| Author | Message | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 544 Registered: 5-2002 |
Getting rid of the CIS alone is probably nota worth while mod,the car run good now, it will probably run good when the mod is done and might make 10 more hp. Not the money IMO (I think it can be done for closer to $3500). The hp comes from not needing to run the ulta mild CIS cams....or the blower you can add afdter you have a nice tunably fuel system. | ||
| Russ Turner (Snj5)
Junior Member Username: Snj5 Post Number: 180 Registered: 2-2003 |
Eliminating the metering plate supposedly makes a big difference, at least in 911s. Folks that have replaced the Kjet with webers in 3.0 SC's remark while they may have about the same hp, the increase alone in response feels like 40 hp increase. I looked at converting my 3.2 injection - first to the lenz CIS upgrade which priced out at about 4.5 - 5K, and later EFI using a variety of system from MOTEC to SDS - all of which all said and done started at about 5k and went up. When pricing these let me just say the devil is in the details. Decided to go 'retro' this summer with Weber 40dcnfs at about 4k. Seemed the most bang for the buck, simple, and looks the coolest by far.  | ||
| DGS (Dgs)
New member Username: Dgs Post Number: 27 Registered: 5-2003 |
Dunno on the ponies, but my guess would be that getting rid of that CIS metering plate would make it respond to the throttle noticably quicker (given a reasonably fast ECU processor). | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 275 Registered: 7-2002 |
Been down this path a bit with a programmable EFI on a 4 banger running 16 psi of boost. Custom fuel maps, O2 input, MAP, temp sensor input etc. Once all was done: MAF (hot wire type) was replaced with a MAP sensor MAP input enabled the system to change timing and fuel curves (there were 96 combinations as I recall) in response to manifold pressure/vacuum O2 input could be overridden or the ECU put in a lagged learning mode (most common). Either way, a narrow band O2 was good for a range of fuel modification to a set point before the system went open loop. Intake Temp sensor helped smooth out changes in ambient - although many still said air density was critical (and therefore needed to be measured). Had to have fuel/ignition maps, preferrably built with a wideband O2 sensor and lots of dyno time. knock sensor was helpful to tune out areas of leaness/detonation before it became a grenade issue. Acceleration variables (akin to the pump jets on my Webers!) could be dialed in (fuel increase, shape of duration curve etc) Once it was dialled in, it was close to as good as the OEM version in smoothness despite 560cc injectors (stock was 220 or so) and a larger fuel rail. Exhaust air quality/composition was at least as good as OEM (some were better) but with a much greater range of tuning options. And so many variables to play with on a Sunday! My guess is the cost of an EFI upgrade to replace the CIS is significant. Anyone have a sense of the prize from a modern EFI on a 308/328? My gut is that an EFI would take the performance to equal to (or above?) an equivalent Weber set up, but it's purely a guess. Anyone have data? | ||
| DGS (Dgs)
New member Username: Dgs Post Number: 26 Registered: 5-2003 |
There are many options for sensor input. Air isn't exactly an "ideal" gas, but PV=nRT will get you close. (Where MAP gives you "P", displacement and RPM give you "V", and "T" is air temp. What you're looking for is air mass (n is a molar version).) Another consideration is how the multiple sensor options (and the computer) handle failure modes. One of the things I didn't like about early L-Jet systems is that there were tons of sensors ... but the system never knew which one(s) were out at any given time. (And there was usually one or two not up to snuff, given the number scattered around the engine bay.) One of the things you want in a modern ECU computer is internal sanity checks: If the sensors contradict each other, then there's a problem. Hopefully the computer would have enough information to know which sensor was giving the bad reading. Most cars today have a response to this called "limp home mode". And a diagnostic port (such as OBD-II) to report the internal check findings. Again, basic race cars don't worry about failures over the long run, just as they don't worry about O2 loops in traffic (except in a full course yellow). F1 cars may be different ... until FIA bans telemetric data from the cars. | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 543 Registered: 5-2002 |
Just a thought, an O2 sensor shouldn't be a substitute for good fuel maps. I like to set my base maps 3-4% rich so if anything goes wrong with the O2 sensor I know the engine is not running lean. I also set it so the O2 is not active over 20% throtle where performance is becoming the name of the game, I've had good luck this set up. A by-pass air control of some sort is also very nice for cold starts and steady idle. | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 797 Registered: 8-2001 |
CC: A "closed-loop" is standard with an any O2 sensor system. It probably doesn't run well without it, because the system was designed with the O2 sensor in mind. In racing, the design is made without the O2 sensor to begin with. | ||
| C.C.ofAtlanta (Atlantaman)
Junior Member Username: Atlantaman Post Number: 201 Registered: 3-2002 |
On my car I installed a 4-wire O2 sensor which allows the computer to form a "closed-loop" control over the car. doesn't run worth a danm without it | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 542 Registered: 5-2002 |
Henyry, An O2 sensor is nice if you are going to do any highway driving, you get better milage and the plug stay clean so you're ready to run when you get to the track | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 795 Registered: 8-2001 |
No, not scared away, yet......this is getting high tech. From what I read, I would agree with Charles, that a MAF sensor is not needed......seems to be used only in production cars.....hence, an emission thing, rather than a performance item. It seems that there are many options as to what one wants to use as sensor input......even the O2 sensor seems to be unnecessary, in a performance application. Thanks for all the responses. Well, back to the books!!!!!!!!!!! | ||
| DGS (Dgs)
New member Username: Dgs Post Number: 24 Registered: 5-2003 |
Thanks for the feedback, everyone. You can't keep an engineer down. Once I start fiddling, the "recheck all assumptions" provision kicks in. I hope we haven't scared off Henryk. ;^) This has gone from simple upgrade to "redesign". I think we're officially "over the top" now. ;^) (I do have the Marelli maps pretty well replicated in 11 bits of RPM sample, using the stock sensors, if anyone is interested.) | ||
| Charles I Claussen (Atlantaman)
Junior Member Username: Atlantaman Post Number: 195 Registered: 3-2002 |
I agree with Mark on this issue. Before I converted my 2 motors I checked into a lot of different systems (motec, fast, electromotive.) All recommended NOT using MAF. I went with the Electromotive TEC-3's--love them. If you decide to do this--contact me for some critical pointers on setup that will make life a lot easier. PS--IT IS COOL TO KNOW HOW MUCH SUPPORT AND HELP IS OUT HERE. WISH WE HAD THIS AVAILABLE 20YRS AGO. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1846 Registered: 1-2001 |
I think you've got a good point that a widely varying A/F ratio would make controlling/minimizing what comes out the exhaust pipe too impractical, but the A/F ratio vs power output is not a linear relationship (since it's hard to spark-ignite extremely low A/F mixtures). Without a throttle restriction, the only way to limit the average power output would be to create a pattern of intentional (no-fuel-supplied) misses + the occasional (with fuel) firing. Maybe doable over an overall 2-to-1 speed range, but I think you'd have a very hard time idling (about 7-to-1), and even if it could be done, it would be rather "rough" -- JMOs (or are you planning on solving the low A/F spark-ignition problem?  ) | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 539 Registered: 5-2002 |
DGS, Your right, you can do a partial flow through the MAF to get up to any hp really, but then the problem is turndown ratio, which I alluded to earlier. The MAF requires a flow velocity to make a measurement, the lower the flow velocity, the more error there is in the measurement. So if you size for full power, and make a lot of it, the air will be barely moving down near idle and the reading will be erratic and mostly wrong. At a place I used to work, we tried to use off the self MAF to measure the air going into a fuelcell, but the parts to part variation was to big and the turn down ratio was awful. The restriction for a MAF is more (because of the sizing issue)and in addition to the throttle body, which you still need. �wouldn't it be more efficient to run full throttle air, and simply vary the fuel mixture?� you just inventer a diesel | ||
| DGS (Dgs)
New member Username: Dgs Post Number: 23 Registered: 5-2003 |
There's a variety of MAFs at http://www.pro-flow.com (up to 1500 HP). I'm not sure what you mean by losing control off-idle. The MAFs on the pro-flow page measure a portion of the airflow, so I don't think the larger size will throw off the accuracy much, across the flow range. (If you know the unit flow rate at any point, just multiply by the full plenum area.) The MAF measures air mass, so it eliminates the need to compensate for varying air temperature. The restriction on the intake would be about the same as a throttle body. Which brings up a really strange question: In the old days, the throttle controlled how much fuel the airflow would pick up from the carbs. But tests have shown that an internal combustion engine is fairly inefficient at less than full throttle. (You're, in effect, running the engine in a partial vacuum.) Which leads to the question: in a direct EFI system, what is the point of the throttle? In a drive-by-wire system, wouldn't it be more efficient to run full throttle air, and simply vary the fuel mixture? Or would this produce excessive NOx products? (I should have mentioned: To me, the computer is the trivial part -- I know embedded computers, from the simple 8051 controllers up to the "if it flys it dies" type of hardware.) | ||
| Mark Eberhardt (Me_k)
Member Username: Me_k Post Number: 535 Registered: 5-2002 |
Henry, I did a 308QV, it was pretty straight forward. The YR would be the same, just 4 more injectors to buy and wire. I used haltech stuff and it's been working well for me. It will run the ingnition, distributor or dis, or not if you choose. .....and once the cis is off, there is no reason to keep those useless zero over lap cams.....unless you're planning to add a turo/blower as well DGS, DIS saves you having to buy really expensive replacement cap and rotors, but doesn't really add anything from a performance stand point, it will tolerate higher voltage coils better than the stock distributor, but unless your engine is pretty highly modified, you doen't need higher voltagew coils. So if you like the stock look, leaving the distributors is not a bad thing. As for the MAF, the after market systems are design with performance in mind. MAF sensors do a great job down low, but become restrictive at the top end. If you make the MAF sensor bigger, you start loosing control off idle. Also, you limit yourself to find one (or 2) the right size. If you're building a high HP engine, there is on OEM MAF that will work. OEM hps have come up a lot in the last few years, so there problably is something that would work fine for a 308 in almost any state of tune (well any normal state of tune....there isn't one for mine). The ECU makers just don't mess with it, the MAP/TPS setup works well on every engine, costs less, and makes more hp because there is nothing in the air path. I hope that helps. hmmmm, a Motech might be able to read a MAP sensor if you really want one, I'm not sure. | ||
| Paul Sloan (Sloan83qv)
Member Username: Sloan83qv Post Number: 574 Registered: 3-2001 |
Mike, Webber sells Fuel injection throttle bodies that replace their carbs but retain the look of their carbs. Just thought you would like to know. Paul | ||
| DGS (Dgs)
New member Username: Dgs Post Number: 21 Registered: 5-2003 |
Do I gather correctly that the consensus is to eliminate the distributor(s) on any ignition upgrade? I'd have thought that one big advantage to replacing the "bulletproof" CIS system would be to get that big air flow metering plate out of the air stream. From what I see on the Electromotive site, they apparently use MAP sensors and TPS to determine air flow? Wouldn't a modern mass air flow (MAF) sensor be more accurate for an up to date upgrade? (I started out just thinking about replacing the Marelli microplex with a modern processor ... but that AFM plate bothers me every time I see it across the air intake. This could get complicated. ;^) ) | ||
| allan fiedler (Allanlambo)
Member Username: Allanlambo Post Number: 609 Registered: 6-2002 |
I did this conversion to my 1987 Countach. We ripped everything out and replaced it with an Electromotive electronic fuel injection system with distributorless ignition. The difference it made in performance was AMAZING. Same goes for fuel economy, instant starts, etc. I would say it made a 75-100hp difference easily. | ||
| Mike Dawson (Miked)
Junior Member Username: Miked Post Number: 99 Registered: 2-2001 |
Henry & Charles, there is an engineer in California that converted his Lamborghini Espada to EFI. He actually gutted the Webers and retained them as throttle bodies which kept the original look under the hood. Ignition and fuel are controlled by an Electromotive TEC unit. Details are on his excellant web page. http://home.earthlink.net/~laust/espada.htm | ||
| Charles I Claussen (Atlantaman)
Junior Member Username: Atlantaman Post Number: 191 Registered: 3-2002 |
was a carburated 330 gt 2+2--out of the car now--running on spare 308 4v motor-looooong story | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 788 Registered: 8-2001 |
Charles: I notice in your profile that you have a V-12 in your 308. What v-12 is it? Was it one with CIS to begin with? | ||
| Charles I Claussen (Atlantaman)
Junior Member Username: Atlantaman Post Number: 190 Registered: 3-2002 |
actually am putting it on my 330 gt motor too--but not finished yet either | ||
| Charles I Claussen (Atlantaman)
Junior Member Username: Atlantaman Post Number: 189 Registered: 3-2002 |
I just did a 308---errr--still doing actually--sometimes runs great--BUT IT LOOKS AWESOME! | ||
| Henryk (Henryk)
Member Username: Henryk Post Number: 787 Registered: 8-2001 |
Has anyone converted the Boxer, or TR, Continuous Injection System into an Intermittent Electronic FI System? |