Spool Vs A/f Ratio - Please Post Up Your Results

[Dose Pipe Sutututu]

Hi All,

I have been doing research here and there, and it seems Mitsubishis incorporate lean spool by factory. Their ECUs are so powerful in comparison to ours, dual maps (lo & hi octane), lean spool features, etc.. ra ra ra...

BUT I own a Nissan and I love them, enough of the crap

I have been re-tuning my car here and there and I would like to see how others have their A/F set vs Spool.

Currently, I've played with my PowerFC and when the car comes onto boost it's quiet lean, on full boost A/F is around 11.7~12 which is safe and timing is at 13 degrees @ 18PSI, for some reason when I dial in even 1 extra degree I get retarted knock on a 30degree day, but at 13 degrees its fine, knock no more than 30.

So, could everyone post up their Boost vs A/F graphs? that would be great.

R31Nismoid, YES I have looked in the RB25 Dyno results. Mainly its all Power Graphs which I'm not interested in.

[Lithium]

Sorry, I'm trying to establish what you are trying to determine - you mention spool but it sounds more like you are trying to work out why you are knock limited when trying to add timing at 18psi of boost?

I assume you are road tuning? Bare in mind not all things are equal with different cars, an obvious which would apply to your example would be turbo choice. If your car is experiencing high exhaust manifold pressure then you will be able to run far less timing than if you have no major restriction on the hot side. Same would good for good intake charge quality (good intercooling, not maxed out compressor, WMI etc...).

I have no AFR graphs for my car printed, but am targetting similar afrs - ranging from Stoich at very light load to around 11.6 at full (17ish psi on an RB25 running a GT3076R) boost.

Edited January 5, 2010 by Lithium

[Adriano]

I agree, since i started playing with late model evo's, my thoyughts on spool a/f have changed. I no linger have any dramas tuning my cars to run 14.5 at 2psi, and 13.5 at 5 psi, this is dependent on the car and mods though obviously.

[STATUS]

Hi All,

I have been doing research here and there, and it seems Mitsubishis incorporate lean spool by factory. Their ECUs are so powerful in comparison to ours, dual maps (lo & hi octane), lean spool features, etc.. ra ra ra...

BUT I own a Nissan and I love them, enough of the crap

I have been re-tuning my car here and there and I would like to see how others have their A/F set vs Spool.

Currently, I've played with my PowerFC and when the car comes onto boost it's quiet lean, on full boost A/F is around 11.7~12 which is safe and timing is at 13 degrees @ 18PSI, for some reason when I dial in even 1 extra degree I get retarted knock on a 30degree day, but at 13 degrees its fine, knock no more than 30.

So, could everyone post up their Boost vs A/F graphs? that would be great.

R31Nismoid, YES I have looked in the RB25 Dyno results. Mainly its all Power Graphs which I'm not interested in.

um nissan has had all that for decades also...

[Guilt-Toy]

hahahaha lol

yeah because Nissans come with power fc's standard.

um nissan has had all that for decades also...

[GTScotT]

agreed, mitsu is factory tunable. evo 7 and up needs no modification PERIOD to be tuned. plug in and go. earlier models require a 7+ ecu and a minor re-pin, even the earlier models with the different motor. no less than excellent.

Yet I wonder, what would happen if you dropped the AFR to something a little richer and then tried to add the timing. Considered this?

[discopotato03]

Twin scroll IW turbine housings help , Evos 4-10 all have them standard .

A .

[Adriano]

um nissan has had all that for decades also...

Sorry trent, would have to disagree on this one, mitsu ecu's are far more powerful than the nissan rb ecu's.

SInce when does nissan have lean spool, which is an rpm/time/load dependant feature, active(knock monitered) ignition mapping on individual load points, and a total knock count ingition map trim?And mivec of course

[paulr33]

what do you think is causing the knock?

do you think its the AFR's?

do you think its the intake temp?

do you think its the ign timing?

why do you need to run 18psi?

is your compressor efficient at that level

turbochargers once out of the efficiency island give diminshing results, that is, for every psi extra you dial in, you dial in assloads of hot air

the more hot air you dial in, the more the engine detonates

so - reasses - is 18psi efficient and giving you good gains, ie from 17 to 18psi do you gain 10kw or do you gain 1kw?

[Dose Pipe Sutututu]

omg, I just read what I wrote, didn't make sense! trying to multitask at work, failed!

Forget about what I wrote about full load, I'm quite happy with the result I got, I'm just working on getting the boost to come on earlier.

anyways, what I am actually after is the A/F everyone runs when coming onto boost. I know the leaner the harder it will spool due to exhaust gases.

Paulr33, FYI I'm running HKS2535 and supporting mods, so chillax I'm not running a stock turbo like you!

No need to lecture me about turbo efficiency ra ra ra, yes HKS2535 is rated most optimum at 1bar but many have run them at 1.3bar and get quite outstanding results, such as Robo, and a few other people

So what I am after mainly are dyno graphs which have the boost vs a/f ratio pre full load

[Dose Pipe Sutututu]

this is what I am after, so I am able to compare a/f vs boost on spool (does anyone have a combined one?):

Edited January 6, 2010 by johnnilicte

[STATUS]

Sorry trent, would have to disagree on this one, mitsu ecu's are far more powerful than the nissan rb ecu's.

SInce when does nissan have lean spool, which is an rpm/time/load dependant feature, active(knock monitered) ignition mapping on individual load points, and a total knock count ingition map trim?And mivec of course

remmeber compare apples to apples ie year model to year model, the early evo stuff is pretty clunky also. Most of what you post is tweakable with aftermarket mapping gear.

lean spool = R32 gtr ecu feature

active(knock monitered) ignition mapping on individual load points= r32 gtr std ecu feature

total knock count ingition map trim= r32 gtr std ecu feature

mivec= nissan fail not till much later

the mitsy stuff of the same era (1990) was no better but if your comparing evo 6 onwards than yes they are a better beast.

to be honest the best stuff around is the holden (ls) and ford (fg) gear there is more features than nissan and mitsy combined (current r35 excluded)

[STATUS]

this is what I am after, so I am able to compare a/f vs boost on spool (does anyone have a combined one?):

somethings going on with that power curve .

[GTScotT]

somethings going on with that power curve .

knock knock whos there?!

and isnt 10psi and 15:1AFR at 3250rpm bad mmkay? thats just asking for EGT issues IMO...

[STATUS]

knock knock whos there?!

and isnt 10psi and 15:1AFR at 3250rpm bad mmkay? thats just asking for EGT issues IMO...

nah the ramp afr's are pretty much ok, remmeber there is a lag between engine and tail pipe and a cat, so i reckon its closer to 13:1 and 5-6psi.

[Dose Pipe Sutututu]

Trent from your experience, what A/F ramps are safe? do you have a graph I can look at?

Also, I notice I mainly get knock off lift off, why's that? there's no explanation on the web! I tried to alleviate the problem by dialling in more fuel and pulling back timing, it just results in FLAMES on the overrun LOL

[JonnoHR31]

i get random knock spikes at the exact point i lift off too, havent worried about it too much. use it as an excuse to keep going through to limiter

last worshop tune i got was on the very safe side and started at 14:1 at 2psi then linearly down to 11.5 at peak torque at 17psi, then back to 12:1 for the rest of the way. was 13:1 at around 6-7psi

Edited January 8, 2010 by JonnoHR31

[Dose Pipe Sutututu]

anyone else?

how lean is too lean on spool/ramp as some call it?