SD2 tuning

[Scoobum]

Steve once said if you can run low 11's and be quick on the tree...then you ain't gonna lose many races. He ain't wrong. Jason, if you can consistently cut a quick lite...run a consistent 1.6x short time...run the low/high gear 02's in the 770's...you'll only need 23 PSI to run in the 6's easily.

Walking around guys is the wrong way of thinking. Get the low gear fuel and low gear timing dialed in...and don't give the SOB's an inch on the tree. Beat the stuffings outta 'em on the tree...and get it to haul it's ass through 1st and 2nd. High gear will take care of itself...give it enuf fuel so it won't hurt itself. The toughest part is getting these cars off the line...and getting them through 1st and 2nd. Leaving the line will depend on how slow/fast your car reacts...and how much 'roll out' your track has.

1/8th mile racing forces you to be quick on the tree...and forces you to learn how to tune low gear fuel and timing. It forces you to be a better racer...and a better tuner. Fuck up one iota...and you lose.

Something I've noticed. If you have a good lead on most guys...they'll give up...and you'll see them fading back. At this point...let your foot off the throttle and coast...don't ever let them see what you have. Most can't correlate ET and MPH anyway...so they'll think your car's a turd.

[nocooler]

Brad does Eric have launch assist in his chips? It was violent in Bob's chips. It put some heat in the manifolds for sure.

[Scoobum]

Eric has 'aggressive mode' for his 5.7 alky chip. Bump the low gear timing to 129 or higher. This feature is only in his alky chip. I drag the low gear fueling to around 770 and bump the low gear timing as much as 6 degrees over his default to get it to jump off the line. The more heat you can throw at a turbo...the faster it'll spool...and the harder it'll hit. Erics low gear default fueling is notoriously rich. Setting the turn on point for alky is critical as well. The kit I had from Steve, I had coming on around 12-13 PSI. Any earlier, and you're drowning the engine in alky. Think Julios default is about 7 PSI.

[good2win22]

Thanks for the tips Brad!


I know a fella pouring the corn to his Buick and has 33 degrees in low gear with no knock

[good2win22]

Hadn't thought about the change in fuel blends Rich. Again, thanks for all the tips

[Scoobum]

Jason...my reaction time is on the left. I play for keeps...don't give them anything.

[good2win22]

New question for you seasoned SD2 tuners...


I adjusted VE tables for different cruise speeds. 45, 55, 65 and 70 to get an AFR correction +/- 5. Now when I accelerate from a stop, I see that I am getting into some of the same cells in lower gears and the AFR correction is +10 and higher. Am I missing something or is this just the way it is with SD2?

[Scoobum]

Something I learned over the years is that guessing is never a good idea...and to always go to the best source for information.

[good2win22]

Something I learned over the years is that guessing is never a good idea...and to always go to the best source for information.

I don't mind calling Eric to ask the question. Just wanted to throw it out here first

[good2win22]

Well, I had a few revelations today.  For some folks this will be common knowledge but for me lightbulbs were going off.

First, cold start fuel is different than cranking fuel.  Cold start fuel runs for 30 seconds or until the water temp gets above 130.  Crank fuel only applies until the engine is actually running on it's own.  It doesn't matter if the water temp is above 130, cold start fuel still applies for 30 seconds.  I now have the idle pretty damn smooth set with closed loop on and AFR at 13.7.

Second, a little correlation between idle TPS and blocks 5 and 6.  While adjusting the throttle blade to get the IAC down to 15 ( I swapped out the RJC PCV for a stock replacement), the TPS went up to .46.  Looking at the PL, the ECM went to block 6 which is fuel for mild acceleration but not for idle fuel which is reserved for block 5.  Eric's instructions state that blocks 5-6-7-8 are fuel trim blocks for different kpa with block 6 being idle and block 8 being WOT, he doesn't mention anything about the TPS being involved.  I readjusted the TPS back to .40 and then the ECM was back in block 5.

Third, the closer I get the fuel correction to 0, the less erratic the WB is at WOT.

Fourth, Steve you were right.  My combo likes 10.6.  Made a pull at 10.7 and then adjusted fuel and set the WOT AFR for 10.6 and that pull was a whole lot cleaner.

Attached is a log of today's high gear pull with WOT AFR set at 10.6.  Not sure where the 1.0 of KR came from but it was a blip in the middle of the pull

[Steve Wood]

big turbos, and good heads, add alky, and it likes it rich.....glad you are getting it sorted out....

[good2win22]

Made a high gear pull yesterday evening.  Please take a look at the attached logs.  Any recommendation s/suggestions are welcome. Also is a log at cruise and a log at a hot idle from yesterday.

I'll be going to BG this year.  It will be my first trip to the Nats and probably my last.

[Scoobum]

High gear shows a hint of KR at frame 529...but fueling tells me it ain't real. It's a safe tune. Turn the boost to 23...and hang on. That 7 flat run Friday night was at 23...with a lazy 1.71 launch...and I got out of it 50-100 feet before the traps when the knock sensor went off. 23 on up is where the fun starts with that turbo.

[good2win22]

High gear shows a hint of KR at frame 529...but fueling tells me it ain't real. It's a safe tune. Turn the boost to 23...and hang on. That 7 flat run Friday night was at 23...with a lazy 1.71 launch...and I got out of it 50-100 feet before the traps when the knock sensor went off. 23 on up is where the fun starts with that turbo.

Thanks Brad. Haven't been to the track since last years ford vs buick. I'll keep you updated from the track

[Scoobum]

Jason...can you bump the boost up with SD2 and it'll automatically keep the AF at a predetermined value from idle right through to the traps?