Rb26, 2860-7, Slow To Boost?

[stig0000]

high all,, I got a gtr with the above turbos,

its forged internals and minor head work, still standed cams and valves,

power-fc tuned to 380hp at 15psi,

blead up with gfb bleed tap,

I will be going to a electric boost controller at some point but problem I have it I have nothing under 3500rpm, no real pull until 4000rpm when boost comes on,, I went with the dash 7's over the 5's due to lag, tho I think this turbos are lagy as hell, ??

if I fall off boost there is nearly no power at all, is this normal for the -7??

I no a EBC will help it get on boost sooner tho this seems like a lot of lag?

[Guilt-Toy]

what actuators are you using ? what is the base pressure set at ?

[sydking]

Something wrong for sure, not the blowers either

[stig0000]

just the garret actuators they come with and factory boost,, id be guessing 9-10psi?

[niZmO_Man]

D-Jetro or still using AFM? If using AFM, try cleaning them/trying another pair.

When mine started to play up, it would take a while to build boost (standard engine).

[Guilt-Toy]

are they adjustable actuators ? have you checked the pre-load on them ? are they both the same ?

[RB2600]

has base timing been looked at? my new engine from japan was 10 degrees advanced and was VERY laggy.

put it back to 20deg BTDC and it's running perfect.

you'd think the Japs would know how to get it right but you'd be surprised.

The adjustable actuators with any more than about 2-3 turns worth of preload will give more than 17psi boost.

I found out this morning...I'm still yet to tinker with my profec b 2 but am confident that if I have standard preload on the -9 actuators

and adjust the start boost high enough, it will give me my 15psi that I want, nice and early. Which sounds like what you're trying to achieve.

[MrStabby]

You should have about 7psi by 3000 and 15psi by about 3900. You could try disconnecting the boost signal to the actuators and plugging the line then go for a CAREFUL run up to say 3500 or 4000 to see if the boost comes on any better. Dont go further than this as boost will keep climbing! If you notice boost building better, then an EBC should help.

-7s come with adjustable actuators standard so check the preload on the actuators - usually 1cm is a good start. Then apply some air pressure to them via the common feed line to make sure they open the same amount at the same time.

[RB2600]

Regarding actuators opening at the exact same time, what would happen if they weren't exactly the same? I think mine at one stage were one turn off but really haven't noticed any difference?

[GTSBoy]

If one turbo is spooling and the other isn't you can get shenanigans like shuffling happening. It's basically the early turbo forcing the turbo that is dragging its heels into surge by increasing the downstream pressure above what it would be if the slack turbo was running by itself.

Edited July 24, 2013 by GTSBoy

[MrStabby]

^ what he said, and basically youre working one turbo extra hard which cant be good for its long term survival.

[XKLABA]

also cam timing will increase off boost power and bring turbos on sooner

you say forged motor what is the comp ratio ?, base timing, as stated already, makes a big difference

check the actuators are set correctly and a EBC will also bring turbos on sooner by reducing waste gate creep

what exhaust do you have ?

is there a rag in your intercooler ?

[stig0000]

hi all,, it is lowerd compresson but im not 100% sure to what, I haven't checked the cam timming tho will, maby a set of adjusterball cams?

timming was set at tune, if I remember im seen a max of about 43deg timming on boost? id have to check again,

iv tried to set the wastegate's tho the actuator adjusters seem to be pressed onto the threaded sharft? it still has a lock nut on the thread, no mater how hard I tried I couldnot turn the rods on the threads, they are genuan brand new garret turbos, exhurst is a hks 3.75" fullsystem , 3.75 high flow cat,

the rag, youv put the fear of god into me but im 100%% sure there is no rag I left in there

[XKLABA]

I once found a 13mm spanner in the BOV return pipe

Lowered comp ratio will make turbo spool later and make it feel sluggish off boost

A set of cam gears tuned for response will help to

[Guilt-Toy]

I once found a 13mm spanner in the BOV return pipe

Lowered comp ratio will make turbo spool later and make it feel sluggish off boost

A set of cam gears tuned for response will help to

hahahaa thats gold!

[R.3.2.G.T.R]

loosen up the nut and remove the circlip carefully at the end of the rod (magnet the circlip to stop it flying off), then adjust the rod

iv tried to set the wastegate's tho the actuator adjusters seem to be pressed onto the threaded sharft? it still has a lock nut on the thread, no mater how hard I tried I couldnot turn the rods on the threads, they are genuan brand new garret turbos, exhurst is a hks 3.75" fullsystem , 3.75 high flow cat,

[stig0000]

loosen up the nut and remove the circlip carefully at the end of the rod (magnet the circlip to stop it flying off), then adjust the rod

did exactly this, still no bingo on eather turbo,

my 13mm is accounted for so its not that haha, I do think its the decomp motor that is it,, on my standed twins I wasent making fullboost till about 3500-4000 eather, so cams/cam gears it is,

[XKLABA]

1st do cam gears on stock cams

[stig0000]

well this is old

, come along way since then, engine is striped down, getting 87mm wiseco pistons as no6 piston took one for the team,

im going to pumping the boost into this set up, just wating for a spanking new crank to turn up then rebuilt time, ( had been ground to much in the past)

responce is my aim for this, i now have adjusterbull cam gears, still running the -7s( going to set 15psi gate press, then up with a eboost), what cam deg/lift would be a good combo for this?

looking to run around the 20-25psi range with flowing mods,

[Blackkers]

cams. stock should be good with -7s. with adjustable gears.

Should be pretty nice to drive. What compression are you aiming for?