Heading to the Chassis Dyno - any input ahead of time? (2 Viewers)

[zerotreedelta]

I've always been curious to gather some data and see what self-tuning leaves on the table, or what I might be leaving on the table for timing as I just mimic'd OEM dizzy curves. So...I've got a timeslot booked on the local chassis dyno for an afternoon of twiddling. Currently it runs well, especially around "normal" part throttle driving. Above that, it seems a bit "flat", so I suspect I'm either fat-rich or possibly pulling too much timing...but time will tell. Any thoughts or input ahead of time might help get the most from the session, and I'm also happy to share the config file after.

The current setup:

• Stock 2F
  • relatively fresh rebuild .030 over (3000 miles)
  • '76 domed pistons, stock valves
  • factory cam
• Headers + 2.5" all the way back
• Holley Sniper + Hyperspark
  • Mostly OEM timing curve, aside from running 10* as base
• Planning to tune for 87 (although it would be interesting to see what it likes on 91)

For those with the Holley/Hyperspark, I'd be curious how your maps compare. Or for those who have tuned the mechanical/vacuum-advance distributors, how much did you push the curve in the higher RPMs?

Or for anyone else, feel free to ride along and live vicariously...and what's the over under on if we get 150 to the wheel?

 

[charliemeyer007]

Wow I guess there are racing tractors. Myself I'd rather tune for mpg than trying to push a box threw the air a little faster, but hey its your rig and money have fun and enjoy yourself YOLO

 

[zerotreedelta]

Realistically, it will be more of a driveability tune, I'm not expecting too much from the ol 40.

I actually suspect I'm leaving both power AND MPG behind. And I'm sure one could get close with road tuning and a friend in the passenger seat, but that's a bit more time consuming.

 

[Its me shaneus]

Very cool! Hope you share what recipe ends up making it happy. I’ve got a pretty fresh 2F and fuel injection (Fitech) and will be watching with great anticipation!

 

[Skreddy]

Unless your compression is a bit higher than stock, I think the only thing running 91 octane will get you is maybe a little more timing.
Looking forward to seeing what you find out. Interesting to see the 15.5 target afr. I have mine set to 14.5 cruise, 14 idle and 12.5 or 13 WOT.

 

[zerotreedelta]

Yeah, 91 would really only buy a little timing.

I did lean it out a little bit extra down at lower MAP, was dabbling with mpgs and it didn't mind it at the lower power there.

 

[White Stripe]

I run quite a bit more advance under load and ar highway cruise. Although im not running leaner than stoich at highway cruise either like you are.

 

[Wasatch Jay]

I'm very curious what the results are.

I'll take "No" on 150 rear wheel horsepower. ( I'll be surprised if the result is greater than 100.)

Good luck and have fun!

 

[brian]

I'm saying 95 to the wheels

 

[cruisermatt]

The biggest thing to keep in mind is that a Dyno is simply a comparison tool, and horsepower is really just a number.
Ignore the horsepower number other than as an indicator of whether you are making an improvement or not.
It might show you make 200HP on that dyno, and you drive across the street to another shop’s dyno and it might show 100HP in exactly the same tuneup and conditions.
Additionally, the transmission gear you’re in will effect the horsepower a dyno will show, taller gears will show more because it loads it up better. Most dyno operates will not want to run your 50 year old driveshafts at WOT in 3rd gear

 

[Skreddy]

I’ll bet 100-110 rear wheel hp. That’d be 20-25% drivetrain loss from advertised 135 hp. A fresh engine with slightly better compression can do it….

 

[rlong]

In this case, with a Holly FI, a Dyno session should really be about tuning fuel curves throughout the pull. As many carb vs FI "debates" have pointed out the FI learning is really only a few facors with some percentage or ratio overlays. A decent tuner will be able to identify any lean or rich numbers throughout the RPM range and "tune' them out. Hopefully you get a custom tune, installed and saved to a file for when it forgets for whatever reason. You should probably have the saved "self tune" file plus an improved dyno tuner file.

I've never done it but I did fall down the rabbit hole of research regarding tuning Sniper/Terminator X systems. From a tuners perspective the auto learning is the start and could always benifit from some tweaks. Heck just being able to look at the tables on your laptop and understanding you could have 1 or 2 different tune files is huge compared to taking the "robot carburater" (Sniper) out of box and dropping on.

I'm interested in what you learn... horsepower number is just for fun.

 

[zerotreedelta]

Agree 100%, it's really about seeing improvement for the area under the curve. I'm pretty sure the only HP # I'll win is the record for the lowest on the Dyno.

Definitely curious to see what we find for part throttle (main driving) vs closer to WOT (moreso for odd occasions like climbing a hill).
I do have a pretty good history of saved tunes since starting out, so this just adds to the pile.