Re-cored (bigger) CT12As vs a big single

[Ribfeast]

Hi all,

I've heard of people re-coring the CT12A turbos with Garrett ball bearing cores, I think it was a GT25 or GT28 wheel that they put in.
What would be the pros and cons of this vs a GT30xxR or GT35xxR big single setup?

Pros:
No need to buy wastegate
Can use standard dump or existing twin dumps
No need to change turbo piping to the intercooler
Looks factory for the cops and engineers
Can use standard water and oil lines as Toyota intended

Cons:
$2000 per turbo
Factory turbo piping restrictive?
Factory 3-to-one exhaust manifolds restrictive? (port out?)
Heatsoak?
Big single is easier to work on and looks bling

What would the spool time be like compared to the factory CT12As and compared to a GT30R setup?
And what maximum power could I expect, would this setup limit me in any way?

[stradlater]

d00d.. Your going to pay $2k per turbo?? That's a bit silly..

[lojik]

Does this mean your ebay steelies are dying?

I like the idea of using all the standard pipework, but at 2k per turbo its a bit expensive....

[Ribfeast]

Steelies are still going strong, but I like contingency plans...plus it is a good topic for discussion

$4k all up is pretty good...

Compared to buying:
Manifold + making it strong $300-700
Turbo $1700
Intercooler piping mods $100-200+
Dump pipe/exhaust mods $100-200+
Water and oil lines $100-200+
Wastegate $500-800+
Labour $heaps
+ whatever bits I forgot
Plus the hassle of having your car off the road for days/weeks. With the re-cored twins you could do the whole job in a day, probably even by yourself.

[rob_o]

Steelies are still going strong, but I like contingency plans...plus it is a good topic for discussion

$4k all up is pretty good...

Compared to buying:
Manifold + making it strong $300-700
Turbo $1700
Intercooler piping mods $100-200+
Dump pipe/exhaust mods $100-200+
Water and oil lines $100-200+
Wastegate $500-800+
Labour $heaps
+ whatever bits I forgot
Plus the hassle of having your car off the road for days/weeks. With the re-cored twins you could do the whole job in a day, probably even by yourself.

Yeah you make a good point. I paid $1400 for my new GT35R, but you have to factor the costs of manifolds, dumps, wastegate, FMIC piping mods, etc.

[stradlater]

I still don't subscribe to the idea, but I'm sure it'll arouse some interesting discussion.

I don't think your giving it a fair price comparison though.

Because once you uprate the turbos, you really should get a bigger exhaust, and probably should get bigger intercooler pipes too, oh, and probably a bigger intercooler, so at that point your upgrading most things anyway.

[Dieseltrain]

IM all for it!

I know of these on a Stock 1JZ making 270rwkw with all stock pipework and manifolds @ 20psi boost. 440 injectors + stock pump with Pfc. ( wont increase boost as the motor has over 250,000kms on it). Its a manual and makes full boost at 3,800.

I think you would definately Power port the exhaust manifolds, and match port the factory pipework! ( The recored ones have larger openings on the inlet sides of the housings). Hybrid FMIC will do fine still, 3 inch zorst will do a good enough job too, and same with the fmic pipework.

Also, Stock looking, DONT have to get it engineered for Rego or Cop Bait!

Also another set i know of making just under 300rwkw with 256/264 cams in it!

I would be looking into these mainly for the ease of engine bay appearance.

But im sure lots of people will just say " No way man Single all the way".

[Dieseltrain]

Only thing you would have to cost in.... Stally

[The Real Roadrunner]

i would be agaist it for a variety of reasons,
4k + labour to R/R + tune + injectors + power porting and a lot of other small things to make it all work well will soon leave you with a very empty wallet + small turbine housings and only 320odd rwkw.

if you want to do it that way why not just buy a HKS T3G kit for similar dollars?

you could easily have a GT30R or bigger on there for similar $$$$$
with a power potential closer to 400rwkw (for a GT35R) and similar boost response.

i like the idea of it being a 1 day job but the reality is both jobs could be done in similar time once you factor in power porting and other bits and pieces.

if i had a 1jz i know what id do (actually i do and im doing just that)

cheers
linden

[Dieseltrain]

Why do people think that 300rwkw is not enough nowadays?

the main point i like is the fact it looks factory, so no need for engineering, and the way the boys in blue and the rta are cracking down on things, would definately help!

Sure the T3g's are a great upgrade, but your going to pay near 3K for a 2nd hand set as apposed to brand new turbos. Also they are still aftermarket and not stock housings.

Although i have a mate whom is in talks with GCG atm to rebuild the HKS T3G's with Ball Bearing cores!!! Gonna cost an absolute BOMB tho, but he is keen to see the results.

[Ribfeast]

The reason I would sway away from T3G is their lag, and age, difficulty of sourcing parts etc. These would be brand new with warranty from an Aus company, and ball bearings instead of the T3G plain bearings.

They should flow just as much as a big single, I'd be interested to confirm the CFM of a GT30 or GT35 vs a pair of GT2560's.

Stolen off Soarercentral:
http://soarercentral.com/sc-forum/me...tml?1142578620

Garrett GT2560R's compared to CT12a's
with standard housings for each, and a modified CT12a housing to fit the roller turbo:




What a HKS T3G / Garrett GT2x 60 trim compressor wheel looks like
- compared to CT12A(1JZ TT) and CT15B (1JZ VVTi) Soarer OEM compressor wheels




I have an air compressor, dremel, and a set of spare 3 to 1 exhaust manifolds that I can have a go at porting out myself, and fitting the whole lot would be free. Going big single or not, I would still need injectors, strong trans, and aftermarket computer to take full advantage of the setup, so we'll leave that side of things out of the discussion

[A-man]

i went through this before i bought the ebay steelies....

i dnt have a supra anymore i sold it but anyways.

my pov is that more is always better, those steelies i was running 20psi through no worries, i had engine problems though this was caused through fatique of the engine... plus posible overheating of previous owner. anyways i did the maths

for people in perth i kno of with 1jz and a big single like a t78 etc. by time they spent there money on the kits to fit them they run out of money for other bits like ecu, injectors, cams etc. and from what ive seen they only really make 330hp or similar at the wheels, to me 5 grand for 40rwhp or even in some cases 30rwhp is alot of coin to shell out.

thats y i went to steelies and i never looked back, plus it was cheap i did inquire about the bearing internals etc. and it was much the same, in that situation the manifolds rnt really that crash hot i dont know what they would b like as far as porting goes either so maybe in that sense the single might be easier. having said that the t3gs and similar im sure there would b some sort of other internals you could use to rebuild them.. like maybe ct20 wheels or somethin for example (not sayin thats wot fits)

[The Real Roadrunner]

not saying 300kw isnt enough but if you want a streeter the stockers are probly the best thing for the job (with dumps and some sort of ecu that is).

after that if your going to the effort of spending 4k on rollers at least go to the effort of powerporting the turbine housings + all the inlet and outlet pipes to suit the job, by the time you do that it will cost more than a decent single setup.

don't get me wrong im not saying its a shit idea, just if your going to do it atleast do it the right way.(and doing it the right way ain't cheap or quick)

cheers
linden

[Ribfeast]

Well said and good points

I just want 300kW with similar response to the eBay steelies I have currently (or better).
I guess for this project to work I would really need a daily driver so I could do it all without rushing it. Would I need to get a big single engineered (car currently engineered with the twins), and would it be difficult to do so? Car has standard ECU...

[Dieseltrain]

Not sure about this, but a theory.

Would need stock fuel system, stock Ecu, Mega quiet exhaust, but even the soarer ecu's run so rich it may struggle to pass because the single would have different boost responses at different rpm... Therefore, where the stock turbo's make like 10+ psi at 3krpm, they are burning more fuel thus providing a leaner mixture and making the EPA peoples happier...

However , A single @ 3000 might make 5psi, Would the ecu will still provide a 5psi mixture graph or would it be richer as its still @ 3000rpm and the cross reference of the timing and fuel maps cause a much richer mixture?

I dont know, but something to discuss...

Either way... Single or Twins, you will need a Stally as a daily driver imo. Ben did.