How hard is it to fab your own FI manifold?

[derekf]

Ooh.. first technical question on the new board :)

I know that I should just grab something that someone else has already done the R&D on.. but I can't help but wonder:

If I took - say - a complete Chevy TPI setup, how hard would it be to create my own manifold for it? Obviously I'd need some pre-cut mating surfaces for the heads, and I'd have to get the distributor height right, but what about plenum volume and runner size/shape/length? If the injectors are right there at the intake ports, how critical is the rest of it?

I'd think that the programming would need to be modified, but so long as it got all the inputs it was expecting would it work?

[Matt@RFR]

how hard would it be to create my own manifold

Hard. I work with a guy who used to work at Hogans. There's a TON of tricks to building manifolds correctly, not to mention the post-weld machining that needs to be fixtured for and done.

You also need to have runner volume/lengths pretty close to dead on (unless it's for forced induction), plenum volume and shape, etc. Once the manifold is done, Hogans has their in-house porters work them over on a flow bench.

Did you know that the welds at the bottom of each runner on a Hogans manifold is a 3 pass? And at the top...up to 5 passes!! And if you've ever seen one in person (with the top off), there isn't one inch that the porter didnt' touch.

$1500 is CHEAP. :p (Larry, These smilies SUCK. lol)

[derekf]

Wow... only nine members and still a quick, informative post.

I probably should have mentioned that it was, indeed, for a forced induction setup - I know the torque curve of the TPI (for example) is due to the tuned runners so I wouldn't even want to try for normally aspirated, I doubt I'd be able to outdo whatever I was basing it off of.

[Matt@RFR]

I doubt I'd be able to outdo whatever I was basing it off of.


Me either. I've turned down about 5 custom manifolds for this exact reason. Well, that, and price. My price would be astronomical compared to someone who does it every day.

But boy are they cool! lol

[derekf]

So... given that we're talking forced induction (turbo) how critical are runner volumes/lengths/design and plenum size/shape?

I realize that when I'm off the boost it'd be subject to all the same restrictions of a NA car.. but, well, I don't know.. I guess I just want to be able to say "I made it!" and have it work reasonably well.

On the other hand, this may be just a case of me thinking my skills are signifigantly better than they really are. Either way, it makes for an interesting topic.

[Matt@RFR]

how critical are runner volumes/lengths/design and plenum size/shape?



I have no clue! That's why I refuse to build 'em. I know they're important, but don't know how far off you can be and still have it work well. I do know that plenum shape and volume can be real important in not letting fuel puddle. If puddling is bad enough, it can actually hydraulic a forced induction motor. (so I hear)


I hear ya about wanting to be able to claim fab rights for stuff on your car. That's how I got started. I used to be well known for building tools for more money than you could buy them new! But I had a blast doing it.

One note: On EFI, I'm pretty sure you would need to build a jig to set the injector bungs so they line up and seal to the fuel rail correctly.

[derekf]

Is fuel puddling really an issue if the injectors are pointing at the back of the intake valves?

Anybody happen to know an entry-level reference for this sort of stuff?

Oh.. and I'd expected as much on the bungs :)

[Matt@RFR]

I had a brain :fart:

Sorry, fuel can't puddle in the plenum if there isn't any in there, huh? My roots are in drag racing...Dominators on a big ol' Brodix are my thang.

[Ralph LoGrasso]

Matt, get busy building me a sheetmetal intake for an LS1, i want it port matched to the 90mm throttle body as well. :headbang: :cool:

Allocated budget - $25 bucks. :cheers:

[Matt@RFR]

I'm on it.














:screwy:

[Ralph LoGrasso]

:seizure: :D

[derekf]

I had a dream that I built my own manifold from 1/8" thick aluminum, which in itself is odd since I don't own a TIG and don't know how to use one.

Anyway, it was pretty much a box for the plenum about 4 inches up from the valley.. straight runners from the plenum down to the ports.. but the funky part was that the throttle body was underneath at the back.. I know there's some inefficiency created even on forced induction when you make the air has to make a U-turn like that, but it looked pretty cool in my dream.

Note: While the above is true, I really did dream that, my posting of it is just a lame attempt at putting this thread back on track. Congrats, Ralph, you've made the first off-topic post in someone else's thread :)

[Matt@RFR]

I'll talk to my coworker and see if he'd be willing to write you an email so you two can discuss it. I don't know if he'll want to or not.

[derekf]

Sweet - I appreciate the effort, but if he's too busy or just doesn't want to that's just fine, it's not like I'm in any hurry for this or anything :)

[Matt@RFR]

Derek, shoot me your email address and I'll have him contact you. He said he'd be happy to help! :headbang:

[derekf]

(removed to avoid spam-bots) is the easiest to remember :)

[Matt@RFR]

Right on. His name is Rick Jones, and he has a pretty bizarre email address...I'll have him put something you can reckognize in the subject line.

[Matt@RFR]

Hey Derek, please let me know when Rick contacts you. I'd really like it if you could forward all the info you end up getting out of him...I may be building one for somebody, and this would save Rick from explaining most of this stuff twice. Thanks!

[derekf]

You betcha!

[Matt@RFR]

Derek, have you heard anything from Rick?

[derekf]

I got a "Hi, Matt asked me to email you" mail that I took a while to respond to. I gave him the brief rundown of what I was asking about but I haven't heard back yet - it hasn't been too long since I sent the rundown (Sunday?) so I'm not expecting anything yet.

[Vettebob1]

I did the research and looked at many options....
I went with the Hogan's manifold. It's a tad less than $3,000.00 but the nicest looking piece out there. I had him build the manifold that looks like a fabricated big block valve cover.

[TBART70]

I did the research and looked at many options....
I went with the Hogan's manifold. It's a tad less than $3,000.00 but the nicest looking piece out there. I had him build the manifold that looks like a fabricated big block valve cover.


post a pic please!

[Vettebob1]

As soon as I get it I'll shoot some pictures and post them.

Bob