Technical Ignition advance on E85

[Jake@MHD]

The shop where I dyno'd my car builds a lot of high HP big turbo 2JZs.

You can't compare a lower compression PI engine to a high compression DI engine.

 

[veer90]

Did you stop where it was at or continue until you found MBT? Andy said it was 8ish degrees off, so that would mean you were close to 20*, unless the variance narrows at higher RPMS.

I've always understood it that a more efficient head would take less advance rather than more to make the most power, as the piston can be closer to TDC before igniting. Has anyone looked at NA DMEs? Do they have the same "low timing syndrome"?

We stopped at 12.8* and I made 692whp / 570wtq on that tune. Justin said the gains were diminishing and that it was a good place to stop.

 

[veer90]

You can't compare a lower compression PI engine to a high compression DI engine.

I didn't mean it as an apples to apples comparison, more like ballpark.

 

[fmorelli]

I've always understood it that a more efficient head would take less advance rather than more to make the most power, as the piston can be closer to TDC before igniting. Has anyone looked at NA DMEs? Do they have the same "low timing syndrome"?

I understood from comments elsewhere that our heads are actually rather inefficient, if we are viewing efficiency by CFM?

Filippo

 

[veer90]

I understood from comments elsewhere that our heads are actually rather inefficient, if we are viewing efficiency by CFM?

Filippo

That's been known for a while, 6266 will do 800whp on a 2JZ with head work/cams but the same turbo on a N54 is only good for ~750

 

[fmorelli]

That's been known for a while, 6266 will do 800whp on a 2JZ with head work/cams but the same turbo on a N54 is only good for ~750

From Reaper0995:
Just for talking sake, here are some head flow numbers from various engines. Obviously more to the discussion than just the DI space in the head, but an interesting start point. These are values I found on fast google searches, they may be higher/lower but in any case they all crush the N54! These are for the intake ports in CFM, most values are taken around .500 lift, but not al (LS series might be higher).

N54 stock: 165 cfm
N54 ported: 225 cfm
hayabusa motorcycle: 223 cfm
GTR stock: 276 cfm
GTR ported: 330 cfm
B18 stock: 260 cfm
B18 ported: 288 cfm
LS3 stock: 300 cfm
2JZ stock: 225 cfm
2JZ ported: 280 cfm
Evo 8 ported: 277 cfm

Filippo

 

[langsbr]

Let's go back to the original days of EFI and just slap 20* across the entire map, lol. I know old Fox body tuners that would do that. Works for a drag car that only sees 1/4...

 

[Abacus38]

Yeah stock n54 head flow 160cfm .500 lift. A stock 2j head flows 240cfm. Yes our head is shit lol

 

[dyezak]

The shop where I dyno'd my car builds a lot of high HP big turbo 2JZs. The tuner also said when tuning for MBT on E85 he usually ends up around 16*. Kept telling me to send it when he saw my logged timing was at 12.8*, lol

I don't want to make any conclusions based off purely anecdotal evidence but it looks like there may be a difference between what's in the main timing table and actual timing depending on conditions. But it shouldn't matter for a good tuner - you should be able to find MBT whether it's at 5* or 30* commanded timing.

@V8bait had me at 10* tapering up to about 13.5* on e85 when I was FBO as well. Just more anecdotal evidence for you guys.

https://datazap.me/u/dyezak/log-1511319110?log=0&data=3-22-26

(we will be doing 6266 ST tuning *soon* I hope )

 

[bahn]

@jyamona since you have the routines pretty well documented do you know whether or not BMW is using continentals c_iga_ini_h_rng? It's a long shot but I'm wondering if BMW is adding their timing tables on-top of that initialization value (6 degrees). I've also noticed that the timing advance seen in the low to mid range around 1750-4000 rpm at lighter loads is a tad lower in stock form over what I've seen on other stock DI platforms by about 6 degrees.

 

[dyezak]

Yeah stock n54 head flow 160cfm .500 lift. A stock 2j head flows 240cfm. Yes our head is shit lol

Amazing isn't it.

 

[Abacus38]

Amazing isn't it.

Yeah it’s the reason I told Jordan he’s going to have to port S55 motor head if he is going to make more power on 7275 build. I’m guessing BMW thought process was since the motor going to be boosted and have DI we’ll throw a shit head in there to save cost...

 

[dyezak]

Yeah it’s the reason I told Jordan he’s going to have to port S55 motor head if he is going to make more power on 7275 build. I’m guessing BMW thought process was since the motor going to be boosted and have DI we’ll throw a shit head in there to save cost...

I think cramming 4 valves, a sparkplug, and a fuel injector into the combustion chamber made them cut corners. No need for great flow if you can just add another couple lbs of boost. Cost/Benefit calculations probably made them spend their time elsewhere (like our awesome water pump and HPFP, you know hahaha).

 

[fmorelli]

You can port it and get it from horrible to mediocre flow lol. But honestly it is all upside there I would surmise. Drop boost, improve transient response, drop temps.

Filippo

 

[Milan]

Yeah stock n54 head flow 160cfm .500 lift. A stock 2j head flows 240cfm. Yes our head is shit lol

It's not about flow it's about velocity. This is like asking people "how much psi are you on?" it doesn't mean anything.

 

[Abacus38]

You can port it and get it from horrible to mediocre flow lol. But honestly it is all upside there I would surmise. Drop boost, improve transient response, drop temps.

Filippo

Oh yeah there's huge gains to made. Throw some cams and port the head you'll make 750whp on 18-19psi which on a stock head would take you 30psi to do.

 

[fmorelli]

Reliability should go up well. We know anyone that has done this with before/after data?

Filippo

 

[Jake@MHD]

@jyamona since you have the routines pretty well documented do you know whether or not BMW is using continentals c_iga_ini_h_rng? It's a long shot but I'm wondering if BMW is adding their timing tables on-top of that initialization value (6 degrees). I've also noticed that the timing advance seen in the low to mid range around 1750-4000 rpm at lighter loads is a tad lower in stock form over what I've seen on other stock DI platforms by about 6 degrees.

Hah, funny you ask. I looked at this earlier today actually. Production roms are set to 8* for this table, but tracing the routines, it is only used as an initialization value (as expected... all "_ini_" are this way), at ecu reset or engine stop.

I've traced the logged MHD "Timing Cyl [X]" parameters, and they are indeed logging the final ignition advance value that is sent to the base hardware (think: BIOS level) to be realized. This points to the difference being a constant value, probably baked into the hardware layer somewhere. I also found a reference tied to the OBD PID for timing cyl 1 with a comment "Ignition timing spark advance for cyl #1 (not including mechanical advance)," which again would point to a constant offset. Why is it used, I don't know. I've been told "convention" is a main reason OEM's do things like this.

Anyone have a timing light and would like to confirm my suspicion? A constant offset would be nothing of concern, you just would have to add/subtract it if you wanted to compare timing numbers w/ a Syvecs car.

 

[Abacus38]

Reliability should go up well. We know anyone that has done this with before/after data?

Filippo

I know Tony hit 750whp @19 psi and has data on before and after porting and cams. From what I've seen just by looking at common stock 6266 builds most people hit 750whp at 29-30psi. Also Jakes car hit 850whp with a fully built head and cams @ 30psi on e60. I'll have to dig through the forums to find the post for you

 

[bahn]

Hah, funny you ask. I looked at this earlier today actually. Production roms are set to 8* for this table, but tracing the routines, it is only used as an initialization value (as expected... all "_ini_" are this way), at ecu reset or engine stop.

I've traced the logged MHD "Timing Cyl [X]" parameters, and they are indeed logging the final ignition advance value that is sent to the base hardware (think: BIOS level) to be realized. This points to the difference being a constant value, probably baked into the hardware layer somewhere. I also found a reference tied to the OBD PID for timing cyl 1 with a comment "Ignition timing spark advance for cyl #1 (not including mechanical advance)," which again would point to a constant offset. Why is it used, I don't know. I've been told "convention" is a main reason OEM's do things like this.

Anyone have a timing light and would like to confirm my suspicion? A constant offset would be nothing of concern, you just would have to add/subtract it if you wanted to compare timing numbers w/ a Syvecs car.

Thanks for the response Jake I have a timing light and can double check but it wont be tonight unfortunately. I'll test it out tomorrow evening though, I'll also get the scope on the CPS and the cylinder 1 ignition coil.