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Building for response/anyone using a Precision 6235?


el_bandido
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I've had to bin off my V8 plans, as I'm orchestrating a move to the USA and (as far as I can work out) the car needs to have its original engine block and body to qualify for export.

 

With this new goal in mind, I still want something that drives more like a V8 (more linear power) without losing the 2JZ block. The biggest piece of this puzzle is the turbo. The 6235 caught my eye as it seems to be geared towards low lag and good flow, but I suspect it might still be too big (rated to 700hp). I'm not interested in anything hugely above 450hp but I would quite like to have as little lag as possible (something that feels more like a BMW N54/N55 to drive). I'm going to be sticking a 1jz-gte vvti head on my 2JZ GE block and using a 6boost manifold, which appear to have a good range of flange options so I'm hoping that will give me plenty of scope to find the right turbo. I suspect keeping the CT15b on will get me about 80% of the way there, but I'm not capable of driving a car without abusing it and I want to hit that 400hp figure at a minimum, which I think is the top end of reliability for the CT15b. There are a few other turbos with T3 divided housings that look like they might fit the bill, but I'm yet to find anything else that has specs as impressive as the Precision range.

 

Has anyone else been chasing response rather than top end? I'd be interested to see what successes/failures people have had in this regard. I'd also be interested in finding the right cam options.

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Looks like that's too big. Might go for the 5 series with the aluminium forged wheel, there is one on a t3 that only rates to 525hp but looks like it will boost stupidly fast. I want the car to feel like a big NA engine rather than a turbo kick.

 

Edit: it's the 5530 I'm looking at

Edited by el_bandido (see edit history)
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The 5858 might work, would be nice if there was the option for a divided v-band or t4 housing. The v band .64 housing looks ideal. Really can't stress enough that I don't care about top end horsepower/flow above 6500rpm, I want response and a fat torque curve. I'd rather 2000-6500 rpm than 4500-7000 as the meat.

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the problem is that the smaller turbine housing you go the torque drops of massively as they just cant flow even my T6765 with a .68 housing my torque drops from 510ftlb @ 5000rpm too 420ftlb @ 6400rpm

Im in the same boat as you mate don't want top end power but better spool I keep looking at the gtx3576r and gtx3076r , its a hard thing to juggle as the smaller the turbo the more boost you need to have the more boost you have the hotter the charged air is so have to back timing off and loose power

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I'll be interested to see what you end up with, as I've been looking at low rpm spooling turbos for a while.

I'm currently using a borg warner s362, which starts spooling around 3k rpm, and is making full boost by about 3800rpm.

Ideally I would like something that spools similar to a stock tt setup, but without losing much power in the later rev range

 

 

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I picked the 5530 based on the BMW n55 turbo spec, the A/R is a guess, but it's apparently based on the smallest Borg Warner EFR billet compressor wheel. The stock 1jz-gte vvti single turbo hits peak boost at about 2400-2600 rpm, which on 20 year old tech is definitely something I can surpass even with the 450hp goal in mind. I want the boost to be there from the word go, having driven a tuned up 335i, it's exactly the feel I'm looking for. This is why I'm fine with power dropping off around 6500rpm, I'm only wasting 700 revs. My end goal is to have the 8 speed if SRD get it working, so having a big low/mid range torque will couple nicely with 8 gears. It would be the same benefit on the 7 speed dct. The vvti 1j head is designed specifically to spool a turbo quickly, as is the 6boost manifold. I'm torn between the 5530 and 5858 at the moment. If either of them are available as a twin scroll then I'm sold.

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Manifold wise have you considered a log type?

 

Very cheap and really improves spool/response of the turbo. Downside is that they don't really sound great (IMO of course). A high compression, VVTi engine on a log manifold with a nice small turbo would be a pretty good combo :)

 

- - - Updated - - -

 

Manifold wise have you considered a log type?

 

Very cheap and really improves spool/response of the turbo. Downside is that they don't really sound great (IMO of course). A high compression, VVTi engine on a log manifold with a nice small turbo would be a pretty good combo :)

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