ju-on

Austin, btw the injectors on a dsm go straight into the head, not the intake manifold. So one less thing to worry about. But as for chopping apart the stocker, I guess I'd really like to just make a complete one instead of hacking anything apart. The only thing I would consider hacking off it the TB flange, and the head flange, but that's only if I find those flanges to be stupid expensive for new ones.

ju-on

Also I've been finding tthourhat as far as runner length tuning goes, it's much less involved in a FI setup then in a NA setup. In a NA setup you want to calculate the lengths based on the pulse created by the intake valve. While on a FI setup it isn't nearly as important. So those helmzholtz equations and what not for determining when the pulse will arrive back at the intake valve, really aren't needed to much in a boost application.

As for runner tapering. The reason I heard to do it is because it increases velocity of the air. The air on the edges touching the walls will move slower because of the friction, so you taper the runners to help speed it all up. Again from reading it would appear a 2-3* taper is ideal. My problem is, I have no clue how to calculate that. If I have a 7" length of 2.5" pipe, tapering to 2.25", what degree of taper is that?

gon3r

don't do a box plenum... hand form it into the shape you want to get the best/even flow to all runners. too many homebrew manifolds (including my first attempt) are built without flow equalization in mind. i have an idea for my next manifold, but it will probably be a couple years before i get a chance to build it.

absolutezroo

ITB's FTW!

unsivil_audio

What A/R is the exhaust side? If its .48, i'd be willing to bet that your problem. D-series run out of room about 350whp on .48, .63 is much better suited as it creates quite a bit less exhaust reversion effectively extending the powerband. I'm sure switching to a tubular would help quite a bit too though. Whats your power numbers look like right now? 272's will help alot when it comes to making power past 7k as well.

ju-on

I know plenty about my car, it's setup, and it's strengths and weaknesses. I didn't just wake up last week and slap random parts on a car I know nothing about, which is what you seem to be insinuating here.

What I am interested in, is hearing any other advice on making my own intake manifold. I have a few different designs in mind. All of them being pretty simple. The main jist being slightly larger plenum, and tapered 6-7" runners. Just want to figure out the shape I want to make the plenum, keep it simple and cheap and minimal amount of welds.

Thanks for everyones input. It'll be months before I actually get it built since I travel a ton with my job, but I'll post up pics of it when I'm done.

SDRAWKCAB

https://www.homemadeturbo.com/forum/...?topic=85979.0

unsivil_audio

Hardly. IDK, we'll see but I think you may be unpleasantly surprised with the results of a custom IM. Slower spool, and no effect on extending power although you probably will see in increase in power. Not exactly the results you (expressed you were) looking for. Sorry thats the way you received my constructive criticism.

ju-on

You're saying a SMIM won't move my power band right? And won't help me maintain my power levels at the higher RPM's? OK you're advice is noted, but I completely disagree.

But again I don't care what you think about my car, I'm looking for input on making my manifold. I've gotten a couple good links, and talked with some people, and I think I have a good idea of what I'd like to do now. I will hopefully have it done sometime in December, and will put up pics showing how I did it. Thanks all!

Eville140

Here is mine, I just made what ever would fit This motor never came efi so it had to be a diy