300ZX twin TB intake? (Page 1/1)
fliphone NOV 30, 02:12 AM
I stumbled across a stock 300ZX intake that has a factory twin throttle body setup, I'm getting near the end of my LQ1 swap which obviously means it's time to start planning out the next car project that will consume my life. Originally I was heavily leaning towards a custom ITB setup, and while its still something on the radar, this twin TB thing might be a good in between. And from what a few minutes of googling and a 19 YO brain can piece together, theirs not any super big hurdles to jump apart from mating the ZX upper plenum to the LQ1 lower plenum. The ZX is a high output (225+ HP) DOHC V6 very similar to the LQ1 so airflow shouldn't be a huge issue, all you need from the intake is a MAP sensor, and find a way to adapt either the LQ1 TPS to the TB's or the ZX TPS to the LQ1 harness. The throttle cable couldn't be that difficult to mate up either, a little bit of fab work here and there and you'll have something pretty unique with a potential for slightly quicker throttle response(?).

ZX intake:
<img src="https://i.ebayimg.com/images/g/4bUAAOSwvtVg-Wp1/s-l1200.webp" alt="Nissan 300zx Z32 OEM VG30DE Upper Intake Manifold Plenum | eBay"/>

ZX Lower plenum:
<img src="https://conceptzperformance.com/wiki/images/thumb/1/12/1990-96-nissan-300zx-lower-intake-manifold_130504025474.jpg/300px-1990-96-nissan-300zx-lower-intake-manifold_130504025474.jpg" alt="Lower Intake Manifold - Z32 Wiki"/>

Not the best pic but this shows the LQ1 lower plenum



I'm sure this is a bigger undertaking than I'm imagining, but are there any other potential issues anyone could see running this intake setup?
Cheers!
82-T/A [At Work] NOV 30, 08:11 AM
I think it would actually be really cool. The only thing I'd be curious about is how it sits on top of the engine dimensionally. Would there be clearance issues with the trunk lid for example?

The other thing, which has more to do with the performance of it... is, how would it affect the performance of the engine? As you know, intakes are generally designed with a certain length and diameter in mind to provide a certain amount of performance at a specific RPM / operating range. That doesn't mean factory is perfect... it's just good enough in a balance between performance, sound (noise levels), and economy of scale (manufacturing that is). I don't know how to do this... so my opinion here is just on the theory of it... but you'll want to make sure that what you're installing (when ideally complete), provides the right intake length and air velocity for the type of performance you want.

I could be completely wrong on this, but these aspects determine the characteristics, so someone correct me if I'm off:

Runner length = sound / flow dynamics
Runner size = volume / speed dynamics


More or less... if the runners are short and small, you'll end up with fantastic off-the-line performance at the expense of top-end performance. If the runners are too long and too big of a diameter, it'll be an absolute pig off the line, but may scream at the top-end / highway. So generally, you'll want the intake to be matched with the displacement (assuming 3.4 here), the cam you've selected, and proportionate flow of the cyl heads.
fliphone NOV 30, 11:31 PM
Ok guys here me out........ snagged an intake setup from a friend of a friend........and there might be something to work with here





The runners are "pointing" in the right direction so the air will travel straight to the valves
fieroguru DEC 01, 07:04 AM
First thing to check is the cross sectional area between the two. If the 3.4TDC runners are larger than the Nissan, then you will not want to use it. If they are slightly smaller, that is OK.

The biggest challenge will be the spacer plate(s) that will take the round ports of the upper intake and gently contour them to oval w/o adding too much height. Unless you can do that yourself, that will likely be a $2K-3K part to have someone design in 3D and have CNC machined. The quality and precision of this part will make or break any performance gain from this modification.

The additional complication is the current bolt holes in the lower intake will be within the ovals of the upper, so you will need to run a multi layer adapter to move all the bolt holes further away from the runners for proper clearance.

Not sure what you are trying to accomplish with this swap. If you want more HP in the upper power band, just make the TDC runners shorter with a larger plenum. This as been done several times. If you want more lower end torque, make the runners longer by strategically cutting and welding 2 TDC intakes together to extend the runners 1-2". Much beyond this and you will need to modify the engine bay to rear trunk wall.

Raydar DEC 01, 06:52 PM
When I bought my engine, it also included a shorter runner LQ1 intake with a large plenum and an LS throttle body, as well as the stock pieces.
You know I'm going to give it a try at some point. But since it's going in a notchie, I'm not sure it will fit.
ericjon262 DEC 09, 02:15 AM
are you after performance, or looks? at a glance, I would guess the runners between both intakes have about the same runner length, so powerband change would likely be minimal, if you felt as though you needed more airflow, it would probably be far easier to put a larger throttle on the stock upper intake, if you wanted to take the powerband all the way to the moon and throw away the torque curve, you could make a breadbox plenum with a TB stuck on it anywhere.

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