Nistune Forums

People could post some screenshots of your PC display, showing AFR 3D trace and corresponding fuel&timing maps ?
Please detail your car setup/engine also.

heres my traces from today. just fitted Z32 AFM ... problem is there is too much reverberation through the AFM ... so time for a plumpback BOV

The design of the Z32 AFM is not good in case of reverberation.
S13/S14/S15 (alloy version) are just designed for this.

Could you post AFR 3D trace with average values ?
What's your maximum boost ? (your TP max=100)
Injector size ?


my setup:
Z32 running E85 bioethanol
Closed loop / stock O2 sensors disabled
740cc
11psi max. on this pic (up to 16 otherwise)
Timing is still more advanced now

What engine are you using? - update: man, i'm an idiot. It is VG30DETT

Just curious.
You are running E85 - that is, 85% ethanol, 15% gasoline, right?
Aren't AFRs different for ethanol? I mean, first of all E85 has less energy per unit of mass and requires a lot of fuel to run.
E.g. 740cc/min injectors on a 6 cylinder engine with one injector per cylinder and no additional injectors elsewhere is good for:
assumption 1: 85% max duty cycle
assumption 2: BSFC of E85 on a piston f/i engine is approximately 0.85lb/hp*hr (some sources state it is higher then this)
calculations show: 423 hp from 740cc injectors. Isn't exactly invigorating compared to some 650+ hp on gas (BSFC 0.55) with the same injectors and input parameters.

AFRs will be very different, so you can not use gasoline engine AFR trace. E.g. your max power lean afr is ~8.5:1, max power rich is ~6.9:1. You should tune against lambda only, since lambda is a relative indicator and shows you percentage of excessive oxidizer or fuel in the mixture. The translation curve of Lambda to actual AFR is absolutely different for E85 than that for gasoline. You get 1.00 lambda with 14.7:1 AFR on gas, but on E85 it will be 9.8:1 AFR.
You should really ask for average lambda maps (or calculate them from maps Matt has posted) and take into account the fact that for maximum power E85 lambdas like to be slightly smaller, i.e. more excessive fuel. My target lambda for RB25 neo, 9:1 static CR, depending on maximum boost is ~0.80-0.84 on conventional 98RON gasoline (a bit on the lean side), yours should be ~0.76-0.81 on E85.
AFAIK ethanol can tolerate leaner mixtures due to its high latent heat of evaporation compared to gas, but you need to be really careful.
I'll post my average lambda values as soon as i get my car from mechanic.

Interested in your project and results
Petros

this is my R31 GTS2 (RB30E+T) with standard T03 turbo running 98 octane with Z32 AFM and 444CC GTR injectors.

getting a BOV this week and getting turbo cam fitted next week

Legionnaire wrote:What engine are you using? - update: man, i'm an idiot. It is VG30DETT

Just curious.
You are running E85 - that is, 85% ethanol, 15% gasoline, right?

Right in summer, more gasoline in winter afaik, but don't remember the amount.

Aren't AFRs different for ethanol? I mean, first of all E85 has less energy per unit of mass and requires a lot of fuel to run.

Yes and no. I run E85 since 1.5 years now on my Z32 and I do it in a pragmatic way.
I'm tuning E85 as I tuned gasoline in the past. On our turbo engines, it's more than usual to run AFR tend towards 11 and often closed to 10 (stock Nissan is too rich).
Personnally, I target 11.5 @full boost 16 spi, i.e. lambda of 0.78, that's fine for E85.
I cruised @AFR17, 16 and even 18 w/o affecting the driveability. EGT is probably higher, right, but E85 runs cooler then ....
I noticed cruising @15-16 makes the car sluggish, @17 feels better.
Idle is the most often @16 (personal choice).
E85 response is not the same than gasoline, right, this is the reason why I increased the values closed loop/cruising area (even if O2 sensor feedback is disabled). Transition to full boost/maxTP is perfect in my case.

E.g. 740cc/min injectors on a 6 cylinder engine with one injector per cylinder and no additional injectors elsewhere is good for:
assumption 1: 85% max duty cycle
assumption 2: BSFC of E85 on a piston f/i engine is approximately 0.85lb/hp*hr (some sources state it is higher then this)
calculations show: 423 hp from 740cc injectors. Isn't exactly invigorating compared to some 650+ hp on gas (BSFC 0.55) with the same injectors and input parameters.

What are you trying to tell me here ?
I get about 18L / 100kms on E85 with mix driving (incl. strong accels), I got 15-16L / 100kms on gasoline before in the same conditions. It's more than useful for me to run E85 for the same boost/power and it's really cheaper here.
I got 10.5L/100 on 95RON for highway cruising, 13L/100 on E85 now.
I even got 13.78L/100 on E85 for mix driving few days ago.

AFRs will be very different, so you can not use gasoline engine AFR trace. E.g. your max power lean afr is ~8.5:1, max power rich is ~6.9:1. You should tune against lambda only, since lambda is a relative indicator and shows you percentage of excessive oxidizer or fuel in the mixture. The translation curve of Lambda to actual AFR is absolutely different for E85 than that for gasoline. You get 1.00 lambda with 14.7:1 AFR on gas, but on E85 it will be 9.8:1 AFR.
You should really ask for average lambda maps (or calculate them from maps Matt has posted) and take into account the fact that for maximum power E85 lambdas like to be slightly smaller, i.e. more excessive fuel. My target lambda for RB25 neo, 9:1 static CR, depending on maximum boost is ~0.80-0.84 on conventional 98RON gasoline (a bit on the lean side), yours should be ~0.76-0.81 on E85.
AFAIK ethanol can tolerate leaner mixtures due to its high latent heat of evaporation compared to gas, but you need to be really careful.
I'll post my average lambda values as soon as i get my car from mechanic.

Interested in your project and results
Petros

It's no more a project, it's daily driving on my side now. Just a new optim phase regarding the 740cc and E85 (I ran stock 370cc and increased fuel pressure 2 months ago for up to 14 psi, 15.5 peak).
Targetting 0.84 on 98RON is on the limit of safety for me (12.5 is fine on atmo), as I told you, on our turbo Nissan engines, it's more closed to 11 stock.
My target AFR11.5-12 is fine (0.78-0.81) according to the amount of timing advance I have @ full boost: I don't run more than 22° in the 16th column. On 110RON, someone told me running ~30°, I think I'm still safe with 22 for an estimated 105RON in case of E85. I would be very interested in increasing more the timing, tell me your results on this.
I have embedded code in my ECU that switchs on the dashboard check engine light in case of knock. I can tell you it switched on in summer with the timing map above, 95RON, @~3500rpm and flooring the pedal. This was systematic. This is the point of the heaviest load in my case.