Header Looking Intake Manifold

I swear I've seen pictures of such a beast before. Very long intake runners such that the intake manifold looked like, and I think was even constructed like, a header. Can anyone point me to examples?

Getting ready to fab up an ITB manifold, and it looks like it would be beneficial if I were able to snake 18" or so of runner length into a space not meant for such a feat.

Quad 4?

Like this? E39 M5. It's normally all hidden inside a big airbox. And it sounds amazing.

Sort of, but even more. The one in my head literally looked like a long tube header.

I remember seeing something like that on a 4 cyl at the local pull-apart before, I think it was on a mazda engine.

I always thought the SHO V6 had a cool looking intake too.

Always thought these were neat too.

not a good pic but of the 01ish toyota rolla

and as mentioned the quad4

^^^^ That's the one I was thinking of, I don't know why I thought it was in a Mazda.

Are you looking for low end torque? Is that why you want the 18" of intake runner? Or are you just trying to remake a factory intake? If you are doing ITBs, you would probably want short runners for better high end power. At least that's what the internet has conditioned me to think.

Thats why the miata and the 4age have variable intake tract thingies; best of both worlds.

RossD wrote: Are you looking for low end torque? Is that why you want the 18" of intake runner? Or are you just trying to remake a factory intake? If you are doing ITBs, you would probably want short runners for better high end power. At least that's what the internet has conditioned me to think. Thats why the miata and the 4age have variable intake tract thingies; best of both worlds.

http://www.bgsoflex.com/intakeln.html

The motor will redline somewhere in the 8500 RPM area. I'm OK with giving up the last few hundred RPM to gain a few hundred down low.

18" gives me the strongest harmonic @ ~ 8k, with useful ones below that.

A short runner (let's use 9" just for S&G) puts both the strongest and the second strongest harmonic above the useful RPM range, and the third strongest just barely there.

image hotlinked from racingjunk.com:

413 cubic inch Mopar "Long Ram" intake.

You will find that most tuned ITB setups place the throttle body as close to the intake valve as possible, and then just use intake ram tubes to accomplish resonant tuning. Reduces the runner volume between throttle body and intake, so when you open the throttle, minimizes the delay. Once you are at WOT, doesn't really matter where the TB is. This can also simplify the packaging, as hanging TB off the end of long tubes can be problematic. It also allows you to easily change the runner length, by simply swapping horns, or by using a length of hose as part of the runners.
YMMV, please post pix of whatever you choose to do.

Yeah - the close coupled ITB's with velocity stacks is the plan.

DILYSI Dave wrote: Yeah - the close coupled ITB's with velocity stacks through the hood is the plan.

You left out an important detail

cghstang wrote:

DILYSI Dave wrote: Yeah - the close coupled ITB's with velocity stacks through the hood is the plan.

You left out an important detail

I wish. Rules prohibit. :(

I always wondered why most intakes look like restrictive logs compared to the better flowing exhausts.

I can't find a decent picture of one, but the '91-'99 DOHC Saturn intake manifolds have very long runners, they have to be almost a foot long.

I'm told longer runners are good for torque and low-RPM power, shorter runners are good for high-RPM horsepower, in general?

In reply to Twin_Cam:

That's roughly my underinformed understanding as well, though I'll go out on a limb and list the two separate factors involved:

There's the harmonic effect, as referenced above, with after effects (pressure) of closing valves cruising back up the tract, reversing, and then arriving just in time to help cram a last little bit of intake charge in there just before the valve shuts again. As noted above, it takes a looong runner to get this into usable RPM ranges on most engines.

The other part is just with respect to the inertia of the column of air in the intake tract. This, I think, can help all the time, though a longer intake tract does add restriction at higher revs. The other part of this is that a smaller-diameter tract increases velocity, which increases this effect, but then also causes more restriction at higher revs.

I think the inertial part is really just a straight low-speed/high-speed tradeoff, where if I'm not mistaken, the harmonic bit can also create flat spots where the timing is absolutely wrong instead of absolutely right.

Hopefully I don't have anything really thoroughly wrong there, but I clearly don't have all the details, either...

In Sheet Metal Handbook Fournier did a prototype sheet metal intake, maybe some ideas there

you mean like the really long runners on a 2.1 Saab 900?

You should see the Suzuki "Cultus" intake. It doesn't look like a header, but it has the most awesome tapered runners I've ever seen, and it weighs just about nothing. Apparently it changes the sound of the 1.3 DOHC motor completely.

I'll let you know in about a week

Am I wrong in thinking the diameter of the runner has just as much to do with the tuning as the length does?

later, matt

In reply to xFactor:

Huh. I thought that really only affected the intertial part of the proceedings, but a quick Google suggests that it does also apply to the resonant part (and that I was thinking Heimholz and it appears to be Helmholtz...)

The Escort/Tracer 1.9 from '92-96 used a nice set of long runners 'folded' to fit.
It's a brazed assembly of thinwall tubes for runners, plenum, and end caps, with a casting for the TB, and a casting at the head that carried the injectors.

I was thinking the same thing for my 2.2 pushrod S-10. It has the older 2 piece intake, where the top half is an open chamber with a cast in small diameter TB. I wanted to make a new top piece that was tubes that end at a flange for the TB from like the Vortec 4.3. I'd love to see what you come up with.