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grim369

Custom vg30/33 intake manifold

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Hello gentleman, I have been over at z31peformance forums for a while and I figured I would share with you what I have been working on, as well as collect anyone's input or advice on how I could improve my design and possibly sell a few.

 

some pictures of the process so far.

 

started by making the bottom plate.

intake1.jpg

 

holes

37594710151296973307868.jpg

 

welds

10491101512972352978681.jpg

 

here are the inlets in an early stage of bellmouthing.

25441110151301320402868.jpg

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Interresting... So what is your goal here? The Z31 stock intake is pretty short on the block. Are you looking for more volume? a Turbo intake? What is your motive for all this work? I'm certain you've looked at a few plenum designs and the science behind them. It's a pretty cool project.

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this is my setup as it sits today. 

 

v9b8.jpg

 

still needs a few things...

 

as you can see im building a turbo setup. the stock manifold doesnt have enough volume and the gutted manifolds apparently flow worse than stock and i can see why. turbulence is something that kills flow which is why i have done everything in my power to keep flow as high as possible. every on of those joints in the pie cuts have been ground and sanded, the intake is the same diameter from the exit of the turbo all the way to the inside of the plenum (3 inch) my DP will be pie cut and the wastegate will probably be mounted upside down below the turbo and vent straight to the ground. yes, i have done quite a bit of research and development on this setup and hopefully my calculations show results.

Edited by grim369

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Pretty much like my effort except mine was a rear entry because in a 280ZX there was more height to be had there. Height is needed so that air can turn 90 degrees into the inlets instead of skipping over their tops. Good on you for having a go, just make sure that there is a significant improvement to be had at the end of the day. See my thread on the viability of the good old single cam VG :)

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You might look at some of the other designs we have seen on here.  Most notably a couple points on these: 

 

1. The designed plenums usually have most of the internal corners filled and shaved.  That way as air flows by there's a lot less turbulence than you'd otherwise see.  

2. Another point is to note that on most of the custom intakes, the volume gets much smaller as you get father away from the throttlebody.  The effect of this is air velocity. As you move farther away, the air loses momentum. Having the Plenum narrow toward your back cylinders ensures even combustion.   Look at the plenums that Mark made in this same v6 section. you'll see what I'm talking about.

Edited by Pharaohabq

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It helps if you can visualise what is going on when the engine is running, keeping in mind that air (like water) under pressure naturally wants to go straight ahead. If air is required to turn the widest arc possible is best at the start, tapering down towards the last cylinder. Just takes a bit of thought because even air flow to each cylinder is the most important factor of all.

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WOW its been a while.... i dont think the links to the pictures i posted even work anymore lol but i still have that hideous plenum i made back then but it sits on a shelf now to remind me of my humble beginnings lol my work has improved slightly since then.

15107234_10154842967932868_2086853034380
 
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this is my car as it sits today, although it isnt the car i had when i started this post i did buy it specifically to put the 33 into. 
 
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while initially i just wanted to build my own car and make it cool but people started asking me to make them stuff and now i make other peoples cars cool too or at least thats what i try to do. i hope all the people who were extremely nice and helpful to me are doing well and i just wanted to give a little update to this 5 year old thread lol
 
although i have already worked very hard on making this intake the best design i am capable of producing, if anyone has any other input on the design of my intakes i am always interested in where improvements can be made and welcome criticism. 

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The air intake from the throttle body to the upper plenum should be straight, put any bends in before the TB with a straight as possible immediate entry to the TB. Otherwise it's hard to tell much, looks tidy enough.

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