35 psi boost and resultant running problems

[R.O.R-2.0]

i think ideally u would want the vanes to be closed from idle, then open until peak boost, then open more according to rpm.  honestly tho if i were doing it i'd just control it with a boost can and call it good enough ha

If they're closed at idle you'll start building boost at idle, which you probably don't want.  In terms of efficiency, you want the vanes open as wide as possible all the time, closing them only to give you the amount of boost you're looking for - otherwise you're just poking a potato in your tailpipe the rest of the time. 

yea, you want them open as possible for ANY situation.. the more open they are, the more efficient the turbo is..

the VNT is a HUGE restriction when the vanes close..

you want the vanes closed down at idle, and until boost comes on. once some boost comes on, you want them to start opening up. then you want them to open to a certain point to limit boost at that point.. eventualy, the vanes ALMOST act like a wastegate.. the vanes are what controls the boost level..

[regcheeseman]

I've a tuning factor built in to the code, I can preload vane opening by up to 100%

[Turbofan]

I've a tuning factor built in to the code, I can preload vane opening by up to 100%

Does this adjust the pitch of the vanes using vacuum like the VNT did stock, or are you using pressure?. I'm sure it's using vacuum, but I thought I'd ask. This ardunio based controller looks totally awesome and I think I'll have to build one now.

[RabbitJockey]

hes using a servo or stepper motor, i am guessing the preload will help if the controller is reacting too slowly?

[regcheeseman]

The preload is an addition a variable in the code

The required servo position (sp) is given the value 0 - 255 (0 is open)

When Sp is calculated from boost value and throttle position I multiple boost value by a tuning factor (originally set to unity =1)

If I change this factor to 1.5, it means at low boost the vanes response remains pretty much as it was originally but as the boost climbs the vanes will have greater tendancy to return to full open position.
It wont change the speed of operation as such

[andy2]

I think that you'll find that your orginal problem is excessive EMP's which cause the exhaust valves to float.The hydraulic lifter then takes up the slack and you lose compression for a moment.Once the exhaust pressure drops off the lifters back off.I've had this happen before on 3 different engine's.In 2 cases the engine actually quit running and would not start until the lifters had backed off.Tight valve guides and/or excessive EGT's can also contribute to the same problem.

[regcheeseman]

I think that you'll find that your orginal problem is excessive EMP's which cause the exhaust valves to float.The hydraulic lifter then takes up the slack and you lose compression for a moment.Once the exhaust pressure drops off the lifters back off.I've had this happen before on 3 different engine's.In 2 cases the engine actually quit running and would not start until the lifters had backed off.

Where is the 'I'm not worthy' emoticon?

Thank you very much for your answer, that would explain the fault symptoms exactly.

Cheers!

[RabbitJockey]

thats about as interesting as it gets haha.  neato

[BlueMule]

I think that you'll find that your orginal problem is excessive EMP's which cause the exhaust valves to float.The hydraulic lifter then takes up the slack and you lose compression for a moment.Once the exhaust pressure drops off the lifters back off.I've had this happen before on 3 different engine's.In 2 cases the engine actually quit running and would not start until the lifters had backed off.Tight valve guides and/or excessive EGT's can also contribute to the same problem.

Hey Andy2, I like your thinking on this. I would like to add that high boost levels without enough spring rate for the intake valves will cause the intake valves to float, and of course with the ever popular loss of compression, and the ever possible piston to valve kiss.

Reg, since this is experimental, you might want to plumb in an inexpensive BOV from greddy or someone else, it is cheaper than a waste gate, but it may be good insurance. It is interesting that the Dodge Sprinter uses a stepper motor with a small electronics package built in. Also how about some Pics of the Regmobile cruising through Chedder Gorge ?????? 

Oh and it could have been worse
http://www.youtube.com/watch?v=AJTjwRni8ow&feature=related

The Blau Maultier