Mid engine Karmann Ghia

[vwbloodline]

I didnt know for sure where to post this so here it goes. First off thank you to everyone who has answered my questions in the past you have been a great help to me.

Realistically how would a 220hp/200ft 2500lb mid engine Karmann Ghia drive. I am looking to get a loan and start building my daily driver and was wondering how a car that light and that much power would be like to drive. I will be using an ej20t and the subaru transmission. With that said how would a 300hp/300ft Subaru engine and transmission driving experience be. I assume no one has done that but I am new to building a mid engine car and was wondering was equivalency it would be in terms of speed and handling compared to other cars. I will be more than likely using and opel gt front axle and double a arm rear suspension. Thank you

[evilC]

Originally Posted by vwbloodline

I didnt know for sure where to post this so here it goes. First off thank you to everyone who has answered my questions in the past you have been a great help to me.

Realistically how would a 220hp/200ft 2500lb mid engine Karmann Ghia drive. I am looking to get a loan and start building my daily driver and was wondering how a car that light and that much power would be like to drive. I will be using an ej20t and the subaru transmission. With that said how would a 300hp/300ft Subaru engine and transmission driving experience be. I assume no one has done that but I am new to building a mid engine car and was wondering was equivalency it would be in terms of speed and handling compared to other cars. I will be more than likely using and opel gt front axle and double a arm rear suspension. Thank you

Nice to see that you are ambitious. I would question the weight though. You should aim for around 2000lbs and accept say 2100lb plus driver and with that the Scooby would provide around 250 - 340 bhp/ton. That would put you into supercar territory alongside Ferraris and Turbo Porsches. The gearing on a Scooby is good for about 140 mph so unless you put longer legs on it the acceleration will be quicker. Consider a Macpherson/Chapman strut rear suspension as it should be easier to accommodate and will be no less quick than double A arm.
I am unsure of the Opel GT front end but that does seem a bit down market when you've got such a specialist engine, drivetrain and rear suspension. It would be almost as economic to build in a proper double A arm front end. Also, consider the braking. The performance being in the supercar bracket will demand supercar brakes albeit less than the exoticars as they are heavier and will be faster (due to gearing). With the different front/rear weight bias and a relatively clean sheet of paper you could tailor the brakes very closely to the ideal and not be hampered by the Opel 30 year old design.
On the tyre front, don't over tyre it as you will have a a lightweight design that will need to make the tyres work. I would have thought that < 205 section for the front and < 225 rear would be ideal. Wheel diameters would be a function of the brake disc diameter more than anything but don't get lured into silly low profiles as the taller profile tyres are more tolerant of imperfect suspension design.
Be also aware that the power you are contemplating putting through the KG is much more than even Dr Ferry Porsche envisaged so that a fabricated structure might be necessary - certainly the existing floor pan won't be up to the task. The KG separate body does however, give you the possibility to fabricate a lower frame with all the components attached that the body just fixes to.
Anyway, those are my (rambling) thoughts but it does sound like an interesting project though.

evilC

[vwbloodline]

Thank you evil c for you valuable information. The Opel front axle is a double a arm suspension set up with a leaf spring running across from one side to the other forcing a loss of friction of one side onto the other. The corvette c 4 uses the identical design for a front axle. I may however end up fabing up my own a arms depending on how much the Opel axle weight, I already have the ope axle is the reason why I assumed using it, however I did plan on adapting the factory spindles to which ever brake design I go with. Chassis wise I am going to buy a full tube chassis from RLR, I am waiting for an estimate to get one fully welded and shipped to me. What size brakes would you recommend running, along with wheel size? I was looking to run 16~17" wheels as they seem to match the car best to me. The only brakes I have now are off of a n/a 85.5 944. I imagine I should upgrade, however I don't know how large I should go, or how many pot calipers I should run. Here is a c4 front axle however the opel is steel and definitely doesn't have 13" brakes.

[evilC]

Interesting. The Opel GT was never known for its suspension IIRC and was an off shoot from the original Kadet design? I realise that the 'vette uses a transverse leaf spring but its the only performance car to do so. That means that transverse leaf spring knowledge is a bit specialist.
I would junk the idea of leaf springs and apply the KISS principle and use double A arm or struts that there is masses of info about. Besides do you know could fab up a custom leaf spring? also, the Opel front end looks a bit weighty - I suppose it had to hold up a front engined car with the Opel cam in-head 1900cc that was a bit heavy - I know I've rebuilt one.

For 16" wheels the easiest fitting disc size is 300mm (12") although it might be just possible to squeeze 330mm discs in. the 17" will accommodate the 330mm discs and I would run 4 pot alloy calipers front and rear. The Porsche 944 turbo setup will work quite well, is alloy and all the parts are readilly available. If your after a custom set up then Wilwood, AP Brembo etc all offer whats required. With such a one off you might consider a racing discs with alloy bells that would allow you to tailor the set up more closely as well as providing performance improvements. The 944 set up also provides for a separate rear parking brake that is very effective and better than any of the separate disc mechanical calipers.

evilC

evilC

[vwbloodline]

Hmm, A arms it is, I will probably just do a similar design to the ones RLR sells then with a lower a arm and upper coil over. Thank you for bringing up the point about the transverse leaf spring and not getting one special made. I saw a link somewhere going to the aulstrailian website that sells the lock out kit to make a subaru transmission awd to 2wd, does this ring a bell to anyone. Also has anyone seen a write up on making shifter linkage? I have seen a few mid engine sand rails and imagine someone has pictures close up somewhere.

Vwbloodline

[STIDUB]

im not sure how strong they are but i believe the earlier impreza's were front drives not awd... mite be worth looking into, sounds like an interesting project though, look forward to pics

[vwbloodline]

I have only found ones with a 1.8 or 2.2 that was only fwd. So I figure I will just make the awd transmission fwd.

[ricola]

Converted awd are stronger, Saker sportscars sell the kits among others..
Rich

[pantswagen]

you intend on building a full tube frame and installing ha viva van front suspension?

that is comical.

go and fint a picture of a 944 gearbox/transaxle

and some 928 front suspension

the 'only' reason the vette uses a transverse leaf, is due to the fact that the car is made of plastic, thus utilising a 'back-bone' chassis - ie its non monocoque, so simply cannot mount coilovers into


so, its transpires, find a 944 donor, an auto would be a sinch
weld in its torsion housing, with all the mounts for the transaxle, the arms -fit the big brakes, put the scooby on the back seat
leaf the front stock, or then fit some 928 stuff-2 a arm up front, then fit the gts 322mm brakes, 299 on the rear, which is the same as 944


ps, there is an auto 944 in the breakers under the m49 in london, 'stable way'
near the pikey place, behind the 'westway sports centre'

[vwbloodline]

I already have a 944 rear torsion, however it is about 6" wider than the ghia, don't really want to flare the fenders out yet.

[volkdent]

Here's about as much tire as you can get under those fenders, I think these were widened slightly starting at the body line, but I couldn't find pics of that:

http://www.bader-racing.de/de/home/home_aktuelles.htm

Jason

[evilC]

With a mid engine design there is so much deviation from the original VW layout that I see no reason why anything from the 944 or 928 should be used. The adaptation would be as comprehensive as starting afresh hence the A arm rear and indeed an A arm front is a completely viable proposition. The KG body will therefore just be a usable cloak for the new chassis and running gear and to hang all the incidentials off.
The principle is really the same as the Brit Thunder Saloons (silouhette racing)

evilC

[volkdent]

Don't mean to hijack, but this is a related question for EvilC.

Given the mid-engine layout that VWBloodline is proposing, where do you think the battery should end up?

And then, given my engine location 900lbs front/1300lbs rear with me in it (260lbs ) where do you think would be the best place for mine? My engine layout is identical to a Lotus Elise and the battery is currently where the windscreen washer bottle would be behind the spare, and I've recently moved it to the floor of the spare tire well as an optional location.

If VWBloodlines proposal works out, his weight should be distributed more forward of what I have and I think that may get it close to 50/50.

Jason

[vwbloodline]

Of course if I won the lottery I would just buy one of these and put a ghia body on it. http://www.sterlingsportscars.com/in...id-engine.html

[evilC]

Originally Posted by volkdent

Don't mean to hijack, but this is a related question for EvilC.

Given the mid-engine layout that VWBloodline is proposing, where do you think the battery should end up?

And then, given my engine location 900lbs front/1300lbs rear with me in it (260lbs ) where do you think would be the best place for mine? My engine layout is identical to a Lotus Elise and the battery is currently where the windscreen washer bottle would be behind the spare, and I've recently moved it to the floor of the spare tire well as an optional location.

If VWBloodlines proposal works out, his weight should be distributed more forward of what I have and I think that may get it close to 50/50.

Jason

Hi Jason,

The ideal layout is to contain all the mass or a good proportion of it within the wheelbase of the vehicle and as close to the centre of gravity as possible. Also, a 50/50 weight distribution is desireable so as to equally load the tyres for maximum benefit. The geometry of all the mass locations is governed to a large extent by the physical limitations of the bodywork but I personally look to locate all the masses close to the centre of gravity in preferance to equalising the weight distribution. Keeping the mass close to the CofG means the vehicle reacts quicker to external forces eg. driver but makes the car less stable. In a bug the standard battery location is nearly ideal being about the line of CofG and therefore its moment of inertia is small (Mass x radius of gyration around the CofG). Moving the battery forward to say infront of the scuttle means that although the mass is relatively small say 15-20lbs the radius of gyration is 6ft(?) then the moment is 90-120lbft whereas previously it was in the region of 30-40lbft.
If you move the battery to the front wheel well all of the mass is on the front axle but the moment of inertia has significantly increased. With the battery placed just behind the axle line most of the mass is still on the front axle but the moment of inertia is somewhat reduced (typically 30-40%)
Just to add even more variables into the thinking - rally cars benefit from having the majority of the mass over the front wheels so that the rear end can swing with least resistance to aid turn in where the surface or the bend shape is uncertain. In fact a rally car set up is probably more appropriate to our increasingly uneven (UK)roads than a track set up that is favoured by the supercar builders.

Originally Posted by vwbloodline

Of course if I won the lottery I would just buy one of these and put a ghia body on it. http://www.sterlingsportscars.com/in...id-engine.html

This sports car looks remarkably like the Novas being produced in the UK in the late '70s and early '80s that were fixed to standard bug chassis' The tube chassis looks particularly unsophisticated and I would question it torsional rigidity that would affect its handling. I would at least bond sheet metal to the frame structure if not redesign it a bit. the spine looks particularly weak.

evilC