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Glenn Bunch's GT-Spanking Challenger
#1489751
08/24/13 03:03 AM
08/24/13 03:03 AM
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Joined: Sep 2005
Posts: 115
Tampa, Florida
Road Ronin
OP
member
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OP
member
Joined: Sep 2005
Posts: 115
Tampa, Florida
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For those who haven't heard of Bunch, or seen his Challenger run, it is truly an amazing machine. http://www.youtube.com/watch?v=Bj1RB6_497cI could watch this video 100 times and not get tired of it. And if you read his story (http://glennbunch.com/car-history/original-dodge-challenger), which is very enlightening, you find out he put this bad beast together himself. 
Leslie will lose; your automobile will lose; I WILL WIN! I shall build the greatest automobile in the world and I will win! Fate the Magnificent! MUAHAHAHAHAHA!!!
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Road Ronin]
#1489754
08/24/13 05:45 PM
08/24/13 05:45 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Quote:
For those who haven't heard of Bunch, or seen his Challenger run, it is truly an amazing machine.
http://www.youtube.com/watch?v=Bj1RB6_497c
I could watch this video 100 times and not get tired of it. And if you read his story (http://glennbunch.com/car-history/original-dodge-challenger), which is very enlightening, you find out he put this bad beast together himself.
That is a good candidate for poster car of this forum IMO. Frankly first time I read about a hemi powered stock bodied purpose built sports car. actually car seems like a "Tran Can" series unless there already is such a class.
I assume with all the rear end ratios he talked about it was a ford 9"?
Thanks for sharing 
I reread the article, I think the pic shows a quick change, which answers that question. He also talks about the advantages of a floor pan frame x brace, which I would not have thought would add as much stiffness as he mentions. A few times over the years members here have talked about adding or using instead of SFC a large floor pan x brace, and I and others have poo pooed that idea, might need to rethink that.
Last edited by jcc; 08/24/13 06:40 PM.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Road Ronin]
#1489755
08/24/13 10:44 PM
08/24/13 10:44 PM
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Joined: Sep 2005
Posts: 6,516
Santa Cruz, California
Lefty
master
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master
Joined: Sep 2005
Posts: 6,516
Santa Cruz, California
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Quote:
He also talks about the advantages of a floor pan frame x brace, which I would not have thought would add as much stiffness as he mentions. A few times over the years members here have talked about adding or using instead of SFC a large floor pan x brace, and I and others have poo pooed that idea, might need to rethink that.
I wonder as well. Maybe there is a way to test it the same way as back in the day with a model? 
Being a x brace how would one install it rocker - rocker without having interference problems with exhaust, driveshaft, etc.?
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Lefty]
#1489756
08/25/13 12:08 AM
08/25/13 12:08 AM
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Joined: Sep 2005
Posts: 115
Tampa, Florida
Road Ronin
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OP
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Joined: Sep 2005
Posts: 115
Tampa, Florida
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Convertibles used X-braces in the unibody with no driveshaft or exhaust clearance issues, so it can be done. And his is a custom-built chassis so I'm sure he tweaked the design until he could get clearance. Unfortunately in his photos of the chassis I couldn't see the bottom of it that well to see exactly what he did. As for exhaust clearance, you can see in Picture 25 his headers come out the side dry-lakes-style. The X-brace might be one of many ways Bunch thinks "outside the box." Did you catch that he relocated his radiator(s?) to behind the rear wheels in an effort to balance against the weight of the Hemi up front? Seems a bit crazy, but all his crazy ideas work together pretty well. I think the video makes it pretty obvious this does not handle like a nose-heavy car. And here's another sweet clip: http://www.youtube.com/watch?v=7D4dpsC8eVESeems to me he's a little late getting back on the throttle at the apex many times, but he's still got everybody so outgunned that he just blows their doors clean off along the straights. 
Leslie will lose; your automobile will lose; I WILL WIN! I shall build the greatest automobile in the world and I will win! Fate the Magnificent! MUAHAHAHAHAHA!!!
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Road Ronin]
#1489757
08/25/13 12:21 AM
08/25/13 12:21 AM
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Joined: Sep 2005
Posts: 115
Tampa, Florida
Road Ronin
OP
member
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OP
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Joined: Sep 2005
Posts: 115
Tampa, Florida
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BTW, for those who read the story: has anyone else experienced similar carburetor problems on road courses?
Leslie will lose; your automobile will lose; I WILL WIN! I shall build the greatest automobile in the world and I will win! Fate the Magnificent! MUAHAHAHAHAHA!!!
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Road Ronin]
#1489758
08/25/13 04:08 AM
08/25/13 04:08 AM
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Joined: Feb 2011
Posts: 4,302
Nebraska
72Swinger
master
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master
Joined: Feb 2011
Posts: 4,302
Nebraska
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I'd say the driver was "careful" getting back to the throttle. Probably something he learned after some time with the car. Something none of those types of cars have is TORQUE, Ferraris,Porsches,Beemers etc. none of them. Except maybe the Audi R10 Diesel lol!
Mopar to the bone!!!
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Road Ronin]
#1489759
08/25/13 06:59 AM
08/25/13 06:59 AM
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Joined: May 2003
Posts: 96,665
On The Boat, On The Lake, Wa. ...
amxautox
Still Retired. Still Posting on Moparts. A Lot.
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Still Retired. Still Posting on Moparts. A Lot.
Joined: May 2003
Posts: 96,665
On The Boat, On The Lake, Wa. ...
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If you get on the throttle too soon, even at the same spot on the corner as the other cars, the hemi/high torque engine will just boil the tires, and so you'll spin out.
Tom
"Everyone should believe in something; I believe I'll go fishing."
-Henry David Thoreau
Men and fish are alike. They both get into trouble when they open their mouths
author unknown
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: jcc]
#1489762
08/25/13 08:43 PM
08/25/13 08:43 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Quote:
I reread the article, I think the pic shows a quick change, which answers that question. He also talks about the advantages of a floor pan frame x brace, which I would not have thought would add as much stiffness as he mentions. A few times over the years members here have talked about adding or using instead of SFC a large floor pan x brace, and I and others have poo pooed that idea, might need to rethink that.
An X brace could help keep the frame from parallelograming on him. SCF's were probably developed for straight line purposes. Which is not to say they don;t help in turns, but the X brace may be a better idea, assuming clearances you mention. If you have ever looked at an old MoPar body on frame setup, they are all X braced. At least back to 38, in my experience. They also have a substantial driveshaft loop.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Supercuda]
#1489763
08/25/13 09:06 PM
08/25/13 09:06 PM
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Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
dangina
pro stock
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pro stock
Joined: Nov 2008
Posts: 1,491
Lethbridge, AB, Canada
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very cool article (and read some of his other ones) I noticed he mentioned that he's not running a rear sway bar. I was wondering about what he said when he said she was prepping the cage and car for paint
"Once back in my garage, I made all of the brackets to mount the body and drive train, fitted and welded all of the brackets in place, assembled and then disassembled it for painting. The entire frame and roll cage weighed 320lbs! The body on the new car used the roof and the metal around the doors, as required, which I cut out of an old Challenger. Then I mopped it down every day with pure sulphuric acid, which, after two weeks, removed 32 pounds…"
is the sulpheric acid thinning the metal?
I like his body panel modifications and would like to build a car someday to this potential..
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: amxautox]
#1489765
08/25/13 10:12 PM
08/25/13 10:12 PM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Quote:
Quote:
is the sulpheric acid thinning the metal?
yes
Or he tells the officials he is using steel to neutralize his extra acid.
Sounds like Mr Bunch is of the thinking the rear sway bar is only needed when fixing another issue, when it arises.
Using car frame design back to '38 as rationale for needing a lower X in modern times is a risky proposition, IMO, with 70 years of experience, Computers, FEA, 4+ post testing, etc. available today. mainly what I am saying is the needs back then and today maybe completely different, but by chance the solution might be the same. I don't know.
Everyone on this forum should read the article.
He would be an interesting speaker at a Carlisle type event
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: jcc]
#1489766
08/25/13 11:03 PM
08/25/13 11:03 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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Quote:
[
Using car frame design back to '38 as rationale for needing a lower X in modern times is a risky proposition, IMO, with 70 years of experience, Computers, FEA, 4+ post testing, etc. available today. mainly what I am saying is the needs back then and today maybe completely different, but by chance the solution might be the same. I don't know.
It is a fact that a rectangle is notorious for parallelograming. Back in the early body on frame days, Fords had no cross bracing to prevent it, Mopar did. As a sop to rigidity, it is common to box the frames on those old Ford's when adding HP. Not need on the same era Mopars.
Cross bracing is still how you prevent a rectangle from parallelograming. Mr. Bunch's car was a body (draped) on frame car, hence the need for cross bracing. To an extent unit body cars have that built in by tying the "frame" into the body as a unit. Now, the stresses of racing might very well exceed the ability of the fairly thin sheet metal floor's ability to keep things square. There is little direct cross over between Mr. Bunch's race car and what you are driving simply because they are apples and oranges.
Just because something is old doesn't mean it isn't valid or useful. If you look at most of today's latest tech in modern automobiles, the ideas were invented a long time ago. It just took this long for them to become commonly used.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: Glenn Bunch's GT-Spanking Challenger
[Re: Supercuda]
#1489767
08/26/13 07:20 AM
08/26/13 07:20 AM
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Joined: Dec 2003
Posts: 22,696
Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Quote:
Quote:
[
Using car frame design back to '38 as rationale for needing a lower X in modern times is a risky proposition, IMO, with 70 years of experience, Computers, FEA, 4+ post testing, etc. available today. mainly what I am saying is the needs back then and today maybe completely different, but by chance the solution might be the same. I don't know.
It is a fact that a rectangle is notorious for parallelograming. Back in the early body on frame days, Fords had no cross bracing to prevent it, Mopar did. As a sop to rigidity, it is common to box the frames on those old Ford's when adding HP. Not need on the same era Mopars.
Cross bracing is still how you prevent a rectangle from parallelograming. Mr. Bunch's car was a body (draped) on frame car, hence the need for cross bracing. To an extent unit body cars have that built in by tying the "frame" into the body as a unit. Now, the stresses of racing might very well exceed the ability of the fairly thin sheet metal floor's ability to keep things square. There is little direct cross over between Mr. Bunch's race car and what you are driving simply because they are apples and oranges.
Just because something is old doesn't mean it isn't valid or useful. If you look at most of today's latest tech in modern automobiles, the ideas were invented a long time ago. It just took this long for them to become commonly used.
The question however is, are the forces that the x brace was intended to solve in say '38, the same or similar forces we deal with today. Back then all the x's purpose was likely in preventing parallelograming, and not sure when that force existed except when hitting a tree off center. Adding an x brace to a flat plane by itself does little to resist torsion, its beneficial when added to a 3 dimensional structure when regarding torsion. The body mounted on a frame of yesteryear vs today's unibody I believe react much differently. A tube is really just a piece of thin sheet metal, and is the most efficient design for torsional resistance. The thin shear plane of the floor of a unibody can, properly designed, be very efficient. We also today benefit from a much better understanding of the forces involved thru computer analysis, that was not even dreamed of in days past. Of course that doesn't change physics. Mr Bunch's application is agreed much different from the uses we normally face on moparts, but my surprise and Mr Stock car Products is that he found it made such a difference, few others chose his solution in his times, and whether any of that applies to us today, and I still don't know.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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