1G Custom intake manifold

Wanted to help increase top end flow on my 1g 6 bolt without spending a couple hundred dollars on a sheet metal intake manifold. So I made one. Reduced top end power drop by a lot
I'll have to find the pictures of the difference between factory on stock cams vs custom on stock cams. On the logs from link there was a reduction in power drop from 6200rpm to 7250 of only 11hp using stock cams vs the stock intake manifold with stock cams of around 50hp reduction at the same rpms.

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Here are some installed pictures

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If you would like to do this yourself tools required will be:

• Super clean degreaser works wonders on removing all oils from the aluminum before welding. Which welds really good if cleaned really well.
• A couple of brushed and scrappers to get all carbon buildup out and any old gasket left overs.
• Tig welder
• Sawzaw/band saw
• Hand grinder
• A couple of flats wheels
• A direct grinder or dremel to clean the inside of it up and any imperfections you see in the runners or plenum which there are a lot of.
• And a way to make sure the flange stays perfectly flat when welding so it will not warp the flange to prevent further boost leak issues.

As far as making goes I did this to help bridge the power drop off at the top end which plagues the factory 4g63. As most notice power drops heavily before redline. And it has been tested stock cams can only flow so much which this is true. But it's not the limiting factor. Long intake manifold runners have always been used on almost every factory car to help low and mid range power vs short runners do the complete opposite.

So my goal was to make this intake manifold in an attempt to help with that fall on its face issue. For me it was cheap to do because I already had the tools and such to make it and I had a spare intake manifold laying around but many can pick up any factory intake manifold and go crazy with it. And factory intake manifolds are cheap.

 

[Eclipse5150x]

Would love to see some actual logs or numbers showing if you picked up more power or just lost power. Dyno? I'm a bit confused because you said you wanted to increase top end flow but then you said it reduced top end power by alot.

 

[Taylor4ghindman]

Would love to see some actual logs or numbers showing if you picked up more power or just lost power. Dyno? I'm a bit confused because you said you wanted to increase top end flow but then you said it reduced top end power by alot.

I meant as in reduced that top end fall off that is noticed with stock cams and stock intake manifold. There was non of that after making this intake manifold using stock cams. If I had stronger springs I could have revved it up to 8500rpm and still not have that fall off.

 

[Taylor4ghindman]

Would love to see some actual logs or numbers showing if you picked up more power or just lost power. Dyno? I'm a bit confused because you said you wanted to increase top end flow but then you said it reduced top end power by alot.

I know it's been awhile but I finally found those logs

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