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I'm going to upgrade my old T-51 (basic early generation) with either a GT-42xx or a GT-45. Both will work with my HKS T4 (single wastegate-44mm tial)manifold. While there is a good amount of information on 2JZ's with the GT-42 seres turbos, I haven't found much on the GT-45. T04R.com doesn't have data on it in their Turbo section at all. I thought this might be good for the people out there thinking about upgrading to one like myself. The performance, specifically the responsive difference is the real thing that isn't well known yet. I've read speculation on it having similar performance to the Gt-42 seres turbos. But the one thing that grabs my attention right off is THE SIZE of it. IT looks like a HUGE bodied turbo to me, a 5' outlet/inlet!
I have a 3.3L, ported head with 1mm oversized valves, AEM-EMS, HKS-DLI, 4' core FMIC, 1000cc injectors, Virtual Works Plenum W/90mm Accufab throttlebody, 6-speed, ect, ect. I have good supporting mods, and would like a bit more power ([email protected]/[email protected] currently-no NOS) as I feel the T-51 isn't the best match to utlize the engine mods. I'm not looking for just a dyno sheet with a high peak HP number, I want streetable power and not an excessive amount of lag. I realize there is going to be some. I was all ready to buy a GT-4204 when several people told me that would be a mistake, that a GT-45 would be a better choice since I had the stroker/headwork/ect. Also when I upgraded to the Virtual Works Plenum from the stock one with 70MM TB (no other change), I actually LOST power indicating that the T-51 was lacking in the volume department.
While we all know the GT-42XX works well for the Supra, it isn't well known if the GT-45 does. Now, more than ever, Supra owners are buying stroker kits, having headwork, better valves, methanol kits and support mids that make larger turbo's more practical and useable than before, when adding a big turbo and a big peak HP was what people wanted. Supra owners are always on the edge of performance, wanting more and getting it through research, better products and taking the chance of what might work better. The Supra community is also much more supportive of trying new things! Which is a very good thing. Thy adding a "unique" modification and discussing it if you own a 300ZX or RX-7! To me, they seemed to think "if it hasn't already been done-it won't work". Not so here at Supraforums!
Also another question; would a shock tower brace (A TRD one in my case) be able to be used with a GT-45? I'm not sure there would be room unless perhaps a special manifold was used with it? I'm pretty sure the 4204 allows the TRD brace to be used.
So I'd like to open a discussion as to whether a GT-45 is a GT-42XX plus 1 (regardless of supporting mods) or is it more for people who want top end performance and are willing to accept the short commings that come with a GT-47 and similar turbo's that offer that level of power. Or is it not a good choice for a 2JZ at all?
So what do you guys think? Is the GT-45 a streetable turbo? Is it a good high HP turbo? Is it a step beyond the GT-42XX? Or is the reason we don't see many of them on MKIV's is they aren't a good choice? Opinions, dyno sheets and evidence welcome!
 

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I have almost the same set up as you with GT45R.

3.2 - 3.3 stroker with Garrett GT4508R (80mm) with 1.28 a/r, race ported head, 1150cc injectors, aem and 6 speed. I'm happy with the responsiveness of the turbo. I had 74mm with .81 a/r before this and it does spool a little later than 74 but not by much.

Made 1033rwhp at 39psi with no NOS. In my opinion, go with it and go with 1.28 a/r!

No, I wasn't able to fit TRD tower brace but I have Full Race manifold so it might be different for you.
 
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