peterk

Tom yes i see your point, the 2.0 is much easier to go with in time and money. I do like the idea of buying a new engine and just doing the cam work upgrades, will just take a day. Surprisingly the 2.0 and 2.5 cost the same new from the factory. In regards to your own 2.0 car, what HP and torque increase do you get with the crower camshafts jenvey ITB.? I havnt seen any figures stated anywhere. For the OP, I understand the same camshafts can also be used on the 2.5. More power to you on your build, i have built complete engines and know how it is when you get into it all. Peter

Tom Which car do you prefer, the 2.0 or 2.5 birkin for the road given your experience in them.? I understand the 2 engines are basically the same weight, so it woint effect performance (power/weight ratio), the 2.5 a tad higher in height. Seems the 2.0 is a much cheaper option money wise, just change the cams. People often say its best to upgrade the internals on the 2.5 as its a stroker version of the 2.0 .\ regards Peter

yes, i should have chosen my words better. It should read "rev the engine higher at a lower speed" If the car is a road car, speed limits where i am at 110kph would get you to 3rd gear, but a little more refinement with the differential would allow you to hit 4th gear at 110kmph. I guess it depends on whether you count the "music of the engine gear changes" a part of the fun of having a birkin 7. Some people install 2.0 duratecs as they say it allows them to rev higher , which is more fun. But colin chapmans philosophy in designing the car never really mentioned that the engine should "rev" easy, so its not part of a lotus 7 design feature. Here in AUstralia, everyone uses the 2.0 duratec, seldom the 2.3. which are being phased out, and no one i know of has a 2.5........ yet

waltermitty what if any mods are you doing to the internals of the engine? If you upgrade the crankshaft and the rods + pistons you could do huge HP and torque. Seeing as the engine has more torque than your normal 2.0 engines, are you going to use a higher ratio differential . I know the caterhams with 2.3L engine used those higher diff ratios(lower number).. some even suggest 3.14. That would allow you to rev the engine higher at lower rpm. have you made any decision on that? Anyone driven a 2.5 duratec AND a 2.0 Duratec... ..... what differences does one feel at the wheel? regards Peter