SCCA EMod MGB GT V12 Build

Love this pic, picking the inside tire off the ground:

Love the car. I'll be on the lookout for you in Lincoln just to say hi. Amazing work and amazing car.

My Hat is off to you sir great looking car

So I had 8 runs on the test n tune course in Lincoln. I started off with shocks set to full soft on fast and slow compression and right in the middle of rebound. The car was a little understeery and the back end would hop on corner entry. My time was 29.2. I concentrated on changing compression settings only and stiffening them didn't make much of a difference to anything and my times were 29.0 and 29.0 on the following runs.

Then I tried lowering the panhard bar (and rear roll center) and the car hopped less but understeered more, time was 29.3. I lowered the rear roll center another inch and the rear felt more planted with just a slight hop and my time was 29.0. Then I went full stiff on the rear sway bar and full soft on the front one and the car felt more precise and surprisingly my front tire temps were 10 degrees lower than before, probably because they weren't being dragged across the concrete as much. My time was 29.0 again.

Then I made a radical change and stiffened the front suspension and the front sway bar. This was actually a mistake, I had intended to soften the spring rate and stiffen the sway bar but I moved the bolt the wrong way. Anyways, the car had the least amount of understeer yet and my time was 28.9. For my last run I only softened the front sway bar and the car felt the best yet, and my time was a 28.1.

I took notes on everything and stared at the results as well as looking at the data from the MaxQdata and concluded that I had actually been running the tires too hot so some of the results of testing can just be thrown out. Tomorrow I am going to soften the front like I had intended, keep the tires cool and see what happens.

Loose, I watched your video and was struck by how QUIET that car is. I was expecting full-on V8 rumble... That bugger sure looks quick.

stroker wrote: Loose, I watched your video and was struck by how QUIET that car is. I was expecting full-on V8 rumble... That bugger sure looks quick.

Yes, at the Springnationals I was warned about being too loud so I quickly welded in two more mufflers, so the car is pretty quiet now. I have plans for a new, lighter exhaust system because I need to chop 400 lbs out of the car. Ok, quick update until I can get all the data together. We went to the Solo Nationals, had a great time and the car was an absolute hoot to drive. Even Briget said she had fun driving it so basically I've changed my mind about selling it. I will continue to develop it but the pace will be a little slower than before and we may or may not run it at the 2013 Nationals but it will definitely be making more appearances. I have some cool videos and pictures to post later. On the list of improvements: 1.Changing the car from a coupe to a roadster (less weight, more aerodynamic) 2. redesign of front suspension geometry 3.Change rear diff ratio 4.Complete fiberglass body kit

We got to Lincoln and signed up for 4 Test N Tune sessions. I started off by doing one change at a time but it became quickly evident that with hi/lo speed compression, rebound, pre-load, front and rear sway bar, motion ratio, Panhard bar and tire pressures to be sorted out, there weren't enough runs available. Here is one of my sheets from the first 3 sessions:

We did an additional TNT and the car just kept feeling better and better. Then Briget did her runs on the West course and reported that the car was neutral with no wheelspin. I left the car for my runs and I guess I was driving different than Briget because I had wheelspin and hopping. Here is my quickest from the West course: http://www.youtube.com/watch?v=oRB06E0fkxY

Dan Wasdahl, KJ Christopher, Peter Raymond and Del Long came over and gave me some suspension tuning advice and they all seemed the agree that I needed more camber in front and more damping out back. These guys have driven or built more Championship winning cars than I can count on my fingers and toes so I listen to them carefully. I went back to my paddock spot and added 1 degree of negative camber in front and reduced toe out to 3/16 total. The next day Briget went out on her runs and said the car has never felt better and was a lot of fun to drive. Here is Briget's quickest run from the East course: http://www.youtube.com/watch?v=7b9zC3GloFY

I went out later in the day for my runs and I had to agree, the car felt fantastic. I made no changes to the car for my 3 runs, I just concentrated on driving better. Here is my quickest scratch run from inside the car: http://www.youtube.com/watch?v=3iyeXo2rWVE

And from the side of the car, and this one has speed and G-force data: http://www.youtube.com/watch?v=DXaFIy77T6s

In the end I landed up 9th out of 15 drivers and I think a trophy was within my grasp except I didn't drive well enough on the East course. I walked it 4 times and I guess it wasn't enough because things kept coming at me faster than I was anticipating and I overcooked some elements. Still, it's obvious that with some further development the car will be in the hunt for some hardware. Dropping 400 lbs to get down to the class minimum would be a good place to start.

Not that my input means anything but I wouldn't change the GT to a roadster. the stiffening required would negate any weight savings and an open car is less aerodynamic, not more so. Besides, this car is very cool the way it is. I don't know if you can get 400 lbs out of it even with no roof. 100 lbs and a season of driving it as a sorted car might be worth a trophy.

Jerry From LA wrote: Not that my input means anything but I wouldn't change the GT to a roadster. the stiffening required would negate any weight savings and an open car is less aerodynamic, not more so. Besides, this car is very cool the way it is. I don't know if you can get 400 lbs out of it even with no roof. 100 lbs and a season of driving it as a sorted car might be worth a trophy.

I guess you haven't followed the build from the beginning but the body contributes nothing to it's strength, it's a tube frame car with the body just hanging off it. I will be cutting the roof off and that will allow me to get in the car without opening a door, which means the door frames/latches/hinges can all go as well as the tubes going over the door opening. The rear hatch is a real heavy lump of steel and removing the roof, the hatch, the top bars and door structure should lose 100+ lbs. Then a fiberglass body should lose another 150-175 lbs and the rest of the weight savings will be a little harder to come by.

As for being worse aerodynamically, the MGB-GT has an upside down wing shape that causes lift, the air passing over has to travel a farther distance than the air travelling under, causing the air to speed up and create low pressure above the car. The sunroof and side lexan pieces have been sucked out of the car several times because of this and I'm sure removing the whole roof, windshield and rear window will allow the air to have a better shot at the rear spoiler.

I have absolutely been following the thread since post 1. I understand it's a tube-framed car. That doesn't mean the bodywork won't flap in the breeze at the speeds this beast is capable of.

If the body moves around because of the big hole in the middle of it, wouldn't that cause the rear spoiler angle to change. If lift is a problem now, won't air get in underneath the bodywork from the hole and make it worse? Is there some kind of "tonneau cover" in the plans?

Jerry From LA wrote: I have absolutely been following the thread since post 1. I understand it's a tube-framed car. That doesn't mean the bodywork won't flap in the breeze at the speeds this beast is capable of. If the body moves around because of the big hole in the middle of it, wouldn't that cause the rear spoiler angle to change. If lift is a problem now, won't air get in underneath the bodywork from the hole and make it worse? Is there some kind of "tonneau cover" in the plans?

I would like to put a small windscreen on the car and have a tonneau cover so the wind doesn't whip around inside the passenger side. There will be new sheet metal and fiberglass at the back to form a trunk where the boot lid is now. Only 4 more events before the transformation can begin

The widebody racing kit has been ordered from Spridgetech!!! I will still have to modify it to fit over my wider tires but it should look amazing when done and chop a lot of weight off. Here's some pics of the kit on another car:

The transformation from hardtop to ragtop has begun and by my estimation, I removed 150-200 lbs:

That's gonna look epic.

You seem to be on the road to an IMSA look-a-like. I say go for it.

So I guess this means you're not selling it now?

Ian F wrote: So I guess this means you're not selling it now?

yep, a few posts back, he said the Mrs really liked driving it, and its getting more and more competitive, so hes keeping it.

I think that widebody is gonna look sick! I really do love this car!

I think the car looks even better as a ragtop and I agree that with the widebody kit, it's going to be amazing.

Wow, for stock 'B' I prefer the hardtop, but this is shaping up to look all kinds of awesome

4cylndrfury wrote: yep, a few posts back, he said the Mrs really liked driving it, and its getting more and more competitive, so hes keeping it.

Ah... dug through the recent posts looking for that, but obviously missed it. Good to hear, regardless.

When I cut the top bars out of the roll cage, the car sagged in the middle, check out the picture of the body line where the door closes. I fixed this by welding in reinforced door bars. Without the need for doors that open and close, I was able to cut out the door handles, latches, hinges and door structure. I couldn't believe how much all that stuff weighed, and am now left with just a door skin which rivets to the door bars.

I picked up the fiberglass panels for the car today. The 4 fenders, boot lid, hood, valance and air dam together with the boxes they came in and packing weighed a total of 75 lbs!! The panels are beautiful and well done but I gave a quick test fit on the car and it's going to take a lot of work to make everything fit right. It's not the fault of the Spridgetech but there are some big differences between my heavily modified GT and an unmolested roadster.

First off, the front fenders of a GT must be different than roadster fenders because the profile where the fender meets the cowl area is completely different and is going to be tricky to match up. Also, to allow the old V12 to fit behind the front crossmember, I moved the entire front suspension forward 2 inches and moved the rear suspension forward the same amount in order to keep a 91" wheelbase. This was all fine because I was cutting away metal to clear the tires anyways. But with the new fenders, the tires are no longer centered in the wheel opening and would look funny, so the whole front and rear suspensions will have to be moved back 2 inches-ouch!!

Wow. This car never stays static, does it? Yes, roadsters and GT's do have different front fender profiles.

I much prefer the roof off look and weight savings that result from that but I think you'll need to do more than those little angle braces to the door bars to stiffen the chassis back up.Those big slicks will test the chassis for sure. Moving the suspension again eh?I'm known for my big projects but I'd be thinking about throwing in the towel with the fitting of the new panels and the suspension rework.

kevlarcorolla wrote: I much prefer the roof off look and weight savings that result from that but I think you'll need to do more than those little angle braces to the door bars to stiffen the chassis back up.Those big slicks will test the chassis for sure. Moving the suspension again eh?I'm known for my big projects but I'd be thinking about throwing in the towel with the fitting of the new panels and the suspension rework.

Once I figure out where the radiator will be, I will add more braces, most likely a cross brace from behind drivers head down to passenger footwell.

I cut away all unnecessary material for the rear fenders and attached them temporarily with rivets. It turns out that the tires still stick out the side by an inch. If I want the fenders to cover the tires, I need to a) Run narrower tires b)Narrow the track width which would involve moving frame rails or c) Widen the fenders. I really don't like the idea of trying to widen the fenders because the risk of them becoming ugly or heavy is too great, so I am going to widen the whole car by 4 inches. That's right, each side of the car will be moved 2 inches out, which means the front spoiler and hood will have to be widened but that will be much easier to do than slicing and dicing the fenders.