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Discussion Starter #1
Can anyone out there tell me what the biggest Compressor/Turbine wheel I can put on the CT12 with modification (meaning boring it out for more space)?

I a company in Japan (Revolfe S.A.) is doing an upgrade of the J-spec TT (CT12B) with a bigger wheel in a bored out housing, strong actuator and a Ball Bearing CHRA (Center housing rotational assembly). But this will cost at least ~$4k.

I want to do this myself and send out an used turbo for boring and installing new wheels, B.B.CHRA, and a stronger actuator. I know this may sound stupid considering all he options of single turbos there are now days. But I want a stock looking engine (smog).

Can anyone tell me the manufacturer/size or any constructive suggestions or ideas they may have?

Thanks guys,
Kaz
 

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My understanding is that you cannot reliably upgrade the stock US Spec. Supra turbo's. The shafts are too small and any larger compressor wheels have resulted in snapped shafts. I don't know anything about the JDM ones though, it may be a different story.
 
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Discussion Starter #3
If you are swaping out the whole rotating assembly (cartridge with compressor/turbine) and boring out the housing to accomodate the size increase while still allowing it to fit the stock manifold you wouldn't have any shaft problems. I'm asking here I don't know.
 

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for 4k I would just invest in a regular turbo system like a SP 57 or 60 setup that way you dont have to add more money for a fuel system. when your throwing down 4k, 1k more isnt much. then your done with it.
 
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Discussion Starter #5
Valid point but some of us want to keep our sequential TT set up if we can. Myself I like the whole technology thing.
 
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Discussion Starter #6
kzsupra1 said:
Can anyone out there tell me what the biggest Compressor/Turbine wheel I can put on the CT12 with modification (meaning boring it out for more space)?

I a company in Japan (Revolfe S.A.) is doing an upgrade of the J-spec TT (CT12B) with a bigger wheel in a bored out housing, strong actuator and a Ball Bearing CHRA (Center housing rotational assembly). But this will cost at least ~$4k.

I want to do this myself and send out an used turbo for boring and installing new wheels, B.B.CHRA, and a stronger actuator. I know this may sound stupid considering all he options of single turbos there are now days. But I want a stock looking engine (smog).

Can anyone tell me the manufacturer/size or any constructive suggestions or ideas they may have?

Thanks guys,
Kaz
Hi...

My stock turbos have been rebuilt by a company in the UK. There are a few of over here with these turbo's and I have never heard of any reliability problems but I guess that is dependent on the quality of the workmanship and the parts used. My turbo's have been rebuilt using Garrett internals.

Converting from £ to $US my turbo's cost US$2575.00 fitted.
 

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Re: Re: CT12 upgrade

Gavin Loughton said:


Hi...

My stock turbos have been rebuilt by a company in the UK. There are a few of over here with these turbo's and I have never heard of any reliability problems but I guess that is dependent on the quality of the workmanship and the parts used. My turbo's have been rebuilt using Garrett internals.

Converting from £ to $US my turbo's cost US$2575.00 fitted.
Any power estimate using this setup? I'm on the verge of going single, but would love to see how this setup worked out power/spoolwise.

Where abouts in the UK did you get this done? I am originally from the UK and visit frequently.
 
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Discussion Starter #9
Can anyone tell me what I can use?

My understanding is that you cannot reliably upgrade the stock US Spec. Supra turbo's. The shafts are too small and any larger compressor wheels have resulted in snapped shafts. I don't know anything about the JDM ones though, it may be a different story.
This is the exact reason why I want to replace whole internal.


for 4k I would just invest in a regular turbo system like a SP 57 or 60 setup that way you dont have to add more money for a fuel system. when your throwing down 4k, 1k more isnt much. then your done with it.
Yeah, I don't want to throw away $4,000 instead, I want to do it myself so I can save alot of money.

My stock turbos have been rebuilt by a company in the UK. There are a few of over here with these turbo's and I have never heard of any reliability problems but I guess that is dependent on the quality of the workmanship and the parts used. My turbo's have been rebuilt using Garrett internals.
Do you know what kind of Garrett internals they used? How do you like this setup?

Can anyone tell me if any Garrett GT series internal will fit the compressor/turbine housing of the CT12? If not are there any other brand internal that will fit a CT12 housing (bored of course)?
 
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Discussion Starter #10
I checked this out for a while and asked many-a-expert. Everyone said stay away from it if at all possible. I found a company (forgot the name) that would bore them out and put in larger wheels for much MUCH less than 4 g's. But it's way too unreliable. Trust me, I've checked this option out - it's the law of open market essentially. If this was such a great option everyone would be doing it.
 
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Discussion Starter #11
Oh I did forget to add that you can throw in some decent sized twins, I know a guy in Atlanta has done this. He replaced them but I doubt he kept the sequential setup. If you get an SP57 you'll make more power w/ the same amount of lag you get in the stock sequential twins. Plus it'll be a LOT more reliable.
 
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Discussion Starter #12
it's the law of open market essentially. If this was such a great option everyone would be doing it.

I know its not the best option.



Oh I did forget to add that you can throw in some decent sized twins, I know a guy in Atlanta has done this.
Do you know exactly what he did? Did he just replace the whole turbo or just the wheels or CHRA or the whole stock setup (header etc...)?



Can anyone tell me what I can fit inside the CT12???
 
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Discussion Starter #13
Kaz check my post for the latest on Turbochargers.com. Peace bro
 
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Discussion Starter #14
I was referring to changing to mid-sized twins instead of HKS twins. The other problem is that the stock sequential setup is too harsh for aftermarkets, you're gonna have to run TTC, and then you might as well go single.........trust me - just get a single that isn't polished and you'll look pretty stock.
 

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the closest sized garrett is probably the GT-15...

I know why you're considering this route but you may find it too much difficulty for too little gain.
As many reputable turbo places will tell you the CT12 is a good little turbo but pretty much at it's limits. Plus the flow of the stock manifold to the turbo, even when ported, isn't very good. Even with the turbos upgraded and the manifold completely flowed you will still not realize the performance of the average single on low boost and stock fuel.
You can always have a nice Hi-flo cat welded into the DP for your single and tune it to pass smog.
If you like the twins that much just do all the BPU stuff you can and be happy with still beating most cars on the street... :D
 
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Discussion Starter #16
The problem with all this is that you just can't get away with a big turbo conversion, and pass smog in CA - be ti with a cast manifold, catalyst or whatnot. Wasn't that the original point to this post? Everyone knows that a single or aftermarket twin setup is the best way to go, performance-wise. As a fellow CA Supra owner, I too would like to know of a way to substantially increase performance while still passing a smog-check visual inspection. Until a shop steps up and does the necessary paperwork to get a CARB EO number for their kit, a single conversion will be out of reach for many of us!

Bob
 

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There is a guy from m2performance .....

Just today I spoke with a guy from the RX-7 site, m2performance, he posted a thread on here about doing just that - boring out the stock housings, replacing the center sections w/bigger garrett centers, porting the exhaust manifold, upgrading the wg actuators and replcing the oil/water piping. He was talking about getting 500rwhp on pump gas at 17/18psi. The cost he mentioned to me was 3500 bucks. He did say you would have to upgrade injectors (720/740's) and fuel pump, probably adj fpr as well. He is offerring to anyone willing to go lab rat with his kit, a decent amount off the price (700 bucks) to install his kit and advertize dyno numbers, etc.... Send the guy an email if you are interested, I'm going to pass. His name is Bret at m2performance.com.....good luck.
 
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Discussion Starter #19
does anyone know of some turbos u can just slap on the stock manifold? I dont understand why there is not. Like on a eclips how u can just buy a decent turbo and bolt it on the stock man. This would be cool cuz u could keep it looking stock and wouldnt cost much. It pretty much sucks that when u go single no matter wich way u look at it your out about 8-9 grand and the value of your car probly goes down.
just my opinion
-joe
94 tt bpu
 
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