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ITB Setup on a VG30e


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I've been kicking around an idea for a different intake option for the my z31 because the stock plenum sucks pretty bad and i think it would be cool to do something unique and potentially very efficient. My plans are to build the engine as much as i can without putting a turbo on it (ported heads, bigger cams, oversized valves, stiffer springs, bigger injectors, etc.). This manifold is designed to bolt directly up to the lower intake manifold on the vg30. The runners all have the same amount of deflection to keep it as even as possible between cylinders. The throttle body design and the velocity stacks are just rough estimates on size and shape but its pretty close. Eventually when I do decide I want to turbo the car, I could simply swap out the trumpets for an intake plenum similar to that of an rb26dett. Any ideas on if this is worth trying to put together? If it will help or hurt performance? I've done some looking and haven't found any examples of this on a vg30e.

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Height is one of the biggest issues right off the bat. Not many cars have a high enough hood to clear that type of design. You might need to put a bend in it, like the pathfinder manifold.


The performance benefits are likely to be noticeable, but it becomes a question of best spent money. Cool factor is the best thing about designs like that, but they usually cost a lot of money, even if you build it yourself. If it's worth it to you, then it's with doing. If good power is the goal, there are better options for more gain from the same dollars.


Like using a vg33 block punched out to take vq45 pistons. Vg34 block will net you a pretty good gain on its own. Port/polish, pathfinder upper manifold, cams, etc will all show bigger gains on the bigger bottom end.

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Height? With something as cool as that, I wouldn't mind having it poke through the hood!


Imagine if they were splayed, like on the 70's Can Am cars! Anodized red, splayed intakes, poking through the hood!!! I'm in!


But then, I don't really like the VG30 as a motor. VQ35...now we're talking.

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I kinda thought about the cool factor as well. Six trumpets poking out the hood would look insane. I know there are more cost effective options for more power be it a turbo swap or a vg33 swap. The idea behind it isn't whether it would be a cost effective alternative to a gutted plenum, but whether it would be a better performance modification. I've heard that ITB setups can sometimes take away from low end torque, wasn't sure if this would be the case on a vg30 or not. The reason I'm not looking towards the angled split throttle route is so that I can later swap the trumpets out for a plenum to accept a single pipe from a big single turbo instead of 2 plenums for a twin turbo like the z32 has. Ideally, this would be in addition to other mods like a punched out vg33 or built heads. Just tossing around an idea and wanted to get some feedback. Thanks guys, if I get any farther on this than just a drawing, I'll surely add to this thread.

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Eh, I'd be alright with notching it out for something like that, but to each his own. If they pop out of the hood, I'd also have to worry about the problem of running it in the rain. Obviously I'd have a filter box around it but I don't think that would be enough to keep from steam cleaning my engine any time it started to drizzle. Living in FL leads to quite a bit of drizzling weather too..

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So I came across an interesting piece of equipment that would lend to an even better backing behind a vertical "through the hood" ITB setup. http://www.emeraldm3d.com/articles/emr-adj-length-intake/From what I understand, having room to grow through the hood would allow you the possibility of tuning the engine per intake trumpet length and adjusting the intake pulse. As well, with the intake out of the hood, you would get the coldest air with the shortest route between atmosphere and engine. Having the system entirely under the hood would actually become a "form over function" solution, pulling in hot air with potentially more turbulence from more bends in the path of the air just to keep the original look of the car. Yes, having the intake pop out through may not be the most conventional option but I could justify this if it ended up being the most efficient system possible.

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Race car efficient vs daily driver efficient. Everything you said applies to race cars only. For a DD, you have to protect from rain and snow and parked under a tree debris. Once you put a plenum over the horns, you've changed air flow dynamics, which changes how the horns perform and will likely result in a reduction from that peak efficiency.


With all the other ways to squeeze a couple of extra ponies out of an engine, this type idea will always seem like it's more about cool factor than about power, regardless of the power gains shown.


It's like the OS Giken L series heads. Freaking sweet pieces of engineering, but there are only two reasons to ever buy one. Either you've done everything else possible to extract every last ounce of power out of your engine, or you think they are awesome. Nothing wrong with either way of thinking, but rare is the engine that actually needs that kind of investment just to make the next hp.

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