Major 500SEL Engine Modifications - PeachParts Mercedes-Benz Forum

dr_mod · #1 09-05-2005, 11:15 PM

1. Thinking about converting the 1985 hydraulic injection system to a more controlable electronic injection system. Are there any fuel injectors on the market that will fit? planning to build and program an ECM for it too. What's a good way to sense the exact rotation of the engine (down to the degree) maybe 50,000 times per second?
2. On some newer cars, there are sometimes individual coils for each cylinder. Is there any reason why one of those, tied into the above ECM, wouldn't work? (spark not powerfull enough.. ect..)
3. Why all of this vaccume stuff? Lets get rid of it all! How can I get rid of the flapper in the intake and drop on a supercharger without loosing my vaccume-dependant components?

I am planning to machine alot of parts from aluminum and a have a good working knowledge of microchip programming and design but I have no idea why these cars are so dependant on vaccume when it obviously could push more horses without the flapper restrictions ect...

If anyone has attempted to do anything like this or have even researched the possibilities, please let me know. The last thing I want is to pass the point of no return without a plan.

wbain5280 · #2 09-05-2005, 11:19 PM

Why not get the FI system from a Ford Mustang 5.0 and adapt it? The displacement's the same and the injectors can be adapted to the intake manifold.

dr_mod · #3 09-05-2005, 11:31 PM

I'll go junkyard surfing in the morning

dr_mod · #4 09-06-2005, 12:59 AM

does anyone know the history of the "flapper" or why it came into use? Or, if there is any intake kits that will replace it? And, are the euro versions of the engine or it's flapper any different?

Strife · #5 09-06-2005, 01:37 AM

Quote:

Originally Posted by dr_mod

1. Thinking about converting the 1985 hydraulic injection system to a more controlable electronic injection system. Are there any fuel injectors on the market that will fit? planning to build and program an ECM for it too. What's a good way to sense the exact rotation of the engine (down to the degree) maybe 50,000 times per second?

Wow, this is a daunting project. First, the degree thing is going to be daunting. An encoder with 360 pulses per revolution on the driveshaft itself that can actually survive under the hood of a car going at up to 6000 RPM for 100K miles is going to be absolutely impossible to find (and never mind an ABSOLUTE encoder, which would always know the exact position). Then, say, 1 pulse every degree * 6000 rpm=36,000 interrupts per second (while doing other fairly critical things) is going to require a fairly decent processor. This is "race car" stuff, with unlimited budgets. And then, a race car doesn't have to go thousands of miles without maintenance. This would require some fairly serious out of the box thinking - maybe I'd start with mounting a 360 toothed disk on the harmonic balancer with (maybe) a tiny hall-effect sensor (no way you could keep an optical decoder clean in there). A "home" sensor would also be required in case you lost count. Maybe a sawblade would be an interesting place to start (but be careful, watch max RPM of the blade, etc).

The way most cars get away without absolute position decoding (my guess) is that they wait until they hit "home" (the sensor mounted near the lower pully in my case) from the starting crank before they actually start doing any calcs, injecting any fuel, etc.

t walgamuth · #6 09-06-2005, 09:45 AM

cars have the same system...flapper and all.

tom w

dr_mod · #7 09-06-2005, 10:21 PM

I was kinda hoping that I could use the clean area inside what is now the distributor to do the position readings. I would love to have it all done with just one reference point and a counter for the reading but I can't think of a processor (that I know how to program) that would be able to count the notches and run spark and FI timings at the same time. This is where it gets fairly hard. If I had an absolute reading ( 0 to 255, or even to 1024), I could have the processor start working anywhere in mid-stroke(usefull if the system glitches) and it wouldn't have to multitask (which I don't know how to program yet) But all of this stuff is something I am most likely going to have to come up with on my own. What's really bothering me is this awefull flapper. I know it's nessesary to get the proper vaccume but if I were to create another source for the vaccume, say the input end of the smog pump, (or whatever it's called) would it be sufficient? also what sensors would I need to bypass or adjust?

Also I will be posting an online Journal of all of this with lots of pictures as soon as I have time.

dkveuro · #8 09-06-2005, 10:58 PM

Try this for starters...http://www.msefi.com/msinfo/index.html

There is a large following of DIY's on this system plus a lot of info from 'Been there done that' types.

Go here :
http://forums.vwvortex.com/zeromain?id=3
and use the search utility for Megasquirt. There is a lot of info' on this forum and others about this stand alone system.

.

#9 09-07-2005, 03:28 AM

You really need to look at making a new inlet manifold and converting to a MAF setup to run late model EFI.

Matt.

t walgamuth · #10 09-07-2005, 08:44 AM

going to change the complete fuel injection system to ford, it would perhaps be simpler to just change out the entire engine... and while your at it the tranny.

for good measure you may also want to jack up the engine after that and put a ford under it.

now why you wanting to completely re engineer the fuel system? economy? performance?

tom w

dr_mod · #11 09-08-2005, 02:45 AM

I like being able to change things. It part of why i am doing modifications to my car but really why i'm doing it is to make it more adjustable and eventually more efficient and powerful. As for replacing the engine totally, I feel that is out of the question! This is a Mercedes! As if i could possibily put ford parts in it on that large of a scale! Might as well be blaspheeming. No engine beside what is already in there will ever be in there as long as i can help it. But the whole point why i bought a mercedes is beacuse it will last longer and it's made by people who've been doing it a long time. I think if i were to put an American engine in it, it should no longer be called a mercedes. But I figure I'm a litle over half blooded German so it will still be German engineering going into it

On the other hand though, I do want this car to be more fuel efficient and quick, but not at the expense of neagating it's past. but do not fret yet chaps. I've not yet taken the engine apart. My attention lies inside the cabin where plenty of new-fangled electronics are being placed and a new interior is being aranged in my mind.. I'm thinking navy blue and Light brown. what do you think?

t walgamuth · #12 09-08-2005, 07:35 AM

sounds good to me.

tom w

dr_mod · #13 03-12-2006, 08:10 PM

As for those new-fangled electronics... I've created a prototype circuit board that interfaces certain electrical aspects of the car to a (regretably) windows-based PC in the trunk! I can now change the position of each of the four windows and the sunroof by tapping on the touchscreen connected to the computer. All is working according to plan and the theory has been applied. Something good and bad has happened on the other hand... My other car (the maker of which is a four letter word... use your imagination) has entirely turned to crap (another four letter word) the transmission is gone and there is no logical reason to rezurect it. but the good news is that I am forced to drive my 500SEL to work and on errands. It is getting far more attention no that it's my only working car. It does feel weird though, driving without a dashboard to hold my instrument panel. but anyways, it has risen to the top of my list of things to work on. Which brings me to my problem. It idles close to 2000 rpm and i'm afraid of moving it too much because i've read it'll kill my tranny. gasp... i've done everything i could think of and everything the shop manual said but it said nothing about what to do if the idle controller has no 12v positive on pin 2... I've tried to put 12v to the pin and it doesent seem to help... i've also traced that 12v wire to a weird relay with a fuse on it's top. that relay will not click when i put power to it either. unfortunately, i no longer have the time to re-vamp the engine. otherwise i'd have different problems. So now, either there are at least two problems or I'm missing something. Please offer any advice you can.

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