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z31 engine swap. VG30DETT? RB26DETT?


Guest Mark300zxTurbo

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wow, you guys are full of some great information. I have alot to think about. I think I'm gonna grab some vg heads at a salvage yard, and port and polish them. if it goes well. then get a transmission. I looked up forged internals and they are pretty pricey. I think I might just get a crank out of a maxima, in indeed they had forged cranks. and Z32 rods. then if I find a good deal on forged pistons slap them in there. the only ones that I can find are like $1,000 a set though!

 

The Maxima crank is cast, though even if it was forged I wouldn't even bother swapping cranks. The cast crank is very strong... you'll have a very hard time breaking that thing.

 

For forged pistons you could go to Atomic Speedware or BRC Performance for very affordable pistons that are custom made to whatever specs you want. If you use the Z32 rods, be sure to let them know that so they will make the hole for the pin correctly.

 

The stock pistons are quite strong though. As long as your fuel system is top notch and you don't allow any detonation, the stock pistons will handle some high power. Aftermarket pistons will be slightly lighter though, which will help make more power so they definitely wouldn't be bad.

 

anyway, I was doing some research on transmission. and was reading about this guys 300zx with a 240sx transmission. here is what he wrote. "the transmission is out of a 1991 240sx it has better gears and shifts alot smoother than the stock trans did." do they actually have the same transmission at the 300zx? if so, would I be correct to quess that its the FS5R30A? if so that would be so badass!

 

Edit: I did some looking around online and found this: "the FS5W71C found in any 5 speed non turbo Z31. This transmission is internally the same as the transmission used in the 240SX, 180SX, Silvia, etc." does anyone one know if its the same transmission case? or is it just the same internals?

 

Transmission wise I would use the 87-89 Turbo 5-speed. Its the FS5R30A and is strongest of the Z31 transmissions. The early turbo 5-speeds were Borg Warner T5's and could likely be built up to be a very strong tranny.... but I've banned Borg Warner from anything I own because they pretty much make ♥♥♥♥. If you ever get a Maxima you'll understand what I'm talking about. :lol:

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actuallyl, the Z31 woudlnt require tht much modding to get a VG twin cam in there. they came stock in japan in the 88 model years. it was called a 300ZR. it had a VG30DET, single turbo. that would be the engine to get if I were you.

 

The VG30ET is a good engine no doubt, but the DE/TT IS that much better. stronger everything and also capable of 2000 more RPM of usable powerband.

 

but then what do I knwo, Im an I6 guy just jumping around forums!

 

i thought the 300zr had an RB20?

 

**edit**

 

im an idiot ;) i was thinking of the 200zr

 

on the transmission, if memory serves, i think the output shaft has to be swapped out on the s13 trans. i do believe the s12 trans is a direct fit (into your housing)

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  • 2 weeks later...
The later Z31 Turbo tranny is supposed to be stronger anyways.

True, but consider the numbers....

 

Compare there were 5,187 87-89 turbos made with the manual transmission to the 135,969 84-89 NAs made with the manual transmission.

Source: http://www.az-zbum.com/cgi-bin/z31registry.pl

 

The NA transmission is more than strong enough for 95% of the Z31 population. Once you start putting 400 hp down at the rear wheels, then you might want to consider the 87-89 turbo transmission.

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  • 3 weeks later...
Guest 84t-tops

This is my first posting as well, so let the introductions begin: My name is Joe and I am in the process of obtaining an '84 VG30E. The current owner has receipts that the enigine in the car now was completely rebuilt less than 14K miles ago, so I'm very excited to hear about the hp potential of this engine. To swap out a brand new motor would just be stupid. So my first question would have to be "How far can I go on stock internals and what do I have to do to go turbo?" Is my E weaker than an ET, or is it the same nearly indestructable workhorse you have been discussing in this thread?

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Guest 84t-tops

Forgot to mention, I know what I need to go turbo as far as parts, I'm just wondering the best way to go about it. Should I use the turbo mani from an ET or just skip to an aftermarket alternative, etc. etc.

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The VG30E and VG30ET engines are virtually identical. The only real differences are the pistons, oil pump, and some idle control junk on the intake plenum. Heads, block, crank, rods, and most of the motor is exactly the same.

 

No, you don't need to do much of anything internally to an NA motor to put a turbo on it. But you will need to swap injectors and you're best off intercooling it.

 

Read more about an NA to turbo mod here:

http://www.redz31.com

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Guest 84t-tops

I have read this, but it mostly just covered the conversion from an E to an ET, not any mods to be done in the meantime. I was just asking which parts I should use from a turbo car and which I was better off just getting aftermarket, as I would probably have to swap them anyways once I start pushing more boost. My goal is not to end up with a stock turbo z31, which is what that write up covers. I'm not into wasting time and money with swaping parts into the car that I'll just take back out later.

 

you're best off intercooling it.

This is a great example of what I mean, and I thank you for it. Why would install it the stock way when I could just save some time and intercool it right off? You're right, I wouldn't. So injectors and an intercolling system should be aftermarket, but what else is worthwhile and not a million dollars that makes sense to do at this point?

 

Also, I'm very glad to hear that the stock NA internals are strong enough to withstand some boost, as a rebuild is out of the question. This car is intended to be a daily driver. A kick-ass daily driver, but still not something I can do without for a long period of time. Also, the engine was recently overhauled by a Nissan Certified Master Technitian, so why mess with stuff that's as good as new? I wouldn't even consider a rebuild till I'm pushing the safety on the stock internals. Thanks for that bit of good news!

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Guest 84t-tops

How similar are the ports on the E vs the DETT heads? Would it be possible/plausable to do a twin-turbo setup on the SOHC using the maifolds from a DETT? Would this even reduce turbo lag enough to be worth it?

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ok get a sr20det with a big turbo big exhaust and front mount and tuning under $3000 in parts you will make 400hp at the wheels and be reliable and if you turn the boost down you will get 28mpg thats what im going to do just waiting for the old 6 to give out

 

Why downgrade? Downgrade you ask? Because the VG will move a car of that size a hell of lot better than the SR20 could ever dream of doing. The VG is a torque monster and doesn't require a lot of revs to move the car, which makes street driving much more fun. Good luck getting that VG to break... you'll have to run some high boost and make it detonate or just not run any oil in it. :lol:

 

Besides, it would be cheaper to get the VG up to that kind of power than it would to buy an SR20 and the parts for it to reach that power.

 

How similar are the ports on the E vs the DETT heads? Would it be possible/plausable to do a twin-turbo setup on the SOHC using the maifolds from a DETT? Would this even reduce turbo lag enough to be worth it?

 

The ports aren't quite the same that I remember. I know at the very least the flanges themselves are larger on the DE(TT) than the E(T). It would be easier to just run a single and lag differences would be negligable. It would also be much cheaper doing a single setup than a twin in most circumstances.

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Guest 84t-tops

Thanks to MtCookson for the info. I thought for sure lag differnces would be substantial...My bad.

 

So this is what I've gathered so far...

-go single turbo

-use stock internals and carefull tuning up to about ~400rwhp

-most parts for the ET can be swaped over to the E

 

But the question remains, what (other than an intercooler and external blowoff valve) am I better just getting aftermarket from the get-go? If I'm just going to have to swap something out later, I'd rather just do it right off and save the time and money.

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ok get a sr20det with a big turbo big exhaust and front mount and tuning under $3000 in parts you will make 400hp at the wheels and be reliable and if you turn the boost down you will get 28mpg thats what im going to do just waiting for the old 6 to give out

 

You can get 25-30mpg out of a VG30E-T, just chip your stock ecu tune it right in and OUT of boost. Lean it out when cruising.

 

84t-tops- Your going to want an recirculating BOV with a MAF based system unless you tune for it. With a open BOV, it'll fall flat on its face when you shift. Because the MAF measures the air, then when a non-recirculating BOV opens that metered air goes out and the care bogs because its too rich.

 

Unless you tune the computer to work around an open BOV dont get one

 

As for all the performance parts, just look around Z31 sites.

 

~Alex

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  • 3 years later...

 

I personally wouldn't want a super high redline since I drive my cars on the road mostly. Having more power down low makes the car much easier to drive on the street... that's why I dislike most inline engines. :lol:

 

Sorry to revive a REALLY OLD thread but this is just incorrect.

 

Given the same displacement Inline engines usually make WAY more torque than V engines by design. Mostly due to longer stroke. Also, inline engines are typically stronger than V engines due to more main bearing caps on the crank.

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