Common plenum or individual runners???, for gas milage and drivability Options

[914efi]

Mueller, The TB is just visible at the left rear of the plenum box, it is mounted to the side and faces to the left. It is under the rear lid a bit also. This was a tight fit in the 914.

I have this in CAD if anyone wants the file (Cadkey), I could make a step or iges. One useful thing in this file are the locations of the ports and some of the engine details.(911)

I do have radiused ends on each runner. The runners are welded into the plenum, and then the 'horns' are epoxied on through the cover. The runners are all equal length, they protrude into the plenum different amounts depending on location.

I will take a more current picture and post it. This was built 4-5 years ago before the boom in this stuff really happened. I gues it still hasn't really happened. The megasquirt seems to be getting more people involved.

[914Timo]

Nice job, 914efi (IMG:http://www.914world.com/bbs2/html/emoticons/clap.gif)

Send more pics.

Do you have any pics from the inside. That would be interesting.

Why didnt you 3,2L intake ??

[914efi]

I bought a 3.2 intake on the advice of a local 'respected' porsche racing guy, and the diameters of the runners are way too big. The injectors will not be in the ports of the smaller engines. I have T heads on my engine, and I had to slightly relieve the edges of the ports when I moved the injectors down, but the 3.2 would be too far out. Some of the newer smaller injectors will make this easier to do, but the design of the port injector mount was a bit of a challenge.

[914efi]

another view

[Bleyseng]

Take a look Mueller.

[jwalters]

QUOTE (914efi @ Dec 20 2004, 10:45 AM)

another view

(IMG:http://www.914world.com/bbs2/html/emoticons/wink.gif) wow, thats not bad!!! (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[TimT]

Mike here is the GT3RS plenum, I couldnt find where we put the throttle bodies (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)

[TimT]

nuther

[TimT]

YOu bolt the different restrictors to that round flange. The small restrictors knock almost 50hp off

[Mueller]

thanks Tim,

that is a huge plenum...and dusty too (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[TimT]

QUOTE

and dusty too

grrrrrrrrr We had the dyno installed when we were down in Savannah. The concrete guy promised he would cut the floor with a wet saw. Instead he used a dry saw and cover the whole shop with a finelayer of dust (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/headbang.gif) lets just say final payment hasnt been made for the concrete work.

[Mueller]

concrete dust?? that is even worse.......

can you tell me if there are any baffles or ducting inside the plenum, if not, it's okay, you've done enough with just the picture (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[Bleyseng]

Check out how short those runners are! Nice carbonfiber....so can you make me one for a 4 banger??

Geoff (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[Mueller]

QUOTE (Bleyseng @ Dec 20 2004, 10:33 PM)

Check out how short those runners are! Nice carbonfiber....so can you make me one for a 4 banger?? Geoff (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

it took me 1.5 hours to get home tonight due to traffic and fog...during that time I talked to Sir Andy for about 20 minutes about manifold/plenum design and the rest of the time I spent thinking how the heck can I make something just like the Porsche Motorsport plenum for my /4 (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/smash.gif)

it looks to be all one piece, how do they make a hollow c/f or 'glass part like that??

could you make one from wax, cover it with the carbon fiber and once cured, melt the wax out of it??

with the intake like the GT3RS, one could easily take the plenum off to test it with the throttle bodies exposed directly (add air horns) and you could also keep the plenum on the throttle bodies but remove the butterflies and install 1 single throttle body on the opening of the plenum...3 different methods of induction with one basic design (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[914Timo]

QUOTE

how do they make a hollow c/f or 'glass part like that??

Multi-element mold.

QUOTE

could you make one from wax, cover it with the carbon fiber and once cured, melt the wax out of it??

Wax or styrox (Do you know what styrox is ?? I am not sure if styrox is correct term. The white bubble stuff, you know.)

I have thought the same. Only problem is, that the outside will not be smooth and may look ugly depending how good you are laminating. However, the inside would be very smooth.

One possibility might be put the plenium together from many separate pieces. Then you could use one mold and make all six (or four) air horns from the same mold.

914efi, I see your problems with the 3,2L intake now. Just one question, why you have put the TB in such a tight place ?? Why didnt you put it in top of the plenium. It could be in the cover of that accesshole, or could it ??

[McMark]

That air box looks like it barely fits in there. 1" - 1.5" clearance probably, judging from the shadow cast by the rear deck lid.

[914efi]

I had various ideas on where to put the TB, but when you factor in weather protection, cable position, plenum simplicity, air filtering, etc, it made sense to put it on the side. I was also trying to maximize length of the runners. If I made the whole thing shorter I could have more easily put it on top, but it would have shorter runners and a smaller plenum. I have the runners at a length that allows them to resonate at the torque peak of the engine.

My goal was to build a good street system. Most people are doing this for racing which is a different set of priorities. I also did not want to cut anything on an original six to make stuff fit. So far all of my mods to the car are reversible and I have all of the original parts. The cage ideas might not be so easy to do with low impact!

[914Timo]

Very interesting, 914efi. Obviously you have done lot of work and research. (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif)

You wrote earlier that you have a CAD file from your intake and you could you send it. I would like to have it. Could you send it to me ?? I use AutoCAD and MicroStation. Do you know if I get it open with these programs ? I will PM my e-mail to you.

[Bleyseng]

Mueller, I too after seeing that CF manifold thought of ways to make one. I thought the best way was to make a mold so it you could make a run of them or just make one out of wax.
Geoff

[Jake Raby]

My Carbon Fiber tech has been on the plenum for quite some time now.. To do a part like that in Carbon it needs to be "Vacuum bagged" to pull the resin through the part and make it very strong as well as cosmetically enhandced.

It just takes alot of time and money to make the mold.. I have spent 2K on it so far and I have not even seen it yet... It took him over a year to do the carbon Fiber DTM mold.