At the end of the day, for a street capable car, the areas under the torque and power curves matter...the bigger the areas, the more flexible the engine...and the VR6 will always beat a 16v (NA). Whether or not the engines delivery and weight suit a particular drivers driving style will also have an effect...personally, I just can't drive round the VR6s heavy nose weight...but others do. My view again, but for a VR6 - especially one with a Schrick manifold - a 3.67 works really well, giving a really flexible engine. I'm sure a 3.94 would too...but you'd be further up the revs more often and not using much of the lower down torque you have available. A 16v on a 3.94 is a nice compromise, geared at around 20 MPH/1000 RPM in top....good fast road gearing. With a decent diff fitted, it's spot on. A 16v with a 4.2 fitted is nutty! Geared at around 18 MPH/1000 RPM in top it's wild for back roads...but I'm not sure I would want to commute in it!
3.68 is a good compromise, mine can do 35+mpg on the road in granny mode, and it makes it more lively for track work (I think you could do most tracks in 3rd gear in a stock VR... the whole track..lol!) I haven't had it flat out (honestly occifer) but was reaching indicated 140mph pretty easily before Schwedenkreuz @ the 'ring. Would like to do another day at Bruntingthorpe as we all did in the 16v's in 2005, great fun and being able to use the 2 mile run way for a completely legal vMax run was great.
You have to "drive" the car a bit more, and be more aware of what you are doing gearwise with a 3.9FD VR6 (which is toatally at odds with the VR6's mantra of"stick it in 5th and it'll do 30 - 150+) but from my expirence Vr6's facking fly in a Mk2 with a 3.9FD and I would still have one in mine if it was a dedicated track car. The 3.9FD is just not fun to drive on a motorway
I chose the 3.94 for the Corrado, I've driven MK2 Vr6's with the 3.68 and I agree, it's a good road/track compromise (in the lighter MK2 shell). However, in the 'fat-boy' Corrado the 3.94 really feels good! (I would think also in the MK3 VR6 - Though I have no personal experience of this) Of course as has already been said, the std .84 5th on the 3.9 is only good for 20mph per 1000rpm but with the .717 from a diesel it's almost the same as stock. mph/1000rpm 3.39 + 3.94 6.10 + 5.30 - 1st) 3.300 10.4 + 9.00 - 2nd) 1.944 15.5 + 13.3 - 3rd) 1.308 19.6 + 16.9 - 4th) 1.034 24.2 + 20.8 - 5th) 0.838 - - - - 24.3 - 5th) 0.717 For me the 3.94/diesel 5th combo (coupled with an LSD) is an almost perfect 'fast road' compromise, the 'low' 1st through 4th really do transform the whole feel of the car and when you hit the traffic or M-way you can just shove it in 5th and ride the torque... Plus the chains were noisy so it had to come to bits anyway
