3076 52 Trim Or 56 Trim

[juggernaut1]

Currently have a twin scroll .78 3071 setup on my SR with 290rwks at 22 psi....max power at 7700rpm

I was going to swap in a 3076 56 trim CHRA.......cos I can't stop tinkering and evolving my setup.

However, I note that the Evo X Garrett upgrade turbo specs in a twin scroll format are:

3071 56 trim comp / .73 ex a/r

3076 56 trim comp / .94 ex a/r

This then suggests to me that my current .78 ex a/r might be too small for a 3076 56 trim comp as Garrett has used a .94 ex a/r on a 2 litre Evo motor.

The 52 trim comp 3076 falls roughly between the 3071 and 3076 56 trim. A rudimentary and purely unscientific calc shows that the middle ground of the .73 and .94 ex a/r is approx .83 a/r.

OK so .83 is still bigger than my .78 but I was thinking of having the .78 e/x a/r extrude honed and I have a few other tricks to try which would give it a bit more flow.

There is a .82 twin scroll ex a/r available via GCG however its a different housing altogther meaning it places the turbo in a different position to the .78. The .82 also needs profiling and as it only has a slip joint outlet, a v-band or 4 bolt outlet needs to be welded onto it. Plus I haven't seen any solid results from the .82 twin scroll housing - so its an unknown.

So my conclusion was to stay with a .78 ex housing with extrude hone and fit the 3076 (3037) 52 trim turbo instead of the 56 trim.

I'm after the optimum 3076 turbo comp/ex match for all round efficiency spool/response

Do people concur with my thoughts or am I just over analysing things and should I just go with a 3076 56 trim?

I will try E85 in the future - I have a 205 litre drum at home to try and will run it full time if the stuff every becomes available at the pump<<<<< just mentioning this in case that would sway your decision re a 52 or 56 trim.

Cheers

Edited December 11, 2009 by juggernaut1

[discopotato03]

Its difficult to make a direct comparison of those two turbine housings because they are not of the same family , the 0.78 A/R one is from a GT32 series diesel turbo and the 0.94 A/R one is model specific to the Evo 10 and the GT30 petrol turbo family .

Garrett used to advertise the GT32 as a GT3267 and GT3271 and the turbine was a smaller trim (from memory) than the 84T GT30 turbine .

The theory of TS turbine housings is to go larger in A/R than most would image particularly if going from single scroll turbo systems . The idea is that you want the manifold pressure to be high when the turbine needs it and low when the engine likes it . In a bigish single scroll housing the pressure is low when it needs to be high (low revs) and high when it needs to low (high load/revs) so really the wrong way around .

A TS housing thats too small in A/R gives a pulse damping effect which is not ideal unless you want lots of torque at quite low revs with a small/med capacity compressor - diesel style . Remember those GT32's with an ~ 65mm dia turbine and a 67 or 71mm diameter compressor .

The word on the "street" is that Garrett got around the twin IW valve issues in the Evo 10 spec TS GT3076R but I haven't looked into them since I got my single scroll GT3076R/3037 52T . I can't justify a TS system on my GTS25T and I've seen them go "well enough" to please me without it .

Different if you're racing and need every advantage available to you but for me there are limits to how much torque you can feed into a RWD road car and street rubber .

Cheers A .

[juggernaut1]

I hear what you say re the background of the .78 a/r thats why I mentioned I make peak at 7700rpm as some sort of evidence (or luck) that it does flow at these rpm and makes 290rwkw in the process

with the 3071.

Did you have a conclusion to my "theorising" as to whether to go a 52 trim or 56 trim.

Edited December 11, 2009 by juggernaut1

[ezy_09s]

^^Yes, interesting thoughts Juggernaut...

i too have wondered the same, as i have an sr22vet in a datsun 1600 with a HKS 3037 pro s with the .78 atp twin scroll rear and thought that maybe i had gone for a housing that was a bit on the small side... a .92 maybe something i will have to investigate further if i dont see the numbers im hoping for .

But as you have made 290 rwkw @ 22 psi...im sure my goal of 350 rwkw can be had on E85.

If you were in sydney i would lend you my turbo to do a comparison back to back.

[juggernaut1]

Strewth....a Datsun 1600 is going to be a handfull with a twin scrolled 350rwkw on E85 if your goal is reached.

.78 could be a too small for a 22vet motor. However, E85 seems to somewhat delay the effects of going too small a housing based on what I've seen.

In addition to the .82 I mentioned a 1.06 housing is also available from GCG in T3 format......I see ATP also lists a T4 twin scroll housing for the 3071/76 turbs.

Your only other option would be a switch to the BW twin scroll turb's....although dyno results are as rare as hens teeth.

Edited December 11, 2009 by juggernaut1

[ezy_09s]

It look like the only t4 housing that atp supply is the 1.06,which was not available when i got my rear housing from them.

Though i think i will be happy with the response from .78...after all killer throttle response and a strong curve was more important to me than an overall number which is why i chose to go 2.2 litre with a twin scroll & individual throttle bodies.

I was going to try a borg warner as i have seen & heard good things from them,but i thought i would try the one i have first.

[JonnoHR31]

as disco said twin scroll needs a larger a/r than single scroll for the same targets. i'd go the .94 twin scroll

[juggernaut1]

Unfotunately there is no universal .94 twin scroll ex housing.

The .94 I mentioned is purely a bolt on proposition for the Evo X which of course has a different footprint to the generic T2 / T3 / T4 fottprint Garretts.

ezy 9's: you'll be happy with the throttle response of the .78 especially on a 2.2. If you refer to the Full-Race website, they recommend that you grind back the CHRA bolts so they don't protrude into the volute of the housing.

Edited December 11, 2009 by juggernaut1

[JonnoHR31]

o my bad. i allways thought the evo's used a t3 flange

[phunky_monkey]

Hey Ian, where are you getting the 52 trim from if you get it? Do Full Race offer the 52, and have you spoken with Geoff about it?

[juggernaut1]

Hi Dane,

GCG can get the 52 trim in for you.

I haven't spoken to Geoff about it....and I don't believe they offer it.

[discopotato03]

Yes mine came through GCG as did the port shrouded compresor housing to suit the 52T compressor .

CHRA or cartridge number is 700177-5006 . I opted for the 0.82 A/R Garrett GT30 IW turbine housing . It hasn't been fitted yet so can't give results .

Cheers A .

[phunky_monkey]

Thanks guys.

Ian: I replied to your PM, just let me know what you're thinking mate and we can go from there.

Disco: What's it going on?