SCCA EMod MGB GT V12 Build

After the event I did a post-race inspection, a habit I picked up from karting, and discovered some clearance issues with the new wheels and tires. The right rear tire and wheel had enough deflection to touch the Panhard bar under hard cornering. I couldn't use any more wheel spacers so watch the video and see how I got some more clearance. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6038_zpszyh2basw.jpg.html][/URL]

Video: https://www.youtube.com/watch?v=2uL6m6RFNAA

During the last event, the extra grip of the Hoosiers caused the car to lean a lot more and scrape the splitter in turns. For todays event I raised the front half an inch and made some changes to the sway bar and roll center and the car felt amazing. The end plates of the spoiler were also changed and now are at the 100 square inch maximum. I didn't change a thing through all 4 regular competition runs and had my best PAX finish of 5th. I watched Briget wiggle the car through the course and it appears to rotate around the rear wheels, which is also what Jeff Keisel's Sprite appears to do so maybe I'm on the right track? I meant to try the car on a fun run without the rear spoiler on just to see what the difference was but instead I messed around with roll center. So, the car has 97 autocross runs, 7 road course laps and 3 passes down a drag strip with the worst thing happening being a tire rubbing on a Panhard Bar. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6073_zpsxgqibqop.jpg.html][/URL]

Video of a couple of runs: https://youtu.be/ET3dZHcyVUE

Looks great. Very excited to see how you do at Nationals. It looks like it's really coming together. Emod has a few good cars coming out to try to knock Kiesel off which is great.

I hope to have my car there but it's looking unlikely. I am planning on coming no matter what so I can actually watch Dmod/Emod as I've never ran on the same days as the class my car will be in. I will be sure to stop by and say hi and cheer you on.

In reply to nocones:

Keep chipping away at it, a little every day and maybe you will be able to bring your car. I am very excited for Nationals but don't expect to challenge Kiesel this year unless he has some bad luck. We'll see, maybe there will be some surprises

I was out of adjustment on the axle side of the Panhard bar so I decided to take the opportunity to make the whole mechanism better. The axle side and the frame side were simplified and lightened and I took 10 lbs off the car, much of it unsprung weight. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/DSC_4914_zpsntkyzmer.jpg.html][/URL]

Video Here: https://youtu.be/U4u82SmKnco

Today I had my first chance to try the changes I made. For my first run I was very aggressive with throttle and steering and the car would get sideways in one part of the course and would understeer in another part. Initially, I thought I needed to stiffen front sway bar but on my next run I realized that my driving was a bigger problem. I landed up raising rear roll center a bunch then driving it like a tail happy car I.E. Brake sooner and accelerate through the turn. This worked well and I set Fastest Time of Day and 9th in PAX. The course had great average speed and was very much about speed maintenance, there was very little acceleration or braking except at pivots. I have a ton of work to do before Nationals because the combination of settings is almost infinite. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6224_zpsu0dqgp5s.jpg.html][/URL]

Video here: https://youtu.be/55qjkdMMBek

I went over the engine data logs from the last event and they confirm what I felt was happening. On my first run, I had the gas pedal 100% down for 2.71 seconds where on my quickest run, I had the pedal down for only 0.6 seconds. This week I have had the car in the garage and have been checking everything over in preparation for Nationals. I also changed the anti-squat settings in the rear suspension, installed a switch that only allows the car to be started when clutch is depressed and stiffened the Panhard bar frame mount. If you look at the rear suspension in that last video I posted, you will see that the 2" square tubing Panhard mount flexes as I pitch the car into a turn. I welded a 2" x 1/4" flat bar to the mount so that shouldn't happen again. I blocked off all the openings in the front of the car because they aren't needed for cooling or anything but I made the panels easy to remove if I need more air for the intake. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6257_zpsknrbno8w.jpg.html][/URL]

It was a double header weekend and on Saturday the course was cone intensive and basically a long slalom where speed maintenance was king. For the first couple of runs I had the suspension way too stiff so I pulled the pins on the rocker arms and moved them over to soften the wheel rate. This worked wonders and made the car quite driveable and I landed up with FTD and 10th in PAX. On Sunday the course was fast and wide open with a couple of spots where the course tightened up and you could really hang yourself. Well, I did hang myself and for some strange reason, when braking from high speed the rear wheels would lock up and throw me into a spin. This is only speculation, I can't be sure, but I think it's because I have blocked off the openings in the front end. Maybe it has reduced lift and threw off the balance? I changed the balance and went on to get FTD and 10th in PAX again. Looking at the video of my runs, I left a lot of time on the table-perhaps 2 or 3 seconds just from not trusting the brakes. Check out the video of the spin. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/14100315_1247629791915353_3752242736961299799_n_zpspb5gstot.jpg.html][/URL]

https://youtu.be/5pDNjF2Y8_0

Closing the front bumper openings will have added to your front aero downforce, effectively giving you forward bias/grip at the tires. Just need more rear downforce now. Add wickers to the outsides/top of the diffuser edges.

In reply to stafford1500:

That's a good idea but I don't think it's allowed in my class

I have lots to tell, so buckle up. We arrived in Lincoln on Sunday morning and immediately got out on the test course. The pre-Nats stiffening of the suspension made the car oversteer, spin the inside rear tire and lock up the rear tire under braking. I would make a change then run again but couldn't get the balance right. If I softened the rear suspension, the spinning tire problem would improve but the understeer problem increased. The same thing would happen if I lowered the rear roll center. I tried various combinations of front and rear roll centers, sway bar settings and even changed caster and anti-squat. The test course workers knew us very well after two days of testing. They say the test course times are meaningless but we couldn't help but look at our competitors times and make comparisons. It looked like we were sort of in the ballpark of the other EM drivers except for Shawn and Jeff Kiesel-they were far ahead of us. By Monday evening, we had the car feeling the best that it had been. It was still slightly understeery and if we drove smoothly, the rear tire spin was minimal. Jerry from Bad News Racing contacted me and asked how things were going and I mentioned that it would helpful if boost came up quicker. He showed me what to adjust and warned me that if I went too far, the car would start to buck violently. On Tuesday morning, first day of competition, I made the change to the tune and was doing a checkover of the car. It was then that I noticed a big difference in how much rear suspension droop there was from the left side to the right side. The car was sitting perfectly level but the right rear drooped 3 inches and the left rear drooped 1.5 inches. After some thought, I realized that the 80 lb weight difference between left and right side of the car could be the source of my handling problems. At the time I scaled the car, I didn't think much of us because the car used to have a passenger seat and my lap times weren't too affected by having a 200 lb passenger. I borrowed 65 lbs of lead from Del Long and placed it in the drivers seat and got Briget to sit on it. Sure enough, once the car was re-adjusted to be level, I had a bunch more droop on the left rear suspension. Nothing more could be done because we had to work then run the East Course. Briget pulled up to the line, not having a clue how the car would feel because we never had a chance to test it with the lead attached. She came back reporting that the car felt much better and the boost came up quicker, too. I went on my run and was too conservative but the car did feel pretty good. I made another quick change to the tune to bring the boost up quicker and went a little harder on my next run and got into some marbles but still ran 3/10 second quicker. I changed the tune again and drove harder on my 3rd run and lopped a second off but tipped over the last cone on the course. I was not happy with my lousy driving but the car felt pretty good. We went back to the paddock and I took the lead and bolted behind the rear axle and just above the diffuser. This increased the left rear droop by another half an inch. On Wednesday morning, I took the car out on the test track and with stone cold tires on a cool 8:00 am track, I matched my best previous lap time. The car felt amazing and I hopped out and let Briget have a go. She came back pretty excited about the handling, too. I increased the rate that boost comes up and went out again. The turbo lag improved and I changed it again. If I was going to go too far with it, I wanted it to be on the test course. I kept increasing it and now the turbo was making a loud whistling that I hadn't heard before. Then it started to rain and I got to see how predictable the car is in slippery conditions. I was very surprised how hard I could push and not lose control, the car was quite good. The braking problem seemed to be cleared up, too. A couple of hours later, it was time to race the West Course. Briget had been comparing herself to one of the other drivers in the class and on day 1, their times were almost identical. With the changes we made, she was now 3 full seconds quicker! I went out for my first run and overshot two turns pretty badly, getting into the marbles and losing a ton of time. I was still only 1.6 seconds slower than Jeff Kiesel and was pretty confident I could get a lot closer on my following runs. On my next run, I corrected the mistakes from my previous run but made all new ones, getting off the racing line and into the marbles. I changed the boost control again and was now way beyond what Jerry has been able to do on a stock Buick Regal without running into problems with bucking. The boost came up quick and strong with no problems at all but I drove far too conservative and was unable to improve my time. Clearly, the car is much more capable than I am and I need to learn how to drive the beast. Attached is a video of a run from each course and I'll be sharing more videos in the next few days. Also, a number of GRM'ers came by to check out the car in person and I really appreciated the compliments and enjoyed chatting with them. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6396_zps75se7orj.jpg.html][/URL]

https://www.youtube.com/watch?v=ml5IFdbKfhY

It will be interesting to hear your plans to improve the driving.

But you've got a heck of a good start there- seems like a lot of gross tuning was taking place this year- and better raw understanding on how the car works and how to fix details. And if I got your timeline right- this entire season was sorting out the car. Which isn't done yet- if I read your National's experience.

Bearing that in mind, both of you are really fast, and it seems as if (based on your posts) each of you are not really near with the car can do at the moment.

So... while next year will still be a major learning year, I would be bold and bet that you can trophy in 2017. And Bridget could probably win EM-L, if she chose to, next year. You were both taking seconds off of your time- which I would still expect for about half of next season, by the end, you will be chasing the 1/10ths. And given that you are just over a second out of a trophy from this past event, well... the math is there for the taking.

Pretty sweet car.

Just remember to tweak this off season.

Very cool.

In reply to alfadriver:

I think you are right. I have spent a lot of development time chasing problems that were just a weight balance issue. It seams pretty silly in hindsight. With the extra weight, I came across the scales at 1980 lbs and class minimum is 1750. over the winter, I will move fuel tank and battery behind the rear axle, get an aluminum driveshaft and get a smaller intercooler mounted behind the engine and closer to the left side of the car. This should improve balance and lighten the car.

Car looked great on course. You should be very proud of the result for the amount of testing you had. Next year I have a feeling you will be up there with the Mineharts making Kiesel work for it.
I Had fun talking to you and Bridget and hope to join you guys next year.

Its really interesting how much a difference in weight difference side to side can make. Last weekend my dad and I came to the conclusion that my car runs faster with a passenger than just me in it. In the last three days of running my fastest times have all come with a rider. Its good to hear your making progress, its really fun when you start to gain on the other people in your class.

nocones wrote: Car looked great on course. You should be very proud of the result for the amount of testing you had. Next year I have a feeling you will be up there with the Mineharts making Kiesel work for it. I Had fun talking to you and Bridget and hope to join you guys next year.

It was great meeting you in person, I hope I didn't act too distracted (I tend to act that way when concentrating on something). We will come back next year better prepared and faster, no doubt about it. Jeff Kiesel has something big in the works and hopefully we can keep up

Some updates on what I'm doing with the car, the picture is a clue [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6493_zps2qhtnbrp.jpg.html][/URL] Video here: https://www.youtube.com/watch?v=ksYuvFGUEMg

With all local autocross events over and some engine tuning still to be done, I went to the last drag race event of the season. The tech inspector warned me that if I went quicker than 11.5 seconds in the 1/4 mile, I would have to wear a neck collar and wrist restraints. I fully expected to go quicker than that because I car of my weight and horsepower should, with proper chassis tuning, be able to do 10.3 seconds at 134 mph. I knew I would never do that because I don't have the suspension or tires to launch that hard and my car maxes out at 119 mph. but it should still be really quick. I did a little burnout and pulled up to the line. The lights came down and I launched in 2nd gear, the tires just lit up and were spinning all the way through 2nd gear. I shifted to 3rd and they tires got traction briefly then spun almost all the way to redline. I was doing nearly 80 mph by this point and when the tires finally caught and the boost came up, the car pulled pretty hard to the end of the 1/4. My time was a pathetic 12.0 seconds but my datalogger indicates that I lost over a second to wheelspin. I drove back down the return road and the officials stopped me and told me that I had dropped gravel for 50 feet down the strip. I noticed that mine were the only tires that picked up rocks and I stopped in the staging lanes and cleaned them off but as soon as I moved forward, they picked up fresh gravel again. My day was over and I didn't learn anything except that my little Ecotec makes pretty good power and that the car is rock solid at 119 mph. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6552_zpspnber81u.jpg.html][/URL]

Video here: https://youtu.be/G7eCRM7P6mI

Just got caught up on this thread and I have a few thoughts:

1. You might want to forget about that clutch switch for survivability reasons, if you don't have one then it's much easier to drive the car with a clutch failure - you can launch using the starter and then float gears. If you do have a clutch switch, you can't launch without a push-start. I've never owned a car with a clutch switch and I've never been inconvenienced by the lack of it.

2. I wouldn't recommend putting the fuel tank in the very back-left corner, it will make your corner weights change greatly as the fuel level changes. I'd keep the fuel tank in the rear center and put the battery and small tanks in the far corner. Also I wouldn't get a smaller radiator, just shift the one you have to the back-left as far as possible. The smaller radiator will make very little to no difference in L/R balance but will lighten the entire rear slightly which isn't what you want. This leads to...

3. You really need some fine diamond-pattern mesh to protect the parts in the rear from pebbles flung up by your rear tires, you've already got some nasty rock strikes on the radiator.

4. Your plan for the intercooler isn't bad but I'm not sure it's the best. It should indeed perform better than what you have now and improve balance, but what about the effects of charge pipe volume on lag, and the changes to CoG? If money's no object you might want to consider an air-to-water intercooler in the front with a dedicated radiator at the front of the stack in the rear. This is expensive and a bit heavy but will give you great charge cooling and have the least negative effects on lag, boost drop etc. and there won't be so many high-mounted parts (well, relative to the height of this car )

In reply to GameboyRMH:

Thanks for the input, it's well thought out and insightful. The clutch switch is just hooked to the starter button circuit so I don't start the car in gear by accident. It fires up so quickly that the car would be driving towards destruction before you could stop it. The fuel tank only holds a total of 18 lbs of fuel and the car isn't a gas guzzler so I don't expect much balance change between runs. It probably only burns 1 lb of fuel a run. The radiator I have is way oversized, it's for a big V8 and another competitor runs the same Ecotec as me and uses a VW Golf radiator mounted in the back with no overheating problems. My car is too heavy so a smaller radiator and less coolant is a good place to start. Mesh is a great idea and I have some protecting the intercooler. The damage to my rad is from the old mounting of the fans, not from rocks. As for the intercooler, the current one has 3" inlet and outlet and total length of of piping is 72". The new intercooler has 2.5" inlet and outlet and around 60" of piping so the total volume of air is much less and I expect throttle response to improve. I like the idea of water to air intercooler but have been advised against that unless I need ballast because it's a lot heavier than air to air. I have the new fuel cell, intercooler and rad already so work should begin soon.

Subscribe to my YouTube page for video content that nobody else gets: https://www.youtube.com/channel/UCe50QeA3lG1KogAVpWraiIw

I finally started on the off season modifications and here's a quick video showing what I'm up to: https://youtu.be/KUqPvEiksAU

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6754_zpsubhuoddn.jpg.html][/URL] I am way overdue for an update on the car so here is a video of what has been going on: https://www.youtube.com/watch?v=ummQ9ZpZAKg

Recap: At Nationals, the higher grip levels revealed a problem with lifting the inside rear tire and locking up the rear tires. I determined that this was due to the left rear tire having 90 lbs less weight on it than the right rear. To correct it, I moved the battery, fuel cell, surge tank and overflow tank to the left rear side and also moved the intercooler and radiator. Here is a shot of the scales before I did all that: [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6493_zps2qhtnbrp.jpg.html][/URL]

And now after I have made the moves [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_7142_zpsbkwcdckn.jpg.html][/URL]

As you can see, there was significant improvement in rear weight bias, left/right balance and overall weight. I now have 54.3% weight over the back tires and almost 50/50 left/right balance. This should make the car accelerate, turn and stop better.

Since I no longer have the giant twin fans on the radiator, I have room for a better diffuser. The old one didn't have the right shape for low speed stuff but the new one should be much better. I will be painting it but for now you can see it in it's unpainted form. Here's the video on how I made it: https://youtu.be/ow-NYMjkEHI

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_7161_zpsrohguzbp.jpg.html][/URL]