By the Power of Bubskull ...... Friday's long read
Here's a thing about Beetle engines, and when I say 'Beetle', I mean real Beetles not those Golfs in party frocks, you can get seriously meaningful power and torque gains with very little effort and at reasonable cost. Of course 'meaningful' and 'reasonable' are entirely relative!
First we need to define our terms; Power, Torque and how they relate to Bub and then discuss the options
Power comes at the top of the rev range so you have to thrash your engine to reach it and keep it there, torque come in low and peaks low. The best driving comes where max torque meets power.
Torque gets you away from the lights, spins up your tyres with a stab of the throttle, lets you run a higher gear and drive off smoothly. Torque means nicer driving, more fun, more controllable lunacy, better fuel consumption. The problem is one of price, on modern petrol cars we can expect to spend £75 - £100 or more per extra BHP and once you're getting to really high power gains you usually sacrifice reliability.
They say you can't beat cubes, and you can't beat diesels, for low down grunt and aircooled VWs are not known for high power but have a reputation for reliability, low down torque and the ease of which they can make big gains for reasonable money.
Back to Bub
The standard 1300cc in Bub's engine bay (1973, not listed below) originally made around 44bhp and 72ftlbs which sounds as weedy as it is. 0-60mph in a car with decent aerodynamics and only 800kg was still 16 seconds and incapable of turning the +14% gearing from the big tyres on the motorway so something has to be done
Firstly I could simply replace the engine with a 1600cc and get 50/75 for £250 (used), then add twin carbs for another £250 (used again) to achieve 55/85. From experience this will make Bub a nice little driver (I did this in 1987) but I'm looking for more ... much more.
Next options touch on the 2 maxims of aircooled engine lore; "you can't beat cubes" and "let it breathe".
To increase volume is a simple job of unbolting the 2 cylinder heads, the 4 cylinders and pistons and replacing with bigger ones. The chart below shows the approximate gains using standard parts. The normal engine sizes (without getting silly) are 1600, 1641, 1776, 1835 and then up to 2200cc - all standard options fitted to various VW vehicles over the years. Anything beyond 1641cc need the engine case machined (£££) and can be less reliable when built on to a 1300cc engine case.
Making it breathe better is the really easy way to gain power and torque. Around 20% of the power gains come from heads with bigger valves and if you make sure the inlet & outlet ports are smoothed and polished, married to a bigger bore, balanced exhaust you will get maximum results. The longer exhaust header pipes, all of equal length, will pull the exhaust gasses out smoother, faster and more fully, allowing the fresh charge of fuel/air to enter the cylinder with as little exhaust gasses left behind as possible - its called scavenging.
My options
Firstly I have a budget, a modest one and all my plans have been thrown around by circumstances. I need reliability to manage several thousand miles at motorway speeds across Europe and North Africa in 3 weeks, be able to get up to speed reasonably rapidly, maybe not 8 seconds but within sight of 10 and not have to thrash it senseless and have to stop every 100 miles for fuel.
The 1300cc engine feels really good so its a fine base to start from. I could rebuild it to a bigger capacity with twin carbs:
Now I can turn to the crazy shit ....
Considering there have been 60 years of crazy people doing stupid things with VW engines, I have a lot of sources of information. I can chuck the engine and fit a V8, a Subaru wrx engine, a later aircooled engine up to 2.2L ... endless options ... I can turbo it, supercharge it, as well as fuel injecting it .... too many options and all very expensive.
I said months ago that I would get a supercharger, instant low end grunt, loads of driveability rather than the top end silliness of a turbo and fewer cooling issues. I spent ages looking at options and a supercharger is a different method of getting massive increases in power/torque for decent costs without big fitment issues with the advantage of being modular - I can always fit it to another engine or a different car without major customisation issues.
Joe Blow in Adelaide do a supercharger kit for £1700 which increases power by 60% and torque by 45% (a guesstimate). This could be the answer; it bolts onto anything from 1300 to 1776, no cooling issues for normal use (it'd need better filtration but that's easy) and would be very entertaining.
Somehow I think that a car weight less than a tonne fully loaded with 120bhp/138ftlbs should be able to keep up with the traffic? The only problem with this plan is money, I'll be selling my MX5 in the Spring and I've got a couple of potentially lucrative jobs in the offing but still .... I suspect I'll be hunting for a used 1600cc engine for £300 - time will tell.
First we need to define our terms; Power, Torque and how they relate to Bub and then discuss the options
Power
Power is what everyone discusses when comparing engines. It's the definition of engine performance, measured in Horsepower (HP/PS/DIN), brake horsepower (BHP), or kilowatts (kW), and is the measure of the maximum output of the engine . Everyone understands BHP but HP is 1.4% higher and kW (which no one really understands) is 34.1% lower. I'll talk in HP because that's what VW quoted and what information is available, not forgetting that I'm being general as 45 years cars may have had 50 horse power when new but not only are the horses geriatric but many of them will be dead! Seriously, short of running on a dyno (which I'll do one day) there are so many variables it's silly to try and be precise.Torque
Torque is the twisting force of an engine. Normally measured in foot pounds (ftlbs) its what give an engine flexibility and drivability. In the real world we should only talk about torque because that is what we feel and use in 90% of our driving. Power matters when racing, torque matters the rest of the time.Power v torque?
Imagine one of those huge Big Top tent pegs needing to be hammered in. Power is like having 100 children with small hammers battering at it in a frenzy, torque is like having 4 strongmen with huge sledgehammers each hitting it in turn once per second.Power comes at the top of the rev range so you have to thrash your engine to reach it and keep it there, torque come in low and peaks low. The best driving comes where max torque meets power.
Which is better, which should I be chasing?
Torque gets you away from the lights, spins up your tyres with a stab of the throttle, lets you run a higher gear and drive off smoothly. Torque means nicer driving, more fun, more controllable lunacy, better fuel consumption. The problem is one of price, on modern petrol cars we can expect to spend £75 - £100 or more per extra BHP and once you're getting to really high power gains you usually sacrifice reliability.
They say you can't beat cubes, and you can't beat diesels, for low down grunt and aircooled VWs are not known for high power but have a reputation for reliability, low down torque and the ease of which they can make big gains for reasonable money.
Back to Bub
The standard 1300cc in Bub's engine bay (1973, not listed below) originally made around 44bhp and 72ftlbs which sounds as weedy as it is. 0-60mph in a car with decent aerodynamics and only 800kg was still 16 seconds and incapable of turning the +14% gearing from the big tyres on the motorway so something has to be done
Firstly I could simply replace the engine with a 1600cc and get 50/75 for £250 (used), then add twin carbs for another £250 (used again) to achieve 55/85. From experience this will make Bub a nice little driver (I did this in 1987) but I'm looking for more ... much more.
Next options touch on the 2 maxims of aircooled engine lore; "you can't beat cubes" and "let it breathe".
To increase volume is a simple job of unbolting the 2 cylinder heads, the 4 cylinders and pistons and replacing with bigger ones. The chart below shows the approximate gains using standard parts. The normal engine sizes (without getting silly) are 1600, 1641, 1776, 1835 and then up to 2200cc - all standard options fitted to various VW vehicles over the years. Anything beyond 1641cc need the engine case machined (£££) and can be less reliable when built on to a 1300cc engine case.
My options
Firstly I have a budget, a modest one and all my plans have been thrown around by circumstances. I need reliability to manage several thousand miles at motorway speeds across Europe and North Africa in 3 weeks, be able to get up to speed reasonably rapidly, maybe not 8 seconds but within sight of 10 and not have to thrash it senseless and have to stop every 100 miles for fuel.
The 1300cc engine feels really good so its a fine base to start from. I could rebuild it to a bigger capacity with twin carbs:
- 1300cc - £0.00 boring, underpowered 44bhp/72ftlbs
- 1600cc - £490. Safe, good, reliable, 55bhp/78ftlbs
- 1641cc - £530. still safe, good reliable, 60bhp/85ftlbs
- 1776cc - £1080. needs the case machined £200 less reliable, needs extra cooling ... 75bhp/95ftlbs
- 1600cc - £590. Safe, good, reliable, 60bhp/88ftlbs
- 1641cc - £635. still safe, good reliable, 75bhp/95ftlbs
Now I can turn to the crazy shit ....
Considering there have been 60 years of crazy people doing stupid things with VW engines, I have a lot of sources of information. I can chuck the engine and fit a V8, a Subaru wrx engine, a later aircooled engine up to 2.2L ... endless options ... I can turbo it, supercharge it, as well as fuel injecting it .... too many options and all very expensive.
I said months ago that I would get a supercharger, instant low end grunt, loads of driveability rather than the top end silliness of a turbo and fewer cooling issues. I spent ages looking at options and a supercharger is a different method of getting massive increases in power/torque for decent costs without big fitment issues with the advantage of being modular - I can always fit it to another engine or a different car without major customisation issues.
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| fancy a blow job? |
Joe Blow in Adelaide do a supercharger kit for £1700 which increases power by 60% and torque by 45% (a guesstimate). This could be the answer; it bolts onto anything from 1300 to 1776, no cooling issues for normal use (it'd need better filtration but that's easy) and would be very entertaining.
- 1300cc standard - 70bhp/98ftlbs
- 1600cc standard - 83bhp/109ftlbs
- 1641cc standard - 90bhp/119ftlbs
- 1641cc - 120bhp/138ftlbs costing £2,500 including extra cooling, filtration etc.
- 2200cc to achieve the same? £5,400 .....
Somehow I think that a car weight less than a tonne fully loaded with 120bhp/138ftlbs should be able to keep up with the traffic? The only problem with this plan is money, I'll be selling my MX5 in the Spring and I've got a couple of potentially lucrative jobs in the offing but still .... I suspect I'll be hunting for a used 1600cc engine for £300 - time will tell.
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