing is affecting this as this is roughly how i have been explained it)

So yeah unless someone has a better theory other then saying the actuator is f****d id like to hear their input.

[Simon-S14]

ok so in the last few days i have done the following.

-Bored out the wastegate hole in the rear housing

-enlarged the wastegate opening in the dump pipe area

-die grinded all edges to give the best possible flow path

-welded the flap onto its hinge to overcome seating issue

-modified the actuator rod so its not on such an angle

-wound a tiny amount of pre load onto the wastegate

just took it for a drive with EBC off, and just running off the actuator, seems in 3rd gear it stays around 0.9 bar now and peaks at 1.1 - 1.2 bar near the limiter... so this i can live with. still pulls bloody hard so i will retune the car and get the thing ramping up earlier with some more preload.

[Dale FZ1]

Simon you may find that the EBC can now go about its job of allowing boost to ramp earlier, so sounds like the efforts have paid off to a degree. The right sort of preload would probably help further. It would be nice to get it perfect, but Trent has obviously seen some issues with various combinations. Have you called GCG or HPinabox to check if there are similar experiences with your spec 3071, and if so what is the fix (if any)? I guess if you can get it to the point that it is "satisfactory" then all ok - go and DRIVE it

Just to clarify Phil, I wasn't actually concentrating on nutting out the issue your GT-RS has. My comments were directed solely to Simon's setup, and no, I have no opinion as to the cause of your overboosting. I hope you can get it right.

Suggestion: If you believe your timing is retarded, then assuming you have a programmable ECU why not try progressively advancing the thing to see what happens? I can confirm that retarded timing DOES result in elevated exhaust temps. While tuning my PFC, I had the whole map retarded by about 6-7 degrees due to the position of the CAS. Pyrometer read +150 degrees C on cruise, and the car ran like a dog. Would not pull. Believe me, if you have retarded ignition you will know about it.

[PM-R33]

Just to clarify Phil, I wasn't actually concentrating on nutting out the issue your GT-RS has. My comments were directed solely to Simon's setup, and no, I have no opinion as to the cause of your overboosting. I hope you can get it right.

Suggestion: If you believe your timing is retarded, then assuming you have a programmable ECU why not try progressively advancing the thing to see what happens? I can confirm that retarded timing DOES result in elevated exhaust temps. While tuning my PFC, I had the whole map retarded by about 6-7 degrees due to the position of the CAS. Pyrometer read +150 degrees C on cruise, and the car ran like a dog. Would not pull. Believe me, if you have retarded ignition you will know about it.

Woops my bad man.

Yeah its running a stock ECU at the moment so timing would be incredibly out. Microtech is going in soon though.

[Simon-S14]

Simon you may find that the EBC can now go about its job of allowing boost to ramp earlier, so sounds like the efforts have paid off to a degree. The right sort of preload would probably help further. It would be nice to get it perfect, but Trent has obviously seen some issues with various combinations. Have you called GCG or HPinabox to check if there are similar experiences with your spec 3071, and if so what is the fix (if any)? I guess if you can get it to the point that it is "satisfactory" then all ok - go and DRIVE it

Just to clarify Phil, I wasn't actually concentrating on nutting out the issue your GT-RS has. My comments were directed solely to Simon's setup, and no, I have no opinion as to the cause of your overboosting. I hope you can get it right.

Suggestion: If you believe your timing is retarded, then assuming you have a programmable ECU why not try progressively advancing the thing to see what happens? I can confirm that retarded timing DOES result in elevated exhaust temps. While tuning my PFC, I had the whole map retarded by about 6-7 degrees due to the position of the CAS. Pyrometer read +150 degrees C on cruise, and the car ran like a dog. Would not pull. Believe me, if you have retarded ignition you will know about it.

GCG have been more then helpful, They state that its rather common for cars with very open exhausts and no cats such as my track set up. there a couple of solutions that we will prob try after this competition that im attending in melb this coming weekend

[33drifta]

man, i wish i was having your problem. mine is the oposit, boost only getting to 13psi then droping off to 9psi grrrrr.

[Simon-S14]

if you look my dyno graph up the top, you'll see i had that same prob with the stock turbo lol

[33drifta]

hey and good luck with the comp, ill be there watching so i hope to see you do well and take home some of that FAT prize money!

[Simon-S14]

Got the boost down lower now, still makes 265 rwkw, so the set up is great now, ramps up earlier and pulls so damn hard! wharts more even tho it was hot, we did run after run and the power was repeatable so heat wasnt too much of an issue

did have fuel issues again, turns out my walbro intake which feeds the external bosch was breaking down internally and causing a restriction.... also turns out that its not a genuine walbro and its a copy!! all this time i thought it was a genuine! dodgy shit, only way to tell was to put a known genuine one side by side with the copy and look internally where the filter pick up goes. externally they look exactaly the same.

MASSIVE THANKS TO JEFF TSL AND THE BOYS FROM TURBO TUNE!!!!!!!!!!!!!!!!!!!!!!!!!!!

[STATUS]

good luck this weekend

[Haines]

And how did you get boost down lower ?

[STATUS]

And how did you get boost down lower ?

best way is to increase preload on the actuator.