How difficult is the CIS to EFI conversion and how expensive ?

[Maxx1]

Is the EFI more straight forward and easier to tune than the CIS?

If I heard right, the CIS is good for about 400 RWHP. What is the HP potential on the EFI? Are the parts easy to come by and at what general cost?

[DRV2FST]

Parts are easy to come by but you will not really know which ones you need until after you bought the wrong ones.

EFI is much easier to tune. You can turn your engine into scrap metal with just a few keystrokes.

EFI always costs $5,000 more than you have already spent. After you are done it will only cost $5,000 to start over and do it again right this time.

Me bitter? Nooo.

Actually, EFI is great but it is no magic pill. You still have to tune your engine. You have to figure out which parts and sensors work correctly for your setup. After-market sensors are not as reliable as OEM sensors. It always costs more than you expect. It will not be as reliable as CIS for a while until you get all the details sorted.

[dyerkes]

With regards to tuning either systems...leave it to the experts with the proper equipment. Too lean for only a few seconds and you're doing a rebuild.

The potential for an EFI system is totally dependent on so many other variables (exhaust system, turbo, cams, heads, fuel injectors, etc.). The EFI system relieves the mechanical limitations of the CIS system, and allows for precise delivery of fuel, and if you also have crank fire ignition, a more accurrate delivery of spark. The only way to take advantage of EFI's potential, is to have all of the components of a system perfectly matched, such that the least efficient device becomes your limitation for HP.

Speaking from experience (I'm right in the midst of my conversion to EFI), the best approach is to determine a budget and a desired HP. Than you can enlist the help of both a professional builder, and tuner in order to determine what modifications will be necessary in order to achieve your goal, and from the parts list alone, determine if you are within budget alone. Cost aside, your best choice would be to enroll the services of the professionals to take care of all of the details and trials and tribulations. This board is full of professionals in the industry and DYIers that can assist in supplying an endless amount of information and experience. The purchase cost of the EFI system ($3k to $10k) is the cheapest part of the conversion. The first issue is, whether you're do for a bottom-end rebuild or not, replacement of your rod bolts (which are limited to 450HP at the crank), followed by upgrading the "other" HP limiting items mentioned above in order to achieve your HP goal. Assuming that you can do all the mechanical work yourself, you'll still need to take your car to a tuner that is expert with the EFI system you installed. Since I'm currently still on that slippery slope, I can definitely say that you shouldn't even ponder going EFI unless you have a bare-bone budget of at least $10k. Will you meet your budget, no way. If for no other reason, you'll run into at least one "while you're in there you might as well...".

Good luck on your decision,
David
186 911 Turbo

[David]

I spent over $10K for EFI parts, but I think you could build a good system for half that. Figure another $1K for dyno tuning. If you want to do it yourself, I recommend finding a very experienced tuner first and either buy the parts from him or buy what he recommends. After you have the parts installed and the car running well enough to drive it, take it to the tuner to do the rest. I am surprised there aren't "good" EFI kits available for 911/930's.

[David]

Originally posted by DRV2FST
Parts are easy to come by but you will not really know which ones you need until after you bought the wrong ones.

EFI is much easier to tune. You can turn your engine into scrap metal with just a few keystrokes.

EFI always costs $5,000 more than you have already spent. After you are done it will only cost $5,000 to start over and do it again right this time.

Me bitter? Nooo.

Actually, EFI is great but it is no magic pill. You still have to tune your engine. You have to figure out which parts and sensors work correctly for your setup. After-market sensors are not as reliable as OEM sensors. It always costs more than you expect. It will not be as reliable as CIS for a while until you get all the details sorted.

I'll second that

[DonE]

Originally posted by 125shifter
I spent over $10K for EFI parts, but I think you could build a good system for half that. Figure another $1K for dyno tuning. .... [snip]

Ummm... Maybe $1000 to get a good WOT baseline, but not drivability (hot start, cold start, idle, altitude, IAT correction, ECT corrections, etc.).

[Maxx1]

Originally posted by 125shifter
I spent over $10K for EFI parts, but I think you could build a good system for half that. Figure another $1K for dyno tuning. If you want to do it yourself, I recommend finding a very experienced tuner first and either buy the parts from him or buy what he recommends. After you have the parts installed and the car running well enough to drive it, take it to the tuner to do the rest. I am surprised there aren't "good" EFI kits available for 911/930's.

Man! This is an eye opener. I thought there would have been a 'formula' so to speak - some guide to follow by now or perhaps an aftermarket bolt on kit, but it looks more like black magic from what I am hearing.

The reason I asked is, I am trying to determine what the next step of performance is beyond headers, cams, an intake and dropping weight? EFI sounds much more costly than I imagined.

[JimCulp]

I think Imagine Auto developed a kit using the pancake manifold.

The problem with EFI is the "while you're in there syndrome". As someone mentioned above- the entire setup is only as good as it's weakest link.

You can waste a lot of money in the process, so think everything through before you do it. I blew a bunch of money balancing and Extrude Hone-ing parts that I didn't even end up using.

Usually, people who convert to EFI want power in the higher end of the spectrum (500+hp). If this is the case with you, then you will have to beef up the internals of your engine (balance all reciprocating parts, upgrade the connecting rods, ARP studs, etc) that all costs a good chunk of money.

IMO if you don't want big power, I don't see the point in going EFI- there are lots of good components on the market that allow for darn good CIS engines. I have spent about $20K in just parts for my EFI build. Now that includes an upgraded turbo and I/C, headers and muffler and other things that aren't directly related to EFI per se, but like I said, if your going for big power, it's not just a matter of bolting stuff on and lighting the candle. It's a pretty complex process as I have come to find.

Measure twice and cut once kimosabe.

[RarlyL8]

If you do an exhaustive search on EFI for the 930 you will find the actual "need" only occurs if you wish to go past 400RWHP.
At that point your costs skyrocket.
If your goals do not include exceeding that boundry (by much) there is no significant advantage to EFI over CIS.
There are 930 EFI kits for sale by tuners. They start at about $7000 but I would expect to pay more than that before it is all done.

[dean]

Here is my expirence with EFI.

I went with EFI cause I was running lean with CIS. I hated CIS and Porsche should have be ashamed to use it when VW was using EFI in the early 70's. Rant over.

EFI was the hardest thing I ever did to cars. I am not a computer guy. I did everything myself so it was really hard for me. EFI is also the coolest thing for cars since they were invented.

I paid $4k for EFI parts plus $2k for other hardware parts. ie intercooler and plumbing etc.

If you pay someone to do it for you, then EFI is easier. If you do it yourself then it is harder.

[David]

Originally posted by DonE
Ummm... Maybe $1000 to get a good WOT baseline, but not drivability (hot start, cold start, idle, altitude, IAT correction, ECT corrections, etc.).

On second thought that's true, my tuner said he usually charges $750 for a basic tune. I'm up to $950 and still not done and I think he's been generous with his unbilled time.

[hobieboy]

Well, I'll add a different perspective...
Yes, EFI is not easy; particularly if you expect turn-key, run like a dream out of the gate. But, in my case, I used an "open-source" ECU, I did A LOT of research, spend A LOT of time making it work, and so far had been tuning it 100% by me WITHOUT dyno (yes - I'll get there by end of summer).
Its been a long road. Its not exactly smooth. But, my car is used on the track most of the time, but I also drive to/from the track, so I also need to have good-ehough driveability.
I don't know how mine compares, but she runs well now; after 15 months since rebuild & EFI change. And I'd do it again if I have to. And parts probably cost me <$5K.

[Maxx1]

Originally posted by RarlyL8
If you do an exhaustive search on EFI for the 930 you will find the actual "need" only occurs if you wish to go past 400RWHP.
At that point your costs skyrocket.
If your goals do not include exceeding that boundry (by much) there is no significant advantage to EFI over CIS.
There are 930 EFI kits for sale by tuners. They start at about $7000 but I would expect to pay more than that before it is all done.

Well, thanks for the input. It looks like for my budget I am going to be limited to the 400 hp mark. Actually, 400 horsepower isn't all that bad .... it will kick butt on 90% of the cars on the street, and considering the 930 hooks up and launches so well, it will beat many cars with more HP.

[DonE]

After having spent the last three years making my EFI project work, I would have to say I would have been a lot better off selling the 79, taking the cash I spent on the EFI and bought a newer model. And for the money I spent, I could have bought a nice late-model. On the other hand, I am a die-hard DIY person and enjoyed designing it, working on it, and tuning it. One other comment - I could have never paid someone else to do the work I've done - it would have been far too expensive, even with the problems I've had along the way. And unlike some, I think CIS is very capable on these cars, even modified.

[DRV2FST]

If I had known how long it would have taken and how much it would cost, I would have bought a 997 turbo or GT3. I like my car and it is really fast but no car is worth the trouble I went through to get to this point.

[RarlyL8]

You would be AMAIZED at what properly set up CIS 400RWHP 930 will whoop up on. How about a brand new Z06 or Viper?
Full boost before 2600rpm, 22+mpg, and perfect A/F ratios are all possible while still using CIS. There are many threads on tuning and modification of CIS if you are interested in going that route. The down side (maybe) is that you are best to do the tuning yourself with an LM-1. You need to be one with your engine. Zin and the CIS.

[SCHNELE]

Brian you are delusional, I love you man but a 400 hp car on CIS is not healthy for a long time and further, no way you are getting 22mpg I am getting tired of conjecture, black magic etc post the bloody data that supports your claims until then unless you need more 930 parts please simmer down. On CIS my car an 87 930 3.4 made 379 rwhp and 368ftlbs of torque, a pretty square engine. The mods included B & B headers, exhaust, Ruf hybrid Turbo, Andial intercooler, Andial SC cams, stock bottom end, stock wastegate with a boost controller (dial a death) C02 was set a 3% and the thing ran pig rich spewing unburnt gas everywhere. Sorry Brian not trying to flame anyone I am only interested in seeing some empirical data to support your claims.

[WERK I]

Originally posted by SCHNELE
Brian you are delusional, I love you man but a 400 hp car on CIS is not healthy for a long time and further, no way you are getting 22mpg I am getting tired of conjecture, black magic etc post the bloody data that supports your claims until then unless you need more 930 parts please simmer down. On CIS my car an 87 930 3.4 made 379 rwhp and 368ftlbs of torque, a pretty square engine. The mods included B & B headers, exhaust, Ruf hybrid Turbo, Andial intercooler, Andial SC cams, stock bottom end, stock wastegate with a boost controller (dial a death) C02 was set a 3% and the thing ran pig rich spewing unburnt gas everywhere. Sorry Brian not trying to flame anyone I am only interested in seeing some empirical data to support your claims.

I think you just proved RARLY8's point. You haven't touched the heads which can bring some serious gains, you are running "pig rich" as you stated, running an early turbocharger and you are within 21HP of Rarly8's claims. As far as mileage goes, I suppose 22MPG is very doable with a weight reduction and R&P gear optimization, but at this point, who cares? With over 470 HP at the crank, you're are not in the same league as the Prius's of the world.

[kellcats521]

Originally posted by SCHNELE
Brian you are delusional, I love you man but a 400 hp car on CIS is not healthy for a long time and further, no way you are getting 22mpg I am getting tired of conjecture, black magic etc post the bloody data that supports your claims until then unless you need more 930 parts please simmer down. On CIS my car an 87 930 3.4 made 379 rwhp and 368ftlbs of torque, a pretty square engine. The mods included B & B headers, exhaust, Ruf hybrid Turbo, Andial intercooler, Andial SC cams, stock bottom end, stock wastegate with a boost controller (dial a death) C02 was set a 3% and the thing ran pig rich spewing unburnt gas everywhere. Sorry Brian not trying to flame anyone I am only interested in seeing some empirical data to support your claims.

He is FAR from delusional - I expect he simply knows how to properly set up and tune a motor. Getting a CIS car to have good A/F ratios throught the rpm range is not black magic, it's actually pretty simple. Real Porsche 'experts' have been adjusting the 'non-adjustable' WUR for over 30 years - it really baffles me that the aftermarket tuners can't handle this task so instead they sell bigger fuel heads and 15K EFI conversions....

[RarlyL8]

I understand your skepticism and I don't take it personally.

The "crazy talk" about mileage, elimination of lag, and A/F ratios has come at great expense and time from many people. I don't claim to have created any of this myself, it is an accumulation of knowledge from several sources. Most, if not all of those sources will not tell you how it is done. Why? Because they make HUGE bucks selling and tuning EFI. An adjustable WUR only costs about $300.

That being said, I am not an EFI hater. You just need to know what your options are before spending the money. I would be livid is somebody told me after spending $10K on EFI that I could have spent $300 for similar results.

Remember, power and CIS are two different entities. You have to build the engine to make power using CIS compatible components, THEN tune the CIS to optimize it.

All of this banter is pointless if you don't like or don't want to learn and work on CIS. There is no option with CIS but to do it yourself. Folks like Brian Leask will help you but ultimately you are the one doing the tuning.