56. The heartbreak effect

Well, today was an interesting day.  I still haven’t installed my side windows and the forecast had called for a 40% chance of rain the evening before.  When I woke up this morning I looked outside and sure enough, the ground looked like it had been sprinkled on.  Things were starting to dry up a bit so I figured it would be OK to venture out in the SLC – I had made arrangements with Kushan over at Excelsior Motorsports to tune my motor and it was scheduled for 9AM, sharp.  I got up extra early knowing there’d be traffic but at least there wasn’t rain!

To my horror, as my garage door raised and I looked out … it was raining!  It was a light sprinkle but … with no side windows just how much of that was going to get inside my car?  Would the rain get heavier?  I stood there hemming and hawing for what seemed like an eternity.  Screw it.  I walked outside and looked North – skies were clear and the wind was blowing clear skies toward me.  Maybe I’ll luck out and the rain will get lighter.

After playing musical cars I strapped in and drove the car out.  Thankfully in the time it took me to move cars around the rain had eased up even more – just enough to see some sprinkles on the windshield but not enough to get the interior of the car wet.  SWEET.

The skies were ominous looking.

I’ve never been to Escondido before so I relied on my navigation system to get me there.  Waze told me it would be 10 minutes quicker to take the 52 instead of the 8 – OK, whatever you say.  Getting to the 52 wasn’t too bad, just a few minutes – but once I hit the merger things ground to a complete standstill.  I mean – parking lot on the off-ramp, parking lot on the freeway itself.  This was going to be fun, hopefully I don’t kill the clutch by the time I get there!  My GPS showed a long red trail of traffic.  Eventually we got through the red and speeds picked up.  Once I hit the 15 things started moving and the rest of the trip was pretty uneventful.  The skies were still threatening rain but luckily nothing heavy.

See those cars off in the distance?  Yeah … I’m at the tail end of THAT line of cars … and this is only the entrance ONTO the parking lot … err… freeway.

When I pulled into the industrial complex where Excelsior Motorsports is located it was obvious to me they specialized in GM cars, especially Corvettes.  It appeared there were 4 race prepped corvettes and a pretty mean looking Camaro parked outside.  Inside were 3 other race prepped corvettes and another old school classic.  Lots of Chevy horsepower all around and some very serious track cars.  From online reviews I’d gathered that Kushan is the LS motor guy for the San Diego area and it’s obvious he had some pretty serious customers that trusted him with their track weapons.

Before we got the car on the dyne Kushan wanted to take a look at the ECM and verify things would be kosher.  We opened up the back of the SLC and Kushan proceeded to hook up his EFI Live harness and laptop.  A minute or two later and I noticed there were some red Xs lit up on his screen – uh oh.  A few more tries.  Nothing.  Hmm… bad cable?  Laptop need a reboot?  We tried a few things, still red Xs.  Kushan then tried using his HP Tuners system.  Nada.  Time for tech support … pin the OBD2 connector.  Ground good.  Power good.  Can pins present.  Wire colors look good (I didn’t mess around with the OBD2 port when I re-harnessed the engine).  Yep, all looked good.

Kushan digging into the harnessing.

I was getting desperate.  It was time to call in the big guns.  I burned another one of my “Call Allan” cards.

I got his voicemail.  “Uuuuhh… Hey Allan, it’s Cam.  I’ve got this weird problem and I’m at the tuners, hope you can help me out, please call me back.  Please … ” I may have sounded a little pathetic because I was pretty frustrated at this point.

Screen Shot 2018-10-04 at 11.31.02 PM.png
Me getting pretty desperate and reading everything I could about OBD2 diagnostic ports not functioning on LS motors.

A few minutes later and Allan calls me back.

“Did you modify the harness?”  Nope.

“Did you pull the CAN signal from the diagnostic port?”  Nope.

Me: “I know the CAN signal is working because the data’s coming up on my AIM display.”

Allan: “Aah .. that’s your problem.  The Aim display is drawing too much current from the CAN signal, the OBD2 port won’t work with the dash installed.  Unplug it.”

WHUT?  This made no sense to me but I had faith in Allan.

I removed the Aim display and unplugged it.  Literally 20 seconds later and EFI Live was communicating with the ECM just fine.  FML.  I hate electronics.

Believe it or not, this did the trick.  It’s like that famous cigarette lighter fuse.  Apparently in some GM cars the OBD2 port can get disabled if the fuse for the cigarette lighter blows.  Whut?

We then got the car into the shop and here’s where things got real interesting.  Excelsior Motorsports doesn’t use the typical Dynojet dynamometer with rollers.  They use a Mainline Automotive ProHub dynamometer.  There’s 2 modules; one on each side of the car.  The drive wheels are removed and a shaft from each module is bolted directly to the car’s hubs.  Eliminating the tires removes tire slip from the equation.  This type of dynamometer is supposed to be more accurate.  It’s also been referred to as the “Heartbreaker” dyno by some – Kushan doesn’t like the use of that word, Heartbreaker.  Hub style dynos typically output horsepower numbers that would be lower than on a roller style dyno.

Here’s a video comparing results from each style of dyno, using the same car.

Getting the car positioned and dyno sensors installed.  Look ma – no rear wheels!
Buttoned up and ready to make a few runs!
Close-up showing the Mainline ProHub dyno attached to my rear hubs.
View from the front.

Knowing this was the case, I wasn’t expecting big numbers.  In fact, I really didn’t care about squeezing every ounce of power I could.  I was more interested in getting a solid idle, good street manners, and 100% reliability.  If it meant I got a few more ponies, even better.

I sat off to the side while Kushan worked his tuning magic.  He went through every setting in the ECM and discovered GM had omitted a few key items.  After the first run at WOT we discovered the factory tuning was running things on the high side for Air Fuel Ratio (AFR).  The ideal AFR for these LS motors seems to be about 12.9-13.1 from the internet sleuthing I’d done.  GM’s factory programming was more like 14!

Here’s where we started:

  • 424.7 hp / 345.1 ft-lb

And here’s where we ended:

  • 449.8 hp / 364.4 ft-lb
Blue = baseline, green = tuned.

Based on Kushan’s experience the baseline run came in pretty close to GM’s advertised 525hp at the crank.  EricM’s (Grifter) LS376/525 crate engine also measured 525hp on an engine dyno so I’m pretty confident my engine was making the advertised power levels when we started.  Factoring in a driveline loss of 14% and a ~20hp delta for the “Heartbreak effect” puts me right at about 545hp at the crank – so it looks like we maybe found a few more ponies in there!  Actually, what’s most important from today is my AFRs have been lowered to a safer level and the idle appears to be steadier.

A note about unsteady idling – Kushan reviewed my installation of the MAF sensor and thought it might be better positioned a few inches closer to the throttle body and further from the air filter.  He thought turbulence from the air filter might be tripping the MAF up, causing for some unsteadiness at idle.  This is based on the many cars that have come through his shop.  Whatever settings he changed seemed to help as idle behavior has improved since the tune.  If there’s a builder out there struggling with unsteady idle, take a look at the MAF location and maybe try getting it further from the air filter.  My installation location was per GM’s instructions included with their controller kit.

I still haven’t gone WOT but my confidence was up and I leaned into it a little heavier on the way home.  WOW.  It pulled like a freight train and seemed to have more when my shift light blinked me into upshifting.  After reviewing my in-car footage it doesn’t appear I even hit redline.

I think it’s time to find those big boy pants and a quiet stretch of road …

My sincere thanks to Kushan for sticking with it today and troubleshooting the initial issues.  He really showed a lot of care for my car during the entire tuning session and made sure I was happy with the results before I left.  It’s clear his passion for tuning, suspension and aero design, and customer focus are what keep his business going.

Also a HUGE thanks to Allan for saving the day with that tidbit of trivia.  I never would have figured the dash system was somehow connected to the OBD2 port not working.  I don’t know how he figured it out and I don’t know what kind of troubleshooting sorcery he went through – but take note for any builders intending to use an Aim dash system!

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