My second T4, operation de-chav

[Activ8]

I take it the drive to work this morning was less than inspiring?

Are you/Colin shutting the wastegate using any different methods?

Nope.
We have changed the wastegate and cleaned the port up following initial install & lack of boost (11psi). Originally just capping off the top port held 19+psi but with v2 map we applied pressure to the top port as you did but wound the boost to 24psi during trials. DP is the modified Volvo original. Identical v2 map too. Had it stable to 24 psi before the Summer hols too trialling v3. Although he opted to return to v2 for France. [emoji6]

Something must be going on with differential exhaust manifold pressures either side of the turbine - I'm trying to work it out in my head whilst pretending to do some work but I had a couple of stellas last night and all I have at the moment is the monkey on a tricycle playing cymbals on a tricycle in my head.

Nice for a Monday morning.



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[regcheeseman]

Cycled to work this morning.

Sounds like the actuator needs preloading by some other method then.

Did you get the limping problem I get when cruising at sixty on a very light throttle - you often don't notice it has gone into limp until you go to accelerate and there is nothing much happening - cue rapid ignition key flick off/on.


Why have I got a nine in my name in your quotes?

[Activ8]

[QUOTE=regcheeseman;111702]
Sounds like the actuator needs preloading by some other method then.
Take the cap off and add/change the spring? Is there a similar KKK fitting type but pressure controlled with a single port it could be swapped with? Never looked tbh?

Did you get the limping problem I get when cruising at sixty on a very light throttle - you often don't notice it has gone into limp until you go to accelerate and there is nothing much happening - cue rapid ignition key flick off/on.

On Colins no - but he's yet to do the 5th gear mod though, however I had it - a lot - mitigated by changing down and increasing the revs then up again (Cannot recall the rev range it ceased at) but PITA on motorways. Then I mapped it out when the 3 bar sensor was fitted. Happened once since, whilst mapping the K24 but it was boosting max (3+ bar) at the time!

Why have I got a nine in my name in your quotes?

Fat finger not-smart phone user .... but just an err! However.... Reg Cheese-9(Nein)-man has some mileage m'thinks?



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[regcheeseman]

[QUOTE=Activ8;111711]

Sounds like the actuator needs preloading by some other method then.

Take the cap off and add/change the spring?

This was my plan - I didn't have a suitable vee band clamp to re-clamp the top back on once the original had been cut off. Could have welded it...and possibly melted the diaphragm.

Is there a similar KKK fitting type but pressure controlled with a single port it could be swapped with? Never looked tbh?

The issue is..... why is boost pressure even opening the wastegate - unless it is passing/bled off through the N75.

Unplugging the N75 line to the actuator would prove this - providing it didn't limp before hitting full boost.

On Colins no - but he's yet to do the 5th gear mod though, however I had it - a lot - mitigated by changing down and increasing the revs then up again (Cannot recall the rev range it ceased at) but PITA on motorways. Then I mapped it out when the 3 bar sensor was fitted. Happened once since, whilst mapping the K24 but it was boosting max (3+ bar) at the time!

mitigated or initiated?

When mine goes into limp it's as flat as a turd - fuelling drops right off as the turbo just wont make any boost. No way round it, either stop trying to accelerate or ignition flick whilst rolling, big puff of black smoke as it chimes in and the van takes off again!

[Activ8]

Found some pics.
In the middle of receiving some deliveries so I'll come back to this later.

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[Activ8]

You can see from the pic of the casting theres errosion on this one. It was leaking boost.

If you want to open the wastegate to replace the spring and try to weld the cap I've got another wastegate here. But these parts must be used to taking serious constant heat 500°C (?)

Alternatively you could modify the OEM system to vacuum control, which would set up the wastegate control for a VNT turbo too. It's not difficult to do and parts are cheap. I've got the parts needed apart from a vacuum reserve/sphere(?). Might need a little mapping to get it spot on for your build.

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[regcheeseman]

You can see from the pic of the casting theres errosion on this one. It was leaking boost.

If you want to open the wastegate to replace the spring and try to weld the cap I've got another wastegate here. But these parts must be used to taking serious constant heat 500°C (?)

Alternatively you could modify the OEM system to vacuum control, which would set up the wastegate control for a VNT turbo too. It's not difficult to do and parts are cheap. I've got the parts needed apart from a vacuum reserve/sphere(?). Might need a little mapping to get it spot on for your build.

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My idea is to remove the port on top of the cap, fit a preload screw with a lock nut. This'll act on the wastegate in a linear fashion - rather than using boost as a preload which varies from nothing to too much and causes the N75 additional work.

If you want to send me a spare actuator, I'll mod it and fit it to mine; If it works, I'll mod mine and send it back to you, if not you'll get mine back unmodified.

[Activ8]

My idea is to remove the port on top of the cap, fit a preload screw with a lock nut. This'll act on the wastegate in a linear fashion - rather than using boost as a preload which varies from nothing to too much and causes the N75 additional work.

The spring will preload it? Going to have a look at the spare in the garage.

If you want to send me a spare actuator, I'll mod it and fit it to mine; If it works, I'll mod mine and send it back to you, if not you'll get mine back unmodified.

Sounds good.

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[regcheeseman]

The spring will preload it? Going to have a look at the spare in the garage.

The spring is already in there and preloaded from factory, I'm guessing, pressing up against the top face of the cap. If you add an adjuster to press more onto the spring it'll increase it's preload.

The other option would be to change the spring to a different rate/length or add some washers but all of these options would be non adjustable and changing the spring rate will affect the N75's response.

[Activ8]

The spring is already in there and preloaded from factory, I'm guessing, pressing up against the top face of the cap. If you add an adjuster to press more onto the spring it'll increase it's preload.

The other option would be to change the spring to a different rate/length or add some washers but all of these options would be non adjustable and changing the spring rate will affect the N75's response.

But won't too much preload put more strain on the clutch / gear box? The benefit of the OEM K14 is with a 5-6 psi preload then control with the N75? So you're now losing the useful lower psi control with the N75 for daily running. Assuming the spring rate is 10psi what do you intend increasing it by?

I think moving to vacuum control would be more beneficial with broader psi contol. I've ran vacuum control so have the map(s).

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[regcheeseman]

But won't too much preload put more strain on the clutch / gear box? The benefit of the OEM K14 is with a 5-6 psi preload then control with the N75? So you're now losing the useful lower psi control with the N75 for daily running. Assuming the spring rate is 10psi what do you intend increasing it by?

I think moving to vacuum control would be more beneficial with broader psi contol. I've ran vacuum control so have the map(s).

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Not being negative - but no, no and no

Nothing to do with clutch/gearbox

Preload should not affect boost - though there is something going on with either ex manifold pressure or boost leaking past N75

Regardless - you will still have full N75 control, it may have to up it's duty cycle but then I'm sure the N75 map ups the duty cycle as the differential between MAP and actual MAP increases? Therefore it'll be self regulating and linear, any system which uses a variable control signal (such as boost or vacuum) is prone to imbalance. For this reason I see vacuum control as a step back, offering no advantages over the current (bodge) forced closed by boost method.

I take it you intend to open the wastegate by vacuum on the top port - in which case, how will you shut the wastegate over 10psi, when it seems like exhaust pressure are blowing the wastegate open, somehow there is a greater pressure downstream of the turbine than upstream - god knows how this can even happen. which is why I think the N75 leaks by design.

A knackered seating face isn't helping my turbo though.



so..... VNT and a 2256? Are you using the BMW turbos? Or have you switched allegiance to the chinesium turbo? was its AR suitable, thought you said it was big???

[Activ8]

Not being negative - but no, no and no

Oh thats OK, I thought you meant nein, 9, and njet?
Increase the preload more torque can be delivered (difference betwen OEM 6 and say 14.7psi) earlier in the increasing rev range, over 14.7psi the N75 can manage the boost if mapped to do so.
So more air is produced as the wastegate is closed = more boosted air = potentially more fuel if the driver dictates it and the smoke and torque maps allow it.
More fuel = more torque earlier and as the revs increase transferring more to the clutch and gearbox.
Theres no map control as its mechanically closed. (Could throw it into limp mode too as it may be outside the mapped parameters)
Been here and done it.... balancing pre-load with N75/boost maps with OEM K14.

Preload should not affect boost - though there is something going on with either ex manifold pressure or boost leaking past N75

The N75 map has a "leak" built in - discovered when I investigated electronic wastegate control.
You can see it when reviewing the turbo data on Ch11. It never shows 0% or 100% unless its remapped to fully close or fully open.

Regardless - you will still have full N75 control, it may have to up it's duty cycle but then I'm sure the N75 map ups the duty cycle as the differential between MAP and actual MAP increases? Therefore it'll be self regulating and linear, any system which uses a variable control signal (such as boost or vacuum) is prone to imbalance. For this reason I see vacuum control as a step back, offering no advantages over the current (bodge) forced closed by boost method.

N75 map axis' are fuel and revs and is fixed, yes adjust the duty cycle to suit the balance required to meet / match the boost required.
The AXG/AHY uses vacuum and - I think - all VNT's are vacuum wastegate controlled (unless electronic).
Having run an AXG map for 2 .5 years I know they work identically to the AJT/ACV with no smoke or mirrors or unicorn piss that makes them special.

I take it you intend to open the wastegate by vacuum on the top port - in which case, how will you shut the wastegate over 10psi.

Thats how Volvo did it, what I don't know is how Volvo modifiers changed the boost as alot did but mechanically - very few had an expertise in mapping the older ECU's.
I'll do it through mapping, might take a few runs but nowt to trouble moi! I'll have to fit my hybrid Volvo on.

...when it seems like exhaust pressure are blowing the wastegate open, somehow there is a greater pressure downstream of the turbine than upstream - god knows how this can even happen. which is why I think the N75 leaks by design.

I've ported all of my Volvo housings as theres a lot to remove but it does flow better, and opened up the manifold to T25 size with the adaptor plate.
Yes the N75 leaks/bleeds and unless mapped to switch "off". Been messing with this on my Hybrid K24.

A knackered seating face isn't helping my turbo though.

The Volvo units I originally bought were stored badly and had corroded, the units I got that were just pulled off of cars were always good.

so..... VNT and a 2256?
Are you using the BMW turbos?
Or have you switched allegiance to the chinesium turbo? was its AR suitable, thought you said it was big???

Easy to do and map.
Got a 2260 from a 330d with electronic wastegate but done nothing with it. I'm tickling a GT2559 (water cooled)
I'm further with the "Maxpeeding GT2871WC "water cooled" but its not fitted yet. End of the month should be on and running.
I'm running my Hybrid K24 presently and enjoy running it at 25psi. It scares the Mrs which plasters a smirk

[regcheeseman]

Increase the preload more torque can be delivered (difference betwen OEM 6 and say 14.7psi) earlier in the increasing rev range, over 14.7psi the N75 can manage the boost if mapped to do so.
So more air is produced as the wastegate is closed = more boosted air = potentially more fuel if the driver dictates it and the smoke and torque maps allow it.
More fuel = more torque earlier and as the revs increase transferring more to the clutch and gearbox.
Theres no map control as its mechanically closed. (Could throw it into limp mode too as it may be outside the mapped parameters)
Been here and done it.... balancing pre-load with N75/boost maps with OEM K14.

Preload should not affect boost - though there is something going on with either ex manifold pressure or boost leaking past N75

Increase the preload more torque can be delivered (difference betwen OEM 6 and say 14.7psi) earlier in the increasing rev range, over 14.7psi the N75 can manage the boost if mapped to do so.
So more air is produced as the wastegate is closed = more boosted air = potentially more fuel if the driver dictates it and the smoke and torque maps allow it.

The key word there is potentially. Potentially you can smash a gearbox and twist the crank at low rpm if you just shove a whole load of fuel in and let the turbo go mental (Sausages was trying to do that as his torque map was stupid)
But provided the smoke and torque map are good all should be fine

More fuel = more torque earlier and as the revs increase transferring more to the clutch and gearbox.

Torque map is king here and should limit fuel to preserve geartrain - that is it's sole purpose

Theres no map control as its mechanically closed. (Could throw it into limp mode too as it may be outside the mapped parameters)

It always was mechanically closed - it is just 'more' mechanically closed with preload - in a bid to overcome the 'leak' tending to open the wastegate.

The N75 map has a "leak" built in - discovered when I investigated electronic wastegate control.

As suspected and good to know, you could map it out and not need additional preload then?

N75 map axis' are fuel and revs and is fixed,

Really!?! I'd have thought it worked on boost levels - could it be changed to different parameters?

I take it you intend to open the wastegate by vacuum on the top port - in which case, how will you shut the wastegate over 10psi.

Thats how Volvo did it,

Solely? Just using Vacuum? I don't think so as they have the hard plumbed boost signal? VW do the same on a few models, using vacuum as an assist to the boost signal.

Got a 2260 from a 330d with electronic wastegate but done nothing with it. I'm tickling a GT2559 (water cooled)
I'm further with the "Maxpeeding GT2871WC "water cooled" but its not fitted yet. End of the month should be on and running.
I'm running my Hybrid K24 presently and enjoy running it at 25psi. It scares the Mrs which plasters a smirk

Electronic actuator is the way to go. Ultimately it gives most accurate control, minimal hystresis. I tried to do similar on my mk1 GTD engined nutter car with a VNT turbo blowing 35psi.
The original vac/boost actuator was replace by bowden cables and a power valve servo motor from a yamaha EXUP system, the controller was bespoke and as it got developed I used more and more signals from around the engine until I realised I was nearly halfway to a proper ECU built from scratch. It worked fine but the servo motor just wasn't quick enough and could keep up with the ridiculous rate of spool I was getting from the small VNT. Torque steer would make it change lanes just by booting down in 3rd or 4th.

Scaring the missus is always amusing, I took the boys out first when I got ver 2 map running properly with full boost. The looks on their faces was priceless "DAD!!!!!!"

[Activ8]

What do you mean by "minimal hystresis" .... looked it up which was interesting but not clever enough to apply it in your context?

Electronic actuation in our vans using the existing ECU is limited to the existing tiny map table. Unlike a mechanical actuator you cannot fully "close or open" it (if mapped) so you're giving up quite a lot of the "control". Unless you reprogram the safety features of the actuator of course (never tried). Even VNTs have their issues, the Merc GT23 I fitted, the vanes just got coked up and almost failed completely. I realise that I spent a lot of time experimenting but it was only on for 3 months before I recognised the data was changing and reducing power. Hence why I went back to oldskool.

We need a new ECU or an after-market unit for electronic control. Upto EDC16 you're basically getting the same Bosch unit with a few more "comfort" inputs but the maps are the same/similar sizes or more of them if it's economy related. So you're looking at an EDC17 and then picking it to pieces, losing 50+% of it to run your old 2.5! No point m'thinks.

Did you find a source for your ARP head bolts?

What turbo set-up does your mate run in his super fast Caddy? Or post a link if it's too much to type. Just interested.



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[regcheeseman]

I did of course mean hysteresis.

The signal you are trying to control is also the signal used for that control

So with 10 boost and the ecu decides that is too much, it uses a 10 psi signal to adjust the actuator, the boost falls away but so does your control signal the wastegate may now close again. leading to flutter and spikes in the signal line - they try to eliminate this with PWM control and probably succeeded given the very crude nature of a bypass wastegate.

Why can't you fully open or close a electronic actuator - dont get ya? Surely it is capable of moving to either extreme of travel? Just needs a signal voltage from 0v to 100% ?

A VNT doesn't go open or closed though, it goes from less to more!

I have no description to source ARP bolts - gearbox mod is number 1 priority at the mo.

Dunno what turbo he was running, there's certain people on the internet that may elaborate the truth or spin you a yarn.