Dyno Tuning

[MiniDave]

Once again proved its worth....

Yesterday, in the midst of the huge storms rolling thru our area, Mini owner Zac took his freshly rebuilt Italian Job up to Jesse Prather Racing in Topeka, Don and I followed along in Don's JCW to watch and provide moral support!

The storms have dumped so much rain on the area that Jesse had to remove a ton of water from the well that the dyno roller sets in so that the tires would stop slipping under power.

In addition to the rebuild Zac had replaced the HIF38 with a Weber DCOE 45 and tho he had changed the jet sizes a couple of times it still didn't run well, so Jesse took over. What a difference a guy with the proper tools and knowledge can make.

He wound up taking the mains down from the 165 Zac had it running on to a 140 to get it leaned out, and adjusted the timing to 38* at 4K! That surprised me but he said it's what the engine wants and since we aren't getting any detonation it will run there just fine. Between the timing changes and jets the HP went from 61hp to just under 70. not only was it more powerful but also smoothed out considerably. Zac said the difference was immediately apparent as we drove home, stopping for gas a few blocks from the shop. The rest of the drive home was uneventful, we were at the tail end of the storm so we only had to deal with light rain the rest of the way.

Sorry for the poor pic, it seems my phone camera and the TV screen were at odds....the green trace was the starting one, notice how rough it is compared to the later blue trace. A 10% increase is pretty significant! Also note the lower section - the dotted line is ideal A/F ratio, the green trace was well below the line - rich - and now it's dead on from 3500 up, and a little lean below that RPM. Fuel mileage on the trip home was hugely improved too!

[94touring]

Very good

[94touring]

Now that I'm actually awake....what are his engine specs?

[MiniDave]

Pretty standard, 60 over 1275, Evo 1 cam, no head work other than new hardened seats and a good valve job. New rockers (1.3) nothing crazy, tho he went with the Weber carb. Next up he's going to put a bigger exhaust on it, the one he has now looks tiny, but we think it's an RC40. He may have to go  back to the dyno after he does that, but it's not going to be right away.

[94touring]

He really needs a worked head then. The exhaust gains will be minimal.  I made 10 more with similar specs but a performance head.

[MiniDave]

Yes, we've talked about that but for now he's happy with it, it really runs nicely now.