Custom ITB EFI build
 

Heres some pics of my current project. I'm modifying some throttle bodies off of a couple of Polaris 650cc snowmobiles to fit on my 911, I decided to give it a try after seeing other members using motorcycle tb's on their Porsche's. The tb's are 46mm which may be a little on the big side for my mostly stock sc but they only cost me $65 shipped so I'm gonna give them a try. I've already machined up a set of manifolds for them so now I just need to get my engine back together so I can bolt them up and start figuring out the throttle linkage and everything.

Heres the pics

http://forums.pelicanparts.com/uploa...1245207147.jpg
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http://forums.pelicanparts.com/uploa...1245207323.jpg
http://forums.pelicanparts.com/uploa...1245207342.jpg

I have more shots If anyone cares to see more.

I'm in, post some more.
These throttle bodies line up with 911 intakes?

sounds like fun! I found a website that uses parts off old fords to make a wasted spark distributer-less ignition system for about $100.00 that would be great to build an EFI engine for way under a grand!!

Looks interesting!

Yes, please more pics and info. Are the bores on your manifolds tapered? (nice work, btw) What ems are you planning on using?

I've got all those parts. Its called "EDIS-6." Needs either a dizzy or crank angle sensor with a 36-1 tooth wheel. Even better is pair it with Megasquirt or other ignition control with a map.

yes, more pics and keep posting.. my brother and i have been contemplating for months how to put hyabusa tb's on the 3.0

Very interesting, please more pics!
Keep us updated.

Nice....I did a simililar conversion but I did not make the manilfolds. I used the 964 intakes and the rubbber boots. Everything lines up perfectly. I did have to buy a set of adapters to mate the two bolt intake studs of the older motoros to the three bolt intake studs of the the 964 intake....I got those from Jerry Woods. I like your approach of making the intakes much better.

So far, I've only run the motor on my dyno, and its very sweet. You will like its tunability...

I will be interested in how you develop your throttle linkage. Mines crap for now...but ok for dyno testing.

Here's a pic of my set up with the 964 intakes. I still have to make some plugs so I can eliminate the old 964 fuel rails.

http://forums.pelicanparts.com/uploa...1245247848.jpg

Wow!

Nice work!
I think those will work perfect.

Glad to see someone is making progress on this, and close to home, too. You should hook up with Al Kosmal in Mount Vernon. He and I chatted long ago about solving this very problem with these (among other) recreational vehicle ITBs.

Wow! I wasn't expecting so many responces so quick. I will upload some more pics when I get home but to anwser some questions the tb spacing is 116mm which I think is 1 or 2mm narrower than the 911's spacing, yes the manifolds are tapered from 46mm at the top down to 38mm at the bottom, I am planning on running with a Haltech e6x unless theres something better for the money and as far as throttle linkage is concerned I won't know for sure until I get my topend back together but I was thinking of replacing the steel bracket that connects the three together with and aluminum part that I could link the throttle off of but its hard to tell without it bolted to the engine. Thanks for all the positive replies and if theres any more questions feel free to throw em at me.

Hey Avery what does the outside of those 964 manifolds measure? I need some sort of rubber coupler to mount my tb's with and if the 964 boot fits good I will just buy them.

Hers some more pictures! some of the parts look bent but it's just the camera lens


http://forums.pelicanparts.com/uploa...1245288037.jpg
http://forums.pelicanparts.com/uploa...1245288053.jpg
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A few thoughts:

My TBs are big too, 48mm on a stock 3.2. When come to think about it they are 48mm at the bottom but they are tapered, so the throttle plates are probably closer to 50mm...
The main disadvantage I have seen this far is the non linear throttle response and that I have to run the engine incredibly rich when cold, or rather, when it's not at operating temperature.
Otherwise torque is pretty even from 2000 rpm up to 6000.

I used a small piece of rubber hose to connect my TBs to the "intake adapter".

*You will need to fabricate a throttle linkage that has a progressive opening to get the best out of it.
*Build the intake stacks as long as you can.
*Get the engine mapped by a proffesional on an dyno, saves you a lot of time an worry.

Just got back from Texas yesterday and had some parts waiting for me. Here's some pics of the tb's mounted to the manifolds with 964 intake boots and a couple shots of the 6AN fuel rail material I ordered. The 964 boots are a tight fit but they slide right on if you twist them while you push.


http://forums.pelicanparts.com/uploa...1245888695.jpg
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http://forums.pelicanparts.com/uploa...1245888819.jpg

nicely done

Here's a picture of what I did with mine, unfortunately due to completely dis-assembling my car to rebuild it, the motor has just been sitting ever since.

http://forums.pelicanparts.com/uploa...1245893825.jpg

http://forums.pelicanparts.com/uploa...1245893867.jpg


I used Kawasaki KZ750 TB and Weber manifolds. I was also able to use the normal Weber throttle bar by making some adjustable linkages.

http://forums.pelicanparts.com/uploa...1245894015.jpg

Wow, very cool. like to play with something like this someday... too many other things now though. Guess I will live vicariously for now.

Kudos to both Avery and rvanderpyl both of their setups look very promising. I'm trying to figure out how to do my throttle linkage but I cannot find any sources for ball-cup or any other type of joint for the linkage just cheep plastic rc parts, does anyone know of a source that sells linkage parts?

Here are a couple photos of how we do our linkage pieces..I don't know if you could apply any or all of it. We make our own rods from aluminum and all the other billet pieces.

http://forums.pelicanparts.com/uploa...1246659865.jpg

http://forums.pelicanparts.com/uploa...1246659953.jpg

http://forums.pelicanparts.com/uploa...1246660282.jpg

so once you go itb/efi you would be using a crank fire type ignition?

Yes. We use a billet crank pulley with a 36-1 toothed wheel on our 3 liter setup.
You can also use the late model flywheel with a 3.6 engine with the factory Motronic 60-2 setup.



http://forums.pelicanparts.com/uploa...1246661241.jpg

Well done guys! If I didn't have a turbo, I'd have to go ITB.

Scotty, those linkages are gorgeous. More pics/details please :D

Not local to you, but

McMaster Carr has them.. they do ship everywhere

I had a Q about my setup via PM which I'll answer here so everyone sees it.

The setup I created is based on Kawasaki KZ 750 throttle bodys. These are used as they bolt together and can be seperated and realigned for my purposes. They come as a set of 4 so you buy two sets. I got mine off of ebay for around $50.00 a set.

I used Weber manifolds ($150.00) which I removed the top studs from, filled the holes with aluminum plugs and redrilled and tapped new holes to match the TB stud spacing. The adapters between the TB and the manifolds are the standard TB boots used on the bike, I got those off of ebay as well, about $10/set.

The injectors from the bike are discarded and injectors from a Honda/Acura are used as they fit the injectors ports by using the BIkes o-rings. The injectors I bought were from a 6 cylinder Acura, I based that purchase on the HP per cylinder vs what I was expecting to make. Those cost $135.00 new.

I then bought fuel rail, fittings and hose from a local hot rod shop.

These guys http://www.cbperformance.com/category.asp?categoryid=6 sell linkage parts.

I bent the standard linkages that join the TB to allow for the farther seperation when installed on the Weber Manifolds. This allows for the TB adjustments to sync the plates to still be made using the existing adjustment screws.


So I currently have around $500.00 into this system to create all the hardware. I can't remember at the moment what the size of the bore on these TB are, however you can also get TB from the 1100 which are considerably larger if you are looking at a big bore motor.

It will be some time before I can find out how this all works as the car is still in pieces, and I am going to be going in for ACL surgury in August so won't be able to work on it again for a few months. Hopefully by next spring I can finally get it back together and fired up

Great stuff! RSScotty. Is it possible for you to provide me with the cad files so I can make a copy? Or can you sell a set? I have access to a CNC machine and would like to replicate your set up for my personal use.

I have another question: What are people using for the MAP manifold? I'm looking for dimesions on the manifold, etc.

You can see a partial view of the MAP manifold in the top picture. It is secured to the breather cover. The linkage parts are available through Rothsport.

Thanks for the links I havn't looked too hard on the mcmaster carr site yet but it looks like cbperformance has what I need, and thanks rsscotty those pictures did give me some new ideas to play with. Now I just have to wait for my cylinders to show up so I can start fitting everything together.

I haven't built an ITB setup yet - but in bench building them, I wonder if motorcycle shift linkage rod-end joints would work. Plentiful and cheap used, and should be more than string enough. Just another possible option for others.

Love this thread.

Itb
 

It's been a while, but i thought that it was time to reply

Regards,
Al


http://forums.pelicanparts.com/porsche-911-technical-forum/573869-my-triumph-speed-triple-project-update.html

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