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Garret -7's Just Installed

locoloc

By locoloc,
in Engines & Forced Induction

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locoloc Community Regular

locoloc

Posted
Posted

iv'e just got -7's installed and not hitting full boost till 5000rpm.

my mods include...( exhaust, PFC, adj camgears, -7' turbos, hks actuators. )

currently boost is tapped into the stock boost controller.

things that have been checked by my tuner.:

- boost leaks

- cam gears in right position

- vacum leaks.

- tightened actuators, ( but when its tight i hit 20psi of boost which i dont want )

- loosened actuators in order to stay at around 16psi.

my tuner has suggested that i get a decent EBC so that he can tighten the actuators off as that

may be a reason for boost leak?? ( but im not sure how much this will fix my problem )

The power is there once it hits boost and on the dyno ran 288kw at the rears on 16psi.

My dilema is that it takes for ever to hit full boost.

Just wondering if there was anything obscure or even anything simple that may have been missed

that i might be able to check/replace/tighten etc...

Any experience or suggestions would be greatly appreciated.

cheers

loc

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BLSTIC Contributor

BLSTIC

Posted
Posted

I used a turbotech boost controller (essentially a pressure reducing valve) on my Legacy GT. Cost $30 or so delivered and the boost came up fast and smooth. With a 4psi actuator (stock for most ecu controlled turbo systems) and the valve set so that I would just miss the boost cut (14.5-15psi) I would get 12psi in 1st, 14psi in 2nd and 3rd, 14.5 in 4th and 5th. On cold nights it would hit the boost cut under heavy load (ie car not accellerating much but at full throttle for a while).

After fitting the large exhaust the boost rose maybe 1psi in all situations (so I had to back off the boost controller to avoid hitting the boost cut), and I was able to get 13psi in 1st while still avoiding the boost cut.

I really don't see why you need better boost control than that, and it's worth spending $30 on something that has a good chance of working (and is easy to set up) before spending $300 on something that is guaranteed to do the job but takes a lot more to set up. Plus you can sell it again if you don't use it.

Incedentally taking the wastegate line off saw no change to boost response below 9psi with this particular controller, so no boost controller is going to bring boost up faster to that point without an anti-lag system.

bradsm87 Proficient

bradsm87

Posted
Posted

run a line and t-piece directly from the plenum to the actuators, preload the actuators to about 2psi lower than the boost u wanna run then put a turbotech in and wind it up to the boost u want. This setup will give u pretty much the fastest possible boost response.

MrStabby Grand Master

MrStabby

Posted
Posted
An EBC wont make that much difference - esspecially if you've allready put more preload on the actuators and your still only getting boost at 5000rpm. Still sounds like you've got an issue.

Roughly how many rpm is "much"?

BLSTIC Contributor

BLSTIC

Posted
Posted

Want to know how much? Disconnect your wastegate lines and go for a very careful blat. No boost controller, however many lights, buzzers, displays, and functions it has, can get better than that regarding lag. Just be very careful that you don't over-boost, as I'm assuming you no longer have a boost cut. With no functioning wastegates, your right foot can be stronger than your engine (except for GTR700, but that's too cool to mention again in this conversation).

If you still have lag issues without the wastegates connected, you have other issues.

-Ben

locoloc Community Regular

locoloc

Posted
  • Author
Posted

thanks for the replies,

i think i may not haave been totally clear,:

i wasnt after info on which boost controller is best, more so, whether or not

installing an aftermarket boost controller in order to tighten/seal off the actuators will

help boost come on quicker..

or even if there where other mechanical malfunctions that may be causing the lag.

im starting to get paranoid now and hoping its not one of the turbos, or both.

bradsm87 Proficient

bradsm87

Posted
Posted
To clarify, i'm interested in what the difference is between a manual boost controller (spring + ball type, not dumb bleed valve) vs EBC. Ballpark. 100rpm??

A turbotech and an ebc with the gain set to max it'll go without spiking will come on to boost pretty much the same so i'd say zero rpm difference.

tangomatt Proficient

tangomatt

Posted
Posted

Hi,

Certainly sounds strange that the turbos are not boosting up sooner. In my R34 GTR, these turbos would be spooling up around 3k to 3.5k rpms and pretty on full boost by 4k rpms. I doubt that its the turbos' fault as they were running fine before they were dismantled from my engine.

Hope you get it sorted out.

Pm me if you have any concerns re turbos etc.

Cheers

femno Grand Master

femno

Posted
Posted

There is NOTHING wrong with the standard boost controller! I was running it coupled with a special piece of tube to increase boost, with excellent response and flatline hold.

What are the cam gears set to? Advance inlet, retard exhaust? This combo brings boost on nice and early.

What AFR does the car run while building boost? A lean or excessively rich tune while building boost will make it much laggier than it should be.

Swiper the Fox Grand Master

Swiper the Fox

Posted
Posted
There is NOTHING wrong with the standard boost controller! I was running it coupled with a special piece of tube to increase boost, with excellent response and flatline hold.

What are the cam gears set to? Advance inlet, retard exhaust? This combo brings boost on nice and early.

What AFR does the car run while building boost? A lean or excessively rich tune while building boost will make it much laggier than it should be.

yes...spot on.

gtr fan Experienced

gtr fan

Posted
Posted (edited)
What are the cam gears set to? Advance inlet, retard exhaust? This combo brings boost on nice and early.

I am about to get some 2860-5's and was going to use adjustable Cam Gears. However I am also being strongly advised to by some Tomei Type B Poncams as well. Are the response gains from the camshafts worth the outlay?

Edited by gtr fan
bradsm87 Proficient

bradsm87

Posted
Posted
I am about to get some 2860-5's and was going to use adjustable Cam Gears. However I am also being strongly advised to by some Tomei Type B Poncams as well. Are the response gains from the camshafts worth the outlay?

Shit yeh. Tomei already use different cam timing for best balance of response and power so the cams wouldn't cost as much if u just get the cams without gears. Most tuners don't take the time to tune cam gears to their best anyway.

gtr fan Experienced

gtr fan

Posted
Posted (edited)
Shit yeh. Tomei already use different cam timing for best balance of response and power so the cams wouldn't cost as much if u just get the cams without gears. Most tuners don't take the time to tune cam gears to their best anyway.

Souonds like cams are the way to go. Out of interest have you discussed cams with your tuner lololoc?

Edited by gtr fan

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