VGT turbo VE compensation discussion?

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SiFlyBy
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Re: VGT turbo VE compensation discussion?

Post by SiFlyBy »

I have an intelligent friend who is interested in my Garrett turbo/VGT tomfoolery. He also happens to have an Integra with an engine capable of handling the power. Hopefully this spring we will get some testing done.. :indiff:
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SiFlyBy
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Re: VGT turbo VE compensation discussion?

Post by SiFlyBy »

OK, I finally got him interested, he found PCBs that will work for cheap and hes getting started on planning/math/code. The idea is here to control the vanes by using MAP and RPM as inputs since VE is tuned using these two key inputs. Keep the vanes more or less open in high vacuum situations for fuel economy, have them in the middle(more or less) up until 5 inHG or so and then closed(85% DC) until close to MAX BOOST and gradually open them to somewhat regulate boost. This system will not be perfect and will still likely require the use of a wastegate but it is alot better than TPS vs. RPM.

Any input/thoughts?

Chris
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Re: VGT turbo VE compensation discussion?

Post by baldur »

If you have a system where the VE changes in a way that you cannot reasonably predict the only smart option is to use a MAF, but I think you're over complicating this.
However, I've used a Garrett VNT25 turbo since 2004 and I just have a 2 port actuator on the vanes, I feed vacuum through a check valve with a bleed on one side to open the vanes at low loads and I feed modulated boost pressure on the other side from an open loop RPM/throttle map. Fuelling is just speed density with a MAP sensor, it's a bit rich on transients but otherwise it fuels fine and drivability is good.
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SiFlyBy
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Re: VGT turbo VE compensation discussion?

Post by SiFlyBy »

Some very intersting points you make that would be very useful to Aero(if his car ever runs again!).But, your turbo has a pneumatic actuator.

I have no choice but to use electronics because of the way the CHRA is designed. THe actuator on my turbo is hydraulically actuated by the engine oil that cools/lubricates the turbo bearings. The actuation is controlled by a PWM solenoid that directs oil flow to either of 2 sides of a piston connected to the actuator arm. I may play with a he351ve in the future, but if the elctronics work well, I will probably go that route. I dont think the components will cost more that $50.
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Fred
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Re: VGT turbo VE compensation discussion?

Post by Fred »

Good point on the MAF. The Nissan V8 ones are pretty big and capable of good power, I'm not sure what else there is around. Some of the yanky stuff must be pretty big though.

I guess it would be pretty much 100% fine if you simply based VNT opening on RPM alone. This would help a lot and not be much worse than better schemes and make it entirely predictable.

Fred.
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Aero
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Re: VGT turbo VE compensation discussion?

Post by Aero »

I have thought about the MAF option for this. I really onjoy the benefits of SD though. I don't get stranded if a IC pipe blows off, less restriction etc.

I just need to get the thing running again so that I can continue testing and especially log some actual back pressure readings to see how badly it really changes.

As it sits now i just have it transition to fully open at relativly low boost so that any tuning complications are under lower load sections and therefor a bit less critical.

Baldur, is that the VNT from the turbo dodge cars?
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Re: VGT turbo VE compensation discussion?

Post by baldur »

Yes it is indeed from the limited production Dodge Daytona turbo.
Bought a new-old-stock unit in 2004 off ebay, been running it in my car ever since.
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