Lotus Elan

Converting a DHC into a FHC

PostPost by: stevebroad » Sun Jul 07, 2013 6:30 pm

At the risk of being lynched, has anyone done this? And if so, how?
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PostPost by: cliveyboy » Mon Jul 08, 2013 8:29 am

Steve
DHC to FHC is certainly a bit different.
You need to define what you mean by FHC are you wanting to make it a true Coupe with roof bonded onto the body or are you just wanting a roof for winter etc.
My first thoughts were just sell the DHC as they tend to be more collectable than Coupes and buy a FHC.
(I have a FHC Sprint).
My choice would be get hold of a removable hard top and graft in any fixing points you might need. (which should be straight forward) that way you have the best of both worlds DHC but with roof option.
If you don?t want a removable roof then I cant decide if buying a roof section and bonding it on is better than just buying a Coupe body. You could ask around the specialists and see if any are doing a FHC to DHC conversion so you could buy the roof.
Personally If I was going to the trouble of grafting on additional body panels I think I would go the full way and make an ?Elanbulance? estate or make it into a Shapecraft.
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PostPost by: UAB807F » Mon Jul 08, 2013 8:57 am

I don't see any reason why not, but I'd check out the parts books and make sure you can get all the parts before heading down that route. Rear screen would be my first point of call and then if you want to have the S3/4 air vents then you'll need the exterior chrome trims. (Brian Buckland's book is a good reference for the differences and options available.)

Personally I'd take the suggestion above and look for a good hardtop if you want a plastic roof for winter. A quicker solution and you'll retain the price premium that dhcs have over fhcs.

If it's the smoother lines of the fhc you're after, then I think it's quite possible but would entail some work. When you do a fhc to dhc conversion you cut part way down the front screen pillars so presumably if you managed to obtain a new roof section, that's how it would need bonding in place.

The rear deck has a bigger lip on the dhc which would need cutting back but otherwise I think it would just bond in place at the sides. A lot of work though and no doubt you'd need paintwork on the new sections plus both rear wings.

DIY it's mainly your time, but any professional work and it will be expensive. Maybe cheaper just to do a swap at somewhere like Paul Matty's ?

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PostPost by: stevebroad » Mon Jul 08, 2013 10:35 pm

Spent too much time and money modifying car to consider changing it . Also, had it for over 30 years so it's part of me now :-)

I am primarily looking at improving the high speed aerodynamics (160mph+) with improved chassis stiffness a secondary plus. The DHC body does nothing in the stiffness stakes but I'm thinking that a fully bonded hard top might. I already have a Lenham hardtop ready and waiting, although the glass window is heavy so will probably replace that with plexiglass or similar.

Personally, I think that the Elanbulance estate and Shapecraft Elans are abortions, totally destroying the beautiful and simple lines of the car. If I wanted a GT6 I would have bought one :-)
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PostPost by: UAB807F » Tue Jul 09, 2013 5:54 am

stevebroad wrote:(part quote) Also, had it for over 30 years so it's part of me now :-)


I understand that all too well Steve, I have the same T-shirt :)

I can see the theory about improving overall stiffness but I think it will be marginal. The front screen pillars are still the same flimsy things on the dhc, it's only the rear quarters that are broader and even then it needs the rear screen in place to really stiffen things up. That's based on a hazy memory of mine before it went from fhc to dhc, so I've nothing to back it up other than a feeling.

A fully bonded hardtop might be different given it's originally designed as a free standing structure rather than the fhc roof panel, so I'd expect it to be stiffer. But if it's stiffness you're after, isn't a roll cage the more effective option ?

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PostPost by: Spyder fan » Tue Jul 09, 2013 7:21 am

stevebroad wrote:I am primarily looking at improving the high speed aerodynamics (160mph+)

Steve,
Remind me which engine you are using? :D :shock: 8) :mrgreen:

Forget stiffness, lift will be a problem at that speed. A modsports approach will be needed methinks!

modsports Elan.jpg and
Kindest regards

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PostPost by: stevebroad » Tue Jul 09, 2013 10:58 am

Image

Hi Alan and Brian

Ignore front suspension set up, dampers, engine mounts, alterantor mount and crank pulley as these have changed since photo was taken.

Yes, aerodynamic mods are on the list :-)

Roll cage will be fitted but every little helps.

Interesting thought about separate hard top being stronger than FHC roof.
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PostPost by: UAB807F » Wed Jul 10, 2013 6:19 am

:shock:

Well, I didn't have that in mind......

If you're serious about that sort of speed then I think I'd be looking more at aerodynamics than stiffness. Certainly bonding on a hardtop with smooth radii and I'd even think about modifying the front & rear screen apertures to accept a flush bonded screen, fixed headlamps with perspex cowls, etc.

Brian

(why have you stuck a Smiths "snail" heater blower from an A35 on the side of that engine then ? You'll never get it to reach the heater from there.... :wink: )
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PostPost by: john.p.clegg » Wed Jul 10, 2013 7:17 am

Brian

Don't be silly it's not a heater blower but a car horn....still a funny place to put it...

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PostPost by: stevebroad » Wed Jul 10, 2013 11:17 am

UAB807F wrote::shock:

Well, I didn't have that in mind......

If you're serious about that sort of speed then I think I'd be looking more at aerodynamics than stiffness. Certainly bonding on a hardtop with smooth radii and I'd even think about modifying the front & rear screen apertures to accept a flush bonded screen, fixed headlamps with perspex cowls, etc.

Brian

(why have you stuck a Smiths "snail" heater blower from an A35 on the side of that engine then ? You'll never get it to reach the heater from there.... :wink: )


:-) The power box is ticked.

Also looking at sprints and hillclimbs, so stiffness is important.

Fortunately, I have access to a suspension/areodynamic guru who is helping me for free as he thinks it is a fun project and is confident we can achieve my 1/4 mile et aim.

I haven't looked at how to fit the screen yet. Pop up headlamps have gone in favour of small diameter units and perspex cowls.

Splitter fitted with the possiblility of canards. Hope to avoid a rear wing and get away with just a spoiler. Undertray will be smoothed out and added to where possible with a diffuser under the boot.

Don't be silly Brian, it's not a heater as that would weigh too much. John is correct, it's a horn and it is very loud as it's an air horn :-)
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PostPost by: billwill » Wed Jul 10, 2013 12:10 pm

Was that a Lotus twin cam under that lot before you started bolting on all those goodies (bling?)
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PostPost by: stevebroad » Wed Jul 10, 2013 12:37 pm

billwill wrote:Was that a Lotus twin cam under that lot before you started bolting on all those goodies (bling?)


No, a Ford Cosworth YB.
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PostPost by: Elanintheforest » Wed Jul 10, 2013 2:58 pm

Great to see a YB getting a good home at last. The Escort boys have been doing this for many years now, and there's less room under the bonnet of an Escort than an Elan!

What sort of state of tune are you going for....the girly 350bhp, the challenging-to-keep-it-on-the-track 500bhp, or the oh-shiiiiiiiiiiiiiiiiiiiiiiiiiiBANG full blown 900bhp? I have driven the girly version in an Escort, with 0-60 in 3.5 seconds and a theoretic similar top speed to the one you're after. It was a lot of fun and a lot more manageable that I would have thought.

Interesting to see what driveshafts you use!!

Mark
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PostPost by: stevebroad » Wed Jul 10, 2013 7:56 pm

Elanintheforest wrote:Great to see a YB getting a good home at last. The Escort boys have been doing this for many years now, and there's less room under the bonnet of an Escort than an Elan!

What sort of state of tune are you going for....the girly 350bhp, the challenging-to-keep-it-on-the-track 500bhp, or the oh-shiiiiiiiiiiiiiiiiiiiiiiiiiiBANG full blown 900bhp? I have driven the girly version in an Escort, with 0-60 in 3.5 seconds and a theoretic similar top speed to the one you're after. It was a lot of fun and a lot more manageable that I would have thought.

Interesting to see what driveshafts you use!!

Mark


I'd swap the space under the Elan bonnet for that under the Escort bonnet!

We wanted it to be usable and have a resonable rebuild time interval, so we went for 520bhp with low end torque. In a car weighing around 650kg traction is the limiting factor.

Drive shafts are bespoke and spec'd for 650bhp:

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PostPost by: Elanintheforest » Thu Jul 11, 2013 8:35 am

The old girl should get along a bit, Steve!

The McLaren F1 6.0 V12 sits at around 550 bhp/tonne
The Bugatti Vayron 8.0 W16 is 644 bhp/tonne
By my reckoning, if your car is similar weight to a standard car (680kgs) then you should have something like 764 bhp/tonne.

Probably enough :shock:

I think that you may need the roof panel bonded onto the roll bar !!

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