SCCA EMod MGB GT V12 Build

Fingers crossed!

I wasn't going to do any aero stuff this year but I figured that a good splitter will also protect my bodywork from cone strikes so I built this. I used Alumalite, it's a layer of Coreplast sandwiched between two layers of thin aluminum and is fairly light and strong. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5636_zpsxeknmglz.jpg.html][/URL] [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5635_zpses5jkboj.jpg.html][/URL]

During SpringNationals, the car never overheated but when sitting on grid with the radiator fans going, the hot air would swirl around and make the very hot driver even hotter. This would go away if I removed the rear valance panel but then I leave myself open to protest because air can travel over and under the diffuser. The answer is to leave panel in place but cut holes in it and cover with aluminum mesh. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5634_zpsr8ieffwq.jpg.html][/URL]

I made a video with one dyno pull with the V12, one with the V8 and one with the Turbo 4, and I list the HP and torque numbers of each. And I found a home for some stickers. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5657_zps7zuoejgx.jpg.html][/URL] https://www.youtube.com/watch?v=MTrpCU7BKw8

I put a smaller master cylinder in for the front brakes to increase pressure and did a string alignment of the car [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5840_zpsoernqwii.jpg.html][/URL]

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5838_zps3qlagttj.jpg.html][/URL]

Video here: https://youtu.be/GgYDZBX1pt0

I can't see the pics at work, so it has taken me a while to look at the build. I am very impressed with your work, very nice. so glad you chose to post it!

In reply to TiggerWelder:

I'm glad you like it. After the changes I made to the brakes and the updated tune that Bad News Racing sent me, I needed a place to test them and the Winnipeg Sports Car Club had a lapping day so I signed up. I know my tiny little brakes are not up to a full attack of the Gimli Road Race track so I accelerated hard down the straights but lifted and coasted before the turns instead of doing any hard braking. According to my datalogger,the car was accelerating at .74 G at 60 mph and still pulling .45 G at 100 mph but I ran out of gearing at 120 mph and just bounced against the rev limiter all the way down the straight. The car felt pretty good but as the speed increased, it got twitchy and I don't know why but I suspect it is aero related. I only had the front splitter installed but not the diffuser and I think the aero balance is pushed forward at high speed. 2 of my 3 GoPro cameras ran out of battery almost immediately so I didn't have a lot of video to choose from but here's what I have: https://youtu.be/1N98OI8Q1gc

Briget and I competed in another local event that took place on a road course with some fast sweepers and good acceleration zones. The balance of the car was great, as was the acceleration and braking, however neither of us were getting the lap times we needed to do well in PAX. My best time was good enough for Fastest Time of Day but was about 4 seconds too slow for a PAX win. I may have not been driving like an alien but I felt that my times should have been better. I looked at the data when I got home and my peak lateral load was only 1.05 G so it's clear that my 4 year old Avon tires are done, done, done. I had the diffuser on for this event and the car was noticeably more stable at high speed so that's all the incentive I need to move forward with aero development. Check out what a pylon hitting Alumalite at 70 mph looks like: [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5886_zpspp9fw00c.jpg.html][/URL]

Video of one run here: https://www.youtube.com/watch?v=uz_raUIiah8

In reply to loosecannon:

I finally switched to the beautiful Keizer aluminum wheels

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5907_zpsudvzmilw.jpg.html][/URL]

Video here: https://youtu.be/Jb2UMfdetYg

SWEET

I know you have tiny little brakes for autocross so this might be of interest to you.

http://www.motoiq.com/MagazineArticles/articletype/articleview/articleid/2215/modeling-braking-braking-harder-means-less-brake-fade.aspx

loosecannon wrote: During SpringNationals, the car never overheated but when sitting on grid with the radiator fans going, the hot air would swirl around and make the very hot driver even hotter. This would go away if I removed the rear valance panel but then I leave myself open to protest because air can travel over and under the diffuser. The answer is to leave panel in place but cut holes in it and cover with aluminum mesh. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_5634_zpsr8ieffwq.jpg.html][/URL]

Have you considered sealing the area behind the radiator to this opening? For sure, it will make sure that the air does not circulate back into the radiator inlet. Which should help keep the hot air behind the car.

And, when moving, the low pressure generated by the splitter will force air to be drawn through the rad without the fan.

One final, way long term question... with a full belly pan, and I bet suspension coverings- have you looked into the aero effects of the air passing through the car? I know the benefit may be minor or nothing- but it may also slightly increase the pressure over the splitter- but have you looked into the Meredith Effect? If you can cleanly get air to the rad, well- I don't know if it would do anything. But at least it would cool more effectively.

In reply to alfadriver:

Ever since I added those screens, no hot air gets back to the driver. The car has never overheated so cooling does not seem to be an issue. However at some point I would like to put a smaller, lighter rad in so maybe then I will have to take extra steps. Aerodynamics is such a complicated issue and without a wind tunnel, I think everything is just guesswork or speculation. I expect to be driving the car for years and the winters here are long so I will have time to try things but for now I am just going to go after the low hanging fruit, like a rear spoiler.

In reply to DaewooOfDeath:

I wish I had seen that before I went on the road course

I hate the spoilers used in EMod because they don't look good on anything but it's all we are allowed and having one will make me quicker so I built one. It's the same Alumalite I used for the splitter, riveted together. I will be changing its color to mask it a little bit. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6008_zpslnsdd6om.jpg.html][/URL]

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6007_zpscovpqcsz.jpg.html][/URL]

Video here: https://youtu.be/KT6NGfkIDKM

Are you going to Kieselize it and take it all the way to the farthest outside edge of the rear fender flares?

Why not go with polycarbonate for the spoiler so that it doesn't stand out as much?

In reply to MrJoshua:

Jeff has had to reshape the rear bodywork to accommodate spoiler and now has a section in the middle that shoots out forward so he can comply with the 10" high rule while at the same time having a spoiler taller than 10". It's all complicated and requiring a lot of extra effort and for now it is beyond what I'm willing to do.

Gimp wrote: Why not go with polycarbonate for the spoiler so that it doesn't stand out as much?

I see a few cars at Nats with the clear poly spoilers but it seems that they need a lot of strut supports because the material is really flexible. I want to limit the number of struts so I can pull boot lid and spoiler off easily.

DaewooOfDeath wrote: I know you have tiny little brakes for autocross so this might be of interest to you. http://www.motoiq.com/MagazineArticles/articletype/articleview/articleid/2215/modeling-braking-braking-harder-means-less-brake-fade.aspx

Worth noting: he misses an important variable in his analysis. The speed of someone who is braking later (and harder) should be higher than someone who is braking earlier. He assumes the same speed at the time of braking.

Really, it doesn't pass the sanity test. For a given speed and a given car, I'm going to convert the same amount of energy to heat with my brakes going from velocity A to velocity B no matter how much time I take. His own graphs show that while the brakes cool to a lower temperature on entry, they immediately shoot up to the same temperature during braking.

Indeed, his own graphs even show that the peak braking temp for the 'hard' braking case are higher than the 'easy' braking case over time. And I would argue that this is what we really care about, more so than what the 'low' brake temps are on entry to the corner.

I had my first event today with the Keizer wheels, Hoosier tires and spoiler and I don't know how much each of those things contributed to my performance but I think I was 2-3 seconds quicker than before based on my times relative to my competitors. Despite the extra grip of the tires, it was much easier to spin them and I'm not sure if it's because the rotating mass is so much lower or because fixing all the boost leaks has resulted in a bunch more power. The braking was also much more confidence inspiring and I didn't hear or feel any lockups but I did smell something when I hit the brakes hard for one of the hairpin turns so maybe a tire was locked up. Because of the extra grip, the car now leans a lot more so I stiffened the front sway bar one notch and raised rear roll centre. I had my best PAX result yet (10th) and had Fastest Time of Day by nearly 4 seconds but it wasn't all rainbows and unicorns, the right rear tire and wheel rubbed on the Panhard mount so I need to make some changes to the rear track width. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6021_zpsrjcd1hf8.jpg.html][/URL]

[URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_6023_zpsor8lsjld.jpg.html][/URL]

Video of quickest clean run: https://youtu.be/58VaZ3RL5fs

Spot the change...

NOHOME wrote: Spot the change...

Yeh, it's comical how much has changed but it just shows how much I've learned in my 5 year education on how to build a race car. I was thinking of getting some stickers to put on parts that carried over from the original car to this one, there's wouldn't be many stickers.

Front scuttle in front of the windshield.

Front Grille.

Did I miss anything?

NOHOME wrote: Front scuttle in front of the windshield. Front Grille. Did I miss anything?

Those are the only MGB parts from the original car, you're right. There is one other MGB part on the car and that is the rear deck (the part that holds the rear fenders and boot lid). As far as parts from the original build, the rear brake discs, diffuser, shocks, seat and gauges are carryovers.