Rb26 E-flex Ignition Vs Boost

[6InlineTT]

Hi there, I recently finished rebuilding my rb26. I am looking for insight into how much I can advance my ignition map with my recent swap to eflex fuel.

Currently sitting at 17.5psi and 14* this made 305rwkw which to me seems like there is much more to be made.

If anybody has been road tuning I'd love to see what your maps look like. I'm just looking to fiddle myself now that I have the AFRs correct.

I am new to RBs but 14degrees@18psi seems mild to me. Would 22psi be more likely to see around the 14degree mark? Provided I have reasonable knock levels.

Setup inc

Built rb26 8.5:1

Hks 264s

Hks 2540s

33gtr Fmic

Full 3inch exhaust. (3.5inch ready to go on)

Hard pipes

+all supporting fuel sys for eflex. (Haltech plat pro reads 61% ethanol content.

Any ign maps for 98 or e85 would be great if you are happy to share.

Cheers

Blake.

[G37Sam]

I'll tell you what everyone will tell you, without a dyno and careful knock monitoring with ign advance it will be hard to tell as every setup will run different.

[GTSBoy]

You'll be able to run at least a few extra psi and/or a few extra degrees (or suitable combo of the two) and I agree with Sam. No dyno (or at least no knock ears), no safety.

[6InlineTT]

I'm not looking to extract every last kw out of the car, just interested in seeing how my ign map compares to others with similar setups. Being told that 20degrees with 21 psi blew your ring lands and sent egts over the moon is kind of what I'm after. I was browsing the EVO e85 threads and a surprising amount of people are road tuning and sharing maps.

Obviously every engine is different but I and I'm sure others who enjoy fiddling would enjoy seeing others maps.

[Hadouken]

The guy doing the road tune still has knock headphones on

[6InlineTT]

I understand that it isn't particularly as safe as with all the correct gear. I'm only asking to see others maps or thoughts on my timing vs boost. I'll get the ball rolling

My base map 17.5psi 14* at full load.

My xr6turbo 21psi@10degees timing.

I don't plan on blaming anyone for blowing it up haha

[methz]

mines up around 17.5 degrees on 24psi tuned on united 85 if that helps

[6InlineTT]

Excellent! Exactly what I'm looking for! Thank you Methz.

[Blackkers]

At 8.5:1 and e85 you're unlikely to nuke anything without drastic changes

E85 brings your EGTs down a fair whack which means you can run relaxed timing without the fear of melting your turbos. So you can use boost to make power if you're not confident touching the ignition. That's what I do anyway. Keep an eye on afrs though as you increase boost

A small amount of timing and boost would be fine 9 times out of 10 in your situation

I'm starting to sound like Johnny

[6InlineTT]

Yeah I am not so worried about blowing it up, I have done a bit of road tuning before, I was just curious as we know every engine is different. And the Ford 6s I have been tuning are most likely different in the amount of advance they like. Evos seem to like up to 10degrees less than the rbs according to the maps I have seen

I also set up my anti lag launch control (2step) the haltech seems pretty user friendly.

[6InlineTT]

I noticed that the e85 actually coughs and splutters when it is too lean as opposed to 98 detonating/melting itself. It's really great stuff.

[Dose Pipe Sutututu]

and it coughs when it's too rich...

and if it's too rich it will knock

and if it's too lean it will just misfire

and AFRs aren't that important with E85

and you can happily cruise leaner than stoich with no dramas

E85 is awesome, minus the crappy economy

I've got 14 degrees advance at 3900rpm at 1.6bar, it then slowly climbs to 16 degrees by 5100rpm and then finishes up at 19 degrees at 7500rpm

Probably could take more as my exhaust manifold started to glow on a long pull.

[Dose Pipe Sutututu]

At 8.5:1 and e85 you're unlikely to nuke anything without drastic changes

E85 brings your EGTs down a fair whack which means you can run relaxed timing without the fear of melting your turbos. So you can use boost to make power if you're not confident touching the ignition. That's what I do anyway. Keep an eye on afrs though as you increase boost

A small amount of timing and boost would be fine 9 times out of 10 in your situation

I'm starting to sound like Johnny

hahahaha MORE BOOST

yes lazy, inefficient way of tuning but at least you won't grenade stuff... on 98RON it's not such a smart idea as your EGTs will go through the roof and you'll end up melting stuff on the hotside, include exhaust valves.

[Badgaz]

accurate mixture control combined with the best timing would be ideal in any situation. my rb25det runs 18degrees at 1.2bar on 98octane.

where do you want the most power to be? top end of the rpm or as early as possible?

[6InlineTT]

I'm not too fussed Tbh, with the 2540s it's never going to do much under 4500rpm. My understanding is that with rpm after peak torque you increase timing gradually to make up for loss of cylinder pressure.

So with the old setup, HKS GTSS twins, it made 312awkw @21psi unknown timing. Bp98

Swapped for 2540s added e70 eflex, didn't touch ignition but added 30% fuel trim. Dumped at 17.5psi @14* 305rwkw

So what I might do is bump boost up to 21psi again, 14* and go from there. Seeing as I only have my 3inch cat back on there for now I'll cap it at 21psi and add a degree or two and see how it goes.

[6InlineTT]

My goal here is to enjoy fiddling with my car while learning /practicing my tuning. I'm not fussed on outright numbers, I'm just having fun, and being a test mule if anyone has any ideas.

[Blackkers]

I've got an idea. set anti-lag launch end RPM at 8000 and get a mate to film from outside the car. You know, for science

[Badgaz]

I'm not too fussed Tbh, with the 2540s it's never going to do much under 4500rpm. My understanding is that with rpm after peak torque you increase timing gradually to make up for loss of cylinder pressure.

its not for loss of cylinder pressure that you increase timing its because the time between firing events (spark) is less when rpm increases.

[Scott Black]

you want peak cylinder pressure at around 12 degrees atdc,any more or any less and you lose torque, you therefor need to ignite the mix so it burns at a rate that gives peak pressure at that angle, as revs go up, the piston moves faster so mix needs to be lit earlyer or peak pressure will occur after the desired angle, and waste power, yet you dont want to advance to much as the other side puts stupid amounts of strain on the motor and wastes energy to.
however as more load is placed on the motor, more heat is in the chamber so mix burns faster, so timing needs to decrease to keep peak pressure at the right angle, or else your firing to early and can cause damage from to much strain.

this is on a motor that isnt limited by knock,
most rb25 with big turbos and huge boost will be knock limited at some point, so wont actually be able to be at 12 degrees atdc with peak cylinder pressure as the burn is to unstable and starts pinging so in these cases peak pressure ends up being later atdc to keep things working without damage

how do you measure this?
knock ears and a dyno,
increase timing in a cell while holding steady state on the dyno and watch the torque fiqure, it will plateau and then drop, at the start of this plateau is where you want your timing to be, any more or any less and your wasting power and arnt helping the motor at all,

if when advancing the timing it starts to ping before it plateaus, thats how you know the engine is knock limited, and timing needs to be put back to stop the pinging


slight changes in engine setups, and even just slight tollerance differences between motors, is what could make one map work perfect for one persons motor, and make another persons motor need a tow truck, so be careful when playing with ignition timing without the correct tools

Edited January 12, 2015 by Scott Black

[GTSBoy]

its not for loss of cylinder pressure that you increase timing its because the time between firing events (spark) is less when rpm increases.

Actually, it is both. You can't run as much advance around peak VE when the engine is knock limited, which is the short way of saying what Scott said above.