How much quicker are modern than old assuming same power?
Discussion
Dam good question. If all things were equal, like weight, gearing and tyres, theoretically there shouldn't be any difference just because the engine is 40 years old, but then again, the characteristics of the engine would also affect things, like torque and where peak power is produced.
I await the definitive answer with interest.
I await the definitive answer with interest.
A 25 year old crossflow car would probably have a live rear axle rather than De-dion. A bit less sophisticated but surprisingly little difference to lap times in my experience. The live-axle cars would have rear drum brakes, again less sophisticated but again not too much change in lap times. The suspension permits less camber on the live axle (front and rear) so a little time lost there. Finally, live axle is actually a bit lighter.
The actual changes are quite significant, but they won't add up to a huge difference on track. On the road, however, the de-dion car will be much smoother and more planted over rough roads.
The actual changes are quite significant, but they won't add up to a huge difference on track. On the road, however, the de-dion car will be much smoother and more planted over rough roads.
Indeed, the cams needed to extract 125bhp from a xflow or simllar 8v engine would be much hotter than those needed on a 16v engine, this would seriously affect the torque curve and give bad manners when off cam. A modern engine would be properly managed so the power delivery will be more linear and the area under the torque curve more substantial. The peak torque figure would in all probability be around 10% higher on an equivalent 16v engine.
That would make the more modern car quicker and the performance would be more easily attainable.
Dave
That would make the more modern car quicker and the performance would be more easily attainable.
Dave
according to here http://westfield-world.com/engineandtransmission.h... cast iron cross flow is a little heavier than more modern all aluminium engines, even with their considerably bigger heads.
Apart from the rear axle are there any other chassis changes that might have an impact?
Apart from the rear axle are there any other chassis changes that might have an impact?
Shoestringracer said:
Apart from the rear axle are there any other chassis changes that might have an impact?
Depending on the age of the car, there's the move from using the ARB as a link in the upper front wishbone to using a separate wishbone in parallel to the ARB. As I understand it, this was because increased braking loads from more modern tyres were causing too much flex with the original arrangement.Chassis has been stiffened a bit over the years (the chassis basically functions as an undamped spring in series with the tyres and road springs), but torsional stiffness is still pretty comical compared to something like an Elise.
And with the deDion there's the option of the Watts linkages (an awful, ghastly, cobbled-together solution that's completely contrary to the Chapman ethos) replacing the trailing arms.
In the scheme of things, I'd expect these changes to have a fairly minor impact on performance, though.
Iv had a live axle, and there is not much in it, the LA is about lighter (40Kg?) than a DDion, if the LA is jumping around then the shocks need adjusting or replacing (if they are the original SPAX), and buy some Yokohama Ao21R's in 185/70R13 (£45ea).
Only issues with older cars are. LA centre A frame bush, needs changing about twice a year (£3+15min) and some might be *short cotpit* (pre1991) so the taller of us might not fit.
On the plus side its probably on Weber 40 carbs... so you get THAT BEAUTIFUL NOISE!!!! (its really that good)
Only issues with older cars are. LA centre A frame bush, needs changing about twice a year (£3+15min) and some might be *short cotpit* (pre1991) so the taller of us might not fit.
On the plus side its probably on Weber 40 carbs... so you get THAT BEAUTIFUL NOISE!!!! (its really that good)
Shoestringracer said:
I'm interested in the evolution of Caterhams. Say you had a x-flow era Caterham with 125bhp and a modern one with 125bhp, would the new one be much faster, say on a hillclimb? Lets assume they were fitted with the same tyres. Please explain.
Thanks
I would agree with the poster who pointed out that the way in which the power is delivered is critical. The difference between the pick up on my Weber-ed Crosflow and my injection K Series (both very outdated engines now) is extremely noticable.Thanks
What you're all forgetting is the driver....
Crossflow pilots are made of sterner hairy chested stuff, having to breathe a constant stream of oil mist and petrol vapour, coupled with the need to have a spine made of granite to withstand the live axle ride, and all this whilst wrestling the controls of a fire-spitting monster.
Balls that big don't hang around.
Crossflow pilots are made of sterner hairy chested stuff, having to breathe a constant stream of oil mist and petrol vapour, coupled with the need to have a spine made of granite to withstand the live axle ride, and all this whilst wrestling the controls of a fire-spitting monster.
Balls that big don't hang around.
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