Sunday, June 11, 2017

The Day of Reckoning

I had a friend in high school named Blake. Blake was one of the nicest guys you'll ever meet and also drove the most stereotypical redneck truck imaginable (1979 Chevy pickup, lifted 6 inches with 33" tires, Flowmasters, and a carburetor that was way too big). Blake also got really nervous when he went on dates. So nervous in fact that he would sometimes have to excuse himself during the date so that he could go puke. I'm not a terribly nervous person by nature, but there are a few things in life will give me the Blakes. Those things include but are not limited to: getting married, drinking the water in Mexico, and going to the dyno.

My appointment with Church Auto Testing was at 2PM on Friday, so I worked a half day. Even though Grace has run reasonably well for the past 2 years almost, that whole morning doomsday scenarios ran through my head. I was about 50% sure that the head gasket would go, or the intake manifold endcaps would pop off, or the driveshaft would rip itself in half, or... 

The time eventually came and I met my buddy Vaughn for lunch and after a good 'merican burger we drove down to Church. Church is just off the 110 freeway in the Port of Los Angeles. As a side note, I love ports. I could just hang out there for hours and watch ships come in. My wife thinks I'm crazy, but who doesn't love cargo ships and shipping containers?? I've got a friend who loves them so much, he's building a house out of one!

We arrived a little early and Shawn, the tuner, was still out to lunch, so we pulled in and looked around. Inside the shop sat more than a few performance cars. Besides the cars in storage there were just two dynos in the shop. Church has been around for 15 years and does nothing but tuning. They use DynaPack dynos which is one of the reasons I chose them to tune my car. A lot of shops use DynoJet dynos, which are an inertial dyno. This means that the dyno doesn't have the ability to hold the engine at a steady speed or load, and as such, is not useful for tuning part throttle or part load. Dynapack dynos connect directly to the hubs of the car, which meant that we had to remove the wheels to mount the car on the dyno. Unfortunately the rear wheels on my car are a huge pain in the arse to remove and even worse to re-install, so prior to going to the dyno I mounted a set of skinny trailer tires to the rear that I had borrowed from Vaughn.

Once we were mounted up, the tuning began. Shawn started tuning for with the 91 octane gas that was in the tank. First he roughed in the low load and part throttle area of the map, and then got the acceleration enrichment dialed in. This took about about 30 minutes. Now we could start some full power runs so we started at the base boost of 10 PSI. When this came out at 242 HP / 238 lb-ft, the nervousness was gone and I knew that this was going to be a good, puke free dyno day!

After a few runs we worked up to 17 PSI, this is the video for the run:

I suppose we could have kept going, but I wanted to keep the the tune conservative, and I figured 320 HP was sufficient. Vaughn and I then drained the fuel tank of all the 91 and added 12 gallons of e85. The flex fuel sensor read about 75% ethanol. This pretty normal for e85, which is rarely actually 85% ethanol.  When we restarted the engine it ran a little rough, but after a few minutes of tuning all was well.

Shawn set the boost to 20 PSI and attempted a pull. At about 4500 RPM he shut it down because it started to run out of fuel flow. This was a little strange because the fuel system should have been able to keep up. Shawn had me attach a fuel pressure gauge to the pressure regulator and watch as he made another pull. I saw that as RPMs got above about 4000 RPM, the pressure began to drop. This told us that while the injectors should be large enough, the fuel pump was not providing enough flow to keep up.

Despite the fuel flow problem, Grace made 348 HP and 378 lb-ft by about 5000, which I considered to be freaking rad. With sufficient fuel flow Shawn thinks 380 HP / 400 lb-ft is easily achievable. He dialed the boost on e85 back to avoid any damage, so at about 10 PSI, it's making 275 HP and 270 lb-ft.

But enough about the numbers, let's talk about the shape of the torque and power curves. I had initially intended on sweeping cam timing to find the best setting. After the first few runs, I got a pretty good idea of what the curve looked like.  For any given boost level, peak torque is at about 4600 RPM, and peak HP is reached right around 6000 RPM. This isn't a terribly wide spread in peaks, but once full boost is reached, the torque curve is reasonably flat. I have to also remember that this engine was designed the same time John Fogerty was hitchhiking home from Woodstock, so it's not going to have the same mesa shaped torque curve as a variable-timing twin-cam motor designed in a new-fangled CFD program. That said, I was pretty happy with the horsepower peaking at 6000 RPM, so I didn't feel a need to mess with the cam timing.

My turbo, a Borg-Warner EFR series turbo, marketed as a responsive, and early spooling turbo. I run the 6258, which is the baby of the bunch topping out at only 450 flywheel horsepower. As you can see on gasoline, it reaches full boost (17 PSI) by about 3300 RPM. On e85, the spool happens a bit quicker, but with the higher 20 PSI max boost, it is reached at about the same 3300 RPM. For a Ford 2.3L that should ultimately put down 380 HP to the wheel, I think full boost at 3300 RPM is pretty awesome.

I arrived just before 2PM, but didn't get tuning until about 2:30. We spent about an hour and a half on the dyno which cost me $550. Dyno tuning is never cheap, but with a good tuner it is money well spent. All in all, I'm very happy with the result: Grace made plenty of power, didn't leave any ventilation holes in the side of the engine block, and I didn't puke.

That face when your engine doesn't blow up on the dyno, and makes more power than you expected

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