Part 8: In tune! (12-11-01)
Wow -- almost two months have gone by. Time for an update.
First things first: As you may have surmised by the cam timing article, I am now running a different cam. This is not a knock against the C270, just an acknowledgement that the C270 is optimized for the stock AFM/ECU combo (little overlap, relatively short intake duration), and I am pretty far beyond that setup. Besides, the C270 was creating too much cylinder pressure, which was leading to pinging, which was something I wanted to avoid. So on Gary Meissner's suggestion, I gave the CompCams 260S a try. Impressions: nice cam, turbo friendly, and decent low end torque. Doesn't have quite the low end torque that the C270 did, but it more than makes up for it in top end power. I am currently running it 2º retarded to take advantage of the high flowing cylinder head and exhaust. I may change that, but it seems to make sense for now.
OK, with the new cam installed, and the detonation problem addressed, it was time to get this sucker tuned. Almost exactly a year had gone by since I picked up the new motor, and several months had gone by since I made a first attempt at tuning it. The time had come to bring in a ringer: someone who knew what he was doing, preferably with my particular computer (Speed Pro).
Well, December 10th was the day: I took the day off and drove the two hours or so out to Elk Grove, CA, to meet with Dan Fodge, the only authorized Speed Pro dealer/installer in Northern California (and a former Formula 5000 race car builder/driver). It was an interesting afternoon, one that produced some great results.
First, I should say that even though I was really looking forward to this day, I was also very apprehensive about getting the truck tuned, because I had no idea how skilled or knowledgeable Dan was -- he came recommended by the folks at Speed Pro (now Fuel/Air/Spark Technologies), but I didn't know if that meant that he had gone through one of their training courses or had merely bought into their dealership network, or what. Furthermore, I was more than a little apprehensive about tuning the engine for max power -- if I was gonna break something, it seemed to me that this would be a good day to do so.
Luckily, Dan turned out to be one of the most knowledgeable automotive professionals I've ever met. His shop, in a nondescript industrial park in a very nondescript Central Valley city, doesn't have any sort of identification on the outside -- no lettering in the window, no banner, no nuthin'. When I passed through the office he shares with his son, I stepped into some sort of automotive fantasy land: the shop is spotless, with tidy little tables adjoining milling machines, toolboxes, and a heady selection of exotic cars and hardware. In the front of the first bay is a 427 Cobra replica -- not the cheesy fiberglass kind, but the aluminum bodied knock-off that Carroll Shelby Enterprises produced in limited numbers. It's being fitted with four pairs of individual EFI throttle bodies, shaped to look like Weber IDE carbs. These are not the pieces that TWM sells, but some custom throttle bodies that Dan has machined himself. In fact, milling custom throttle bodies seems to be one of his specialties, and his shop had an impressive collection of updated versions of classic Hillborn pieces, as well as some very slick one-offs, including some FUCKIN' MASSIVE bazookas grafted to a big block Chevy intake manifold.
Anyway, sorry for the digression...just wanted to set the stage...
So happily, Dan turns out to be the embodiment of automotive knowledge. After a quick look-see under the hood, he grabs his computer, settles into the passenger seat of my truck, and plugs into my ECU. And here's where we run into the one problem that plagued us the whole day: my ECU is reporting that something funky is going on w/my wideband O2 sensor, and we can't seem to clear the trouble code. After trying various combinations of harnesses, sensors, and finally a replacement ECU, we determine that the trouble is with my ECU, and proceed to hook up a "stunt double" ECU so we can at least get the engine tuned. I will need to send my ECU off to the manufacturer to get it repaired, but finally we start the engine and get busy tuning.
In 5 minutes in front of his shop, Dan is able to clear out the mess I had made of my idle tables, and has my motor idling like a kitten at 850 rpm. We now drive over to a nearby frontage road, and begin to tune in earnest. This road has a very straight section that's about 3/4 of a mile in length. We begin to head up and down this stretch, me driving, Dan working the laptop. Things quickly begin to take shape. Dan doesn't speak much, and when he does, it's usually things like, "bring the revs up more," "step on it," and "hold it steady there." He gets a rough fix on the fuel table in about 15 minutes, and then a rough fix on the timing table in 10 more minutes. We play around with boost a little, and opt for less boost in favor of more timing. Then it's maybe another 10 minutes fine tuning.
By now, I am seriously wondering how he can possible use this stretch of road, which parallels the highway, for runs of this speed. I am easily hitting 95+ mph in 4th gear, and the engine would certainly go higher if I had more room and more confidence that I wasn't going to get pulled over at gun point. (Dan later tells me that he has taken some vehicles to almost 200 mph on this stretch of road, something I can't really dispute...) Anyway, by now the truck is running GREAT! I can march through the gears very solidly, and third and fourth pull STRONG, with LOTS of top end power right up to my arbitrary redline of 6500 rpm. (I have the cam 2º retarded, which I may need to change...) And it feels good! The temp gauge is happy, the intake air temp is a mild 110* F at WOT, and the EGT gauge is screaming...about which Dan is unconcerned ("It'll take it," he offers with a knowing half grin.) Anyway, after maybe 45 minutes of actual driving, we have the engine tuned better than I could have managed in a week of intensive effort. Even Dan agrees that the engine is running great, praise I can't take for granted given the other cars he's got sitting around his shop. I rank this as one of the single best purchases I have ever made for this engine project, and that's saying a lot!
We cruise back to his shop and swap my ECU back in. Of course, even with the same program, the thing isn't running as well as it was with his ECU. We think this is due to the intermittent problem with the O2 sensor (he did all of this tuning in open loop mode, so the sensor isn't a direct part of the feedback to the ECU, but there's probably some other circuit that's also affected by the same voltage drop we were seeing on the O2 sensor). Still, the truck is running lots better than when I brought it in, just not as well as it was when I was running the fully functional ECU. I agree to ship the ECU off to get it repaired ASAP, and he promises to help me retune things at no additional charge if the repaired ECU doesn't perform as well as the one from his shop. I hope to have it back by the end of the week, so maybe I'll get some closure on this engine "real soon now."
Anyway, sorry to be so long winded, but as you can tell, I'm pretty jazzed by this. The engine project is finally (FINALLY!!!) within spitting distance of being done, almost 14 months after I pulled the old engine out, and one year after I got the new engine back from Tim. Once I do have it running properly from my ECU, I'll get it dyno'd one more time, just to put up some final numbers. My gut feeling is that I am seeing 250 - 260 hp at the rear wheels at ~12 psi of boost, which is less than I had hoped, but this is as much a limitation of the 91 octane squirrel pee they sell as premium in California as anything else. And it IS plenty of fun to drive: it sure does haul ass, which is the most important thing :-)
So that's where things stand. Expect one more installment in a few weeks and some final (God willing!!!) dyno numbers, and I'll call this sucker DONE!
