Anyone turbocharged a 986 or early Cayman?
Discussion
You've got it - Zingy is what I want, although I find it hard to describe in words.
Wife has a 986 Boxster 3.2S and it feels lovely and light and responsive on the throttle, unlike any of my previous 993's, but it could do with a bit more power.
I drove a 997.C2S and a 996 GT2 and they felt very Zingy.
So I wondered if I could get a bit more Zing out of a Cayman 2.7 by maybe turbocharging?
SLK55 is all wrong for me. Way too heavy. I want to touch the throttle and go back in the seat.
Wife has a 986 Boxster 3.2S and it feels lovely and light and responsive on the throttle, unlike any of my previous 993's, but it could do with a bit more power.
I drove a 997.C2S and a 996 GT2 and they felt very Zingy.
So I wondered if I could get a bit more Zing out of a Cayman 2.7 by maybe turbocharging?
SLK55 is all wrong for me. Way too heavy. I want to touch the throttle and go back in the seat.
993kimbo said:
I think it's going to be a 2.7.
(I've just seen how much the road tax is on a 3.4)
Ive had both a 2.7 and a 3.4S...I liked the 2.7, reminded me of an old fashioned light weight sports car from the past with a 1.6 engine that you had to hammer and wring it to get performance out of it, did find I drove it hard most of the time and did wish for a bit more grunt, but I would have another.(I've just seen how much the road tax is on a 3.4)
You could always fit a second hand 997 Carrera S induction system (inc larger throttle body, air intake and MAF), sports exhaust, 200 cell cats and some nice headers to compliment them. Get it mapped to suit the changes and should be good for at least another 50bhp.
Perhaps go LW flywheel too when it needs a clutch for some extra zingyness
Perhaps go LW flywheel too when it needs a clutch for some extra zingyness
IF you turbo it properly, it could be very good fun. I'm thinking the sort of turbo install where you get zero boost until about 3,500 rpm, then lots of extra shove all the way to around 6.5 - 7k rpm. The sort of turbo charging from the days when turbos were fun. If you go for a modern style turbo that just boosts torque at low revs, then runs out just when things should be getting interesting, then it won't give you what you're looking for. If this were me, I'd look to turbo the 3.2S unit for best results.
LeighB said:
You could always fit a second hand 997 Carrera S induction system (inc larger throttle body, air intake and MAF), sports exhaust, 200 cell cats and some nice headers to compliment them. Get it mapped to suit the changes and should be good for at least another 50bhp.
Perhaps go LW flywheel too when it needs a clutch for some extra zingyness
I have all but the 200 cell cats - and the rollers say no where near even half your quoted figure.Perhaps go LW flywheel too when it needs a clutch for some extra zingyness
The TB and DIY intake pipe will "wake up" the engine and provide a perky driving experience, but the dyno will only say 6bhp and 12lbft over the whole rev range.
A remap will add about the same again.
P4TT said:
I have all but the 200 cell cats - and the rollers say no where near even half your quoted figure.
The TB and DIY intake pipe will "wake up" the engine and provide a perky driving experience, but the dyno will only say 6bhp and 12lbft over the whole rev range.
A remap will add about the same again.
So the Boxster anniversary has a 10bhp gain over a standard S with just a TB and a sports exhaust, so surely there's more to be had by doing the rest?The TB and DIY intake pipe will "wake up" the engine and provide a perky driving experience, but the dyno will only say 6bhp and 12lbft over the whole rev range.
A remap will add about the same again.
Regardless, it's a cheaper way to perk up Mrs Kimbos car without breaking the bank.
Just my take on this subject.
"JERK" is an interesting scientific/physics issue that was never covered in my education - it is the rate of change of acceleration and seems to have been overlooked in standard engineering education (at least it was when I was learning).
Turbo's set to produce boost at high revs feel quicker because the rate of change of acceleration as the turbo kicks in is huge and for the driver is felt as a huge push indicating high acceleration and putting a smile on your face. It also results in big changes in suspension loads and the weight transfer of the car's weight - making tyre contact difficult to control.
Unfortunately friction at the tyre contact patch doesn't like "Jerk" and responds with wheel spin. Once a tyre has started spinning it will spin with less power delivered and slow acceleration. As a result (unless you have huge wheels and tyres with soft compounds) this type of turbo while exciting is difficult to drive fast round a circuit hence for example the old 944 turbo slower than an S2 and the more boost it ran the slower it was round a circuit.
Acceleration is proportional to torque (not power) and so - in the revs between gear changes from maximum revs to the next gear - the maximum torque you can deliver will be the fastest to accelerate the car (providing it can be delivered by the tyres and not upset the balance of the car too much and result in wheel spin). That torque could be a typical graph shape or more flat.
When I was developing the successful Armstrong 350 racing motorcycle I used this principle and created an engine with a flatter torque curve. Riders didn't like it because it didn't feel fast but it won everywhere (and not just because it was ridden by the brilliant Neil McKenzie).
One of the reasons I have been such a Porsche enthusiast is because they have always understood this and tried to create engines delivering flatter torque curves (I suppose with the exception of the first turbo's - the early 3 litre 911 and 924T). All the work done since to vary valve timing, valve lift, induction lengths etc has all been to increase the spread of torque and make the torque curve flatter - absolutely right IMHO.
Some years ago we wanted to prove this theory that a powerful turbo charged car could accelerate quicker if the torque was delivered at a more constant rate (i.e. the rate of change of acceleration would be low because the torque was more evenly delivered) and built a 944 turbo into a 3 litre engine but with the standard turbo and running gear producing huge torque from 2,500 to 4,500 rpm then dropping off a little to 6,250 revs. Despite being much more powerful than a high rev boosted example - it would not spin up the wheels nor pitch the suspension about and could be driven very quickly around a circuit. It was much faster than it felt though.
All this combined is why an engine that produces a flatter torque curve over a wider range (and from a lower start point) without a "Jerk" will actually accelerate quicker and handle better - but it will not feel as much fun. I think this is because in the same way that you feel no speed in an aircraft at constant 450 mph say (because you are travelling relatively at constant speed to the surroundings) I think our brains do not detect much of a sensation at constant acceleration (once the car is rolling) but do detect a rate of change of acceleration (or Jerk).
So making cars with turbo boost at lower revs makes a car faster and to handle better - but unfortunately not feel as exciting not able to be driven as quickly.
A very good way to make an engine produce more torque and more constant torque (N/A or Turbo) is by enlarging the capacity but leaving everything else the same.
This is because if it had been designed as a larger capacity engine in the first place it would probably have had a slightly larger inlet and exhaust system (as ultimately peak power is restricted by volume flow rates) - but by increasing the capacity and leaving the inlet and exhaust standard you shift the power and torque down the rev band. It will still produce more peak power (because the capacity is greater and the pressure from combustion is pushing down on a larger piston area or at a better crank mechanical advantage ( if the stroke is increased) or both.
So To make a car faster, handle better yet not need the added complication and cost of adding turbo's, waste gates, intercoolers etc a simple capacity increase produces very startling performance results at modest cost.
If however you are more interested in driving something that feels more exciting, doesn't handle too well but feels amazing (and you can afford it) then the turbo route is the best answer (perhaps until the guy with the same car but a larger increased capacity N/A engine leaves you at the lights and disappears round the next corner while you fight against the car your in to keep up).
Baz
"JERK" is an interesting scientific/physics issue that was never covered in my education - it is the rate of change of acceleration and seems to have been overlooked in standard engineering education (at least it was when I was learning).
Turbo's set to produce boost at high revs feel quicker because the rate of change of acceleration as the turbo kicks in is huge and for the driver is felt as a huge push indicating high acceleration and putting a smile on your face. It also results in big changes in suspension loads and the weight transfer of the car's weight - making tyre contact difficult to control.
Unfortunately friction at the tyre contact patch doesn't like "Jerk" and responds with wheel spin. Once a tyre has started spinning it will spin with less power delivered and slow acceleration. As a result (unless you have huge wheels and tyres with soft compounds) this type of turbo while exciting is difficult to drive fast round a circuit hence for example the old 944 turbo slower than an S2 and the more boost it ran the slower it was round a circuit.
Acceleration is proportional to torque (not power) and so - in the revs between gear changes from maximum revs to the next gear - the maximum torque you can deliver will be the fastest to accelerate the car (providing it can be delivered by the tyres and not upset the balance of the car too much and result in wheel spin). That torque could be a typical graph shape or more flat.
When I was developing the successful Armstrong 350 racing motorcycle I used this principle and created an engine with a flatter torque curve. Riders didn't like it because it didn't feel fast but it won everywhere (and not just because it was ridden by the brilliant Neil McKenzie).
One of the reasons I have been such a Porsche enthusiast is because they have always understood this and tried to create engines delivering flatter torque curves (I suppose with the exception of the first turbo's - the early 3 litre 911 and 924T). All the work done since to vary valve timing, valve lift, induction lengths etc has all been to increase the spread of torque and make the torque curve flatter - absolutely right IMHO.
Some years ago we wanted to prove this theory that a powerful turbo charged car could accelerate quicker if the torque was delivered at a more constant rate (i.e. the rate of change of acceleration would be low because the torque was more evenly delivered) and built a 944 turbo into a 3 litre engine but with the standard turbo and running gear producing huge torque from 2,500 to 4,500 rpm then dropping off a little to 6,250 revs. Despite being much more powerful than a high rev boosted example - it would not spin up the wheels nor pitch the suspension about and could be driven very quickly around a circuit. It was much faster than it felt though.
All this combined is why an engine that produces a flatter torque curve over a wider range (and from a lower start point) without a "Jerk" will actually accelerate quicker and handle better - but it will not feel as much fun. I think this is because in the same way that you feel no speed in an aircraft at constant 450 mph say (because you are travelling relatively at constant speed to the surroundings) I think our brains do not detect much of a sensation at constant acceleration (once the car is rolling) but do detect a rate of change of acceleration (or Jerk).
So making cars with turbo boost at lower revs makes a car faster and to handle better - but unfortunately not feel as exciting not able to be driven as quickly.
A very good way to make an engine produce more torque and more constant torque (N/A or Turbo) is by enlarging the capacity but leaving everything else the same.
This is because if it had been designed as a larger capacity engine in the first place it would probably have had a slightly larger inlet and exhaust system (as ultimately peak power is restricted by volume flow rates) - but by increasing the capacity and leaving the inlet and exhaust standard you shift the power and torque down the rev band. It will still produce more peak power (because the capacity is greater and the pressure from combustion is pushing down on a larger piston area or at a better crank mechanical advantage ( if the stroke is increased) or both.
So To make a car faster, handle better yet not need the added complication and cost of adding turbo's, waste gates, intercoolers etc a simple capacity increase produces very startling performance results at modest cost.
If however you are more interested in driving something that feels more exciting, doesn't handle too well but feels amazing (and you can afford it) then the turbo route is the best answer (perhaps until the guy with the same car but a larger increased capacity N/A engine leaves you at the lights and disappears round the next corner while you fight against the car your in to keep up).
Baz
Edited by hartech on Thursday 21st January 15:17
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