SCCA EMod MGB GT V12 Build

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owning a building with enough open space under roof to operate a racecar should be a constitutional right

I checked over all the bolts to make sure they were tight and I replaced some with shorter ones to save a few ounces. I also zip tied any loose wires and hoses while I was in there. Since I do not have an air filter, I added a fine aluminum mesh to the opening of the air box to catch anything big enough to cause damage.

My old alternator tensioner was actually attached to the frame because I had solid engine mounts, but I was worried that if there were any flex in the mounts or frame, my belt would loosen and slip off. So I built a new tensioner that is all attached to the engine:

And bolted the fenders, spoiler and grille on, so I am essentially good to go.

I need to test everything I can before the first event so I backed the car up to the acid etched part of the kart track, revved it to 3000 rpm and dumped the clutch. I did this four times in a row and everything felt great and nothing broke. It also launches HARD. This new T5 trans grinds going into reverse but I discovered later that many T5's do this and the cure is to shift into 5th before going into reverse. And FYI I am running the recommended trans fluid in it and the clutch is adjusted properly. Here's videos from different angles of the launches, check out the sparks coming off the tires, it's from metal shavings stuck in the slicks: http://www.youtube.com/watch?v=82IvLIbLO8c

http://www.youtube.com/watch?v=FWhljJS2Nnc

http://www.youtube.com/watch?v=BSEKdH0-l6w

http://www.youtube.com/watch?v=E6IYDQ8ppcQ

Watching that makes me smile. A big glassy eyed smile. I like that car.

sounds like a pro stock car launching...as in AWESOME. Never noticed how low you sit in that beast. Its a testament to your fabrication that you can launch that motor, with those meats, at that RPM, and everything stays where you welded it. Nice work!

I don't have an event for another 3 weeks and it's going to drag on and on-I want to drive it in anger NOW!!

As usual, this build rocks. Can't wait to see videos of it in action OUTSIDE.

I added a heat shield between the muffler and fuel filter, just in case there may be a heat soak issue.

And I was concerned about Briget being strong enough to rapidly turn the steering wheel so I switched from a 2:1 steering quickener to a 1.5:1. I can switch between the two quickeners by just undoing a couple of bolts.

I had my first shakedown test of the Pink Panther on the road course and it went very well. Nothing broke and the car has no strange handling vices but I learned some interesting things, like that the diffuser really works and you can feel the extra grip with it. The ignition would start to break up above 5000 rpm, which prevented me from exceeding 110 mph (175 kmh) on the straight. Up until that point it pulls like a freight train and once the tires are warm, I can stand on the throttle coming out of turns as long as I am in 2nd gear or higher. The rear of the car jumps going over bumps and I will try to tame that with shock tuning. Neither Briget or myself were brave enough to drive the car at even 8/10's. We both felt that the limits of the car are a lot higher than ours but we will be ready to push in Lincoln.

The rear tires rub on the inside of the wheel well but a spacer should fix that. The aluminum mesh I used in the grille does not let enough air through but the coolant temp only rose too high after 3 or 4 hard laps, and dropped as soon as I took it easy. Even when I push the car too far, it comes back fairly easily but does get twitchy above 100 mph. I attribute this to the aero on the car, I think it starts to push one end down harder than the other at high speeds. On the way home I called the guy who did my engine tune and he immediately diagnosed my problem: I have the wrong spark plugs in the car. If it clears up the misfire, that car is going to be seriously fun.

It was a lot of fun and if we can move our hands fast enough, it should do ok at autocross. However, the pivot cones are going to be a problem but fortunately, that is only a local problem. I only have video of my very first drive of the car and Briget's first 3 drives because the battery in my GoPro crapped out. Here's the first video http://www.youtube.com/watch?v=E4Z9BSx_osg

Man Im sure that was a blast. Please let us know what you find with those plugs. Its weird to see that sound come out of that car (watched the drive by's on Youtube). Sounds wicked. Nice work, you should be proud. I cant wait to hear about your times in Lincoln.

4cylndrfury wrote: Man Im sure that was a blast. Please let us know what you find with those plugs. Its weird to see that sound come out of that car (watched the drive by's on Youtube). Sounds wicked. Nice work, you should be proud. I cant wait to hear about your times in Lincoln.

Check out the difference between the wrong plug and the right plug. Notice the wrong one is a tapered seat and extends much farther into the chamber than the flat seat correct one. And the heat ranges are different, too.

FYI, pre-92 Mustang T5s did not have a reverse brake designed into the transmission, which is why it grinds when trying to go into reverse. I have found it easiest to go into 3rd then reverse, but if 5th works for you, then use it.

That looked really quick and really twitchy.

Looks like it will reward smooth and punish abrupt. Love the noise. It sounds right.

Sounds fantastic! Can't wait to hear it run (at least on-line) with the right plugs...

DaewooOfDeath wrote: That looked really quick and really twitchy.

Yes, it is both. I looked again at my notes on suspension set up and I am running a lot stiffer rear suspension than front, I will be changing that before my first official autocross this weekend.

Today was dyno day and things went great. A stock 5.0 makes 165 hp at the wheels so with aluminum heads and new cam I was hoping for 265 at the wheels, and that is also what a computer simulation said I would get. I got 264.8 hp @ 5307 rpm and 271.6 ft/lb @ 4839 rpm and a power curve that rises extremely smooth and linear. It showed no signs of a misfire so either the new plugs fixed it or my ram air system is so effective that it's putting the engine into a lean condition at speed. Here's video of the dyno session and a picture of the power curve. http://www.youtube.com/watch?v=UtKhT_L8CDM&feature=youtu.be

Awesome car! It's interesting to see the different approaches you and your wife both have... I know it was a test and tune, but did you get a sense of what style the car's going to like?

Just a (YouTube) observation... does Bridget need tighter belts? She sure seemed to be tossed around in the bumps.

What did she think of it?

4Msfam wrote: Awesome car! It's interesting to see the different approaches you and your wife both have... I know it was a test and tune, but did you get a sense of what style the car's going to like? Just a (YouTube) observation... does Bridget need tighter belts? She sure seemed to be tossed around in the bumps. What did she think of it?

My video was my very first drive on the track and Briget's video was after she had covered 20 or more laps. I had no diffuser on so the car was missing some rear downforce, she had it on. I shifted gears on every lap and she just left it in 3rd and used it's torque to get her around. We both thought the belts were too loose but the lap belt was out of adjustment and couldn't be tightened, and tightening the shoulder belts would suck the lap belt up around our chest. I have since corrected the problem so we should be belted in tight for this weekends event. The car seemed to like slow in-fast out and changed direction quite willingly. I didn't find it scary at all and neither did Briget. At first we were both unsure and nervous but that quickly went away when we realized how forgiving the car is. However, the rear suspension was too stiff and would hop over bumps that the front suspension didn't even realize were there. I have softened the rear suspension and stiffened the front so the new suspension settings are 155 CPM in front and 137 CPM out back. I think these convert to 2.58 Hz and 2.28 Hz.

You might want to consider 2 sets of belts in the car. I have seen several enduros lost 'cause tall skinny driver took tons of time getting the belts tight. (Or vice versa...)

Not such a big deal at a regional autoX event, but bigger, faster run, large events with 2 drivers in a run group.....2 sets of belts helps the transition.

Rog

So, even though we actually broke the car today, I think our first autocross was a success. I drove first and the car really, really bounced around on the rough surface we use and understeered everywhere. I didn't know what was going on until I watched Briget drive, and it looked to me like the car was bouncing off the bump stops. I stiffened the rear suspension a couple of steps and went out for my second run. It was a lot better and started to go through slaloms much easier. For my 3rd run I stiffened the rear another step and also stiffened the front by one step. It was even more controlled but the rear still really bounced in a couple of places. The high speed compression was already at full soft so I adjusted it to full hard but left the low speed compression and rebound at full soft and sent Briget out on her run. Going over the first massive bump on the course, the bracket holding the short arm of the Woblink broke, allowing the rear suspension to move around-our day was done. I got the car back to the shop and took a good look at it. There was enough flex right at the end of the bracket that after Friday's track day and todays autocross, the piece failed from constant flexing. I boxed it so flex has been eliminated and we won't have that problem again. Here's a pic of the broken link:

The data from my 3rd run shows that the car was pulling .6 G at 50 mph (the only time I got on the gas in 2nd gear) and was hitting over 1 G in either direction so it has potential but I certainly was not getting the most out of it. I'm confident that it will be a lot better on a smooth surface without pivot cones. Just check out the video and you will get an idea how violent it was inside the car.

http://www.youtube.com/watch?v=bpaycLEkkTE

I was still trying to understand what the rear suspension was doing (other than breaking) so today I put zip ties on the shock shaft to see how much compression they were getting, and I aimed a camera at them. The car was really unstable under braking but was better over the big bumps.

When I got back, the zip ties were shoved up against the bump stops. I changed the high and low speed compression settings from full soft to full stiff and sent Briget out. When Briget was on course I could see the axle moving back and forth and for a moment thought that the newly fixed bracket broke again, but that was not it. The zip ties were not up against the bump stops this time so that was positive.

Once in the pits I tried to determine how the axle was moving back and forth and couldn't find anything at first but once I had Briget shake the car back and forth really hard, I found a fracture in a different bracket. Obviously the forces on the Woblink are greater than a typical lateral link like a Panhard or Watts because these brackets were pretty robust and were still snapping solid steel plate.

I know from trying different roll center heights at the lapping session and autocross that the car likes it set above 8" high, so I am going to remove the troublesome Woblink and install an adjustable Panhard around that height. Here is a very interesting video of the rear suspension during a run, once you stop being mesmerized by the shocks moving around, notice how much the diff is moving back and forth due to the broken Woblink. http://www.youtube.com/watch?v=3WjlfxcqCdI&feature=youtu.be

Wow! The feel of that rear end "Setting" in a corner must have been unnerving.

MrJoshua wrote: Wow! The feel of that rear end "Setting" in a corner must have been unnerving.

I would like to know when the brackets first broke. When I built the Woblink, it added something like 120 lbs to the car so I look forward to the simplicity and weight savings of a Panhard

I'm sorry to hear that suspension didn't work out. I wonder where all that force could be coming from. Perhaps whatever bearing you used in the bell crank was binding?