Opel / Vauxhall restomod
Discussion
Last week, my good friend and I took delivery of a 1986 Opel Manta Coupe. As with many cars of this era it has some rust to sort but thankfully limited in the most part to the underside whilst the bodywork itself is in pretty good condition! We will restore and build the car so it drives like a modern one: that means a vastly increased power output (actual engine model to be decided) backed by a suitable 5/6 speed transmission, uprated brakes and a fully sorted suspension and steering setup both in terms of geometry, spring and dampers rates and ultimately improved handling. The interior will be completely custom to match the theme that will run through the car including paint and wheel design. Externally the car will rely on the natural lines rather than adding any sort of body kit.
I won't attempt to explain the appeal of a 'restomod' as this is well documented elsewhere but suffice to say the Opel Manta will be a project car to develop into something very special. Our combined 'collection' currently includes a first gen Mazda RX7, Mercedes 190e Cosworth, third gen Pontiac trans am, Vauxhall Chevette, Mini Metro and now the Opel Manta. Nearly all were considered for this process but the Opel it will be to start with..
We both have many years experience working with race cars in most forms of motorsport and specialist road cars. Developing suspension systems for these cars is a day job and working with other restomod projects has all led to this point deciding to do it ourselves.
The reason for posting on here is primarily to get people's thoughts on what is reasonable in terms of modifying without detracting from the character of the car itself. I know purist will probably hate what we are doing and we have to tread carefully so below is a list of the various aspects of the car that require further discussion so that that we don't go too far!
Engine: We are aiming for circa 400bhp, most likely turbocharged. There are obviously many ways of acheiving this goal, some staying within the GM family, some a complete step away. Ideas include the Saab B204/234 or later models, Ecotec 2.2, Honda K20, VAG 1.8 to name a few. Some are quite capable of this amount of power with little modifications, some others requiring all new forged internals. So how important is brand loyalty when the ultimate goal is to produce something the can produce this level of power and be reliable? The newly installed engine will have a fully custom built intake and exhaust systems so any plastic / log / cast components will no longer be present.
Gearbox: Omega / Carlton swaps are well documented and straightforward but obviously they are getting older now. Mazda RX8, BMW E46 can be swapped in without too much hassle, are very strong but again we are losing any connection with GM.
Rear axle: The standard rear axle is well know to be a weak point at higher power levels so it is a given that this would be replaced. There are plenty of common Salisbury 4HA conversions that are often accompanied by a conversion to 5 link but this often requires cutting the floor to do properly. The standard torque arm (tube) design is not perfect but with some modifications could be drastically improved upon without and cutting of the shell. We have provisionally looked at a independent rear conversion but once again this taking a large step away from the original Manta specification. Solid rear designs get a bad rep but I know from first hand experience that they can be made to work very well. Consider the mk2 Escorts that are regularly right up there in the results tables at rally events competing against 4WD WRC cars!
Overall we would be grateful of any constructive opinions as we try to put together a vehicle that ticks most if not all the boxes of a Opel / Vauxhall fan that wants the looks and character of an older car but drives like a modern sports car!
I won't attempt to explain the appeal of a 'restomod' as this is well documented elsewhere but suffice to say the Opel Manta will be a project car to develop into something very special. Our combined 'collection' currently includes a first gen Mazda RX7, Mercedes 190e Cosworth, third gen Pontiac trans am, Vauxhall Chevette, Mini Metro and now the Opel Manta. Nearly all were considered for this process but the Opel it will be to start with..
We both have many years experience working with race cars in most forms of motorsport and specialist road cars. Developing suspension systems for these cars is a day job and working with other restomod projects has all led to this point deciding to do it ourselves.
The reason for posting on here is primarily to get people's thoughts on what is reasonable in terms of modifying without detracting from the character of the car itself. I know purist will probably hate what we are doing and we have to tread carefully so below is a list of the various aspects of the car that require further discussion so that that we don't go too far!
Engine: We are aiming for circa 400bhp, most likely turbocharged. There are obviously many ways of acheiving this goal, some staying within the GM family, some a complete step away. Ideas include the Saab B204/234 or later models, Ecotec 2.2, Honda K20, VAG 1.8 to name a few. Some are quite capable of this amount of power with little modifications, some others requiring all new forged internals. So how important is brand loyalty when the ultimate goal is to produce something the can produce this level of power and be reliable? The newly installed engine will have a fully custom built intake and exhaust systems so any plastic / log / cast components will no longer be present.
Gearbox: Omega / Carlton swaps are well documented and straightforward but obviously they are getting older now. Mazda RX8, BMW E46 can be swapped in without too much hassle, are very strong but again we are losing any connection with GM.
Rear axle: The standard rear axle is well know to be a weak point at higher power levels so it is a given that this would be replaced. There are plenty of common Salisbury 4HA conversions that are often accompanied by a conversion to 5 link but this often requires cutting the floor to do properly. The standard torque arm (tube) design is not perfect but with some modifications could be drastically improved upon without and cutting of the shell. We have provisionally looked at a independent rear conversion but once again this taking a large step away from the original Manta specification. Solid rear designs get a bad rep but I know from first hand experience that they can be made to work very well. Consider the mk2 Escorts that are regularly right up there in the results tables at rally events competing against 4WD WRC cars!
Overall we would be grateful of any constructive opinions as we try to put together a vehicle that ticks most if not all the boxes of a Opel / Vauxhall fan that wants the looks and character of an older car but drives like a modern sports car!
Go and have a look at Bahnstormers web pages , German community for mainly GM products .
Tuning and modifications to the Manta family is more popular in Holland and Germany and I would have a look on forums in these countries .
The SAAB turbo units can easily be tuned to 400+BHP and drivelines from various GM overseas models can be made work . Monaro , GTO ETC .
Most of the old school bits for the rally Mantas came from other GM models .
Tuning and modifications to the Manta family is more popular in Holland and Germany and I would have a look on forums in these countries .
The SAAB turbo units can easily be tuned to 400+BHP and drivelines from various GM overseas models can be made work . Monaro , GTO ETC .
Most of the old school bits for the rally Mantas came from other GM models .
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Nice project! I'll be following. A friend and I have an ongoing project with a manual Omega V6 that at some point may be getting the Z20LER (2.0 turbo) engine that I have in my snotter Astra.
That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
Good luck with the project.
The Manta is a great car. Hugely under rated. I’ve no idea what they drive like in original form, probably terribly and I’ve no idea what sort of performance they had, probably poor but they lost ones fantastic and never got the recognition they deserved.
I’m a great believer in the restomod movement but I do think that you need to try and keep all the key parts in the ‘family’. I don’t know why but I feel it’s just the right thing to do. Probably not quantifiable logic to it.
The Manta is a great car. Hugely under rated. I’ve no idea what they drive like in original form, probably terribly and I’ve no idea what sort of performance they had, probably poor but they lost ones fantastic and never got the recognition they deserved.
I’m a great believer in the restomod movement but I do think that you need to try and keep all the key parts in the ‘family’. I don’t know why but I feel it’s just the right thing to do. Probably not quantifiable logic to it.
Jimmy Recard said:
Nice project! I'll be following. A friend and I have an ongoing project with a manual Omega V6 that at some point may be getting the Z20LER (2.0 turbo) engine that I have in my snotter Astra.
That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
Thanks! The chevette that we have has your current running gear in 3.0 flavour being (very slowy) put in to it midship (still in the front, but bulkhead cut out so engine is about 6 inches further back, making the back of the cylinder head about where your knee would be) - the omega is good fun! Z20LER is a good one too.... as you say there are a few GM options, and it would certainly fit with what we are thinking for the car. Just hard to ignore the non GM stuff such as the honda k20/24, but we are not sure if it's something that would negatively affect someone's view of the car as a whole or enhance it as an leftfield option That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
DonkeyApple said:
Good luck with the project.
The Manta is a great car. Hugely under rated. I’ve no idea what they drive like in original form, probably terribly and I’ve no idea what sort of performance they had, probably poor but they lost ones fantastic and never got the recognition they deserved.
I’m a great believer in the restomod movement but I do think that you need to try and keep all the key parts in the ‘family’. I don’t know why but I feel it’s just the right thing to do. Probably not quantifiable logic to it.
Thanks! Well i've always been of the opinion that they are one of the better thought out cars of the era, what with having double wishbones up front, but the actual suspension certainly left a lot to be desired! Yeah, i know what you mean on 'keeping it in the family' (so to speak The Manta is a great car. Hugely under rated. I’ve no idea what they drive like in original form, probably terribly and I’ve no idea what sort of performance they had, probably poor but they lost ones fantastic and never got the recognition they deserved.
I’m a great believer in the restomod movement but I do think that you need to try and keep all the key parts in the ‘family’. I don’t know why but I feel it’s just the right thing to do. Probably not quantifiable logic to it.
)RIR18 said:
Jimmy Recard said:
Nice project! I'll be following. A friend and I have an ongoing project with a manual Omega V6 that at some point may be getting the Z20LER (2.0 turbo) engine that I have in my snotter Astra.
That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
Thanks! The chevette that we have has your current running gear in 3.0 flavour being (very slowy) put in to it midship (still in the front, but bulkhead cut out so engine is about 6 inches further back, making the back of the cylinder head about where your knee would be) - the omega is good fun! Z20LER is a good one too.... as you say there are a few GM options, and it would certainly fit with what we are thinking for the car. Just hard to ignore the non GM stuff such as the honda k20/24, but we are not sure if it's something that would negatively affect someone's view of the car as a whole or enhance it as an leftfield option That's not a bad engine to consider either.
Either way, if you want to stick to GM, you really are spoilt for choice and the sky is your limit!
aeropilot said:
That's got to be a BIVA candidate now, with the cut bulkhead on top of all the other points loosing changes?
The chevette is the other end of the scale to what we want to achieve with the manta - we very much want to keep the 'character' of the manta in both looks and the way it is constructed, essentially developing 'bolt on' upgrades with absolute minimum shell changes. The chevette is semi space framed, and although using mostly gm parts will in reality be a shadow car.I am old enough to have had Vauxhall products back in the day , several Cavaliers but never an Ascona or Manta .
The first cav started life as a 1.6 but soon morphed into a 2.0L with lots of ex testing/development bits from the bins at Millbrook .
All my mates ran Vauxhalls and would run rings around all the local Ford boys .
The biggest drawback in tuning the early engines was lack of suitable camshafts. Those available from UK firms weren't great and didn't last long , the Irmscher ones worked but were very expensive and not easy to obtain.
The first cav started life as a 1.6 but soon morphed into a 2.0L with lots of ex testing/development bits from the bins at Millbrook .
All my mates ran Vauxhalls and would run rings around all the local Ford boys .
The biggest drawback in tuning the early engines was lack of suitable camshafts. Those available from UK firms weren't great and didn't last long , the Irmscher ones worked but were very expensive and not easy to obtain.
simonsti said:
Have a look at what retropower have done recently...also why not join the manta club Facebook page.
Yeah, we've seen their work - pretty impressive! Nice how diverse the range of things they work on is, not afraid to do something a bit different! We're on the omoc forum also, who are a friendly bunch 
DonkeyApple said:
never got the recognition they deserved.
I wouldn't say that! Mantas were pretty much iconic, fairly ubiquitous at one stage, definitely a blue-collar hero type car alongside E30 2-door and Ford Capri. I think Mantas were a lot less common in the UK than mainland Europe, where I think they were looked down on as being whatever the then equivlent of 'chav' was. There's a popular Dutch comedy series called 'New Kids' where both the protagonist Rikkert and anti-hero The Dave both drive modded Mantas (and wear mullets and shell suits whilst listening to Happy Hardcore). I suspect in the UK the Manta was probably priced a bit too high and lacked the badge appeal of similar products from other German marques.
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