boost flutter??

[DanwinGQ]

Hey all,
I have just finished the turbo install on my Diesel wagon. Got it dyno tuned yesterday and is going much better. Went from 80 odd RWHP to a bit over 146RWHP and nearly 850 NM torque. Running 14PSI and have been told thats about all i will get from the standard injector pump.
I have noticed when giving it heaps it gets to full boost(14psi) holds for couple of seconds then drops off to around 12psi. It seems to hold the full 14 sometimes then drops off other times.
Any thoughts??

[300WinMag]

Waste gate creep can be one cause, as the pressure builds up the actuator gradually opens the waste gate bleeding off exhaust reducing turbo efficiency, and causing waste gate to fluctuate so to speak. If you look on e-bay for boost control valve not bleed valve, this will cure the problem for about $38. Make sure you get the right pressure range.
By the way I don't think those HP figues are correct for RWHP not with standard pump, you would be lucky to get 120-130 RWHP. I am sure others will agree.

[DanwinGQ]

I have fitted a manual boost controler. GFB (Go fast bits). Is that what you mean? I have an early GU pump. Was told it was a little better than GQ. Also have fitted a pwr water to air cooler.

[300WinMag]

Does your pump have boost compensator?
It will probly have a 10mm plunger same size as GQ.
What sort of Dyno did they use?

[DanwinGQ]

I dont have a compensator. its a dynamics dyno.

[300WinMag]

Can you post printout of dyno run.
If your boost control valve is set at a lower pressure than your actuator it can still fluctuate.
The dynamics dyno should be accurate enough if it has been calabrated regularly.
What turbo do you have.

[DanwinGQ]

I'm not real good with computers mate. The print out is next to me but gettin it from there to the computer screen could pose a bit of a problem. Will c if the mrs can help out.
I am running a garret GT28 ball bearing. (Disco potato I was told). I got the turbo and manifold from turboglide. 4" snorkel, 3"pod filter into turbo then short cooler pipes to fit in PWR cooler barrel. 3" dump and not much exhaust.
Turbo was set at 7psi. Then adjusted thru the manual controler.

[300WinMag]

I would ajust the actuator rod to put more spring preload on the waste gate as the exhaust pressure also acts on waste gate.
Sounds like you have a good set up mate, what size is your IC barrel and how many CFM is it rated at.

[vanbox]

Figures dont seem to be too bad for the work done. Have you got a pyro, if not, GET ONE!

My 2001 GU ute makes 140rwhp on dynamis dyno. completely standard motor, 14.5psi boost. 3in dump and exhaust. on 315 radial claws!!!

[xenith]

mate have been runing 25 psi on stock td42 fuel pump and all for 6 years all good

[DanwinGQ]

I'm using the PWR 4" X 10" barrel cooler. Its only a baby and flows 390cfm and 300HP. I will have to upgrade down the track I think if I decide to chase more power.
I have a VDO pyro. Sits between 200 and 300 Deg C when driving. Havnt had it over 400 yet. I keep running out of hill. Is placed in the dump pipe.
Motor is standard and I am running 305/70/16. (33"). Once I pay off this venture I may chase some more power if the motor is still in one piece.

[300WinMag]

Andy is the man to talk to about pump upgrades, and you will need a barrel IC that can flow 450CFM to run 20psi. I take it your stock pump is maxed out?

[coxy321]

I would ajust the actuator rod to put more spring preload on the waste gate as the exhaust pressure also acts on waste gate.
Sounds like you have a good set up mate, what size is your IC barrel and how many CFM is it rated at.

I had to fit a stiffer return spring on my datto to stop wastegate bleeding. Made a big difference!