SCCA EMod MGB GT V12 Build

Haven't checked in for a while but that thing is looking pretty good. Been a long road. The new racecar blues as Burt Levy says.

The more I see this the more I want to say 'screw it ' and turn my B/GT into a clone.

The handling felt a lot better when we were here 3 weeks ago and I haven't changed anything, so hopefully the competition courses are better suited to us. Slaloms are good, sweepers are good but tighter elements that require hard acceleration out of are a problem

In reply to loosecannon:

You mentioned above that you found your lower control arm adjusters were bent. Do you think that could have resulted in an accidentally better alignment than what you intended, or what the car is set to now?

In reply to Pete Gossett:

Hmm, that is an interesting suggestion. The bends would have resulted in less caster and in theory, less jacking across the chassis and less front end bite. It would also have affected toe but I can't figure out if it would have had more toe or less. I think the bigger effect is the differences in the courses. Last time it was just big sweepers and 3rd gear slaloms but this test course was tight turns and 2nd gear slaloms. The necessary steering angles are a lot more this week. We will see what happens tomorrow.

The car felt pretty good for day 1 of competition today. My first run was a little herky jerky and I hit the brakes too early a few times but I cleaned it up for run 2 and it was good enough to be sitting in 3rd place. On my 3rd run, I knew as soon as I let the clutch out that something wasn't right and noticed the boost gauge was not moving. I did my best but the power wasn't there. On the test course the other day, I experimented with some wastegate settings to get boost back where it was supposed to be. We did 8 runs this way and nothing went amiss. Today, overboost occurred and triggered the car into limp home mode. After the event, I cleared DTC's and boost came back. Jerry from Bad News Racing sent me a new tune that is less sensitive to overboost and gives me a little more timing for extra torque. Here is a video of my first run

top 3??? after all said and done?

In reply to loosecannon:

Damn quick run. At those speeds there's no time to be uncertain about the course, that's for sure.

Is your steering wheel all aluminum?

In reply to Pete Gossett:

Yes, I have an aluminum steering wheel but am currently keeping my eyes open for a suede covered one. Today is day 2 of competition and I hope to hang onto 3rd or even move up a spot.

LooseC, will check in on Tuesday for update....

Well then, how'd it turn out this weekend....FTD? trophy? beat Jeff K? Briget took class?

We loaded the new tune for day 2 and Briget came back from her first run reporting that the car was "F%&King Fast!". I went out on my first run and didn't push hard because the course was really confusing on the course walk and I wanted to make sure I knew where to go. My time was slow and I dropped a number of positions but felt I could make that up on my 2nd run. Sadly, I had no boost again on my run and was really slow, and only Briget was slower. She was having her own issues with not pushing hard enough and braking too early, a result of the car being a lot better this year but our brains haven't quite realized it yet. I re-loaded the new tune for her 3rd run and logged the data. She had boost for her final run but as a precaution, I cleared the DTCs and loaded the tune again. I felt immense pressure because nearly the whole field was ahead of me and I had to pull one out on this last run, and hope I had boost for all of it. I took off from the start and boost was definitely there, I tried to take my mind off what the car was doing and just drive it. I felt like it was clean and I rolled to the scales to get my weight. I had no idea if I had a good enough time to get 3rd place back and didn't know until a competitor came over to congratulate me on my 3rd place. I was surprised and pretty happy about it. These were the top drivers from EMod and I managed a 3rd, despite my problems. Here is my 3rd run, I can see a lot of room for improvement.

In reply to loosecannon:

Awesome comeback!

They say nobody remembers who took second, but this third has to be a FIRST emotionally/mentally considering the field. Congrats!!!! Was J Kiesel there?

In reply to 759NRNG:

Thanks for the encouragement. Here are the results and you can see how I lost so much time on runs where I had no boost. I should have been 2 to 3 seconds quicker over two days. I was thinking way too much about what the car was doing than I was about just driving it. the best results I ever had at Nationals was several years ago where the car I was driving broke after 1 run and I had to hop in a car I had never sat in before. All I had to do was drive and I finished 4th in DMod with a car that was street legal with turn signals, windshield wipers and a heater. Once I get past all this on-course analyzing, I can get down to the business of driving.

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_9313_zpsqd2z13zf.png.html][/URL]

In reply to loosecannon:

Like you, I have that same struggle of overanalyzing the course, car, my driving, and everything else too. Unfortunately, trying to talk myself out of doing it usually only makes it worse. Luckily it doesn't happen all the time at least.

Dude, when you sort out the mental, Kiesel will be sucking wind trying to find 1.5-2.0 seconds. When is your next event?

In reply to loosecannon:

How much boost were you losing?

1.5-2 seconds isn't that much. Seems like a lot, but I don't think so. I normally expect a speed up just driving better of 1 second from run 1 to 3. And I did this a lot.

So IF you are losing that much boost, then you should learn what you were doing on the slower runs to go that fast.

The way you are putting it, it sounds like a drop of 50 or more hp, which should have more time effect than that. That's why I'm bringing it up.

In reply to alfadriver:

I went from having 25 psi of boost to 0 psi of boost. The car was amazingly composed with so little horsepower, I was just flat out everywhere. It felt like Miata power. But as I say, I need a set up where I can just drive it and trust it then I'll be quicker. I just ordered a clutch diff that should stop the wheel spin .

In reply to loosecannon:

So if you are only 1.5-2 seconds slower with at least 100hp less, that says something.

Very loudly.

I totally get the need for a consistent and trustworthy set up. And that needs to be fixed pretty badly in terms of the ECU.

But I'd be all over the data to find out why you are so fast with such a slow car, so that you can keep doing the good parts.

In reply to alfadriver:

I wasn't down on hp for my last run, as far as I can tell. I have an obsolete MaxQdata system for things like speed and G forces but I don't usually run it because it's just more stuff to worry about when I should be thinking about the course. Right now I think my primary problem is wheelspin because I have to make the car understeer in order to keep wheelspin to a minimum. Once the clutch diff is in, I should be able to improve handling a lot. I have an appointment with the dyno next week so hopefully my tuner and I can get some great results and figure out this no boost thing.

In reply to loosecannon:

Right- and it was faster than your previous runs by either 2 or 1.5 seconds. With probably more than 100 hp more. IMHO, it should be a whole lot more than that.

And finding out why, and fixing it will probably speed you up another second.

I noticed from my data logs that the engine only builds max boost (25 psi) above 6000 rpm and I would like to have some more punch down low. The factory wastegate opens at 6 psi and there is a computer controlled valve that opens and closes the hose with the boost. I looked into an aftermarket wastegate with different springs but none exist, although I could probably adapt one from a different application. But a spring is a spring right? I just attached a spring to the wastegate arm and now it opens at 10 psi and is fully open at 18 psi. Today I had a local autocross event and data logged every run. Boost peaked at 28.2 psi which is the highest I've seen in the car, and it felt great. The local autocross site is very bumpy, low grip asphalt and the splitter was grinding against the bumps hard, so I raised up the ride height 1/2". For some reason that I don't understand, it understeered less and I landed up looping the car. I raised it up another 1/2" and it understeered even less. I'm sure it has something to do with roll center or camber gain, I just have to do some measuring and punch the numbers into my suspension program to see what is happening. I set FTD at the event but didn't do well in PAX because I just didn't drive well enough. I left the car in 2nd gear and bounced against the rev limiter for the first two runs and set decent times. Then on my 3rd run I shifted to 3rd gear and looped the car. On my 4th run, I shifted to 3rd gear again but was going too fast when the track tightened up and got behind. Anyways, enjoy the YouTube video

Always fun to ride along....makes my eyes water

The change in handling balance with ride height changes is probably caused by a change to roll axis inclination. The SLA suspension should have a pretty good camber curve so you won't get any big changes to camber, and your rear camber is fixed to the solid axle. IIRC there's a panhard bar at the rear and this will cause a big raise to the rear roll center with a raise in ride height unless you adjust the mounting points to bring the bar closer to its previous angle.

If you had a watt's link at the rear with the bell crank mounted to the chassis, the roll center wouldn't move at all relative to the chassis.