Hks Gt3040 Rear Housing

[Craved]

Hi guys

starting to look at other ways to reduce my lag on the HKS GT3040

currently running the 1.12 rear housing..

looking for a 0.84 sized housing to see if i can get the boost on at around 4000 rpm rather than 4700rpm

that look like the normal sort of change in the boost range for that kind of change in AR's ?

only thing is that i want a genuine HKS rear housing to match the setup.

are these still in production? or is it pot luck to find one 2nd hand?

[paulr33]

some things that come to mind when reducing lag

-> is it the wastegate causing it to be extra laggy (leaking)? try a dyno run with it unplugged and see the boost curve. dont go too hard as your running unlimited boost. then hook up the controller and gate and try again, see if they are the same (should be)

-> the state of the tune can bring the turbo on earlier (more ign timing)

-> exhaust. i would run at least 3.5" split dump for that rear housing, even 4"

-> you could try some super hoctane jungle juice

-> change of diff gears perhaps?

-> tomei cams

-> change turbine rear housing

-> do a dyno run with exhaust dropped off, see how laggy it is

[Craved]

- yes the wastegate is sticky and being replaced next week hopefully. 38mm tial vs the current copy crap.. still doesn't over boost though which is lucky

- yes more ignition advance when off boost can help it too

- running 3" straight exhaust,4" high flow cat etc , at near 300rwkw i dont think the exhaust flow would need 4" just yet

- already have poncams

- not gonna diff ratios i dont think, am getting a 2 way LSD this week, hope the ratios are the same

- 1.12 on the rb25 is pretty big, hence looking at something smaller... gonna be end of year til the rb30/25 is finished at this rate.

not gonna touch the jungle juice lol

[paulr33]

yeah why did u go for such a large rear housing??

when does it come on song? got a dyno chart ?

[Craved]

here's a link to the dyno sheet

http://img380.imageshack.us/img380/3472/pic000130hq.jpg

as you can see without changing anything the WG is changing the response i get. and power due to boost level changing.

will have to get another sheet once the new WG goes on and we can play with the settings on the ID3 to see if it can reduce it further.

there was runs that had boost earlier but these 2 show the more average results the turbo gave.

was just told the 3037 rear housing might fit the 3040 .. can anyone confirm?

edit : yeah when i bought this turbo 2 years ago i didn't know as much about it all as i do now.. so yeah it came up, good price so i took it.

just making the most of my purchase back then.

Edited April 13, 2006 by Craved

[BOVed]

- not gonna diff ratios i dont think, am getting a 2 way LSD this week, hope the ratios are the same

Hey craved where do ya get these difs?

[Craved]

- not gonna diff ratios i dont think, am getting a 2 way LSD this week, hope the ratios are the same

Hey craved where do ya get these difs?

im getting mine 2nd hand through a mate, you can buy new ones at alot of places, expensive though.

[R31Nismoid]

Its not really doing anything amazing till 5000rpm is it?

Hrm... 3" - 300rwkw... you are over the limit.

Your into the 3.5" territory. I was 3" aswell... hurt bigtime i tell ya.

Definately hit 3.5" at a min Chris.

Do you have to have a HKS rear?

The .81 garrett would bring you on around 4200... but that all depends on what rear wheel and front wheel.

Lemme know

[Craved]

yeah its all over the shop, but even at 10psi on the street it feels alot faster than it used to be with the std turbo..

well i was only thinking about the HKS rear housings cos i thought they would be a direct fit with the wheels etc ...

i'll see if i have any pics, but since it was second hand i dont have many details on the wheels its using.

anyway to get these from the model number on the tag??

still running std internals so im not aiming for more power atm..

Ash, with the larger exhaust you think it would inprove spool times due to reduced backpressure within the turbine housing?

dont wanna go too nuts on it atm money wise, just need to reduce the lag... i'll more than likely wanna run the 1.12 housing on the rb30.

if running say a garret -.81 housing, id more than likely have to get the housing machined to fit the HKS designed wheels ??

ordered the new WG last night, so should have that next thursday or so.. then install it and see what the difference is on the dyno ..

might drop the exhaust off like Paul said to see if it make a difference to spool times .. if so i'll prob just jump up to a 4" exhaust ready for the rb30 which would require it more than the RB30

[discopotato03]

That Turbo will probably be unit number 700382-23 and cartridge number 700177-9 , check its ID tag if you can get at it . GT3040's use the same turbine as many of Garretts GT30R family and HKS's GT3037 family ie 60mm 84T . Garrett do T3 flanged housings in .63 .82 and 1.06 AR . HKS do them in T25/28 flange .61 .73 .87 and your 1.12 AR . I would be hesitant to use HKS's .61 or .73 or Garretts .63 because of surge reasons . Probably the logical step would be the .87 HKS in T28 flange or the .82 Garrett in T3 flange .

Cheers A .

[Craved]

yeah its using a T25 flange, another good reson to try and get a HKS based 0.87 housing so its a direct bolt on... the exhaust bolt pattern on the garret version might be different too

love to test it out with the 0.73 housing...

Doughboy said he might have some so i'll wait for to get back to me ..

will check the tag tomorrow as the car is at home, while im at work.

[R31Nismoid]

Chris, i really reckon you would benefit from a 3.5"

If not now, especially when the 25/30 is done and your making even more power.

I was told if i wanted anymore than 300rwkw then 3.5" is a given.

On my car however with the low-mount there was no feasible room to fit a larger diameter etc.

So it could not be done.

[Craved]

just checked the details on the 3037 and 3037s, they have the same turbine setup so im guessing it should bolt on..

looks like they use the GT25 flange as well.. hmm options

ahh just notied the surge issues you mentioned regarding the 0.73 housing.. would HKS have brought one out so small if it was going to surge?

[Craved]

i would hate to think of how loud it would be with a 4" but i'll probably do it anyway .. its really really loud now.. well over 100Db .

might just have the 4" from cat back to save on building costs for the new dump pipe..

its a new custom stainless 3" , so im not gonna through the $1100 away just yet. the sound is beautiful atm

[R31Nismoid]

If i was going to go 4" i would have it split into a twin system

nice and quiet

[Craved]

twin 4" or twin 3". noticed there was a bit of discussion over this regarding Bretts (BU5TER) engine.

[R31Nismoid]

well 4" off tyhe dump and split it down the line to at least 2 3/4.

Im gonna run a twin 2 3/4 (or there abouts) off my RB26 this time around and go dual all the way down

[discopotato03]

HKS have to cater to mad Japanese putting big turbos on CA18's , also their GT30 turbine housings should bolt up to GT3037's in 48 and 52 compressor trim . The smaller AR housings are for these smaller compressors to spin fast enough to make some boost on 1800-2000cc engines .

Cheers A .

[Craved]

hmm might get the new dump mad up when i go the rb30 as it'll be sitting the 30mm higher anyway.. then run twin 3" so i can still use the pipe i have now.. see if it'll fit when i change the WG.

ahh yeah thanks for that info Discopotato03 .. makes sense

hmm so need to see if i can get a 0.87 housing..

[discopotato03]

Provided everything else is working properly ie wastegate / fuel system / tune / no inlet leaks the .87 will bring the boost threshold down . It may be worth asking Doughboy if he has the .60AR comp cover as well as it was a HKS GT3040 option .

I know OT but the 3037 52T would be a fair bit more responsive in a daily driven RB25DET .

Cheers A .