2.4 question... from carbs to MFI or EFI?
 

If I were to sell my brand new (rebuilt and shafts re-done) 40mm weber stacks what would it cost to go MFI or EFI on this 2.4 liter twin plug S motor?

How easy is it to do and how common? Where would I source the parts?

Thanks,
Bryan

Check your PM box.

Any other input on this subject? Thanks, bryan

Henry Schmidt @ Supertec can tell you all you need to know about MFI, not sure about EFI. Maybe if you state your goals for changing from Webers to injection, more responses are out there. From what I know, unless your looking for ways to spend money, your Webers are going to be hard to beat.

I think EFI would easily get into $10K with parts and mapping. MFI is really for those who are looking for period correctness and not necessarily better performance. I know MFI produces horrible fuel mileage for instance.

I have said this time before: EFI is MUCH cheaper than MFI and easier to dial in, easier to maintain, cheaper parts and equal or better performance+driveability that is even not comparable to MFI or carbs.

Also I don't know why many people think that the only way to go is Motec or Pectel. Times have changed and for several years there are EFI systems available for much less money but offering equal performance and capabilities as expensive ones. Not to mention that 99% of user do not use any advanced features of any programmable ECU.

All I'm saying that EFI conversion plus tuning on any aircooled 911 can be done for ~$3000 and this is not Megasquirt. I'm ready to prove it if someones challenges my statement. And I have done it too, just for the record.

What EFI are you converting to from carbs that costs $3,000? Oh, I'm challenging your statement.

Yo dude, chill out.
Why all the angst ?
You seem to want to prevent any possible questions as to the validity of you statement as if you have some personal self worth invested in your opinion.

Sorry if it sounded harsh, it definitely was not meant to be and it is hard to show the mood when writing.

It is however a bit bothering to see that on this board EFI usually means DIY cheapskate way or $10 000+ ordeal and noone seems to accept the fact that there are many ways in between also. Is it due to lack of experience or willing to learn something new? I don't know, maybe.

The "prove" thing was included because usually when someone says that something is possible to do cheaper, they think it is just internet bull$hit.

I have not invested much, only that I have done several (successful) conversions.

I've heard many comments about how EFI is better than carbs. That may be true but I have looked for the EFI that will perform as well as 46 Webers and cannot find said EFI for anywhere near the cost of the Webers. We have a couple of pretty successful builders in Houston one of which is, in my opinion, an expert in EFI. He has told my more than once that an EFI system that will out-perform my Webers is going to cost around $10K when it's all said and done.

I'm not trying to argue with you on this and if I could find that magic EFI for $3K it would be on my car yesterday. Please share your knowledge.

I really have a hard time understanding what the expert guy means by "outperforming" because I can't see anything in carbs that could even be remotely better than EFI with ITB's. Maybe he meant carbs compared to regular common plenum EFI? Even then it is not true, because with any decent EFI you can tune acceleration enrichment and advance so that it pretty much matches individual throttles, though ITB's+ EFI is still a bit better.
Here's few comparison points regarding fuel compared carbs to EFI:
1. Injection timing can be changed to desired position in crank degrees, on carbs, not.
2. Fuel atomization is better on EFI due to finer nozzle and higher fuel pressure.
3. You can place the injectors anywhere you like in the intake based on your application (mostly rpm limit).

And that is fuel only, then there's the ignition.

Regarding price, it is easy to spend thousands of dollars if you buy all things from Clewett but you can get/make the same things much cheaper and still get the same result. Even look-wise if you care for anodizing and such.

There are several ECUs that have many (really working) funtions and are affordable: VEMS (my preference), Omex 600, LINK/Vipec, MSIII) etc.

If you do 95% of the work yourself, you can get EFI for less than $2000 (~$800 ECU, 1200 for fuel injectors, rails, FPR, coil-pack etc).

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


regards,
al

I wholeheartedly agree that EFI is a far more versatile system and can generally out perform most other types but cost is always a factor.
Can you show (pictures) a complete EFI system installed on a 911 engine that costs less than $ 2,000.
BTW: when you consider cost, labor is always a factor. Your labor may be valueless but mine certainly is not.

I did a 2.7 conversion for a friend with VEMS ECU using 315 cc Bosch injectors and Bosch 3x2 coil-pack, ITB's from GSXR750 (these already have TPS and injector mounts), custom fuel rail from Aeromotive profile. Total cost of parts was ~1500 euros and labour cost (fabricating fuel rails, installing parts, making harness and tuning) was 1000 euros. I have to dig in my laptop for photos.

But here's VEMS v3.6 PnP on 964, it plugs directly onto stock connector. I installed two Bosch 3x2 coil-packs and 993 fuel injectors (a bit bigger than 964 ones).
PnP VEMS costs ~850 euros, coil-packs were ~100 euros each. This setup made 172 rwKW vs 151 rwKW with stock Motronic.
If you go with generic VEMS (not PnP) for non-EFI 911, VEMS ECU costs ~600 euros with connectors, cost of the wiring harness depends on the guy whom you will have it made but in my case it costs around 200-300 euros.

http://www.porsche-foorum.org/album/..._DSC04847m.JPG
http://www.porsche-foorum.org/album/..._DSC04880m.JPG
http://www.porsche-foorum.org/album/..._DSC04881m.JPG

I agree with the labour cost vs own time. My time isn't nearly as costly as it would be in some hotrod shop so I pay with my brains not wallet. It comes down to personal preference, experience, willing to spend time on the car etc. Always a compromise but I don't think that a person is serious about going EFI if he/she complains about 10000+ cost and does not look for other options which are not any lesser in capabilities or performance.

Al, nice project I have read you thread before. Triumph TB's seem very nice.

Peak HP with EFI is not going to be any different than peak HP with carbs keeping the induction flow the same. Getting from idle to WOT is where EFI has an advantage if there is one.

To build and EFI system that matches the performance of Webers is more than what you describe. Common plenum systems won't get there with regard to throttle response. Individual throttle bodies are not cheap to buy or to build from motorcycle parts. Although these parts can be made to work, not many motorcycles came with 46mm TBs. The Triumph parts in Al's build are 38mm, not near big enough for a hot 3.0.

Your friends 3.6 made 172 rwkw which converts to roughly 230 rwhp if my math is correct. My 3.0 makes close to 240 at 6,800 with Webers and pump gas.

I know an EFI system can be put together with various parts and pieces but it's not what i would call plug and play. I've had a tool box since I was 12 and would not feel comfortable trying this on my own.

As a side note; The NASCAR boys went to EFI this year on top of a manifold. The results? Down about 50 hp across the board compared to last years numbers with CARBS...

19 mpg on the freeway and 15-16 mpg average in daily driving with my twin plugged, high compression 3.0 on MFI. This motor makes 245 hp and 230 ft lbs of torque (216 and 201 at the wheels).

Bryan, don't let anyone tell you that MFI is a poor second or third choice, employed only by those holdouts among us looking for "period correctness" or getting a bit too nostalgic. It's an outstanding induction system that may never be matched for sheer performance. The throttle response is unmatched by anything else, as is the induction sound. It would be the "finishing touch" on your twin plugged 2.4.

Complete, entirely usable MFI systems that would be suitable for your 2.4 are out there, and regularly sell for a fraction of what you would spend on any sort of decent EFI setup. Tired, but entirely rebuildable MFI systems are out there for even less. Even if you have to piece a system together, and get the pump and throttle bodies rebuilt, you still won't approach the cost of any sort of EFI.

Amen

We have all the parts necessary to convert from carbs to MFI.
2.4 liter twin plug, 550 Spider replica sounds familiar.:)

Hey Jeff,

No personal experience with MFI but everything I've read says poor fuel mileage; even Henry mentions fuel "yardage". Just goes to show you can't believe everything you read. I certainly didn't mean to make MFI sound second or third rate as every one I've seen with Henry's signature look like factory race pieces. Personally, I think it's by far the best looking of any choice.

Where would you source a rebuild-able system?

Rebuildable systems come up right here on Pelican every now and then, as well as on the S Registry. You just have to keep your eyes peeled for them.

I KNOW what it takes to make EFI system to match the carbs, I just did not want to make this post longer than it is. I have installed and tuned ~50-60 different cars (around 20 Porsches amongst them) with standalones and these include turbocharged, supercharged, NA, ITB etc engines, starting from H-4 to V12 BMW twin turbo and 800 hp/1200 Nm Mercedes AMG 5.5liter twin-plug 3valve supercharged engine (basically the same as SLR McLaren).

Here it is on an engine dyno: http://img165.imageshack.us/img165/6...cn12591ht1.jpg

And here's a video: http://www.otter-ag.ee/files/AMG2.MOV

The SuperFlow AutoDyn dyno we measured the 911 is conservative on the numbers but if you are even remotely familiar with dynos, what matters is before and after numbers.

You are arguing that it is not cheap to put motorcycle ITB's together and find them, yet I have done this numberous times and ebay is full of suitable ITB's. If you don't feel comfortable and other do and make it work, then perhaps the problem is not the others, isn't it?
I remember someone said once that ITB's and turbos don't work well also, you can't possibly take a person serious after such statement. I fabiracted ITB turbo manifold for my 931 race-car, you can see photos in my garage section here in Pelican.

I won't even go with NASCAR carb vs efi, because how can you expect them to get the same or better results with completely new to them solution and not too much of experience? They had like 50years to hone things with carbs but only one year with efi so keeping this in mind I think it is in fact better.

There is no point in taking this further, if one wants to believe something and doesn't want to actullay do something other than saying it's not possible/right/good, then fine. It's your car, not mine, right :)

Not sure why people think MFI is uneconomical. My 2.7 RS spec motor with compression bump, 3 angle valves, lightened flywheel, boatailed cases, no other mods gives 30 mpg (imperial gallons not USGs which are smaller). Thats on a 250 mile round trip that sees a couple of blasts up to 120, some laid back motorway cruising at about 80, and some pedal to metal country road blasting. Set up by the best man for the job in the UK Bob Watson. Couldn't believe how good it was so went back and checked it again. Same result. Probably only 3 people in the UK that know how to setup the MFI system to this level. Many more think they can though....

Why Sell Your Carbs?
 

Bryan, that setup you have now is very clean and simple. Why in the world would you want to add EFI or MFI?

I'm sure you have a good reason, but I don't think MFI would make you as happy in the end as EFI would, depending on your goals the EFI gives you almost infinite options. EFI wont be cheap especially if you do it to the detail you've done your other project cars and man they all have been very nice!

If it were me I'd just tune those carbs and drive it like you stole it!

Good luck either way,
RCSmileWavy

Kinda what I've been trying to say...

Thanks for all the input guys. It was my curiosity that led me to this question. It was more of me just understanding MFI and EFI more and was curious on the expense of switching and what makes the most sense. I don't mind carbs it is just voodoo to me and I need to get better aquatinted with them so I know how to tune and ensure they are running properly. My motor has roughly 220hp and the car weighs 1,400 lbs so it's not that I need more power. If I do, I would absolutely need and LSD before hand.

This was great reading for sure and appreciate all of your input and expertise.

I will update if I end up doing anything.

Regards,
Bryan

Key is to use a decent datalogging of lambda, rpm, tps and intake temperatures and make adjustments based on those. Many just adjust and go by the butt dyno but most often that approach will not result a well driving and powerful engine but rather poorly running or worse, failed engine.

I have set up only one MFI (on a customer 2.4 S engine with 2.2 S pistons and RS 019 MFI pump) and it runs very well but took few days to get running well with datalogging. I don't know what mpg it gets but it doesn't run pig rich on low loads and hedgehogs are still alive after driving this thing on country roads :)

Wow, I've been tuning MFI Porsche engines for over 30 years and have owned most the latest and greatest electronic devises that technology had to offer and to this day, my butt dyno has served me well.
I guess I just kept getting lucky.
If only Racerboy lived close enough to tune my engines.
I would really like them to run as well as he can tune them.

Just teasing but the arrogance is strong with this one.

And again someone misunderstood me and took it personally. Why start to mock someone just because YOUR opinion and experiences differ?
Perhaps you should try to post a bit more constructive and technical answer than mock me and say that I am wrong with only the fact that you have done something 30 years?

It is not the electronic devices, it is about gathering data. And for example reading spark plugs counts also, what I meant was just turning screws and judging by butt dyno without measuring and checking.

There seems to be some weird attitude here in Pelican, or it just seems like that: there is few guys that are long in this board, have done 911 thing for quite some time and are respected (my respect to you too, don't get me wrong) but when something new, or different is introduced by someone, instantly a protective and unfortunately offensive position is taken.
Guess what, you are not alone in this world who build, tune and hot-rod 911's and Porsches in general. There are many other people who are not wrong automatically because their approaches and methods are different. I guess dynos are for fools and WBo2 plus other datalogging devices are for pussies who cannot tune like the real men (read: who can afford several engines to fail until learned from mistakes)?
I don't know if I have tuned my engines good or bad, I just know that they run well and haven't failed because of tuning error.

If I'm wrong, please correct me.

P.S. If it's ok, I would propose concentrating more to technical stuff and not personal attacks?

Henry, with nowhere near your experience in this game, I did find my LM-1 to be invaluable in setting up my MFI pump on my oddball 3.0 build. I think what this kind of technology has done, if nothing else, is open this up to duffers like me who like to fart around with this stuff. All it really takes is a basic understanding of how the system works, too much idle time, and an LM-1 to tell a guy what is happening, and most anyone with any sort of common sense can make this system sing. And I've had a ball doing it.

Bryan asked in the beginning if he could change from carbs to MFI or EFI. Responses said yes but be prepared for the cost. I don't know the entire cost of MFI but a quick search showed parts alone (before rebuild) are worth $3,500 or so. I'm guessing when I say $7,000 all said and done. I have to admit, it looks awesome!

A proper EFI set-up with ITBs (no disrespect to your assortment of parts) and tune will be $3,000 for ready-to-use ITBs, $3000 for ECU and related parts and about $2,500 to tune. I know you're going to tell me I can use parts from a Voltec 2.4 miser-geezer and coble together my own system for far less. I don't dispute that. Personally, I don't think I would be happy with the look of it.

I had the opportunity over the weekend to run my 3.0 with Webers against a 3.2 with Motec and PMO ITBs. Similar cams, my compression is a little higher, I have headers he has SSI. They were almost identical; he pulled me on the bottom end but did not pull away, maybe a car length by 100. He has a painted interior with roll cage. I have no interior! Ha.

I also tried my luck against a '76 tub with a fresh 3.4 and 50 PMOs for reference. He dusted my ass.

As I said in my first post, it can be done but don't expect anything more than what you already have.

The beauty is in the eyes of the beholder as the saying goes. My point was that the $3000 total EFI+ITB kit does the same job as $8000 and the word "proper" goes to the same category as "beauty" as long the chosen solution does its job as well as more expensive.
As for standalones, if the owner cannot tune itself, all comes down to the tuner who is available nearby and what systems the tuner knows best.
In next month I will be converting a 993 into ITB+standalone ECU combo, the budget for that is also less than $3000 and I can show you results from the dyno afterwards. If someone is interested in this at all that is.

We seem to be going in circles; where is this $3,000 EFI+ITB total system?

Read the above please, it would be a bit silly repeating myself all the time.

What's silly is that you can't provide the info on your calimed $3,000 EFI+ITB system...

What's even sillier is that I keep responding to you. Over and out Raceboy.

Read this:

This was information about this setup. I mentioned about the photos also. It's a bit hard to take photos of the car that is over the sea and I am away from home also at the moment but if you would have a little bit of patience, then I could show them. Or 993 ITB conversion. But since you apparently don't have any interest in EFI system and at first tell that it is impossible, then that it is not proper system, I'm kind of at loss whether anyone is interested in it or not?
What supposed to be technical discussion was turned into personal attacks and I still fail to see any serious facts about your statements besides that "it is not possible" or "it is not proper". If you decide to honour me with communication again, would you care to tell me what ECU's you would prefer and why?

I am interested in your set up, especially the ITBs and fuel rails. A picture would be very good to make it easier to get the right ITBs and rails

My current setup with Megasquirt 2 and EDIS ignition (but without ITBs) must have been well below 3000 btw all complete and tuned, and it works beautifully. Why anyone would prefer another ECU than the versatile and user friendly Megasquirt in their old 911 is beyond me. I can still see how some might prefer an all mechanical system too as I have it the same way with my bikes where I would never consider fuel injection for some reason that I am unable to explain

Regards

The later year GSXR-750 / 1000 Kehin throttle bodies are 42mm and will support about 40 HP; not bad. There would need to be a manifold of some sort fabricated to adapt the body to the intake port and the butterfly needs to be about 200mm above the valve stem. Also, the ITB come in a set of two, two throat bodies. They would need to be modified to use only three of the four throats. That in itself would be pretty tricky. The rest of the set-up seems pretty straight forward.

Carbs, MFI.....ITB/EFI.................these are all great systems with their associated strengths and weaknesses. People tend to focus on the differences without acknowledging that they have some important features in common.

Can you say Independent Throttle Bodies? I knew you could.

I've have enough "hands on" experience with all of them to be dangerous...but I am learning by doing, with the help of others that are also doing.

After playing with Webers, Zenith's and MFI, and going through the search for 30-40 year old parts, etc..................5 years ago or so I started exploring the possibilities of finding a relatively inexpensive approach to achieving the same, or better, results as these systems....using more modern and readily available parts. I also spent many hours playing with the Bosch K-jetronic CIS system on my 77S, so I liked the instant cold start/idle characteristics, but understood the tuning limitations of common plenum intake designs, etc.......................one of the paths i decided to follow led me to motorcycle throttle bodies. Readily available, relatively inexpensive, sized properly for many applications....etc. One thing led to another.

The Triumph Speed Triple T'bodies are 42mm at the top , approx. 41mm butterflies. Not big enough to support big race motors, but great for street-able 911 hotrod motors, for sure..including 3.0 and 3.2's...i would think There are some good choices out there. I have now implemented a few systems using ITB's and Megasquirt. Definitely not for the faint of heart, but definitely for the dedicated DIY hot rodder that wants to combine the features that we love about independent throttle body intakes (like Webers and MFI) with modern engine control. i've used some very nice TWM ITBs and I've used my home brew Triumph set up....also very nice T'bodies, and both work very well. No significant difference, from an end user standpoint, between the two.

The fear factor for most is the education part of it. You do need to study up a bit to gain an understanding of how to "program" the ECU. A lot of the information out there is presented in engineering terms and may or may not be easily understood. Most of us hot rodders grew up on carbs, know them and love them...............and programming the ECU just isn't happening.

(that being said....many of us that love the carbs and MFI........can't, or don't work on them or understand how to tune them either)

But, if you have mad hot rodder skills and are willing to put in the time and want to expand your mental "tool kit" a bit, this is a great entry level way to get into it. I'm having fun with it, while still learning about it. The acceptance is growing and the DIY EFI community is growing...........quite a few of us are exchanging notes, ideas, maps........etc.

regards,
al

PS: I have nothing but respect for those that have a vision, dig in, and produce something that others would not attempt...............Jeff Higgins 3.0 w/MFI runs like a scalded dog..............however I only get to view it from the back, because i can't keep up with him.

X-Factory (Kosmal) ITB/EFI KIT

GSXR throttles from 2001-2002 (K1, K2) are all separate and easily adjustable to different cylinder spacing using custom bushings. Also extensions are needed to be welded on the linkage but that is all that is needed for adaptation.

Making the flange for 911 is also easy: One of my friends made a CAD file in SolidWorks and I just had it watercut out of 10mm aluminium sheet (material + cutting cost me ~50 euros) and welded a hose connections in order to fit ITB's (doesn't let eat and vibration to the throttles and intake, also easy to disassemble).


GSXR 750-1000 are 48mm ID, 54mm OD at inlet and 42mm ID, 48mm OD at exit.

http://www.everettmail.co.uk/pics/mo...000gsxr750.jpg