Mid engine Karmann Ghia

[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