So, I originally wrote up a draft to bring up stuff from before the dyno like 2 weeks ago, however it seems to be gone.
At this point, the engine has 11k miles on it. No issues have cropped up. The avlves have now been properly shimmed for 15-16 thou clearance and is
so much quieter, which is something that matters for later.
MPG in mixed conditions seems to be a solid 25-26, which is also the mpg when doing a sustained 70-75mph on the highway. Going 80, at least going from eastern Mass to western NY, makes the mpg drop down to 23. I really need to do some aero work, likely aero cladding on the belly.
The transmission was swapped to a different T5 in mid November, and while pulling the old one we finally discovered that the cause of the noise for all this time was the mainshaft pilot bearings, because Borg Warner in all their wisdom didn't use any kind of race or cage so they can get loose and start rattling around after some time. Apparently it's a known issue, and why the Cobra T5z spec uses a pocket-style bearing. First second and third are much quiter, fifth is louder, and the second gear synchro is questionable. Third gear, while no longer sounding like the transmission is about to explode, now makes a whine reminiscent of a jet airliner taking off. Either way, worlds better.
To the man that I met in Brookline who owns his own 240 wagon that I talked to about the Volvol for half an hour, I hope you remember to check and see this update.
Anyway, the long awaited day has come, the culmination of 6 years of planning and 4 years of work. There are 3 dyno graphs. In order, they are:
1. The first one is the 87 octane tune with 87 octane fuel. This was the first tune made in early November with RBP.
2. The second one is the 93 octane tune on 87 octane fuel. This is the second tune made, on the same day, after refilling the tank with 10 gallons of 93. The logic here is that when we first started tuning, we noticed how the knock seemed to be completely imperceptible until we really cranked up the advance, so I reasoned that, now that the valve train isn't making a racket with the proper shimming, the knock sensor won't be quite as sensitive and possibly go off for the tiny bit of additional noise made on 87 with the more aggressive ignition curve.
3. 93 octane tune, with 4 gallons of 87 octane fuel in the tank being added to by an additional 5 gallons from a jerrycan, though with octane booster to make sure that the resulting mix is sufficiently high octane that there won't be any knock, in case my above thinking was wrong and more is affected than I thought.
The performance is standard SAE correction, power and torque at the wheels. Dynojet is estimated, because this was at a mustang dyno. To get a clear image of the whole torque curve, I had it start at 1.5k. Divide these results by 0.8 for power at the crank.
Additional comments/observations:
Runs 2 and 3 were effectively within tolerance. With a quieter valve train, 87 octane works fine with the more aggressive ignition, with a very marginal improvement with actual high octane.
I need a higher redline, since clearly the engine can keep pulling/breathing above redline. Probably a touch more fuel because it's running at 14-14.2 AFR when it enters closed loop, and that could give me a bit more power.
Keeping the same cam on a ported head doesn't significantly increase peak torque with the same valves, it will only increase breathing at the high end. I probably would need bigger valves/bigger cam to get that.
If I put any of the bigger redblock cams, my peak power will definitely be beyond redline and be a considerable increase, considering that the V cam is relatively tame and is only considered aggressive when compared to the M and T cams.
