Recently I disabled leanspool via periphery bits, and loved how predictable my tuning became. No longer did I get this nasty rich tip-in upon throttle application. Ripping through all 4 gears produced almost the same exact AFRs.



Here's how lean the fuel map looks:



Yesterday I took the car out to the drag and accidently used a map with leanspool on. I pulled a 12.3@112 with a 1.7 60ft. Mods are in my signature. It's roughly making an sae-corrected 340whp on DLL. Here's a cool video (not of my fastest run of the night though):
http://www.youtube.com/watch?v=lfmz7OaKNQg



Analyzing the log with leanspool enabled, you can see how the AFRs get richer and richer as I go up in gears. With leanspool enabled, I was forced to tune only in 4th gear (since almost half my run is done in 4th) with no regards to how lean things got in gears 1-3. Amazingly, no knock was sensed in the lower gears. This might have played out to my advantage if indeed higher AFR’s produce more power for a drag run (12-12.5). But since the tune pulled those lean AFRs only in the lower gears, where things are brief, it probably was ok. I'd still rather have consistent AFRs in every gear, so this map will be ditched



So my question to those who have good experience tuning for a specific purpose, how do you go about tuning for drag runs? Do you tune with leanspool on or off? What AFRs do you try to achieve for best power and quickest time? My understanding seems to be that you do not want to run such an aggressive drag tune for any other purpose than drag racing.

 

Nice run and excellent vid!

I leave lean spool on all the time. During a drag run using launch control I'm seeing faily solid AFRs in the 11.5 area on pump.

 

Your last picture of your excel graph of a drag run is pretty much how you want your run to go, they created the LS for a reason.

I've never disabled lean spool and I've run fast with every different setup that I've used.

Nice run, you still have some room to pickup time and mph between shifts. I would also come out on the 2-step, you lost some time while your turbo spooled.

 

Thanks for pointing me in the right direction when it comes to drag tunes and confirming that it's normal to run that lean in the lower gears. I'm new to drag racing and am still testing what works well and what doesn't. Heh, next time I go out, I'll try shifting even faster (I felt I was abusing the crap out of that transmission). On my best run that night, I pulled a 1.7 60ft launch, and it definitely shot out of the hole better than what you saw in the video (rpms didn't drop, and I briefly lit up all 4 tires). I'm assuming with stock clutch, I can get into the 1.6s?

The reason I'm disabling lean spool is because I believe it's more consistent for road racing and autocrossing, which I do more of. But for drag racing, I will do whatever it takes to get a good time, within reason .

 

Your belief would be correct. Years ago I did a metric crap ton of on-track datalogging and disabling lean spool made the car much more consistent when I would look over all the data.

When I say metric crap ton of on-track logging I mean examples like this, per lap, zoomed out 100%:





Or a full 15 min session like this (zoomed out 100% again):



In Evo's like this:

 

Bryan, I actually ran into one of your posts about lean spool (it included one of these charts), which convinced me that disabling it was the way to go for my purposes. Thanks!
https://www.evolutionm.net/forums/5841331-post70.html

 

Keep in mind that you can make the effect that lean spool has on your AFR's smaller or greater by playing around with the tables. So you could tune it to have a smaller effect on AFR's, which should give you the best of both worlds; tune it to be where you want it in 3rd or 4th gear, and it'll only be slightly leaner than that in 1st and 2nd.

 

No problem. Stock clutch can surely get into the 1.6's, even the high 1.5's. It won't last forever but it is actually very good for launching. You're getting a real good thud when you shift so you are re-engaging the gear fast enough, but you could gain a bit with more practice. Once your shifts sound like a twin clutch (not twin disc clutch) transmission, you're in the sweet spot .

I had great success and consistency with the stock clutch. I would preload, bounce the 2-step, then essentially dump the clutch. Since you preload, the transmission isn't 'shocked' and the clutch will not noticeably slip momentarily.

The reason we add fuel past stoich is simply for cooling. The first two gears don't last long enough to build up enough heat to cause any problems, thus you're better off a little leaner in those gears and incrementally richer the longer the gear (aka the more load you put it under).

I've got plenty of tuning + dragging experience, you can PM me if you'd like..... But its $200 per tech question Just kidding!

 

Good vid....thanks
I must say for a 1.7 60ft, which isn't that bad, that was a pretty good soft launch. What is the lowest anyone has set their 2-step for a launch??....i.e. poor track prep or for say a tuned car that makes a bunch of mid range torque?

 

Like mentioned earlier, the video isn't of my fastest run where I pulled a 1.7 60ft. I believe the video shows a 2.0 60ft.

 

It is adjustable from zero effect to prematurely enriching if you are catless and are have good octane/cooling. Because it prematurely enriches with its stock settings is not a reason to dislike it, just tune it how you want it. Since we don't have a factory exhaust gas temperature sensor, this facility allows you to have a crispness for a short burst. This might be more relevant on a street or drag car than a circuit car which you can assume will be getting continually cooked.

R35 has something similar that kicks in from about 155 mph from a launch on a tuned stock turbo car (again on a timer). It causes some overfuelling up there on the stock settings, but again is adjustable. Most just turn it off, but you can see why manufacturers put these things there, so that when the car is used hard the fuel is richer to control exhaust gas temperatures and knock.

 

Thanks for the explanation but the slip at the end of the vid is a 1.776 60ft.

 

Thoe99 are you on stock injectors? I have similar mods + psi as you, so I copied your map into my rom. (sorry hope you don't mind) I was wondering how your AFR was at tip in at 2500rpm? I have LS disabled from LS spool start and stop set to 1500. But am running very rich 10.9 at 2500-3000rpm. From there it's perfect mid 11's to high 10's at redline. I have fic 1250's by the way.

Thanks

 

I was on stock injectors during that run. I don't recall having any tip-in enrichment (I can double check that log tonight). Try turning leanspool off via periphery bits. That's the absolute true way to get rid of it. I believe it's bit0 in ECU Periphery1 (FBA). Change that bit to 0 and see what happens.

 

Here's an AFR graph of a pull I did with that same map posted above. No rich tip-in.