Air/fuel reading and mapping

[Madden]

Well now my car is back on the road again i can finally try to learn to map.

I have got the Innovate LM-1 wide band and the fclogit kit.

I know the car has been running really rich from when i have been on dyno's and i thought it would be a good time to learn to map as it has been something that i have always wanted to do. The car started out being 500bhp at the hubs and 408ftlb at the hubs. Since i have reshelled the car it has been down on power. I replace the fuel pump and fuel filter and the car came back to life but still a little short of what is used to be. The car now makes 508bhp at the fly so i reckon I'm down say 60-70bhp and the same in torque.

I logged my a AFR today while driving. This is a third gear run at 1.5bar under load.


I know the car is running really rich on idle and at the top end. On idle the AFR's are 10.2? Im under the understanding that should be around say 13?

I only want to start with the fuel map and then i will start to play with the ignition map as that is really safe and i have never seen any knock above 30 of my power fc.

What would the be the best kind of AFR's ? I think the fueling is fine when coming on boost but once on boost it is way to rich. Should i be aiming for around 11.8 on boost?

I know alot of you guys have played around with mapping so if you can help i would be very grateful.

Cheers

Jamie

[Richard Bell]

I would aim for 14.14.7 on idle. Full throttle AFR`s are a little different as lots of people have different figures they aim for. I would also take EGT`s into consideration.

[Madden]

Right theres another thing? What do the egts mean? Hotter i guess is richer due to a bigger bang or is it leaner?

[Spearmint]

Too high an EGT and that indicates things are getting too lean.

[Gambit]

And/or ignition too retarded

[Madden]

Ah ok cheers for that. So the leaner the mixture the harder the engine is working making the egt's higher?

[Raiju]

A lean mixture means that the air-fuel ratio is too high, causing the mixture to burn like a cutting torch, melting the psitons, instead of cooler burn which causes expansion to move the pistons. If cylinder temps are too high, the mixture can detonate before it's had a chance to be ignited as a controlled burn, this causing pre-ignition. Egt's are widely discussed, some like to aim for 850 as max temps, but others push further to 900 or even 950. Ignition advance affects the point at which the spark ignites the fuel, get it wrong and you will either loose power and response (too much retard), or get det (too advanced).

You will aslo notice a difference in turbo response, as the hotter exhaust gasses move faster, thus far better transferring their kinetic energy onto the turbine wheel, so timing and fuel with have an affect on that also.

[tuRBy]

have a look on the skylines australia SAU website for a t04r rb26 map, most of there dyno runs show the afr curve to rpm, although it will be a rough guide as your running the 280cams

[Madden]

The cams are going back as they are not 9.15mm lift they are like 11.25 lift gutted.

Cheers for the help guys. It all a learning curve and i dont really mind if it does go bang and take the block with it The block is porous so will be building a new engine soon.

The ignition mapping is the bit that worries me. Can i map the igntion with det cans and without egt's? Do i advance it until i get det and then pull it back to get it in a safe zone but with better response? I know my ignition map at the moment is really safe so i know i can get more out of it.

Here is my ignition map.



Would in the best world if det wasn't an issue advancing it through the whole rev range or just as the car starts to spool ?

[roadie]

Your wideband should have a 0-5 volt output that can be wired into the datalogic. You then can log your afr's the same way it logs all the other sensor activity. IMO afr's (high 10/low 11) are preferred for high load/high rpm....

[Madden]

Yea i have seen that fuction but still waiting on the logit box. That will make the fuel mapping a doddle but it just what o you map it to to get better response and still stay safe. I have heard if i map it lean on spool up it will reduce lag and bring it on sing sooner?

[Richard Bell]

The best way to tune the ignition is on a dyno as there is no real way to do it on the road as you will find it hard to feel increases or decreases in torque/power.

Fueling is easy to do on the road as you can log the results and then make adjustments.

Richard

[Raiju]

Originally Posted by Madden

Yea i have seen that fuction but still waiting on the logit box. That will make the fuel mapping a doddle but it just what o you map it to to get better response and still stay safe. I have heard if i map it lean on spool up it will reduce lag and bring it on sing sooner?

This true, leaning it out can help with response. The hotter the exhaust gasses (to a degree), the faster the scavenging effect will be and thus more energy will be retained until the turbine wheel, hence why heat-wrapping exhaust manifolds is a good idea.

[Madden]

Thanks for the help on these subjects. I hope to get the fclogit box next week so that i can start playing around. I will sort the fueling on the road and then borrow a dyno and driver to try and have ago at the ignition. I guess the only way to learn is to play around with it.

I will drop the idle to around the high 13's and then change the top end on full boost to around 11.8 ?

I want to push say 1.8bar on a to4r with stock cams to see what it makes. The more boost i run would the fueling need to be richer. I have my old fueling graph when it got mapped and it was 11.7/8 on 1.4 bar and richer on low boost of 1.2 bar. Would i map the car on full boost and then leave it alone for low boost. Low boost will stay @ 1.4 and then high boost of 1.8.

Cant wait to have ago and see the difference. I want to push my engine to around 600 hubs on stock rods with arp bolts to see it it takes it. The revs will be kept below 8000rpm so i dont see a problem. This will also test the stock gearset as i now have an os giken center plate in it. So lets see what it can take on track and drag racing.

[Madden]

Raiju/Dan how is the car going mate. I see your running 2+bar now? Bet it's got a 9 in it now?