I've a Saab 9-3 Aero with a Maptun tune (was 210hp/300Nm now 260hp/360Nm - how does 40-80 in 5.8 sound?). And there's more to come (I'm looking for 300). Good Porsches are still way quicker though so perhaps I should just be saving up for one!!
Been looking at some oldish track day data logs and I have extracted some useful figures.
In my Caterham back in 2006 with a modded 2.1 Ford Zetec engine (208 bhp @7100 rpm 160 lbs ft @5800 rpm) on one particular strait pulling out of a slowish 40 mph corner, 3040 rpm in 3rd gear the car accelerated to 80 mph (still in 3rd) in 5.17 seconds. On the day there was not much that was faster.
Move onto 2009. The engine has been replaced by a standard 2.0 Ford Zetec (with the exception of the induction and exhausts off the modded engine). The car has 175 bhp @ 6600 rpm and 145 lbs ft of torque at 4500 rpm. Same track, same corner same speeds and rpm 40 -80 mph was measured at 4,95 seconds.
For comparison the Autocar Road Test of the car when fitted with a 135 bhp X-Flow engine had a 40 - 80 time (through the gears) of 6.5 seconds (7.2 seconds in 3rd) a 1.55 seconds reduction for an extra 40 bhp is probably about right. A 1.6 litre x-flow Turbo version with 175 bhp and 178 lbs ft of torque was timed at 5.4 seconds between the same speeds back in the early 80's but I suspect turbo lag may have been an issue back then.
Between the trackdays other than the engine swap (the 2.1 had an oil pump issue which blew out the filter "O" ring and wrecked the crank) there were no other changes to the car.
So how come the car with less power was faster, simple, the low down power was much better and punched the car out of the corner faster. The logs show that by the end of the strait the 2.1 was going faster and they also show that the lap times of the 2.1 were quicker but not by much. At a different track with longer straits and fewer slow corners the difference would have been greater but driving on the public road does not involve driving at max speed and driving round fast corners flat out. In truth when the car was bought back in the early 90's with 80 bhp I could get from A - B faster than I can today, no camers and less traffic. No measurement of acceleration with that 80 bhp engine but a Motor road test of a virtually identical car quoted a 40 - 80 mph time through the gears as 11.5 seconds, in 3rd 12.1 seconds.
Considering that the 2.1 cost me about £2500 to build (including the brand new "faulty" oil pump) and the standard engine cost about £500 direct from Ford brand new in a crate I have not been tempted into finding the extra cost of building another more powerful engine. In fast road use the current engine gets me from A -B in the same time as the tuned engine (too many cameras etc to use most of the power) and the car is far easier to drive, less gearchanging is needed and overtaking is much less stressful, no deciding which gear to use.
MPG is not really a consideration but the 2.1 did about 26 mpg during the 4 years when it was in the car. The current engine has averaged about 30.5 mpg in the 6 years its been in but now its bedded in and correctly mapped its doing nearer 32 mpg. In 2000 miles a year its only a small saving but every little helps.
Just been looking at a What Car test of my Seat Leon TSi 1.4 140 PS. No 40- 80 mph through the gear times but looking at the 3rd gear time and adding the 40 - 60 and 60 - 80 times together its 8.2 seconds. Not bad for something with about 1/2 the power of the Saab Aero and "only" 250 Nm of torque. In truth considering its weight it rather puts my Caterham to shame.
Found a test of the Leon 180 PS turbo diesel. Using the same figures as above the 40 - 80 in 3rd time 7.5 seconds. Only 0.7 seconds faster than my petrol which has 40 PS less and 130 Nm less (the Leon 180 diesel has 380 Nm @ 1750 rpm.
As for insurance its covered by a company called A Plan, think its the Thatcham branch I deal with. They specialise in modified cars.
I talk from experience over many years and I do have the data and a cabinet full of trophs from my hillclimbing days to show its was not just pub talk. But its just my opinion, if people don't want to agree that is their right.
Drive a decent distance over nice A roads from A - B with reasonable traffic levels at "legal" speeds with the 150 PS S40 and the 180 PS S40. Bet there is little if any difference in your journey time. So what is all the extra power doing?
Edited by skidpan on 25/07/2014 at 17:02
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