1/4 mile gains not what I was expecting

[njedwardz]

Hey all,

I recently had a cam/converter swap done on my 2013 Corvette A6, and I was a little surprised by my 1/4 mile times...cam is a Stage 3 by Bourque's Hot Rods: (23x/24x .62x/.61x 115), converter is a 2800 stall ProTorque single disc that I'm not locking at any point during the runs.




here's a vid:



Maybe my expectations were too high.
At the same track last year, mid summer (similar DA), I was running around 12.6xx, with 2.0 60'. Now, I'm running 11.99x with 1.89 60'. I kinda expected more of a gain here (there are guys on CorvetteForum running 10.9 passes with similar power/mods), so I'm thinking something may be off.


The two runs in the video were back to back, both 11.99x @ 119, preloading to ~1600 RPM then rolling into it - no spin at all that I could hear or see in my datalogs. I did one run just flashing the converter without preloading and it spun the tires all the way through 1st, so I'm thinking that may give me a stronger launch with DRs.

Here's datalogs of both runs, as well as my engine/trans tunes, pids, and dash pages: https://www.dropbox.com/sh/v7lq4nsht...sLD9WWYwa?dl=0

Is something off in my tune? I don't see anything that raises any alarms in the scans, but I'm fairly new to all this.

[joecar]

I don't know about the tune (the download from the dropbox is stalling), but I most likely would have gone for 3600 stall.

What is the axle gear ratio...?

[njedwardz]

Gearing is 2.56 (terrible, I know). Car is a street car and, indeed, my only vehicle, so I didn't want to go any more aggressive than a 2800. I don't really care about track times, but I just figured they should at least be a little better than 12 seconds lol. Figured I'd check in here and see if any of you experts saw anything obviously wrong.

See if this works better; same folder but just uploaded here in zip format:

dragstrip 5-27-16.zip

[Manuel]

Hey Joecar, is his commanded PE, 0.88 across all rpm, a bit lean for a cammed car?

[rrmccabe]

Looking at the dyno charts I really dont think your gains are that far off using the converter you are running.

[njedwardz]

I forgot to mention that those dyno graphs are from data obtained on a loaded super flow dyno with an eddy brake. Before the cam went in (the graph with a peak of around 400 RWHP), the car was making 440 on a dynocom (similar to a DynoJet configuration). So I expect that on that dyno it would currently put down 480-500 (I'll never know, since that shop closed right after they took $4k from me without completing any work). That's in line with what most guys running a cam with these specs are putting down on bolt-on LS3s like mine.

Not it that it should make any difference, just wanted to clarify a bit.

[joecar]

Gearing is 2.56 (terrible, I know). Car is a street car and, indeed, my only vehicle, so I didn't want to go any more aggressive than a 2800. I don't really care about track times, but I just figured they should at least be a little better than 12 seconds lol. Figured I'd check in here and see if any of you experts saw anything obviously wrong.

See if this works better; same folder but just uploaded here in zip format:

dragstrip 5-27-16.zip

Ok, I was able to download this zip file to my PC...

A high quality 3200 or 3600 stall in a street car is not that bad, you'll be surprised.

Gearing will not make as much difference as stall... and a higher stall makes much more difference than gearing.

Also remember that the 6L80/6L80 has 4.027 first gear ratio.

[joecar]

Hey Joecar, is his commanded PE, 0.88 across all rpm, a bit lean for a cammed car?

I would like to see commanded Lambda at 0.86 at peak torque... but 0.88 is ok for peak power;

Your PE table B3618 is set to EQR 1.1367 which is Lambda 0.8797 (i.e. 1/1.1367);

set your B3618 to EQR 1.1628 (i.e. Lambda 0.86).

[joecar]

Your spark spark advance at high load and high rpm is about 19*... I think you can run 24* (especially if you run PE at lambda 0.86, i.e. EQR 1.63).

[joecar]

Also, during the gear upshifts, the ECM is reducing torque via spark advance (-12*)... I did notice from your video that each upshift seemed just a little slow (not as firm as I would like)...

for the A6 I'm not sure of the best approach to reduce the torque reduction... I don't know if playing with the torque model in the engine tune would help at all.