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Ljrb20det Apprentice

Ljrb20det

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Hi guys I'm new to this forum stuff but thought it would be a great idea to join to try and answer some of my questions I have.

I have a lj torana with a Nissan rb20det in it. Motor is from a 200zr z31 fair lady. Trans is a 4 speed jatco box from a r32 that is fully manulised with work done to the standard converter and shift kitted. Diff is a ford nine inch with 3.55 gears.

Mods to the engine so far is 700x300x75 front mount inter cooler, rb26 injectors, autronic sm4 computer.

As you can imagine I'm struggling for power at the wheels(145kw) at the moment.

First question is What is the turbo on my motor, it is still standard? I want a bigger turbo but am struggling for room so I want a turbo that has the same outside dimensions but bigger internals. Is the possible, or will I have to make an adaptor to mount of my exhaust manifold.

Second question is what ratio diff do z31 200zr fair lady's come out with? Is it 4.3??? I want to change my diff ratio to something lower and was thinking 4.11 or 4.3. This is a street driven car with a little highway driving!

Hope someone can help, I'm desperate for more power !!!!

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Dobz Experienced

Dobz

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Who tuned the car, What boost are you running? 145kw seems low but the auto won't be helping matters at all.

Where's a pic of the turbo? We don't have crystal balls we can look in to and magically see what your turbo is. Talk to Hypergear about standard turbo high flows.

As for your your diff ratio...... NFI this isn't the Z31 club, you're better off trying a google search on that one.

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blind_elk Grand Master

blind_elk

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The RB20 from the 200ZR is the red-top (NICS) version. They have a variable length inlet runner that changes lengths via a butterfly in the inlet. The butterfly is prone to jamming, and you usually end up with an engine with good bottom end and crap top end, or crap bottom end and good top end. Or, if you are using an aftermarket ECU, the butterfly may not be working at all (so you are probably stuck with the bottom end working).

Because the RB20DET isn't really all that grunty, you need a fairly tall (?, higher numerically) diff to get the car moving. For example, the R32 GTS4 (ECCS engine, 160kW) has a 4.375 diff ratio. When you upgrade to a RB25DET, you can easily drop to a 4.1 ratio. With either of these ratios, highway cruising is around 3000 rpm.

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Ljrb20det Apprentice

Ljrb20det

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Thanks very much for your help!

What is the variable length inlet runner that changes length via the butterfly in the inlet????

Is this an easy thing to check to see if it is jamming??

Is it easy to fix or replace?

Where abouts is this placed to on the engine??

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