edge04

I've seen several for sale ads for cars with tune options as well as tune discussions and of course see shops like LG, Blackdog and many others that offer dyno tuning.

I understand the need for different tunes to meet rules however my question is what type of tune are most track cars running when modifying the stock tune.

SD no MAF
MAF only
or if available combination of the two
Open loop or Fuel trims on
etc

Now I know there are many factors like type of ECM, mods, type of racing, etc. etc. But I am just curious as to what people have done. And what are common changes to a tune for road course purpose, specifically around DE's or TT's. I'm fully aware why GM and others sell cars with the tune that they choose so no need to get into that.

thanks

Scooter70

What is your car? What mods does it have? Most of us are running stock or stock-style hardware, so sticking with the OE style tune (SD and MAF, closed loop) is best. Unless you have a reason for ditching the MAF and going SD-only actually measuring incoming air is the best way to calculate fueling. I did SD on my LS swapped '70 coupe because it was easier for the air intake to remove the MAF.

edge04

I have several and have SD tunes and MAF only. I am tuning a 2006 ls2 with heads, cam, exhaust, CAI, etc. Old tune was SD only has it was FI but definitely want to run a MAF. So right now deciding if I go MAF only as I'm not a big fan of the VVE. Problem is I know that at lower RPM and transient throttle conditions the MAF readings can be sketchy.....although not as bad with the card style MAF I am running,

I'm just curious what others are running when not running a stock config as this is my first road corse tune...if there is such a thing lol. Thanks

Scooter70

Roadracing is all about transient throttle. You're constantly going from 0% throttle to 100% to 50% to 100% to 0%...

My C5Z has heads, cam, LS2 throttle body, FAST intake, ARH headers, etc and still has the stock MAF and MAP sensor. GM does a good job of calculating airflow with MAP and measuring it with MAF and blending the two in the middle. I would adjust VE table and MAF curve as necessary and keep both systems in operation.

edge04

agree that GM does a good job but they leave a lot room for improvement....rightfully so.

being a C5Z I assume you are running a 411 PCM and if so tuning the MAF and VE is much easier. Thanks

briannutter1

Erik at Back Street Performance in Medina Ohio does mine and a ton of high level GM roadrace cars. My C5z with stock ls6 bottom end, TEA 2.5 ported heads with cut down ls3 intake valve and stock sodium exh. Fast 102, 90mm tb, arh 1 7/8 catless through stock ti exh. made 450/400 sae with a EPS 226/234 cam. Routinely hit 7500rpm when it was needed. I went SD with the tune. The biggest thing with the trims is getting quality injector data. He's pretty conservative timing and afr. I wouldn't ever get a canned tune after seeing what Erik goes through to dial a car in on the dyno. No two cars are ever quite the same.

Rx7Rob

My cam / headers / catless 2000 is running closed loop SD. No issues with the tune while at the track (I do need to tweak the timing a bit).

edge04

thanks all

I'll be tuning using the MAF and VE to start.

FASTFATBOY

I run my cars around 12.8 a/f ratio for track duty, you will lose maybe 5 rwhp, but the safety factor if you get a bad load of fuel etc is worth it to me. With a helmet on and the windows down you will not hear knock. I know we have knock sensors yada yada I just do it for my sound mind.

I street drive it like this also, part throttle cruise is still about 15 to 1 ish

edge04

that would be at WOT only I hope?

I can data log runs to look for knock, IAT's, timing, etc.

Supercharged111

Knock sensors take a moment to recognize knock though, so relying on it as a lifeline is a no no. I PE raped my car, commanding 12.5 on low end transitioning to 12.7:1 on the top end anticipating no leaner than 13:1 which seems to be the real happy spot. I still need to run a calc.vet to make sure what's delivered is what's commanded, but those few extra tenths of AFR really do offer quite a cushion for very little loss in power. OP never specified how big of a cam we're talking here, to go SD generally means monster cam or assloads of boost. I assume neither is the case here, so keeping the MAF and O2s in use would likely be ideal. On my truck, which has a 411 swap, I found that by re-enabling the MAF the transmission's adaptive shifting became a thing again and my neck was much happier for it. Without the MAF, the trans defaulted to max line pressure. . . with a shift kit. Much morning coffee was spilled onto my trans tunnel unnecessarily.