What type of engine would you like to use to power your own ‘supercar’? Does the sound and feel of the engine’s power delivery give you a warm glow inside, even after the drive has finished? Do you have a particular allegiance to a brand and type of engine? Do you only want a manual transmission?
If you have answered yes to these two last questions, then this part of the design process will be hard for you!I say this because we must remember some of the criteria that will guide our decision:
- the total weight of the vehicle is 800-850kg,
- it must comply with current ADRs, which for our purposes means that the engine must be from a currently produced, Australian delivered car.
- we have a total car budget of $30-40,000,and
- the drive train must fit into our planned mid engine architecture and thus must be reasonably compact.
These guidelines will mean that some options may not be considered further (although you can of course alter the guidelines for your own ‘Godiva’ simply by spending more money!)
I know that the first choice for many would be one of the currently available V8 engines from Holden and Ford. Either of them easily achieves the target power rating, has loads of character, is easily tuneable and also has iconic status within a segment of the Australian car culture.
The problem with both is that their greatest asset, that is their level of power, is also their Achilles heel, as we need to put that power through a transaxle for it to be of any use in a mid-rear engined car. To do so is not that much of a problem as respectable companies such as Roaring Forties, who produce an excellent Ford GT40 replica, have a number of solutions to the V8 engine/transaxle issues. These solutions usually involve mating the V8 up to a transaxle from an Audi/Porsche or using a ZF/Getrag/motorsport based transaxle. The solution also involves fabricating a flywheel, drive-shafts and clutch to suit.
The quoted second hand prices for the current Ford and Holden V8 engines with ancillaries, computer and wiring loom was universally around $10,000. We might expect that the cost of the supply and adaptation to the transaxles (including flywheel, clutch and drive shafts) mentioned, could be as high as another $8-10,000. This would mean that the total cost of the drive train could be as high as $18-20,000, once all of the engineering and machining is completed. This is an unrealistic amount of money when we consider the guideline budget of $30-40,000.
Of course it is never as simple as just the cost. The V8s exceed our target power output by a comfortable margin and thus would require a larger brake package (more expense), stiffer chassis, greater cooling capacity etc. Thus we would be unlikely to reach our target weight of 800-850kg on the road. We also cannot escape the fact that a longitudinally mounted V8 may not be the most efficient packaging within the desired wheelbase and the V8’s engine/transaxle package may be heavier that we would otherwise desire.
So let us leave the longitudinally mounted V8 off the list of prospective solutions. I can however assure those who really desire this V8 engine option, that there will be sufficient flexibility in the design; such that the rear of the chassis can be redesigned to suit should you wish to pay for it!
So ‘what do we have left?’ you might ask! Well we do not have a limitless supply of engines transaxles, but we also do need be mindful of our budget, as we simply do not have that much money to spend! Because of this important fact, the option to mate up any particular engine to one of the afore-mentioned transaxles should probably be avoided for cost reasons. In doing so we free up money to be spent elsewhere (e.g. dampers/wheels etc); we do not spend time organising the engineering, we benefit from the many millions of dollars that the original manufacturer has spent developing the reliability of the engine/transaxle combination and we make the complete project more likely achievable for anyone else who wants to build a ‘Godiva’. This also helps in another small way in that it narrows down the options for the engine/transmission package.
Because Godiva will be mid-rear engined, we are basically now looking for any engine/transmission option from a front wheel drive car or four wheel drive car that can have the transmission modified. This sounds simple enough, but what has close to the desired amount of power and is the type of transaxle (manual or automatic) important?
Of course the range IS finite and from surfing the internet the following cars seemed to have or were close to having the desirable level of power and meet the ADR criteria:
- Subaru WRX
- Subaru B4
- Subaru Forrester GT
- Liberty 3.0
- VW Golf GTI-VR6
- Toyota Camry V6
- Nissan Maxima
- Mitsubishi 380
- Porsche Boxster
- Renault Megane Turbo
If we look at the Subaru engines/transaxles we need to accept that the transaxles need to be modified for the job at hand.
Subaru engines themselves have developed a deserved reputation for strength and tune-ability. The Subaru transaxles initially had a reputation (perhaps undeservedly?) of being fragile in the early models, possibly due to the misuse that they often suffered as the owners attempted to repeat the high-rpm clutch dumps much reported in popular magazines. However this reputation has not lasted and the more recent Subarus have an excellent reputation for gearbox strength.
For Godiva we would need to make the transaxle 2WD by removing the centre differential and ‘rear’ driveshaft. I have been told that the centre diff can be locked using the usual methods and that the rear drive section can be swapped with a 2WD section from an Impreza. I have not seen any evidence to support this though. Whatever the case the engine/gearbox package (with the current 6sp gearbox) is impressive in its abilities, it is light, compact, tuneable, but does require some engineering/modification. There is also little firm evidence either way as to whether the transaxle’s differential would survive being used in 2WD format with big sticky tyres and an 800kg car, after all we would effectively double the load on it. I am following this up further with someone who has actually done the conversion successfully, albeit with a lighter car.
However more the issue for us at the moment is that I could not find any in Melbourne for sale from wrecked cars. I could get some from grey imports, but we cannot use those as they do not necessarily comply as they are not Australian delivered and complianced.
This availability also may be an issue for the Liberty 3.0. I have been told by an owner that it is a good engine, but not very sporting. Perhaps Subaru intend this, given the 3.0 is in the larger and more touring oriented cars in their range. Whatever the case, it was not recommended by this owner, but I would appreciate any further feedback from readers as to their experiences with this engine/transmission before I take it off the list.
The Golf is an interesting package as in the latest models it combines a frugal, yet powerful engine with an advanced 6 speed gearbox. The initial inspection suggests that it is compact and quite tall in the engine bay. Finding one from a very recent car will be a challenge. Earlier engines have proven easy to source and a cheap package at $8,000 in a front-cut. However apart from the extra ratio in the gearbox, it seems to have little advantage over the larger capacity engine in the 380.
The Camry V6 is a very smooth, compact and compliant engine with the usual Toyota reputation for reliability. Recent press released in other magazines suggests that a more sporting version, perhaps with a supercharger may be offered. Naturally this is of great interest, as the supercharger may make up fora mid-range performance that occasionally feels to lack punch. The Camry also has the advantage of being very common and relatively easy to source…but this does not necessarily mean cheap. Quoted price for a front cut was $11,000, but this was a one-off quote and may not be representative of what they really go for in the marketplace. No Manual transmission option in the V6.
Nissan Maxima’s VQ series of engines has been rated as one of the best ten engines in the world for many years and no doubt for good reason. The 3.0lt is a gem but a bit lacking in the power. However there is the 3.5l engine in the 350Z. Whether this can mate up to a manual transmission that is available in the Maxima in the USA is unknown. I have been able to find used manual transmissions in the USA, but by the time they are landed in Australia the cost will be around $1500. This would then possibly require a rebuild, but it would definitely require a flywheel and clutch to be sourced/made – adding more cost. So simply put, the engine is good, the transmission options somewhat fraught with possible unknowns and extra costs. We will not consider it further.
I have no experience with the Mitsubishi 380 engine and transmission. If it is anything like the most recent Magnas then it will be quite a good thing. I get to drive these Magnas and the equivalent Camrys on a regular basis and the Magna has always been the pick for me as far as engines go. The Magna is as compact and frugal as the Camry, but what I like is that it has more character. By this I do not mean flaws, but rather that it sounds better and also has a much nicer mid-range torque response. I also have appreciated that the Magna holds its gear in the manually shifted automatic mode, even when the revs rise close to the maximum.
However the Magna is not the 380. By report in the current media, the 380 seems to carry on a similar theme as far as the engine specification goes and even gets closer to our desired power rating – a good thing. The hard hitting point at this stage is that the 380 can be ordered as a five speed manual that has switchable (i.e. you can turn it on/off) traction control as standard. This is a very attractive feature given the nature of the vehicle we are designing and its intended purpose. Such traction control would be of assistance on any wet stage, or if the car was used on a hillclimb, or even to restrict the possibilities if the vehicle was shared with another person. It would also be expensive to retro-fit such a system to another existing driveline, even if it were possible to do so and still meet ADRs. We also hope that the 380 will be as plentiful and easily available as the Camry.
The Porsche Boxster engine and transmission are not as expensive as you might think when it is ordered from the USA. However, late model ones are at a premium and it takes a while to find one. Local suppliers such as Porsche-a-Part can be of great assistance here (and with other transaxles), but it may still soak up a very large amount of our available funds. I have never driven one, but watching from the fence they seem to go well enough. The centre of gravity of the flat six engine may not be as low as you might expect, as the engine is raised to allow clearance for the exhaust under the engine and also to match up the crankshaft/transaxle input shaft. Again it is not one to completely rule out, but it may be best left in its natural environment!
The Renault Megane Turbo easily meets our desired power figure, is light, compact and meets current ADRs, but where can we find one and how much will it cost? I will try to find out more, but so far no one is able to answer my questions as no one has seen one written off! Perhaps we will take this one off the list because of the low numbers on Australian roads. Let me know if you disagree!
So if we were to have a short list, the following engines/drivelines would make up the list (not necessarily in order of preference!):
- Mitsubishi 380
- Subaru WRX/GT
- Camry V6
The short-list is now complete and it will not suit all tastes, but we need to be mindful of the budget constraints. We also need to be realistic about the budget spread over the whole component list and prioritise where we will get the most gain per dollar spent. I would think that spending a large amount of money in the engine bay and then reducing the available amount of money on other areas would actually reduce the overall capability of the completed car.
Personally I would prefer to have very high-quality, capable and tuneable dampers on the car than an extra 20kW. On a variable surface such as on a tarmac event, or even on some of our rather bumpy circuits/hillclimbs (they are certainly bumpy when compared to USA and Europe), the better dampers will aid braking performance, corner speeds, traction and confidence in the vehicle…all good things we want to have in Godiva!
In the next issue we will release the concept sketches for the chassis design.