GTAddict
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| posted on 7/1/05 at 11:35 PM |
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Grand touring middy.
Hello again.
Been away for a year-odd now. Funny how work gets in the way. The GTM Libra's finished - been on the road six months now. Took it to
Bruntingthorpe twice, already got through a set of tyres before 4000 miles. 
So, uh, now what?
Given half a chance, I'd be obsessed with a mid-mounted, twin-bike-engine-powered, four-wheel-drive, cut-slick-shod rocketship, built from
leftover MacDonalds' straws and weighing less than a lawnmower.
But.
So is everyone else...
So, I want to build a simple, comfy two-seater grand tourer. With a roof. And space for luggage - like two snowboards, with boots and two medium
softbag suitcases. Powered by an off-the-shelf Chevy LS1 and a Porsche/Getrag transaxle. Not 'locost' per se, but sensible car building
with a couple of extra constraints.
Basically, a properly packaged, comfortable Ultima GTR (with some structural rigidity) and a fuel tank big enough to cover over 300 miles at
100mph.
Am I mad? Or should I be going for a 'busa powered skateboard with a clip for a toothbrush?
Mark.
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imull
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| posted on 8/1/05 at 02:59 AM |
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see my thread "an idea"
something that I would like to do. Acar that can be raced but is practical enough to be used as you will.
u2u me
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Pseicho
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| posted on 8/1/05 at 03:27 PM |
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I really like that idea.
But why would you make it a middy? Why not build a two seater with the engine in front? That would get you some luggage space in the back.
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GTAddict
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| posted on 8/1/05 at 07:27 PM |
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Well, yeah...
Yes, that is an alternative. A six-speed T56 can be bought new for the cost of a s/h Getrag gearbox, but then I have to find a good rear diff for
it.
What I would then have is a Muscle Car, definately an attractive alternative for a practical GT. However, where I work is about to put the most
fantastic two-seater front engined V8 GT (more sports with luggage) car on the road, so I want to do something a bit different to that too. (And,
while they tried really hard, it is still at least 100kgs too heavy, and too much like it's bigger sister car to shed that weight.)
Also, I have some weird ideas about composite monocoque tubs (and I've just assembled a kit with just that) and I'd prefer to keep all the
mechnically bits out the back just for compactness. A transmission tunnel just seems a bit of a compromise to me, and I'd have to extend
'pontoons' far too far forward to mount the front suspension unless I made a subframe to do it.
Also, I'm stubborn, bloody-minded and awkward.
(I did draw up a muscle car. It's basically a combination of '68 Mustang fastback, '69 Camaro profile, '71 Challenger front
end... and the blistered arches of the Lancia Delta Integrale Evo.  Evil looking thing...)
M.
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ERP
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| posted on 9/1/05 at 01:08 AM |
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You could always try using the Audi box that a number of GT40 replicas seem to use.
It's a damn site cheaper than the Porsche unit, and if your not trying to get really excessive power to the pavement, it'd probably hold
up.
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GTAddict
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| posted on 9/1/05 at 12:04 PM |
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Aha, Audi.
The Audi 01E-style box is a good choice for middies, but I cannot quite figure out how much torque a box converted from 4WD to 2WD will cope with. I
would want to remove the transfer section of any 4WD box I used - that, or start with the box from something like the A6 2.6 V6. In fact, this
combination would be good for a mild GT middie.
Of course, I'm clinincally insane, so I would then want the V8 or 2.7 V6 twin-turbo engines from the A8 / first S4. Trouble with both these
engines is either - too expensive to buy/maintain, or much too expensive to buy/maintain.
The S4 engine can be made to be singularly vicious, but it is a little temperamental when you do. 450 horsepower comes off the shelf, along with a
telephone number bill for all the bits.
I can buy a new LS1 from GM for $6k - or say £3,500 - and that comes with a loom and ECU. In a car without power accessories, and with good
intake/exhaust system, that's 400hp at the shaft, all I need is pumped fuel and a battery to make it go.
Now, I can buy $3,500/£2,000 of parts for that engine at any time, and boost power from 400hp to 550hp without having to do drastic work to the bottom
end.
Or, I can buy a custom made short block with a larger swept volume and a forged crank, plus all the bits to make it go for $10,000 total - or say
£5,500 - and when put on a dyno it will make >600hp day in, day out. These aren't pie-in-the sky figures - that's just a fairly
low-stressed 6.5 litre all-alloy small-block.
There are guys out there who then throw money at this basic engine. Lots of it. There is an Ultima GTR with a short-stroke twin-turbo LS1/LS6
engine, which can produce over 1000hp at 'high' revs for a pushrod V8. The car uses a Getrag six-speed transaxle, but they have to detune
the engine because it simply has too much torque for the box.
I wouldn't do this personally - the Ultima is a bit flimsy for my taste, I've had first hand experience of the 'dirty' way of
making it stiffer, and I can see how much engineering is required to bring it up to even a vaguely acceptable level of torsional rigidity - something
I would want to design into my car from the very beginning.
Mark.
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Pseicho
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| posted on 9/1/05 at 01:10 PM |
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So you want to build a composite tub for it?
You can make some luggage compartments in front of the rear wheels, like in the mclaren f1.
And if you design a compact front suspension you can have some luggage space in the front.
So what car can be compared to your car?
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ERP
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| posted on 9/1/05 at 10:40 PM |
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No I agree, because of the incredible aftermarket parts selection good old fashioned American pushrod V8's are hard to beat when it comes to
price/performance ratios.
My project (which isn't a middy as it happens) is based on a Ford 302 (largely because it will fit and a small block Chevy won't) stroked
to 348, all forged internals, should make about 500HP at a 7000 rpm redline. This engine has exactly no ford parts in it.
A lot of the GT40 guys (GT40s.com) seem to be running older Audi 016 boxes mated to 300+HP Ford smallblocks (in most cases). You pick up the audi
boxes in the States for next to nothing. I'm sure you could get an adapter plate made up for a Chevy Smallblock.
I must admit I'm intrigued at your idea.
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sgraber
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| posted on 10/1/05 at 08:59 PM |
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Hey Mark, Welcome back! We missed you buddy! 
Have you thought about transverse V8 packages? This would give you additional space for the cockpit between the wheels and more room up front for the
spare tire (which if you are touring you will want) and if you have a semblance of a rear overhang, you can add a boot behind the engine bay.
The GM Northstar is a good starting point for this. You could do automatic with computer control for the slushbox, or go with what a lot of the
Fiero/Lambo guys are doing and mate it up the Getrag 5 speed. It's a proven combination.
Graber
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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cymtriks
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| posted on 10/1/05 at 10:01 PM |
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Ultima comments
quote:
Originally posted by GTAddict
I wouldn't do this personally - the Ultima is a bit flimsy for my taste, I've had first hand experience of the 'dirty' way of
making it stiffer, and I can see how much engineering is required to bring it up to even a vaguely acceptable level of torsional rigidity - something
I would want to design into my car from the very beginning.
Mark.
3300 ftlbs per degree of twist according to ultimav12.ca (check this website out btw - he mods the ultima chassis and gives the stiffness change for
each mod up to about 10000 ftlbs)
My own FE model also gave 3300 and for what it's worth I think it was probably fine for an eighties kit with a rover V8 which is what the Ultima
originally was.
The big engine bay is hard to triangulate properly and this is where some big improvements could be found, as on the website I gave above. As it
stands the ultima at 3300 ftlbs per degree of twist stiffness and weighing in at around 300 lbs is less efficient than many ladder frames. I reckon
you could get double the stiffness for the same weight.
However to make a really good job of stiffening up the engine bay you'd need to think very carefully about the width of the engine and its
exhaust. Has anyone got any dimensions of the Chev V8 with exhausts fitted?
What were the dirty mods you did to an Ultima? Sounds interesting.
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