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 :)