Injector/Intake manifold design.
 

Guys,
It would seem the root of all my engine sealing troubles may revolve around my intake/injector setup,or more to the point...the bore wash it could be causing.

Possible reasons to believe intake and injector setup is causing bore wash:

-The 560cc injectors(OE is 280cc) are mounted in the stock location close to the valves,they are a split spray mitsi evo 7 injector and are mounted in the approx same location at the same fuel pressure on a evo7,however im not sure where the spray pattern actually hits,ideally the back of the valve or so i have read. it is possible that these are not far enough back to atomize.

-Very short intake runners that are a larger diameter than stock,so i would imagine low air velocity/cylinder filling at low rpm would not help the fuel situation.

-Tuner noted quite a lot of fuel is needed to hold a smooth idle and on cranking!!

-Small amount of black smoke throughout RPM under WOT,even though mixtures look good...hmmm but dont oxy sensors read oxy,they dont read fuel left over on the bore???.

-Engine hesitates once only under boost after idling/cruising in the lower rpm band for a few minutes,(suspect fuel buildup around rings etc)

-Every engine build has ended with fuel in the oil,never any broken rings.

Are these good enough reasons to believe we have fuel ending up around the rings?...if anyone has any experience with bore wash and it wasn't a failed injector please share!.

My plan if i go through with it is to remake my intake plenum with longer runners to allow a secondary injector setup,we would use stock injectors with an additional set of say 300cc up stream,has anyone here ran this sort of setup and were there implications around bringing the second set on smoothly?. other questions are where to locate the secondary injector from valves and how long to make the runners!??.

Its a fairly big undertaking to accomplish this as i need to change nearly everything even the ECU needs changing as i will need 8 injector outputs,new fuel rails,all plumbing on that side not to mention many hours more on the gold plated dyno.

I guess the big question is do you guys think there's enough evidence there to warrant doing all this work?...what if it ends back where i am now?...if mitsi's can run 400hp effortlessly im sure the M111 can...geeez why must it be so hard^^.


Cheers,
Paul

It can very much be bore wash, and it sure is worst at idle when little fuel is usually needed and the rest will just clean the cyl walls dry causing the rings to wear out.

what u can try is plug new places for the inj further back and just close the old ones and run the car few km and then check if there is alot of fuel in the runners and around the valves. if its distance you need for the fuel to atomize then try this and see. if it works out it will save u lots on total make over of the intake and fuel rails / ecu.

Before you change position. I'd try injectors with different spray patterns. Rochester injectors offer a very unique spray pattern that may correct your possible combustion issue. There are many years of engineering involved in injector positioning and design but I believe your problem can be corrected without too much modification.

Thanks guys, both those are options but im unwilling to try them,moving the injectors on my plenum is not feasible and requires heaps of changes,buying more injectors then spending more hours on the dyno is hard work also(huge cost and time and by the sounds i still need to rebuild this engine)...one option im seriously considering is parting out the engine bay and buying a cheap C36 car to transplant onto my manual gearbox...the only problem i can see is getting the stock ECU to work with the security and without the auto's ECU....

Does anyone here know the complications around not having the auto ECU?...do we need to fudge some inputs/outputs?...im in the dark when it comes to autos but its a mercedes and at a guess the ECU probably reduces power between gears to help smoothness??....

At the end of the day if the engine behaves normally without the auto ECU this swap will be incredibly easy.

I believe the very early C36's didn't have the auto transmission ecu trouble, still the old style.
If you do part it out, I'd be interested in the turbo manifold, and flywheel.

the 4 speed 36s dont have ECU for the auto but there is a terminal used by the ecu to reduce timing on shiftup from 1st to 2nd and that should not be too hard to fool. It connects to a sensor called an overload switch.

Thanks guys,
So the 94/95 maybe early 96 C36 would be the way to go for sure...i could install the C36's trigger onto my flywheel and reuse that.
Jay,while on the hunt for C36 info iv seen those vids of your hill climbs,plenty of wheel spin you must have been moving;),is it normal in your country to make people move out of your way in any lane?^^

MagnumPI,pm sent.

LOL, i know i shouldn't have :$
but yeah u can impose on them to move over, and yes the 36 has alot of spin, i have tried everything, new everything including R888 semi slicks as daily driver wheels, the tarmac we have is low grip, in most places.

and this is a heavy 1700kg car. I like it thou, and if this engine is put in a W201 manual it should make a sweet ride.

i do think that C36 before 96 have the old three point trigger. Not very sure info here, so use with care. :)

Interesting! I am getting a custom made Boxy Plenum myself with short runners, velocity stacks etc (for a reason). Are you using a Plenum or just a cut-down inlet mani? You need the Plenum to cause the high volume of air & correct velocity issues (as far as content is concerned).

One thing I feel a need to add here for benefit of anyone mucking around with IM's etc: a poorly-built EM can cause both turbo heat/turbulence probs as well as engine damage. Better believe it! As for the IM. Enrichment probs are very likely due to poor design/fabrication. One area @ least to consider, as OP has touched on ;)

I would have thought this suggestion by 300EVIL both viable & cost effective. I'm pretty sure my workshop is using the Rochy Injectors also. Maybe they are worth a try? Easy mod to do & you can sell off the other set to get some $$'s back surely?......know what I'd be doing.

I know this is concerning EM's but, I personally witnessed a very poorly designed turbo manifold ruin an engine. There was so much turbulence caused by a dodgy 'merge collector' fabricated. Instead of each runner meeting @ a given central point. They pointed @ each other directly, prior to merging down toward the cylinder head ports :eek:

P.S.

Jay, at least you aren't going to break any of the running gear with wheel spin. It's the gripping that will break a diff gear tooth/spline, housing, yoke, u-joint....whatever else takes up the slack :P Interestingly, when I choose the tyres for my beast on the 18's, I naturally want soft compound tyres, especially for wet driving but, if they slip, this equates to a softer pull on the drive chain & much less likelihood of breaking teeth ;)

Impose,maybe not quite the word i would have used^^LOL
Must be time you got an lsd of sorts,as tricky as it may be to obtain and fit one i think you definitly need it!
Either way with the trigger im sure we can make it work,the bits that might be alittle more tricky is the ASR(if i want to make it work again) and things like AC etc which require compensation,im not sure how the ECU knows when its switched on.

Pagz, if the early C36 is like the old merc's (W201/W124's) It's a piece of cake to bypass the trans. There is a 5 wire plug that goes into the shifter: Two small wires go to the backup light on the shifter. The other three go to a relay: The large and small wire's that are crimped together go on one side with the big single wire on the other. Then run a switch to either your clutch pedal or a switch on the dash (what I did). Pressing the switch triggers the relay and the car thinks it's in N or P which allows it to start, and has the N/P rev-limiter. Once's it's started you can take your finger off the switch and she'll run like she's in Drive. So far 15k trouble free miles on my setup that way. Also serves to be a bit of a theft deterrent since my switch is under my dash, so only I know how to start it ;).


As far as the LSD thing goes, apparently the Nissan S13 backplate is close to our merc's and the GTR pumpkin can be put in with it. Just get some half shafts and be done with it, or use ASD shafts and have some adapters made. I'll be trying this soon when my 201 goes FI.

Jay, I had an ongoing thread on this very topic over on 500Ecstacy and none of us were able to come up with a viable solution. If you have one I would love to hear it. I've already tried hooking a "dummy" one up in place of the original, much like how I did the CTS but it didn't work.
Regards, Eric

There are LSD's a plenty in Jay's neck of the woods ;) I enquired about one not long back. Cheap too. Cost us far far more to import one down here where there are absolutely none. Bout six times as much for the 2.3L 16V Cosworth LSD. Most are shagged due to high mileage & need new clutch plates etc anyhow unless you use a block :(

I may be looking into this up ahead as I'm not interested in rebuilding an older, 24v model w124 LSD & importing a C'Worth diff is out of the Q, at least for now

@ BAD: Yeah we have plenty here and cheap too, an ASD Diff is abt 150USD now, an old 2.3 LSD n more than 200+.
Its time that is the issue.

@PAGZ, yeah i know i need an LSD, its probably the best improvement this car badly needs. especially now that the TOYO R888 have doubled in price. from the usual USD800/ 4 to 1500!!!!!.

and all they can do is some 6000miles at best.

@Eric, from what i know your boxes have 2 of those annoying switches. and they aint cheap either.well i am sure they need to be under some pressure for the ecu to read proper, and they need to pass the ecu checkup everytime it starts, so it wont be as easy as i made it sound. Prolly some small electronic board is needed since all what the ECU reads is resistances at each state. so the board should mimic the resistance when the solenoid is activated on start check up. and then the normal resistance say in drive on idle.

this is all assumption and you know what i say abt that :P

post the link here so i can read it all plz.

I would have already posted a link in my post above but the site is down and has been for some time. I'm sure it will be back though and I'll link it then. Thanks for showing an interest!

The only boxes that have 2 of those annoying switches are the ones that are behind the M120 V12s. The second switch is to retard the timing on the 2-3 shift. The rest of the boxes, even the 4.2 and 5.0 M119's boxes, have only one switch which retards the timing on the 1-2 shift.
Regards, Eric

Hey Eric, u know that those old mercs are my interest, as they need special tinkering to get around stuff rather just reflashing an ECU :)

Excellent info guys,i test drove a potential 1995 C36 donor today,they sound great,i have a few questions for you all:

It does not have the infrared key code feature like my 97,instead it has just a standard key,does the C36 ECU need any special code input to allow starting?...currently with my stand alone ECU i still run my stock C230K ECU down in the passenger footwell as it allows the ignition switch work and also to get RPM on the dash.

The engine does sound a bit like a diesel...is this fairly normal?

Apparently the lifters rattle for about 3 seconds on cold start...how close to normal/worn out is that?.

I notieced the accel cable goes all the way to the throttle body unlike the newer drive by wire setups,from what i can see it is drive by wire to some degree,is this the same on all C36?



Eric,you say that it retards timing 1-2 via that pressure switch ,are you saying it flatens the power slightly there?...so ideally if i ran it on my manual box i would NOT want it to retard?.

Im sure we could fudge somthing for the input/output on the ECU to mimic actual operation,if the ECU checks for a value it we may be able to use a timer to change the value on startup.

EDIT, i found the suspension in the C36 felt more planted than my eibach/koni setup so i may change that over to mine as well,do AMG use different shocks/sway bars in the C36 or is it just the springs they change?

K Here goes,
My C36 has the old immobilizer merc used to have, it has a red and green light on the driver door, and I have to open it only by the key fob button. The car will not start otherwise. So if that’s the system you have then u will need the ECU.

All C36 AMG M104s, and Even the M119 5.0AMG should sound like a diesel. The M104 seriously sounding like one on idle, as if the big/small end has play even.

Yes the lifters rattle on start if the oil is a little thick, if its 0W40 then they should only rattle for the few sec you mentioned.

The Cable goes all the way, and it operates 40% of the throttle body. The rest is done by wire. If u drive the car again you will notice the system has good throttle response and has no lag.

as for the overload switch, well it retards timing in first and I believe it does so just over 4000RPM till the box shifts. I claim so since if the switch has gone bad the engine will hunt on full throttle when rpm is over 4000.

I mean think of it the sensor has no idea of the shift point, we can say it can read pressure of the shift point, but what if you r not on 100% Throttle, but rather at 95%, in a merc that means shift point will be some 1000RPM lower and as such oil pressure in the box has to be lower. Thus my assumption that in first gear the ecu above 4000RPM and 70% TB opening will drop timing a few degrees, and I think its 3 points atleast.

I have the newer key code system,It sounds like i will not need to make changes to the security system at all,as long as i keep my original ECU....however because we will be going from the M111 ~60 tooth to M104 3 tooth im not sure how we will get rpm back on the dash unless the C36 ECU puts out the same pulse width as i have now,otherwise i may have to somehow run two pickups of the crank!

So do these sound more like a diesel because of the higher compression and higher cam lift?(at a guess).

Interesting,i would have thought the lifter noise would be due to wear around the lifter,so when the engine was stopped the lifters that are compressed would drain and be noisy on startup?

Even more interesting is that DBW setup,because it needs to control idle and it would possibly used to limit rpm?,would that mean the mechanical part of it shifts the motor setup as a whole,and the motor drive has final say on where the butterfly is??,that is the only way i can see you would get instant responce,though funny you said that i thought the initial response on the C36 i tested was awful^^...however i am used to my incredibly touchy response on mine and it did have some misfire problems which i guess could be MAS or coils/wires.

So is the pressure switch the only electrical part on the auto 4 speed?(apart from gearshift switches)...is there nothing else controlling gear selection?

What u can do is get the newer harness and ecu of the 96 and later C36, those have the 60 tooth wheel.

The sound like a diesel ,mmm, my guess is the intake cam, some say that it sounds like that due to the combination of the cam with some what soft for the cam springs. i am sure u will give us a true answer if u do get this engine.
Others say that the AMG also has piston slap, but i dont agree.

Well it is lifter wear i am sure, but i mean my AMG when i got it, had only 112k KM on it, and it had this sound, so unless u get lifter noise all the time dont be bothered fixing this.

Ok when i said good throttle response i was comparing it to the newer W211 cars, and W220 for when i drove those cars i was stunned on how awful the response is.
I am sure the Mechanical TB is leagues apart.

Yes the gearbox is independent and needs no electronics. its still one of the fastest boxes on upshifts

Hmm I see,so the 1997 C36 runs the bosch ECU instead of the VDO? but if i ran the Bosch with 60 tooth would i have other troubles with the bosch ECU missing its auto ECU?

I really dunno, but in case the RPM doesn't work y not go for the older spec cluster, speed will be fine on either ECU, and the RPM will do ok then, u will lose the white face thou, and i think u like the White face guages , mmmm. TRy working the rpm first, it might work. :)

For what it's worth, I took a M102 flywheel and had M104 timing marks welded on, and it did work.

You got it, i want to keep my cluster ;)
Making a three tooth and screwing it would be ok,its just that changing the pickup will stuff the timing to the original ecu,which i dont want to remove because i think the ignition does not function without it,i know that if i unplug my stock ECU then the original relays that supply my stock ECU and motec do not pull in when the key is turned on,not even the dash lights come up!,im not sure what the link between the two are but i would assume there is some communication between the ECU and security to allow the engine to start...it could also just be basic electrical setup where a relay in the ECU is switched on from the security and a simple bridging of the wires could eliminate the need to even keep the original ECU assuming we had a way to get RPM from elsewhere(C36 ECU)

Surely it couldn't be that hard to make the C36 Bosch ECU(assuming thats what the 5 speed has) work without its auto control unit??...that would be a more ideal way if i could fined the right ECU/loom for cheap as it will bolt up straight where my stock ecu was.

Are there any mechanical differences in the C36 engine between 1994 - 1997? ie running the later ECU/loom with early M104 would work fine?.

no mechanical differences between them. just that u might need to use some older electronic parts like the older style AIR MASS.

I would go with a ME control unit from a 1997 or even a 3.2l control unit from a 1999 3.2l depending on if there were any improvements. The trigger wheel is the same and it will work on your CAN. And the best part is that it can be flash tuned. As far as the stick shift thing then it will turn the check engine light on if it is an automatic, but it will work just fine.. But I cannot imagine that this can not be changed. I would check the epc and build specs in europe if you do not have cars to choose from. I am pretty sure there are c280 stick shift cars.

Ahh so is RPM definitely sent over the CAN to the cluster? Iv assumed this but never gone as far as testing the other ecu outputs to check it!,i wonder if the security is also sent over the CAN?,if so then running another 97+ ECU would require its matching security module for it to start would it not??..or can this be programmed some how? ( i recall seeing ~2000 model second hand MB engines sold with security module,ecu and Keys,so i guess im asking if this applies to our cars too)

Im interested in why you say use a bosch 3.2l ECU?,is that so it can be reprogrammed to suit the 3.6? or can it simply be loaded with a program from a C36??. also,Im trying to stay well clear of any custom ecu tuning on a dyno as the bill is always massive,totally over it.

There are C280 manual trans 202's available here!,they are rare though.