1JZ T3 manifold options

Zedhex

Zedhex

Member
I have a 1JZ toyota with an HKS3037S turbo kit. The original exhaust manifold from the HKS kit had a T25 inlet - which meant great spool, but did choke a bit at high revs. When the manifold fell apart sending shards into my turbo, I had Owens rebuild it with a GT3076R core. However, that now leaves me with a problem: Garrett recommend a T3 inlet with the GT30 range, but trying to find a decent 1JZ manifold with a T3 flange on it is not easy. The only options available are all pretty crappy. I tried a Japspeed RS tubular, and it was basically a bunch of pipework (admittedly well made) for a T4, but with a T3 welded on instead - which resulted in a serious step cutting into the gas flow where the pipes meet the flange. That probably would not matter for peak hp, but for spool, its a major no-no. Every other manifold (XSPower, ebay china manifolds etc.) I have seen have the same problem, they all have large pipework for a T4, but with T3 flanges bodged on top. The single exception to this seems to be the 6Boost from Australia - but at over a grand, they are a little out of range for me. The only option appears to be to go for a T4 flange, but that has problems of its own. I have a T4 manifold which will fit, but the only turbine housings available for the Gt30 are all pretty large (1.06 a/r divided from ATP) which would cut into the main reason I want a GT30 - fast spooling. I very much doubt that a T4 hot side with a 1.06 will ever spool at less than 3500.

I am not interested in big power: what I want is decent mid range (spooling at 3K please), with top end of around 425 - 450bhp. Does anyone know where I can buy a decent 1JZ manifold that was actually designed for a T3 (i.e not a T4 bodge job)? Or do I have to get a custom manifold made up?
 
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Why don't you move away from the HKS turbo and look at something different? If you can get a 1JZ manifold with an as designed T4 flange maybe look at precision turbos for example? I have a 2JZ, T4 with a Precision 6776 turbo, .67 AR manifold. Dual ball bearing, pretty good spool and decent quality
 
Swampy442 said:
Why don't you move away from the HKS turbo and look at something different? If you can get a 1JZ manifold with an as designed T4 flange maybe look at precision turbos for example? I have a 2JZ, T4 with a Precision 6776 turbo, .67 AR manifold. Dual ball bearing, pretty good spool and decent quality
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I don't think its a turbo issue -I already have a dual ball bearing turbo (and its really a Garrett now, with the GT3076R core), and I know it will spool OK with a T3 housing - but there just aren't any good T3 manifolds out there (other than the 6boost for £1200!). The problem is that I don't want a T4 and I want to stay with the 1JZ. A T4 really needs at least 3 litres of swept volume to flow enough at lower engine speeds to give good spool-up, so I don't want to go there.
 
Thanks Phil, I'll check them out - one further thought though: does anyone have a 1JZ on a T4 manifold that spools at 3500 (or less)? if so please let me know your spec.
 
Zedhex said:
A T4 really needs at least 3 litres of swept volume to flow enough at lower engine speeds to give good spool
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What flange a turbo has has very little bearing on how a turbo spools.

Also, unless you going twin scroll, ATP make T4 GT30 housings as small as .63...
Turbine Housing, T4 Undivided inlet 3" V-Band outlet, GT30R (GT/GTX3071R/GT/GTX3076R/GT30 : atpturbo.com

Finally, the reason they only do 1.05 divided, is twin scroll if done right improves spool that much that'd prob spool as fast as the .63 but with far less pre-turbine backpressure etc.
Turbine Housing, T4 Divided inlet 3" V-Band outlet, 1.06 A/R for GT3582R/GTX35 : atpturbo.com
 
After reading a bit more, you may be right - I already have a T4 divided manifold for a 1JZ, so a 1.06 A/R divided housing might work. So why do Garrett recommend a T3 for the GT3076?
 
Zedhex said:
After reading a bit more, you may be right - I already have a T4 divided manifold for a 1JZ, so a 1.06 A/R divided housing might work. So why do Garrett recommend a T3 for the GT3076?
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They don't 'recommend' it's just very few cars that have T4 flange manifolds run a turbo as small as a GT30, so they never made them T4 as it would be a tiny market.

No truthful 'need' for T4 flange until well over 600bhp, but flange dimensions have very little affect on spool.

Just because Garrett do or don't do it don't make it right though, the entire GT and GTX series of turbos until ~GT42 size are drastically under-turbined, far from optimal, just spool ok for their size.
 
Struggled my arse off to find a decent T3 flanged manifold for mine.... Had one made in the end. Should have just got a turbo on a T4 and had done with it, would have been cheaper
 
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