I realize you are asking about the tbitz setup. It may be able to accept a more aggressive cam than the CIS, and thus make more power. I don't know if anyone has tested this yet.

I've got my own EFI 2.7 project happening, but it is different. I'm putting an EFI setup on top of MFI stacks. All this goes on top of a twin plug 2.7

I'm hoping to accomplish the best of both worlds; MFI throttle response, look, power and sound, EFI programmability, efficiency, flexibility.

Still in the parts collection phase, so I can't report on the results.

I like TRE Cup's Recipe

chuck,
that sounds very interesting. do you have an active thread on your efforts to date? but you're correct in what i'm asking about..and no, i haven't heard a peep out of anyone trying it yet..maybe tbitz will weigh in on this thread.
ryan

ahh..re-read your post, chuck..any idea on how long before you have parts installed and reaching the testing phase? i don't guess you have any idea or can speculate as to what power you might be generating? and would it need special octane? i'm guessing this is more intended to be a track application with the twin-plug setup?
ryan

our recipe will work with 91 octane pump for daily driving , but we recommend boosting it with 25% race gas at the track for insurance. CIS tends to go lean at the top end so we think it best to have that extra margin to prevent detonation

Chuck-

I am struggling with Webers and am on the verge of taking the same route. I LOVE the idea, but haven't done much leg work yet.

My *idea*, LOL was to get an old MFI set up, use the pump as a "fuelrail" by modding the internals and just leaving the pump empty but attached for original appearances sake, and going with a megasquirt system or similar.

My first question (see how far I haven't gotten with the idea?? LOL) was how to measure incoming air, or is that even an issue?

You should really start a thread on this for brainstroming..I think it would be very do-able, and totally cool

BTW, two thumbs up on the poly bronze parts I got from you ...neat and easy install. Tonight it's the monoballs in the rear...I hope!

No thread on this yet, I'll start one once I get to the assembly process.

This motor was a 77 so no injector ports in the head. I'm using MFI tbodies/stacks bored to S specs and rebushed - as new.

I'm going to machine a port into the side of the stack to accept an EFI injector. I'll use a traditional EFI fuel rail.

I'm leaning towards the Autronic controller, but haven't settled yet.

Incoming air can be measured in one of 2 ways. You can use a throttle position sensor (TPS) or a manifold pressure sensor. The sensors are fit to the MFI tbodies. Some systems use a combination of these methods.

Thanks Hal. That is exactly what I was looking for. It seems that it isn't as big of an ordeal as I'd thought. I was even getting excited about S cams and PMO's and how that would run and sound, then I read what TRE Cup wrote:


Dave - that sounds like a winner. I really like that idea. I even thought I saw a 3.0 CIS setup on parts for sale the other day. My question to you, then is I see you did not mention twin plugging and I assume that was intentional. Just for clarification, can the Tre Cup "recipe" work with single plugs. I saw you stated it will work with 91 octane for street use. This looks like a great engine idea. Thank you.

Luke - I am curious why you went back to the 8:31 instead of the 7:31. Does it make 1st a "granny gear" stump puller?

I have read about this system. But as you can see, I'm nervous about carbs...imagine the anxiety I'd experience with something like that?:D

Chuck...I can't wait to read about your project. I'll be great day dream material for me.

Grady, thanks for the suggestion. I'll research that one for some info.


Thanks for the ideas everybody. They have helped me a lot and fostered more questions still. I guess the research continues.

single plug will work fine with 10.3-10.5:1 compression with decent gas. probably go with 29-32 degrees advance on the distributor.

2.7 Modified
 

I built a'74 2.7 with 10.5:1 JE pistons. Electromotive HPV-1 Twin plug Ignition, intake & exhaust ports opened up to 36mm, and 40 IDC webers with 36mm venturies, Cam was a mild elgin, bursch headers, and early twin outlet muffler. The car was easy to start, tons of power and super fun to drive. Remember the 1974 911 had a lower gear ratio which would help the acceleration.
SmileWavy

dan,
tbitz' efi setup actually purports to simplify induction and basically you can remove all the old cis parts, vacuum lines, etc. and it's 'tunable' via a laptop computer..sound it makes is also 'throatier', as it gets rid of the big old airbox and puts a much smaller k&n style filter over the throttle body. an added benefit in my opinion would be the fact that that would create room to easily put a 12 volt electric fan underneath the rear a/c condenser to keep running cold in stop and go traffic..but i digress..
ryan

I've been eyeing ************'s TBI/electronic control-crank fire set up as well. The main determining factor is the 8k+ costs, which I'm not really feelin' right now. Mine runs "ok" on 91 octane around town, but I juice it up with about 25% hotter fuel for track days. I'm going to be hiding in the bushes watching what Chuck does ;) and, of course, I always pay some attention to TRE Cup.

Re: 2.7 Modified
 

Hi Vapors,

Sounds like a terrific engine. Man, now I keep thinking about carbs and S cams. I gotta rethink my views on carbs.

Bigchillcar -

I dunno, guess I'm a traditional kind of guy. I guess if I went with a different induction system, it'd be carbs. Probably PMO's. It is an interesting alternative, tho. FI is pretty mysterious to me. I grew up on carbs. And used to know how to work on them. Not a lot of mystery on those.

duffster,

I'd be interested in knowing what system you're thinking about buying for 8k. Can you PM the info to me?? Thanks


Dan

Chuck:
Is there enough material to machine for EFI or are you adding material or spacers for the EFI injectors. I would think that a TPS and MAP would work easily in this application since it shouldn't care if its one big or 6 smaller butterflies.

Dan:
I would have stayed with 7:31 if I didn't figure the HP bug wouldn't hit me in the future. I just went with a 8:31 tranny and later axles now to simplify the move up in the future. First gear is still OK, but could use shorter 2-4 gears with the taller ring and pinion.

I actually doubt I will rebuild the MFI in a future failure....probably go with different induction options as I move for more aggressive cam and compression options.

My .2 cents. Here is the car I had professionally built last year - 1975 911 Carrera 2.7 US. I feel this car is putting out around 200 hp. It is a bad a$$. Still waiting to dyno it.

RS Pistons
SC CAM GRIND (web cam)
Fly cut heads
SSI's , dansk sport muffler
Stock CIS (w/ sc throttle body
7:31 Ring and Pinnion
Engine Case updated and machined by CE
Everything new in CIS from tank to injectors
etc etc...

I have a friend with a 83 SC he just finished cpmplete rebuild with 964 grind, big intakes, euro fuel distributor, ssi's, etc etc... all the upgrades. With a worried look on his face - He is always asking our mechanic why my car is so fast for a 2.7..... :D

http://forums.pelicanparts.com/uploa...1118025667.jpg
http://forums.pelicanparts.com/uploa...1118025689.jpg

By the way one of the best mods I did was install a new RS spec distributor. Made big difference on the curve.

No. I'll be affixing injector bungs to the side of the stack. Basically the stack will just have a hole to spray through.

The bungs will be machined to match the curve of the stack, then affixed with some type of adhesive. I'm using mag stacks.

carreric,
now we're getting somewhere..that's what i've had on my mind for several years, but have been concerned about how much it really improves with the cis. have you seen or heard of tbitz' efi setup? read member 'flipper's' thread on his recent swap from cis to efi on his 2.7..the dude is in driving heaven last time i checked. i'd love to know what it would do on a car like yours..i think it's exactly what i'd wanna do. i think it would be cheaper than carbs or mfi, be more fuel efficient, driveable, programmable. you really need to dyno that car for all of us 2.7 guys you know.. ;)
ryan

carreric,
btw, can a rs spec distributor be swapped for my stock '74 model? i don;t have the 's' cams, but i do have the 7:31..how did it change your advance curve basically in driving terms?
ryan

Carreric,

Sweet car. Seeing as your's is a 75, I assume you converted from an 8:31 to a 7:31. Did you change any ratios in the box? If so, which ones and how do you like your first gear? I'd really like to hear your tranny story, too.

Dan