RB Tuning - software,fuel used, and target a/f's.

[LIGHTSPD]

This is my problem with the internet. That 11.6 number you gave that is a very unquantified number. It is based on what someone else has said. Myself i would have no problem running a bone stock GTR at stock boost at 12 AFR on 94 octane. If I knew the source of the 91Octane I would run it there as well.

Cams don't change your AFR. Fuel delivery is based on some calculation Load determined by Airflow volume and mass or manifold pressure and air temp ( speed density) This calculation is then based on the Volumetric Efficiency of the engine.

You are sort of right about higher octane. What it basically boils down to is cylinder pressure or we can get all engineering about this but lets keep it simple. You want max cylinder pressure before detonation occurs. Timing is necessary because (insert long equation here) it takes so many seconds for the fuel to burn. If the engine is rotating faster you need more time to burn. If you use a slower burning fuel(higher Octane) you need more time. So think if timing as the (amount of time to burn your fuel) fire it off to soon and you are working against the piston trying to get to TDC fire it off too late and you lose power and raise EGT's. Yes I just said that high EGT's can be caused by retarded timng and rich AFR kinda go's against that whole internet thing that high EGT's mean you are hurting you are detonating. Next week we will dispell the myth that over 85% duty cycle on your injectors does not burn them out lol

All knock is frequency you need a sensor that differentiates between frequency to get closer to the actual kock frequency. ViPEC is actually watching a few degrees before ignition and a few after basically creating a window so we can separate normal engine noise and also determine which cylinder is dettonating and retard that cylinder rather than doing a global retard. It is very smart. There are many strategies of setting that up as well to long for this convo. Individual cylinder knock control is awesome though.

Cam

[xcye]

Stock RB26DETT
Twin Nismo R32 Lemon Spec Turbos
1 Bar
AEM
AEM 3.5 Bar Sensor
TPS-based Tune
A/F 12.5 ~ 12.0 91 OCT
Not dynoed yet, Self Tuned.

[Shane_Sawatzki]

r32 gtr
healthy rebuilt RB26
tomei cams
hks gtss
nistune
600cc nismo injectors
+ more
11.5 AFR
457 rwhp 404 tq @ 19 psi

[Skym]

Appreciate the your time Lightspd.

It was based on what the dynochart shows at peak hp, but I guess it doesn't take into account that it's for certain mods, fuel, etc on stock engine. I think was done on 98 octane fuel downunder. I have seen some tuners push to 12.0 A/F ratio at peak hp on dynocharts with 98 octane gas, stock engine. But ran it leaner down low and had knocking problems. I assume heat soak problems of SMIC didn't help.

I've noticed some tuners use between 11.6:1 - 12:0.1. Some are more conservative than others.

A tuner mentioned you run this A/F ratio with this spec cam. Like 256 duration you run this A/F ratio and 260 duration you run this A/F ratio, etc. I'm not sure where they figured that out from, but I assume they calculated it via formula?

Interesting thing I found is that stock R34 ECU has a VE map. I presume stock R33 ECU is similar. Nismo seem to prefer R33 ECU over stock R32 ECU on GTR. I gather from they said, it provides better fuel control (I assume VE map, etc).

Always hear that pulled ignition timing, running engine rich raises EGT's. Isn't it similar to antilag when launching, but the extra fuel can cool the exhaust enough to be safe?

From what I can remember, factory runs injectors at theoretically 102% duty on knock fuelmap (RB20DET). But I assume that's the person who tunes the ECU for factory sets it that way. I think it's way above 90% duty on highest load cell on main fuelmap.

That's awesome, so I assume it has 6x sensors (one for each cylinder), instead of 2x knock sensors, like with factory ECU???

Factory ECU has 2x tables (I assume one for each knock sensor, as they use the same figures) you can adjust with what I can figure is knock count that's worked out by the knock board that's inside stock ECU. It looks like a signal and was baffled a bit by it. I assumed it was the frequency of knock that you would see on a oscillioscope. But failing coilpacks, loose parts on engine seems to raise knock count and I assume makes it harder to setup, so maybe factory settings is best for factory engine. Would you agree??

Factory knock setup seems to be accurate enough, as GTR stock ECU, knock detection device both detect knock at same time. So I gather is fairly accurate. But I guess it still won't substitute for headphones, listening for knock or updated knock detection, like on ViPEC ECU.

[NismoS-tune]

I've never understood AFRs are tuning which is why I've gone with guys like Cam who are not the internet guy but rather a very experienced tuner with many cars and hours done. I too had questioned the lower AFRs I was given compared to others but never worried much about it because I knew Cam was giving me a safe tune rather than a "near threshold tune", that and I run a VIPEC which I know is pretty sharp itself.

Cam, about that individual cylinder knock control business, is that something that I would benefit from compared to the knock box I picked up from you or is it part of the same system though I get more sensors? I've yet to install the sensors so it would be a good time to go ahead with better now?

Possible good information for those who don't know:
Does the VIPEC use the factory knock sensors? Does "the knock box" work with VIPECs for control? I never asked these questions when I bought the knock box, just thought "it's gotta be better"...

[Skym]

But what wideband o2 sensor cost's over $400US??? Only can see a LSM11 costing near $300 AUS. Most LSU4 sensors are not that expensive, up to $100 AUS. Also from what I understand, each wideband o2 sensor available is used for different tasks due to head design. So when pushing limit's, probably would just change the o2 sensor to suit task. I can understand the controller cost changing and causing the AFR difference / accuracy problem. Accuracy can vary from 0.1 (more expensive controller) to 0.61 (cheap controller).

[hozer]

Fully Built RB26DET
Single Turbo
Link G4 Extereme
AFR 11 @WOT
550WHP @ 23PSI
94 octane

[NismoS-tune]

Out of curiousity, when people say 94 octane, is it with 10% ethanol like Mohawk or whaaa. I only have access to Mohawk if I'm gonna use 94 We produce a huge portion of the oil in north america here but we don't get much of it back. regular is $1.03 or something stupid.

[evilgtr]

Nismostune when I say 94 I use Mohawk. It's the highest octane gas available where I live and has proven itself.

[NismoS-tune]

I didnt' know lol. Was never certain if that fuel was any good.

Franc

[evilgtr]

It depends who you ask, myself, and a few of the other high hp guys run the 94 Mohawk with ethanol. Recent news report came out stating all unleaded gas has a minimum %5 ethanol in it so it come down to personal preference. When Cam tuned my car I asked him if I should run shell 92 or Mohawk 94 - his answer was a very confident Mohawk 94 without any hesitation sothat what I run. 520whp less then 18psi with safe a/f's and low exhaust temps so it must be decent gas.

[NismoS-tune]

Thanks for the info. I recall Cam telling that I should run 94 with Ethanol but I had never got back to him about Mohawk being the only available one here and seeing his thoughts on that.

[LIGHTSPD]

ethanol blended fuel Mohawk and Husky

[LIGHTSPD]

But what wideband o2 sensor cost's over $400US??? Only can see a LSM11 costing near $300 AUS. Most LSU4 sensors are not that expensive, up to $100 AUS. Also from what I understand, each wideband o2 sensor available is used for different tasks due to head design. So when pushing limit's, probably would just change the o2 sensor to suit task. I can understand the controller cost changing and causing the AFR difference / accuracy problem. Accuracy can vary from 0.1 (more expensive controller) to 0.61 (cheap controller).

I am not going to get into various testing procedures of sensors as most rightups are based on rumor. These same rumors OK the accuracy of tailpipe installed sensors as well. Not even worth going there. I an just going to say what my experience is and all my highend widebands use a Labgrade NTK UEGO sensor except for my one MoTEC unit and it uses a LSM11. My premium guage sensor comes from Australia but here are some sites selling it on line just not with the right connectors.

http://www.bmotorsports.com/shop/product_info.php/products_id/647

http://shop.airfuelratio.com/product.sc?productId=8&categoryId=3