Thanks for the info (and support) Luke :)

Please please can anyone provide me with detailed photographs and measurements for a 964 plastic intake?

I can then use this as the basis to start developing my custom intake, making improvements where it is believed to be restrictive.

Many thanks in advance fellow Pelicanites :D

Who was it that not too long ago was building up a pretty slick intake in carbon with itb's and machined goodies all over? From what I remember he gave up because producing them would become cost prohibitive.

If this is for yourself then go all the way by all means! In that case it might be in your best interest to "borrow" all the different intakes you would like to build off of, i.e. 964, 993, 993 vario, rs, and all the others. Then you have to take into account what the engine will be asked to do, rev to hell and back, produce smooth power, peak power, streetable all that nonsense. The engineering can become overwhelming but if its just for street and kicks at the track a somewhat off the shelf unit like the Jenvey's becomes very attractive.

Before I even started the motor for my dad's car I gave up on the barrel throttle system I was working on and went with the Jenvey setup. The picture in the first page of this post with the black "runners" or manifold and black trumpets with Jenvey's sandwiched in between I believe was a Steve Weiner idea that I saw a few years ago at the GAF in Ventura. Instead of using the Jenvey crossbar linkage a Porsche Motorsport linkage is used to simplify things. I have seen them on many 993 race setups and it is not simply a one off as others would have you believe unless the dimensions were changed for some reason.

edit: to rsscotty, I call bs on saying that was your own design unless you are in cahoots with Steve Weiner. I saw that exact setup years ago at the GAF. Also the cross linkage system is either the Porsche racing bit or an adaption. While it is rather slick its not like you guys came up with it on your own.

Secondly I dont think that being in SA is a hindrance in terms of obtaining bits and pieces. Plenums on each bank lend themselves nicely to turbo power and somewhat better torque. A modern GT3 RSR runs an almost identical plenum to a Daytona Prototype the difference being the RSR runs two 29.2mm restrictors whereas the DP has an "open" intake although they merely chopped a hole in the top and placed a BMC air filter in there and blocked off the holes where the restrictors would normally mount. This isnt secret info, you can see it in pictures.

Depending on cashflow, troubleshooting, time, perfomance, and any other variable you can imagine there are still many decent options. If I had unrestricted access to a CNC machine then my dad's motor would have some step off intakes cum throttle bodies. Since I dont I went with I thought was the next best thing, Jenveys. The quality, adjustability and performance of these is pretty darn good. You can tailor them by running different size trumpets, different length manifolds, if any at all.

There is a huge amount of chocies of "off the shelf" parts available to you.

Jenvey straight shot or tapered, TWM weber style manifolds or straight shot, 964 plastic, 993, 993 vario, 993 rs, cup, rsr, 9m (nine meister), 3.2 intakes, slide valves, bla bla bla. The only setup I have never seen on a porsche and I wanted to be the first in my mind to do it was barrel throttles. With plenums you can go single throttle, twin throttle, 6 throttles its up to you. For fun I would like to try a 964 plastic manifold with twin throttle bodies. Mount the manifolds on the opposite head as normal pointing outwards yellowbird style and put throttle bodies on the ends. Might be fun.

Whatever you end up doing I am sure you will enjoy. Best of luck

Thanks for all the info Porschekid962 - I will look into what off the shelf parts are readily available locally...

Please can you elaborate on this and maybe post some pics, Im not familiar with it...what would be the benefit over say ITBs?

"The only setup I have never seen on a porsche and I wanted to be the first in my mind to do it was barrel throttles. With plenums you can go single throttle, twin throttle, 6 throttles its up to you. For fun I would like to try a 964 plastic manifold with twin throttle bodies. Mount the manifolds on the opposite head as normal pointing outwards yellowbird style and put throttle bodies on the ends. Might be fun."

Only FYI and a laugh ;). Taken off a running 73 T , CIS. had 2 barrel Holly. http://i138.photobucket.com/albums/q...p/DSCN0789.jpg

barrel throttles
 

Barrel throttles are commonplace in high end motorsport divisions. AER engines use them, F1 motors go back and forth between butterflies and barrel's, JUDD, Cosworth, Illmor have used them on race motors to name a few. Pretty much everyone is familiar with the butterfly throttle so I wont get into that. Then there was the slide valve throttle setup. Great at WOT but not the greatest part throttle response and then there is the problem of airborne particulates getting into the mechanism and gumming it all up. Have not seen a modern race engine using slide valves, barrel's yes. The great thing about the barrel style throttle bodies is their relative simplicity and low number of moving parts. I am going to grossly simplify things here but you basically have a rod/cylinder/pipe what have you inside of a barrel. This pipe or rod has cutouts where the intake ports are and as you rotate the rod through 90 degrees you open and close the throttle.

http://e30m3performance.com/tech_articles/engine-tech/dtm_slides/index.htm

this is a nice write up on slide valve throttles. Notice when the slide plate is at WOT there is a gap through which contaminants can ingress to the inner workings of the piece.

http://www.aerltd.com/products.html

Page from the AER site, its not the greatest pic but if you look at the intake runners its rather hard to tell where the throttles are. That is because barrel throttle mount is cast as part of the head, rather slick and saves a bit of weight. You can just see the upper half of the barrel bore on the left bank of the engine at the base of the intake runner.

http://www.lumenition.com/roller.pdf

still not a schematic drawing but you can begin to see how these throttles go together. I am not on my home computer so I forget exactly where I found it but there is a decent drawing and pictures of the inner workings of a barrel throttle somewhere.

There are debates in motorsport as to which throttle setup is better. No restriction at WOT is great for F1 but even they want some turbulence to aid in fuel air mixture at part throttle and lower rpm's. The butterflies will give you a sharper throttle response though and have been tried over many years. Afaik there is no aftermarket barrel throttle setup available for a Porsche application. One problem that comes to mind on an air cooled motor is the bending and twisting of a barrel throttle bore mounted atop 3 individual heads as things heat up, cool down, rev up and down. This might add undue stress to something that needs to remain very precise.

The potential gain in performance would most likely be negligable over a properly setup butterfly ITB system. The coolness factor would be out of this world though. The main reason I gave up on this was of Jenvey and money. Every time you build a motor you have to compromise here and there. The trick is to minimize these compromises without breaking the bank which is a worry to almost all here. When I can raise enough funds I will build the motor I have been designing for years. Flat 6 will be about as close to factory as it gets with the exception of reusing some internal parts namely the crank.

In order to minimize hassle I say go with the Jenvey stuff. I do not work for them I just see that their stuff is better than TWM. You can get fancy with the steve weiner long runners, not too dificult for a competent machinist to make for you, order some trumpets, get a 993 rsr throttle linkage and your off and running.

have fun

If your plumbing your own runners (tubes) into a fabricated plenum, you might consider 180 degree rolled lip trumpets extending into the plenum. There have been studies showing an increase in flow by installing these small trumpets inside a plenum as if exposed to the atmosphere.

Mark Hargett might be the designer of the intake your speaking of above. He had a great design and had it in plastic rough prototype form. He seemed questionable in his commitment to finish any time soon. Do a search for this.....it might have reference to a itb turbo intake or such. He is quite heavy into forced induction, but quite the craftsman. Good for ideas, if nothing else.

http://www.itsfun.nu/if2_2006/2402/if2_007.JPG
http://www.itsfun.nu/if2_2006/2402/if2_005.JPG
http://www.itsfun.nu/if3/if3_210.jpg

Great looking setup Goran - please post some more pictures if possible...

Off topic question - I see you dont have the standard plastic shroud that covers the alternator and top of engine, doesnt it affect the cooling of the engine?

F.

It's not mine. It belongs to IF2 car and is custom made by company called ML Wankeltrim by a guy who's guru on Wankel engines and induction in general. I'm posting pictures so you can get an idea how optimal turbo intake might look like.

Plastic shroud (well not quite plastic, it's carbon fiber) is there, but was removed during assembly.

Here are few more pictures so you understand how it fits together:
http://www.itsfun.nu/if2_2006/0403/if2_011.jpg

http://www.itsfun.nu/if2_2006/0403/if2_051.jpg

http://www.itsfun.nu/if3/if3_028.jpg

Yeah, like Goran shows on the "trumpets" on the runner design. That is exactly what I was explaining if using tubes and fab'd plenums. A tapered runner can often improve yet again, though this is getting tricky and expensive. Our "sheetmetal" intakes in drag racing are going to run just short of 2 grand and thats for a "V" configuration with straightish runners.

I'm actually surprised that Porsche didn't seem to take advantage of this in their cast runners. Get volume in and then build velocity like an ITB does or old MFI for that matter. Love all the taper in the desing that Goran presents.

They actually did, but only on race models. If you cut 956 or 935 plenum you will find tapered cones for each cylinder.

I guess it was too expensive to include this on ordinary cast plenums.