Z31 Tb

[Vintage]

My dad has 5 or so Z31 parts cars, so when I wanted to get a bigger throttle body, the Z31 unit was an obvious choice, being that its very similar to the 240SX unit, and was available to me for free. Also pictured is the spacer I had made up by my stepfather who works at a machine shop, also a freebie.

 

Z31 on left, stock '83 ZXT on the right.

 

Spacer

 

Spacer test fit

 

I know this is really nothin special, but I never could find anybody else using the Z31 tb on an L6, and I'm kinda proud that it was all free. Incase anyone wants to know, the ID of the TB, after the taper, is about 58 mm, on the start of the taper, I think it was 61 mm. On a side note, anyone want that turbo intake manifold?

[cockerstar]

So everything is working 100%?

 

Good job man!

 

I would personally clean up that space just because its a straight chunk of metal, but thats just me.

 

Feel anything noticeable?

[BRAAP]

My dad has 5 or so Z31 parts cars, so when I wanted to get a bigger throttle body, the Z31 unit was an obvious choice, being that its very similar to the 240SX unit, and was available to me for free. Also pictured is the spacer I had made up by my stepfather who works at a machine shop, also a freebie.

 

Z31 on left, stock '83 ZXT on the right.

 

I know this is really nothin special, but I never could find anybody else using the Z31 tb on an L6, and I'm kinda proud that it was all free. Incase anyone wants to know, the ID of the TB, after the taper, is about 58 mm, on the start of the taper, I think it was 61 mm. On a side note, anyone want that turbo intake manifold?

 

 

Very cool. It is this sort of ingenuity that Z car owners are known for.

FWIW, I just went out to the shop and measured an ‘85 Z-31 TB at exactly 54mm (Mitutoyo calipers, blades against the butterfly from the manifold side). The stock L-28 TB is 50.5mm. The Z-31 TB offers a 3.5mm gain in ID. Regarding CFM at a given pressure drop, this gain is probably akin to profiling the stock L-28 throttle shaft, and at that, power gains for stock or even mild performance setup will be nill to barely measurable. Below is link regarding big throttle bodies. You might want to read through it. Don’t let this deter you from pursuing this modification, just don’t expect much in the way of noticeable seat of the pants performance gains. There is more to be had power gain wise for stock or mild performance engine in just getting the ignition timing and Air Fuel ratios just right, (typically, advance the ignition timing between 5-7 degrees over stock is good starting point for noticeable gain in torque everywhere in the power band).

 

 

 

So everything is working 100%?

 

Good job man!

 

I would personally clean up that space just because its a straight chunk of metal, but thats just me.

 

Feel anything noticeable?

 

 

Cockerstar,

On a stock or even mild performance setup, the only difference he would feel is that ¼ throttle now makes more power than ¼ throttle of the old TB, but power at WOT would be NO gain, regardless if it is N/A, or boosted.

 

Regarding bigger throttle bodies and possible power gains to be had, either real or perceived, here is some real good reading….

 

Click ME for a good discussion regarding stock, large, and HUGE throttle bodies..

[Vintage]

I havnt got everything all together, and I wont really be able to comment on any improvement because the only driving I did on my car before tearing it apart for the turbo build was onto a rollback and into the driveway. However, I suspect once I match the intake side of the spacer up, and port the intake runners a bit, it should be a worthwhile improvement over stock. My car will also be using a Z31T ecu and maf.

 

Edit- Braap, I have already read all the info on the bigger throttle bodies, long time lurker here. I knew going into it that gains would be minimal if any at all, but I figured since I could do it for free, I might as well. I do plan on enlarging the runners on my N42 intake, and possibly building a new intake later. I have begun to model one in my Drafting class in my spare time.

[cholag]

i have a 240sx TB i havent put it on but i was just wondering why do you have to have a spacer and how thick does it have to be. plus on the 240sx TB it has three vacuum line holes what should i do about the other two?

[Vintage]

The spacer is needed so the stock throttle linkage maintains correct geometry, and it also may be needed for the bottom-cooled tb's water lines to clear an EGR manifold.

 

I'm not sure how thick it needs to be on a 240 tb, I believe the Z31 piece is shorter. I think most guys run a 1 incher.