Buying Motec EMS for my 3.4 Build - any advice?

[Iciclehead]

Hi guys, I am getting very close to pulling the trigger on buying a system from Rasant for my 3.4 build.

Rasant has been very good, but I am interested in what this group thinks about a few questions that are floating around in my mind.

Some configuration details already bought or in the plan:

3.4 liter using Turbo crank and 98 MM Mahle 10.3 P/C's (with the valve cutouts), Carillo rods, Turbo oil pump
DC 35 camshaft
Dual plug 911SC big port heads, new valves, guides etc, light polish
PMO ITB's using TPS and MAP
Eisenmann Exhaust, dual catalysts, with dual outlet muffler
Motec with Bosch CoP, Bosch injectors, one lambda sensor per bank, single knock sensor (Bosch)
Clewett cam position sensor
6 speed G50, backdate chassis, Elephant almost everything including ASP, Targett anti-roll bars, Bilstiens

So, questions:

1. There is starting to be ever more E85, should I be putting in a multi-fuel sensor or can that be handled a different way? I am concerned as this car will be moved to Europe so we will be using it on autobahn, likely using fuel with some alcohol in it….do I need the sensor or?
2. It makes sense to tune using lambda vs AFR, any thoughts on that….I suspect there are supporters each way, but lambda feels right to me particularly in an E85 world.
3. The car will have AC, it seems like I should be able to adjust the idle with AC on using timing only, but I have the alternative of using a soleniod to bump the throttle linkage - any advice or been there, done that you can share?
4. I am putting a perforated flap on the muffler outlets so that I can do a little noise reduction - again, any experiences and/or does anyone think it will make material difference in idle or low rpm driving?
5. I'll be putting a single Bosch knock sensor on the engine case, hoping this will be enough to keep the car from detonating itself to smithereens when coupled with a mild tune. I have seen threads using the dual 964 knock sensors/bridges....hoping I don't need to go that far.
6. Do I need clips to hold the CoP's on? I hate the look of the things, but I hate losing a CoP unit on the highway, seems like the Bosch hang on pretty well.....can I live without them or should I just suck it up and put in the clips on the valve covers?

Any last minute advice before I pull the trigger with Rasant? Its a lot of dough....

Thanks all,

Dennis

[Peter M]

Dennis,

I have a M130 running my single throttle body 3.4.

My advice:
1) As a minimum, make provision for a flexfuel sensor in your wiring harness so that it's easy to fit one if you want to later on. Redoing wiring harnesses can be a pain especially Milspec ones with sealed boots. If you are likely to run the same fuel all the time in Europe, you can just tune the car to that. But if you want to run 98 RON one day and E85 the next, a flexfuel sensor is the way to go. Remember to size your injectors to suit the lowest density fuel you'll be using.

2)Use Lamba because it makes it easier to calculate changes in your head.

3)I've also seen an ICV used with ITB's to improve idle quality. Haven't seen an "idle up" solenoid since the 80's! The M130 has a AC function that can be used idle up via a change in the idle speed compensation and/or idle mass flow feed forward to achieve the same thing whenever the AC is on. I don't use any of this on mine as the standard idle control valve manages the AC loading fine.

4) No one has posted that the Eisenmann's are particularly loud so I would wait and see.

5) Knock bridges and knock sensors are cheap and M130 can handle twin sensors. Neil Harvey recently posted that 964/993 knock bridges mounted to the underside of the heads is his preferred option too. Similarly O2 sensor are cheap too. Having twin knock and O2 sensor will then allow you to do individual cylinder trimming for fuel and ignition just like all modern cars. Don't be a tight ass, you've spend a bucket load already!

6) The top CoP will be OK but you'll need to use clips on the bottom ones.

Also consider ceramic coating your headers as there may not be much clearance between the headers and the Cop to install a heat shield.

Yes, it's a lot of dough and a slippery slope!

[Mixed76]

"Having twin knock and O2 sensor will then allow you to do individual cylinder trimming for fuel and ignition just like all modern cars."

How do you trim individual cylinders when your instrumentation is two groups of three? I can see you would be able to adjust each group; after that?

Sent from my Nokia 7.1 using Tapatalk

[winders]

Originally Posted by Mixed76

"How do you trim individual cylinders when your instrumentation is two groups of three?

With crankshaft and camshaft position sensors, the M130 can determine which cylinder has the knock.

I don't see how you can really trim each individual cylinder based on AF ratio considering the lag inherent in that measuring system.

[Peter M]

Originally Posted by winders

I don't see how you can really trim each individual cylinder based on AF ratio considering the lag inherent in that measuring system.

You can't. You still base tune to achieve your overall target AFR's at various loads/rpm zones, but with the engine still on a dyno and still under load you individually trim fuel and ignition settings, above and below your base tune, on each cylinder with regard to knock sensitivity particularly and torque and choose your final cylinder by cylinder trim on that basis.

[Iciclehead]

Some good advice here. I am going to get the multifuel sensor right from the get go, if I don't use it, then at worst it is a few hundred bucks down the drain.

I am also going to install the 964 knock bridges (just have to find a set...anyone have a pair lying around) as I am paranoid about knock/detonation on an engine that costs so much.

...and yes, one O2 sensor per bank...for sure....

I also will have one EGT and one CHT installed (I have a custom gauge already built) so I can monitor one cylinder very closely.

Lambda it is.....but I am presuming it is still a different map for gasoline vs. E85 even though the logical side of my brain says as long as the mixture is at the desired target lambda (E85 or gasoline) all should be well. Advice here from those who know is greatly appreciated.

AC, I will take my chances, the M800 seems to have similar idle options, so I am expecting between timing and general fooling around I should be able to keep a relatively stable idle with AC on. The compressor load is not that heavy after all at idle....

I'll get the wiring for the muffler exhaust baffle built in, the issue is not the Eisenmann's, it is the custom dual exhaust muffler I am building from two stock mufflers....it may need more help.

THanks all!

Dennis

[Peter M]

Dennis,

964 knock bridges are reasonably affordable to buy new, unlike every other 911 engine part!

The ecu will run different maps and the flexfuel sensor allows the ecu to interpolate between them.

If you have a look at the Haltech videos on Youtube, they are very informative on these topics. HP Academy is also excellent

[Raceboy]

If you run lambda table (not AFR) then you can run the same target table (since lambda is fuel independent, not tied to fuel specific stoich value) but that means you need to have full time closed loop and quite big margins for EGO correction. Flex Fuel sensor would allow mixture compensation in real time not based on past events like lambda does it and therefore has better results.

[Iciclehead]

Originally Posted by Raceboy

If you run lambda table (not AFR) then you can run the same target table (since lambda is fuel independent, not tied to fuel specific stoich value) but that means you need to have full time closed loop and quite big margins for EGO correction. Flex Fuel sensor would allow mixture compensation in real time not based on past events like lambda does it and therefore has better results.

I think I understand what you are saying, I am pretty convinced to do lambda tuning and your point about the dynamic correction that a flex fuel sensor can bring.

I do get concerned about a few things logistically, namely that I will need to do a fuel map/dyno test with gas and then switch the contents of the fuel tank to E85 and then redo.
I suspect the reality will be that I tune first on gas and then once I get to Holland I will make arrangements to do the E85 map.

What happens if I get some E85 in the car with only a gas map? It goes too lean right? Or does the lambda sensor sense too lean and increase fuel flow and the car runs OK, just not optimally....need to wrap my head around that.

Dennis

[Peter M]

Dennis,

You might find this page and video useful:

https://www.haltech.com/how-flex-fuel-control-works/

[spuggy]

Originally Posted by Iciclehead

What happens if I get some E85 in the car with only a gas map? It goes too lean right? Or does the lambda sensor sense too lean and increase fuel flow and the car runs OK, just not optimally....need to wrap my head around that.

If you're running on a gas map and fill with E85, then yes, you'll be too lean.

A flex-fuel sensor (a GM one is about $50) tells the ECU what %-age of alcohol is in the fuel, and the ECU can trim fuel (and spark, if you want) maps to compensate.

If you're running closed-loop lambda, then the ECU will trim fuel to the target lambda setting (as long as the injectors have sufficient duty cycle headroom). Because although the "correct" AFR for stoich is wildly different between E85 and gas, 1.0 lambda is stoichiometric for whatever fuel is burning. So if target lambda were 0.85-0.9 lambda on WOT and 1.0-ish on cruise, then the mix would be correct.

For most performance purposes, folks tend to run fuel/spark maps that do what they want. I considered closed-loop - but my lambda reads pretty much what I want everywhere, and running from a map eliminates lambda sensor lag (which only gets longer as the sensor ages).

The factory only used closed-loop for part-throttle; WOT and idle were read from the maps, not closed-loop.

[Iciclehead]

Just bit the bullet with Rasant for the latest M130 system with all the bells and whistles.

I am going to prep my cylinder heads for the 964 bridge, can anyone give me an idea as to the diameter of the "flat spot" the bridge makes contact with as per photos (not my car...I still need to do this to mine):





It looks to be a flat spot of around 12 mm or 14 mm.....need to buy and end mill of the correct size, but don't want it any bigger than needed.

Thanks all for your support!

Dennis

[Essexmetal]

Dennis, note that if a standard endmill does not move across the part it does not cut a flat surface. The end mill has the a slight clearance to the tips and when used to spot it will cut a slight dome. The solution for a flat cut is to use a specific spot face cutter or get a center cut endmill ground to work as a spot facer.

Aircraft spot face cutters work great and have radiused tips so you will never leave a sharp stress riser at the edge.

[Iciclehead]

Originally Posted by Essexmetal

Dennis, note that if a standard endmill does not move across the part it does not cut a flat surface. The end mill has the a slight clearance to the tips and when used to spot it will cut a slight dome. The solution for a flat cut is to use a specific spot face cutter or get a center cut endmill ground to work as a spot facer.

Aircraft spot face cutters work great and have radiused tips so you will never leave a sharp stress riser at the edge.

I stand corrected and will follow your good advice!

Thanks!

Dennis

[Drummer]

I’m using a Motec M600 on my ride, using cops, itb’s, etc., it’s been performing without an issue for 5 years now, it’s the best bar none, reallly good stuff.

[Iciclehead]

Originally Posted by Drummer

I’m using a Motec M600 on my ride, using cops, itb’s, etc., it’s been performing without an issue for 5 years now, it’s the best bar none, reallly good stuff.

Very good to hear, and it is what I want....I love working on my car but I do not like failures or rework, that's why I sprung for the best system from the best provider I could find....did not want any issues in this most key reliability area.

Dennis

[winders]

Originally Posted by Iciclehead

Just bit the bullet with Rasant for the latest M130 system with all the bells and whistles.

Dennis,

You won't be sorry with the MoTec M130. I think I was one of the first to get an M130 setup from Rasant. Andrew has been great to work with.

I went with the WeaponX CoP setup.

I went with Injector Dynamics ID1050x injectors. They would work great for you as they have more than enough flow capability to handle E85 and are designed to handle any fuel type.

Here is my engine freshly installed in my race car: