Boost Control Options

[LRyder]

Hi Team!

Have purchased a Rb25GCG turbo for my RB20. The car will be used for street and track, but mostly track, so will be tuned for the one psi setting. Now I no internally gated turbos do suffer from boost control issue, and I am keen to here you thoughts on options for controlling boost. The turbo has not been fitted yet, so I want to get it right from the start

To start with I have purchased a Greddy Profec B Spec II. But with running a standard rb20 actuator I no I will suffer from spiking and boost tapering off at higher revs.

To give you something to work with, I want to run 18psi, no more.

I would like to here your guys/girls opinions on aftermarket actuators. I no brands such as XTR make 18psi actuators, but wondering the reliability. I have heard actuators can suffer and be quite temperament in different weather conditions.

Also what do you guys think of running a 16psi actuator and using the boost controller to hold the last 2psi.

I want to run the boost controller mainly to eliminate spiking, but keen to here any thoughts or options. (Even external gate if you think 18psi actuator is pushing the limits)

Please feel free to flame, as I tried searching to no avail.

Thanks.

[paulr33]

get the closet actuator that you want to run, ie 16psi actuator and a boost controller to bleed 2psi

is much better than a 8psi actuator and a controller trying to run 16psi

[W0rp3D]

If its going to be used mainly as a track car i would suggest having an external gate welded to the top of the standard manifold, next best option would be an adjustable internal gate, i have a hks one that works well, that is assuming you are only going to use one boost level.

The problem with all internal gates is that they start to bleed boost before they get any where near full boost, an external gate does not do this and does not have boost flare either.

[W0rp3D]

there is a thread about this with pics HERE

And here is the one i just bought off these forums.

[LRyder]

I would love to go external gate. but the price of a gate and the necessary modifications to make it work would nearly cost more then the price of the turbo.

How much did that setup cost you? If you dont mind me asking.

[W0rp3D]

i got the manifold for 175, gates can be expensive, a mate has one on his turbo xe falcon that is a cheap 60mm ebay job, costs around $150-$200 and he has not had a problem, would probably cost about $500 all up, but when you consider a good ebc will cost you $400+ and an external gate will work a lot better then its not all that expensive after all, plus it will be a good set up when you go an even beigger turbo in the future.

Edited August 31, 2008 by W0rp3D

[Tangles]

Ive just got the Greddy Profec-B spec-ii, installed it myself yay

with the HKS heavy duty actuator, no spike at 1.15 bar. havent tried higher untill after a little dynotune time setup

Id say ditch the rb20 actuator and get a $150 hks heavy duty actuator, with your profec, easy to achieve steady 18psi surely

[LRyder]

Yeah. Well no mater what I will have a boost controller as that has already been paid for. I could still run a boost controller with a cheap eBay gate to regulate and prevent spiking. But still interested to see peoples opinions on actuators as it would be a much cheaper solution.

has anyone tried those XTR actuators on http://www.tweakit.net/

?

[LRyder]

Also can anyone recomend any other after market actuators other then HKS?

[PM-R33]

You can modify the standard one to be adjustable, i remember reading some where on here on how to do it.

[phat_man]

ive actually been thinking about this very same situation, for a while now.

as i currently have a rb20, and am thinking of going a rb25 gcg hi-flow.

but ive been thinking of not going the EBC just an 18psi actuator. or will that have to much play with weather changes and heat....etc...

[LRyder]

ive actually been thinking about this very same situation, for a while now.

as i currently have a rb20, and am thinking of going a rb25 gcg hi-flow.

but ive been thinking of not going the EBC just an 18psi actuator. or will that have to much play with weather changes and heat....etc...

Yes my thoughts exactly.

Another option I have been toying with is using a T3 wastegate adaptor, that sits between the manifold and turbo. That plus an external gate, is that all that is needed to run?

Or do you need to block of the flapper port on the turbo?

Still very unsure which is an ideal way to run this setup.

[phat_man]

Yes my thoughts exactly.

Another option I have been toying with is using a T3 wastegate adaptor, that sits between the manifold and turbo. That plus an external gate, is that all that is needed to run?

Or do you need to block of the flapper port on the turbo?

Still very unsure which is an ideal way to run this setup.

i dont exactly get what your saying here, but if your asking if you run a external gate on an internally gated turbo, yea u need to weld the internal one shut.

id rather not run an external gate on this size turbo, doesnt seem very economical, esp for the power these make/amount they flow. im sure you would be able to flow abit more and hold boost abit bettter, but for the amount its going to cost to get it done (with good quality bits) doesnt seem to be worth the coinage. mot to mention all the other goodies you would be able to get to make that extra 5kw. rather get coil packs/cams/more suspension bits... etc....

[W0rp3D]

1) you do not need to weld the wastegate flap shut, the wastegate only opens due to pressure on the diaphram, with no pressure it shouldnt open, a mate of mine did the external gate thing with an internal gate, he had no actuator and just used a spring to keep it closed.

2) the easiest (and dodgy old school) way to adjust your wastegate is to bend the rod, the other way would be to cut it in half and put a thread on each half both in opposite directions (one left hand thread one right hand thread) then get a hollow rod of the right size and put opposite threads in the middle of that, the screw the rods into the middle of the hollow rod when you spin it one way the two inner rods will be pulled together creating more pressure on the diaphram and needing more pressure to open it, turn it the other way and it losen's it needing less pressure to open it.

3) the t3 adapter you mentioned is no doubt the one in the for sale section, 2 problems that spring to mind 1, will this be so big that the turbo now hits the strut tower 2, how will it effect the dump pump and lines since it is pushing the turbo 2-3" out from the engine, but if there is no problems and everything fits then i would go with that option.

4) once again you mentioned boost fluctuation with temps and other factors, the only way to make it accurate is external gate, the internal gate just does not have the flow and accuracy that an external gate has, there is also a big reason why an internal gate costs $100 and an a good external costs $500, you also have to look at the future, no use spending a few hundred on band aid fix's when down the track when you start serching for more power and better response your going to wish you had have gone this way to start with.

These are just things i have learnt over the years, cheap fix's produce cheap results that later you need to spend more money on keeping it going, do it right the first time and your set.

[Marco-R34GTT]

Sry to hijack..

Quick question..

Say I bought a HKS GTRS turbo for my R34 GTT, would getting the HKS actuator make any difference over say, the stock or RB20 actuator???

I'm assuming the HKS unit would be adjustable...

[PM-R33]

The HKS actuator has a minimum setting of about 14psi and is adjustable. The HKS GTRS kit comes with the HKS actuator so a bit pointless to use a standard one on it.

[LRyder]

Quick update. Have emailed GCG and they have offered a 18psi actuator, but it is $250 plus shipping,

what are your thoughts?

[phat_man]

Quick update. Have emailed GCG and they have offered a 18psi actuator, but it is $250 plus shipping,

what are your thoughts?

Wow, didnt expect it to be that steep... might be worth while just to go external then.

[W0rp3D]

The HKS actuator has a minimum setting of about 14psi and is adjustable. The HKS GTRS kit comes with the HKS actuator so a bit pointless to use a standard one on it.

I have one, when i first put it on it was set to 10psi and worked fine, its now just under 14 (.9 bar).

[Marco-R34GTT]

SO 14 PSI isn't the minimum setting for the HKS actuator??