The boost controller we purchased is Turbosmart’s In-Cabin boost controller. This controller has a t-junction that installs between the wastegate and boost source. A remote vacuum line then allows the user to install the boost controller in the cabin for at will changes in boost pressure. This is not a feature we need, however the small t-junction makes routing the lines much easier. There is very little room in this corner of the engine bay and trying to dodge the various charge pipes without melting anything on the exhaust manifold is a bit of a challenge. This is where the t-junction ended up living.We then slip the remote line between the intake and charge pipe where it can meet with the boost controller. We fabricated a simple aluminum bracket to mount the boost controller to the passenger side shock tower.We took the Cappuccino to PSR Performance in Pottstown, PA for tuning. PSR Performance has Brad “Ace” Hettinger, a mechanic, fabricator, and tuner who has worked on everything from 6 second drag racers to DMCC championship winners, to 1,000 horsepower R35s. However you may know Brad as the tuning wizard who helped HOTROD Garage get the Twinpala up and running. He is good friends with Tony Angelo and occasionally pops up on Tony’s Stay Tuned YouTube show. Brad is more than qualified to perk up our mildly tuned Cappuccino.The Cappuccino was strapped down to PSR’s Mustang 1750 dyno with the stock ECU and oxygen sensor. This is a dyno capable of reading up to 2,500 hp. We will be using about 3% of that capacity. We did a baseline pull, then installed the Kei Sport USA ECU. Finally, we turned up the boost to see what we could get out of this motor. Once strapped down we proceeded to reel off some of the slowest dyno pulls ever as we ran the Cappuccino to its 9,000 RPM redline.
We’ve already shown you how we installed the ECU, so let’s get straight to the numbers.
We started with 61 hp and 54 lb-ft of torque. What is interesting about the stock tune is that torque continues to climb as RPM builds. I suspect this is because the ECU is limiting boost pressure: as RPM climbs and the engine becomes less of a restriction, the turbo can move more air without creating more of a pressure differential. Once we removed that limitation, boost spiked at 5,000 RPM, then torque drops off as the turbo reaches its flow limit. We ended up leaving boost at 1.1 bar. The turbo was able to produce more but we were reaching the duty cycle limit of the stock fuel injectors and did not want to get into a lean condition. The other risk with too much boost is stretching the stock head bolts, lifting the head, and blowing the head gasket. We performed all of our tuning with 93 octane fuel, exactly what Kei Sport USA recommends for the provided tune. When we pulled the Cappuccino off the rollers we were making 69 hp and 71 lb-ft of torque.
3 comments
Time for a diff and sticky cheater tires for the cones!
Great writeup! Really looking forward to the Shorai battery details! looks like they have a size perfect for my NA6 Miata
Here’s an old MotoIQ article that discusses the basics of engine management systems:
https://motoiq.com/basic-control-systems/