here is a link to a ford SHO forum's thread started by a coworker of mine showing the work he's doing on his SHO intake plenum. I think the work he's done on it is pretty cool and we are seeing some nice results with it on his car and hope to get some dyno time in once its complete.

http://www.shoforum.com/showthread.php?t=83786

 

here are a couple of pics of my upper plenum just after welding.





grinding and sandblasting will have to wait till tomorrow, my girlfriend is nagging at me to come home heh

 

that's some nice welding! I've only done gasless mig, and all I really did was waste a few ounces of fluxwire and burned holes in things

Welding's supposedly in my blood though, my Uncle is a rigger for Ford in Sterling Hts MI plant. You had to use tig right? I want to shave off my middle supports exactly like that. Did you mill them off, or use a die grinder?

The SHO post looks cool, man what a nicely designed intake. Looks like a BMW with all the throttle butterflies. I have seen an electric supercharger that works, but it was a roots supercharger driven by a planetary gearset powered by three motors. I seem to remember it put out 20psi, and even over-boosed a sentra or something like that -- but it was real expensive and drew a lot of current.

[edit: here is a link for those that don't believe me -- yeah I didn't believe it at first either]

 

yes i used tig welding and i actually used an 1 1/4" and an 1 1/2" carbide hole saw with a long pilot bit on a drill. drilling from the outside of the plenum you can use the bolt holes in the mounts to guide your pilot bit as you cut through. i used the larger hole saw on the two mounts on the left if your looking at the top pic because they are slightly inset more into the plenum due to one of the humps going through those two more than the other two but i'm sure one size would do them all just fine. i haven't yet chosen weather i'm going to touch the remaining two supports or not because i'm just not sure how much they are really needed but i'm really leaning towards maybe taking out the one at the top close to the opening and leaving the other in place.

I'm not sure if you noticed but on my coworkers forums there doesn't seem to be as many open minded supporters of DIY trial and error and experimentation as there are here. i'm glad we can all so constructively work together and support each other like we are in thread.

 

i have a couple more pics from tonight, i did a little grinding and sandblasting of the entire inside and sandblasted the welds on the outside. i will most likely blast the whole outside too before i powdercoat it.





i think its about time to start shopping for some lower plenums, anyone have a revup lower that they are willing to part with

 

I'm envious. Very nice! :-)

 

Thats turning out great. When is it going to be done.

 

Not to make your project seem like a small deal or anything colin but uhh, holy **** I just read all 7 pages... and now I feel privledged to know him.

 

yeah me and sean do alot of number crunching and planing with this stuff. i think sean is pretty lucky compared to us since the SHO intake is so much more complex it has much more room for improvement by tweaking (ex. we have 6 runners, his car has 12). but my upper will be done very shortly and hopefully i will begin work on a revup and non revup lower very soon.

 

I'm kind of a noob. Why would this cause you to lose torque?

 

in short: shortning the length of the runners increases higher-rpm HP at the expense of lower-rpm TQ.


The science behind it is centered around the helmholtz resonance of the intake manifold.

The factory tunes the length and diameter and air plenum volume (Amoung many other variables) so that at a particular RPM, the intake resonates, which basically works like a mini-supercharger.

The gain is small, e.g., you're not going to get any "boost", however it is definitely significant enough to design into an engine. Engine makers decide where they want the peak torque to be and factor the helmholtz resonance into the equation (along with cams, ignition advance, etc...) and use it to boost peak torque.

If you have an engine that is "peaky", you can try to boost the lower end by lengthening the runners, which will move the peak down in the rpm band. Doing so will lower the peak HP, however the area under the curve will get larger and your average HP will get better.

In the case of a purpose-built engine (think top fuel funny car or an offshore race boat) you're only concerned with maximum HP, which means you are going to spin the snot out of your engine. In those cases, you want the resonance frequency very high in the powerband, which means shortening the runners. Shortening the runners also has a side benefit of keeping the cylinders full of air at high speed.

Next time you take a look at a Jeg's or Summit Racing catalog, look how the intake manifolds are designed. Ones that don't have much height (They are curved inside to create a long runner) they are rated usually from idle to ~5500rpm. If you look at a "tunnel ram" which is basically a very short straight runner, it is rated from 4500rpm to ~10,000 rpm.

Hope that helps

 

^^^ great post - well stated!

 

you are absolutely correct, and its because of those points that you stated above that my main focus is going to be on getting a revup lower plenum to work with for my project. i really feel like overall for my application that i need to shift my powerband higher and even lose a little tq down low where it just becomes a waste of spinning tires for me.

I find it funny that you mentioned offshore racing boats too, i actually work for a company called Supercat Rigging and we build offshore racing Cats and high end custom Cats. We work mainly on Marine Technology Inc. (MTI) Cats.

 

Whoa -- I checked out the stuff you guys do and man does that look cool. Out here we got exterminator boats, but they don't look as impressive as the stuff you guys do.

Man the one looks like an AMG twin supercharged v-8?

Yeah moving it up in the band might be worthwhile, as long as your turbos are big enough to not be an obstruction. I forgot what you were running. I know that the stage 2 and stage 3 SRT-4 kits actually decrease boost in 1st and 2nd gears. I got ~12psi in 1st, ~15psi in 2nd gear and in third gear I would peg my 20psi gauge.

When I had a Z28, a lot of the guys would purposely run centrifugal S/C's because if they put drag radials on, and made much more than stock at launch, we would crack the weak 7-5/8 rear diff, but once you were rolling and were at higher RPM's, the power of the centrifugal s/c's really put the power down.

 

nice to see this thread alive and kicking!

FWIW, my plenum is still working great - I just finished a winning autoX season for '07, and am gearing up for '08! (no issues w/ the plenum mods I've done -- no cracking of the GB_Weld, no leaks,...)

reference pic:

 

hey first350 how is the paint holding up on the inside of your plenum?


Its been a while since i've been on, i've been very busy with work so my plenum project has come to a stop for now. The amg motors are actually twin whipple supercharged sterling performance v8 marine engines each rated at 1550 hp but we made some AMG engine covers like you would see on an AMG powered Mercedes. But AMG has a new supercar in the makings with a powerplant that may find its way into one of our boats sometime next year and the boat and the car may be seen at the next berlin auto show or the year after, but due to our agreement with AMG thats all i'm allowed to say about it. But things at work are slowing down a little bit so i'm hoping to get back to my plenum project soon.

here are a couple pics of the Mercedes boat, you can find more pics of the boats at pier57.com or my myspace http://www.myspace.com/redeclipsehrc

 

the paint is perfect...no smearing or fading - I was worried that the oil would degrade it, but no signs of that. (I think baking the paint on helped to make it stick).


BTW: nice boat!

 

Yeah. Geez. Boat has a cocpit like a sports car.
Very nice.
That's gotta cost some big $$$.

 

the special theme boats like that are usually in the area of 1.5 mil.

I got a pm from a member and we are talking money about a rev up lower that i might take off her hands so hopefully soon i will get to work on one

 

nice transition to get it back on topic...