Fuel System Upgrade Discussion, FI or Carbs Options

[KenH]

Assuming the mechanical parts of the 4 Cylinder 914 motor have been modified, Cam, Ps & Cs.

What are the Pro & Cons between Carbs & the FI systems available – Megasquirt, Carson??, any others.
Would the Engine mods dictate which system to use??
Ease of set-up??
Need Dyno??
Cost??
Success stories??

Ken

[Mark Henry]

EFI hands down and I've had my share of webers.

QUOTE

Megasquirt, Carson??, any others

.
Many others.... I have SDS so to me that changes the dyno question.

QUOTE

Would the Engine mods dictate which system to use??

get one of Jakes FI grind cams

QUOTE

Ease of set-up??

my SDS is simple to program

QUOTE

Need Dyno??

with SDS no. others yes
Programmed it by myself as I drove...basic program done in 5-10min.
Then I fart around around with it for awhile.

The programer and WB O2 meter was NOT even on the car for most of this summer. Just turn the key and drive.

QUOTE

Cost??

SDS from about $900 to 1600.
TMW TB's and stuff $1200
The plenum stock set-up works up to 2270cc

QUOTE

Success stories??

4 years and two engines (sold one) and counting (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

[lapuwali]

EFI all the way (and I have carbs on my car now, but that's temporary).

The Kit Carlson system is not available yet, and may never be. It's pretty much down to Megasquirt and SDS, because those two systems have been adapted to the Type IV more than once, so you can get tuning help. MS is also easy to tune, but you do need a laptop, which isn't required with SDS.

A pre-assembled MS ECU is $350 from at least three suppliers, plus you'll need to buy or make a wiring harness. Some of the D-Jet sensors can be used straight with MS, but you'll need to fabricate a throttle position sensor replacement (have to do this with SDS, too). You can also use the stock D-Jet injectors, though they're very big. Even a decent 2270 can use the 1.7 injectors, they're so huge. The 2.0 injectors have to be run right on the limits to get good idle quality.

As Mark says, you can use the stock D-Jet plenum, throttle body, and runners up to roughly a 2.2 to 2.3 engine with a moderate cam. If you go wild on the cam or more displacement, you'll need a different setup for more flow, and the TWM IDF-style throttle bodies are the hot ticket.

Both systems can also run distributor or crank fire ignition, though crank fire with MS is a LOT more DIY than it is with SDS. With the most recent rev of MS (v3.0), you can run distributor fired ignition (you program the advance curve and lock the distributor advance mechanism) without having to hack anything up, just run the extra wires and flip a software switch.

So, if you're comfortable (or adventurous) with electronics and soldering, then MS will save you some money and give you a somewhat more flexible system than SDS. If you just want a plug and play system, SDS is a better bet.

[McMark]

In my experience, tuning FI to a drivable point is much more challenging than tuning carbs to a drivable point. I think most often dyno time is necessary for FI. But I'll still take FI over carbs every day of the week.

[Jake Raby]

My EFI Retrofit kit is based on SDS electronics and works veryt well wityh stock injectors and plumbing. The tuning is much simpler because I load a fuel MAP from a near stock engine into the ECU before it's shipped and we also terminate the wires, etc, etc to make it easier to install.

I have sold at least a dozen of these in the past few months to teener owners
Retro fit kit

[Tobra]

There is a very good reason that modern cars have fuel injection, it is better in essentially every respect.

[fiid]

Firstly I would say that whatever you do, you need to get on the dyno to tune it properly. You can get to a point where something is reasonably drivable with O2 sensor feedback, but it's not possible to get to all the places on the map.

Secondly - FI will always give you more control than carbs. This is principly because FI has more information than carbs do. Carbs get throttle position, manifold pressure and in some cases coolant temperature and have to mechanically figure out how much fuel is correct. You have little or no control over the fuelling at a specific intersection of those variables. FI has measured inputs for Manifold pressure, Intake temp, RPMs, in most cases closed loop mixture measurement from the tailpipe, coolant temp, etc. You can log enough data from an FI system to make adjustments to your curve. It's possible to get an LM1 to log with carbs, but when you determine that your carbs are lean at 3000RPM and 75kPA, you need to translate that information to quarter of a turn on some screw somewhere - or perhaps filing some material off of a needle.

When you tweak carbs you're typically moving a lot of stuff at once which can present the illusion that you are having an easier time of tuning - when you adjust a jet or a screw it's the equivalent of moving entire sections of the map around in one go. With FI theres a lot of rope to hang yourself, you could make your engine run at stoke at 1k, 3k, 5, and 7k rpms and run totally lean (or even cease fuelling alltogether) at 2k, 4, and 6k. It ought to be obvious when you look at the numbers in the map what is going on in this circumstance, but it's not impossible to do it.

When I say FI, btw, I mean something like Megasquirt, KitCarlsen or SDS that you can tune by hooking a laptop up to it. Whilst the D-jet is an FI system and is subject to the same inputs and outputs as a programmable system, it isn't tunable in the same way and most of the ways you can adjust it are by adjusting broader variables like injector size or fuel pressure, which are similar to adjusting the jet on a carb - they move entire sections of the map around in one go.

Between SDS and megasquirt - I think Lapuwali has pretty much covered that one. You should probably be aware that there are some ignition options for megasquirt that may not have been explored that might be better. Conventional wisdom is to run the EDIS module, but some of the newer code is capable of decoding more complex wheel setups and it may be possible to get this running with maybe an optical system and a fan that's missing a couple of blades, or something similar. Perhaps a few holes in the alternator pulley. It all depends how experimental you want to be (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif).

[Jake Raby]

Earlier in 2005, after a bunch of testing I integrated EFI into all my engine packages- If you want carbs its a downgrade...

The problem I'm having with carbureted engines/customers is the fact that no one understands them at local shops any more... New technicians are not taught5 anything about points, condensers and carburetors...

After swapping to EFI as a standard my customers have been much happier and the amount of questions I field about sputering and backfiring are greatly diminished.

[914werke]

QUOTE

A pre-assembled MS ECU is $350 from at least three suppliers

Who are these suppliers?

[MecGen]

Hi

I currently looking at MSquirt, for my 383 Chev Stroker. Its a hard system to beet for the DIYers in the small block world. Lots of info everywhere...if you have the time/energy to spend and not so much bucks.
The "turn key" option is a great bang for the buck, but its out of my price range.

I have Dells on my 2.0l, and am very happy with them, when I get the SS down pat, you dam strait I will be scewing with a 914 and MS. (IMG:http://www.914world.com/bbs2/html/emoticons/type.gif)

Keep us informed on what you chose.

Later

(IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[Mueller]

QUOTE (rdauenhauer @ Dec 13 2005, 08:53 PM)

QUOTE A pre-assembled MS ECU is $350 from at least three suppliers Who are these suppliers?

Prebuilt Megasquirt kits and parts

I've bought stuff from RS Autosport for the MS.

[lapuwali]

RS and DIY Autotune have both had nice things said about them repeatedly on the MS forum, so they seem trustworthy businesses to deal with. There's tons of free information on the MSEFI forum, but the learning curve for this stuff is fairly steep if you've never really dealt with electronics or fuel systems before.

The thing I like about MS is these guys are trying to do EVERYTHING with it. Water and nitrous injection, traction control, every kind of ignition system under the sun, and engines from chainsaw engines to big-block Chevys with twin turbos making 800hp. The downside is there are a lot of options with so many projects going on at once, so it's fairly confusing for the novice.

[KenH]

Mike,

Any results on your MS setup yet??

Ken

[Mark Henry]

QUOTE (McMark @ Dec 13 2005, 04:09 PM)

In my experience, tuning FI to a drivable point is much more challenging than tuning carbs to a drivable point.  I think most often dyno time is necessary for FI.  But I'll still take FI over carbs every day of the week.

Dyno time is NOT needed on the SDS, I've never had it on a dyno. Maybe you could do some tweeking faster with a dyno but that's about it.

QUOTE

When I say FI, btw, I mean something like Megasquirt, KitCarlsen or SDS that you can tune by hooking a laptop up to it.

SDS will NOT plug into a laptop and/or PC.
It is a pendant system, some don't like the idea of a pendant, but it's simple design when done to my ashtray mount it means that the driver can program as he drives.

Most other systems you need the dyno time because you CAN NOT drive and tune at the same time.

[Mark Henry]

The SDS programmer on my ashtray mount.

[crash914]

Just a quick note....the reason us MS guys keep the laptop plugged in....its fun! (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif)

I always think that I can get this point just a little better..do I need to? no! I just want to...I do put all the geek stuff away when I just want to drive and have a ball.

having a car that can now accelerate like I have never felt before is kool too....

I have had my MS working for like 3 years now. One of the problems is the amount of options that you can use. I am now upgrading my CPU to the MSII version so that it will self tune the Ve table based on O2 feedback. Sounds like fun...I don't need to do this..I just want to....where will it end??

[Mark Henry]

Last year the wife was getting pissy about all the wires, etc. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

So I took it off and never put it back on.

This year I sold my engine and stuck my old 1.8 in, programmed it for 2-3 days (2-3 hours seat time), then removed it for the whole summer.

[Bartlett 914]

On a side note that has nothing to do with performance is the difference in sound. I had webbers when I first started out. I converted back to stock FI. With stock FI the air cleaner is heavy and in a central location. The webbers had 2 thin metal air filters on each side. When at full throttle, the sound comming from the engine is a lot louder!

Mark

[Mark Henry]

Yes... but on a hi-po engine with dual TB's (TWM's etc) I think it would be just as loud as webers.

[KenH]

Thanks for all the inputs.

The only comments missing are regarding the the sensors and ease of hook-up - MS or SDS or is it about the same?

Are the proper sensors hard to get and mount??

I still haven't heard what Muller's MS results were???

To Summarize:

FI better than Carbs due to more tuning information available at various engine speeds and demands.

Existing Plenum and injectors usable to about 2300cc.

Megasquirt & SDS are the 2 choices for the 914.

MS is more Do-It-Yourself as far as building and is probably less expensive. Requires a Laptop to tune and see all the pretty pictures.

SDS more expensive but probably easier to tune and allows for easiy adjustments while driving.

I spoke with SDS today and their feeling is that for a race car where Idle and Full Throttle were the most important setting, tuning should be quite easy.

Ken