started when my car was taken for mapping, mapper said actuator was weak so i could not make full desired boost, i said wind bar in and he said no which confused me...

did he say no as it would **** all the wgdc up etc and create more work for him or is there a valid reason?

i dont understand either how pretensioning an actuator up is not the same as putting in a heavier spring on an adjustable actuator

i have actually bought a forge actuator now but need to make a bracket for it to fit and lengthen rod as i have an early style andy forrest td05 20g and it has a modded td04/tdo5 actuator on it

is the best way to set an actuator up to have minimal preload and set with a vac pump so it opens at the same value as the spring so say it moves at 14psi for a 14psi spring???

confused me for a while but both ways seem to be correct

only advantage i have really found is that with a heavier spring the boost becomes more punchy...which could actually be a bad thinig for my gearbox as td series turbos bring the power in quite hard anyway...or they do from my experience

can anyone else elaborate???

 

I still have the standard Actuator on my classic, it too was a tad weak, so i adjusted the preload via the rod, perfectly acceptable as thats what adjustment is there for, to allow for spring tension loss over time, granted if its uber uber weak replace it but id guess that, as he mapped car with a weak preload and set all the wastegate duties up to that, once you adjusted it , it would of needed tweaking again.

 

So he didnt want to have to tit around doing it again then really?

I could of adjusted it and it been ok

That still does not explain the need for stronger or weaker springs if i can have a weak spring and a strong set at the same tension???

 

Bascially yeah.

Mine wasnt weak from wear, my preload wasnt set correctly, once i set this correctly, the actuator wasnt "weak" anymore

If an actuator is weak i guess you would have to go beyond ideal with the preload which isnt good as duty cycles would have to be maxed up a bit, causing solenoid to work more ?!!?!?

Not sure what the benefit over a stiffer spring compared to more preload an a worn actuator is tho (unless its well worn beyond preload settings that is)

 

Regardless of the pre load the gate will still begin to open when you approach the springs pressure rating - but preloaded will help resist it cracking open before that. Normally I prefer to have spring pressure about 1/2 of what the final boost will be - this allows you to drop down to a safer limp mode in the event something goes wrong and still have reasonable part throttle boost control via the ecu tables.

With say a 7 psi spring, reaching and holding 22 psi can be difficult but with a 14 psi spring this is a lot easier on the boost solenoid.

If you only had a small wastegate spring then your heavily reliant on the boost solenoid gradually controlling the wastegate which sometimes isn't possible on the early cars due to their more basic boost control tables.

 

Is there a chance then that my actuator was just never correctly tensioned before being mapped?

How would you actually set an actuator up correctly other than by driving it?

The mappr i used for my classic checked at what point it started opening with a hand vac which proved it started moving at say 6psi and thats when he said i needed one with a 14psi spring i think it was

Is the proper way to match the opening with a vac pump and spring tension?

More spring tension is less whdc to i take it..ibthink thast already been said hasnt it?

Cheers all

 

normally you wouldn't need to drive it to setup the actuator preload. Take the c-clip off and shorten the rod until you have to pull on it a little to get it back on again and jobs done. 6psi is probably a little short if you were trying to get to 22psi say for an STI tune as the wastegate would be working very hard to achieve your target. Regardless of preload, the gate will still be opening when it sees pressure so you end up having to work the wastegate solenoid harder than needed.

With a 14psi spring you would need much less wastegate duty cycle to get your target, which means things aren't working as hard so they will last you longer and be more reliable.

I think your confusing the preload and the rated spring pressure they are different things that work together but you still need to look at them individually and if they meet your needs/goals.

 

So basically tensioning it up is a bodge as it should only really be preloaded enough to just keep the wastegate shut (which is valuable information as to how i make my new rod and bracket but also quite obvious)

It makes sense then also to have a 14psi spring if i intend on round 21psi then for example...makes more sense now

Forge also state though that with a stronger spring the boost becomes more 'snappy' which like i said before is good to feel but most probably bad for my 'weak' dccd box haha

We will see

Cheers

 

yes a stronger base spring rate is more like running an MBC. With a 14psi spring the gate may not start opening until 10psi before being fully open at 14 (different manufacturers vary so you can check with the hand pump) wheras a lower rated spring will start to open much earlier.

Preload should be used to help the gate stay shut before it's rated pressure, but it won't allow you to go higher than the rated pressure, your just changing how much the rod has to move before the gate starts opening.

Normally if your trying to get to 22ish psi then your turbo is probably also quite big. A 14psi spring on a TD04 would be wasteful and feel more like a diesel as the turbo will be spooled at pretty much it's maximum rate possible. With a bigger turbo the spool is usually at a higher RPM so although it's spooling up faster than it would have, you still get some leeway as you control the rest of the spool to 22psi with the boost solenoid.

Your mapper can choose then to maintain a very high wastegate duty and get on maximum boost as soon as possible, or to gradually feed the power in with less duty. Generally if you can smooth about it the gearbox will last longer, but really that's going to be down to how heavy your feet are mashing the pedals.

 

1.7 BAR is your engine standard?Don't mess with actuator Arms get it mapped properly,the day of the bleed valve is so 1980's.SJ.