Maser Sod
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- Messages
- 1,965
Hi all,
I've been meaning to write this guide to modifying a GranSport (or 4200) for a while, but have just been too busy with work. Anyway, I'm sure many of you out there know most of what I'm about to present, but it doesn't hurt to put it all in a single place and add some nice pics. ;-)
Actually, I hope the images display correctly, bear with me if not - I will keep trying.
Big shout to Bigfoot for the original inspiration.
AIR FILTER
This is a cheap and easy modification. It's arguable whether any performance difference can be discerned just by changing out the OEM filter, but every little gain helps, and the combination of various small enhancements can of course result in a car which exhibits a quite noticeable performance hike from stock. The sports filter in my GranSport is an Italian-sourced model resold through Formula Dynamics. It probably adds 2-5 BHP.
EXHAUST
This is where you can get creative, and at the same time find a very noticeable performance gain. Whilst is possible to modify the different sections of the standard exhaust system, arguably the commonest modification is changing out the rear mufflers, with products from companies such as Tubi or Larini proving popular. The 'modder' who proceeds with this change may well be after a sonic as much as a performance enhancement.
A more aggressive performance enhancement can be had from replacing the sections of piping preceding the back boxes. The standard assembly is rather heavy and somewhat restrictive, particularly the kinked section which curves around the front axle. (The kink assists ground clearance but restricts airflow.)
It is feasible to replace these sections with a lighter, 'straight-through' assembly, including sports catalytic converters in place of the standard OEM cats - or even go cat-free (though you may not pass your MOT!). Replacement mid-sections can be bought off the shelf (e.g. Larini X-pipes), or can be custom made.
The set-up I have is custom made from T304 stainless steel, with 100 CPSI sports cats and more free-flowing full bore pipework from the cats to the mid-section (replacing the 'pinched' piping of the original). This gives much greater breathability for the exhaust gases.
The slight downside of this particular modification is poorer ground clearance, especially if the car is lowered, as mine is (more about this later). Hence extreme care is needed when dealing speed bumps and the like. But it is a relatively small price to pay for the noticeable extra performance, probably between 15-30 extra BHP.
I chose not to swap out the back boxes since it is not straightforward to retain the GS sport valve set-up.
The exhaust was custom-made for me by ProSpeed Exhausts in Cardiff. The decision to pursue a custom option rather than an off-the-shelf product was based not on cost but on my wish to have the noise of the finished exhaust system tuned to my liking.
CUSTOM SET-UP FROM UNDERNEATH
CUMBERSOME OEM MID-SECTION
SUSPENSION
The stock suspension of the GranSport is 10mm lower than the standard 4200. I have had my GranSport lowered by a further 30mm, and I have replaced the OEM springs with Formula Dynamics performance springs. The new springs allied with the lowering reduces body roll a little and enhances handling, as well as lowering the overall centre of gravity of the car. The results are very noticeable: the car sits lower, feels very 'planted', and is less 'floaty' than standard. The ride is slightly harsher, but not to the point of shaking out one's fillings. Skyhook helps here, since if the ride feels overly harsh in some conditions then you can simply select 'Normal' rather than 'Sport' mode to soften out the ride.
Altering the suspension characteristics is arguably the single most noticeable change you can make to the performance of your car, and one I would highly recommend. It is also reasonably cheap to do.
There is always the worry of tyre rub into the arch, but I have never experienced this personally.
I did not fit spacers, although this is a common addendum to the abovementioned changes.
AFTER LOWERING - 3/4 VIEW
SIDE VIEW
BEFORE LOWERING
ECU/ECM
As you are probably aware, it is feasible to alter the standard ECU signature of the 4200 and GranSport. This is achievable in different ways. For instance, it is possible to reflash the stock ECU itself. My set-up consists of an auxiliary engine control module, wired in series with the standard ECU. This extra control unit alters timing and the air/fuel mixture.
I purchased it from Formula Dynamics. It is tailor-made to my specification, with the custom signature providing enhanced torque around the 3K RPM range.
The standard GranSport for me has great top-end power, but after moving to a GS from a 3200GT I did miss the rush of acceleration from the turbo boost. I should point out finally that the ECM is calibrated for use with 100 RON fuel, which I always purchase on the premise that every slight improvement to performance is worth taking when offered.
DRIVE-BY-WIRE
It is possible to modify the characteristics both of the throttle response of the 4200/GranSport and also the speed of the CambioCorsa (CC) changes. To achieve this, I have had the Formula Dynamics Drive-by-Wire Enhancement module fitted. As with the ECM from FD, this unit can be tailored to one's individual needs, although the difference is that one chooses from presets. My module has a switch offering two modes: 'aggressive' and 'very aggressive'. I always drive the car in 'very aggressive' mode. This makes the throttle response instantaneous, but can be a bit much for some, and does require a little care at times, e.g. when parking in a narrow garage like mine!
The same 'very aggressive' mode also sharpens up the gearbox changes: 'Normal' mode is no longer sluggish, whilst 'Sport' mode becomes exceedingly quick - perhaps too quick for some. The choice here really depends on driving style. But the fact is that it is difficult to go back to the original gear change settings once you have experienced the enhancement.
It is worth noting that speeding up the CC change can theoretically enhance the longevity of the clutch - the sluggish, protracted changes in 'Normal' mode arguably wear down the clutch rather more than is necessary - however I suspect that too many fast, aggressive changes without easing off the gas pedal could also compromise the lifetime of the CC clutch.
Since I like an aggressive gear change, I also had the PIS setting on the clutch reduced (currently 4.97), and the paddles tighted - I pay attention to detail!. But this would not be to everyone's taste.
INSTALLED FD MODULE (WITH SWITCH VISIBLE)
Total Effect
The total effect of all these modifications is quite noticeable. In terms of measurable performance, I have not dyno'ed the car, but I would expect it to show around 420-450BHP and probably 350-370 lb/ft of torque. The car generally feels a lot faster, more Ferrari-esque, if that description makes sense to you. I will not embark on a Clarkson-esque ramble about how I enjoy all the extra 'powwwerrrr', but the changes I have made, to my mind, really make the GranSport complete. I imagine the mods would work equally well on the 4200, probably producing a car very similar to this one.
I've been meaning to write this guide to modifying a GranSport (or 4200) for a while, but have just been too busy with work. Anyway, I'm sure many of you out there know most of what I'm about to present, but it doesn't hurt to put it all in a single place and add some nice pics. ;-)
Actually, I hope the images display correctly, bear with me if not - I will keep trying.
Big shout to Bigfoot for the original inspiration.
AIR FILTER
This is a cheap and easy modification. It's arguable whether any performance difference can be discerned just by changing out the OEM filter, but every little gain helps, and the combination of various small enhancements can of course result in a car which exhibits a quite noticeable performance hike from stock. The sports filter in my GranSport is an Italian-sourced model resold through Formula Dynamics. It probably adds 2-5 BHP.
EXHAUST
This is where you can get creative, and at the same time find a very noticeable performance gain. Whilst is possible to modify the different sections of the standard exhaust system, arguably the commonest modification is changing out the rear mufflers, with products from companies such as Tubi or Larini proving popular. The 'modder' who proceeds with this change may well be after a sonic as much as a performance enhancement.
A more aggressive performance enhancement can be had from replacing the sections of piping preceding the back boxes. The standard assembly is rather heavy and somewhat restrictive, particularly the kinked section which curves around the front axle. (The kink assists ground clearance but restricts airflow.)
It is feasible to replace these sections with a lighter, 'straight-through' assembly, including sports catalytic converters in place of the standard OEM cats - or even go cat-free (though you may not pass your MOT!). Replacement mid-sections can be bought off the shelf (e.g. Larini X-pipes), or can be custom made.
The set-up I have is custom made from T304 stainless steel, with 100 CPSI sports cats and more free-flowing full bore pipework from the cats to the mid-section (replacing the 'pinched' piping of the original). This gives much greater breathability for the exhaust gases.
The slight downside of this particular modification is poorer ground clearance, especially if the car is lowered, as mine is (more about this later). Hence extreme care is needed when dealing speed bumps and the like. But it is a relatively small price to pay for the noticeable extra performance, probably between 15-30 extra BHP.
I chose not to swap out the back boxes since it is not straightforward to retain the GS sport valve set-up.
The exhaust was custom-made for me by ProSpeed Exhausts in Cardiff. The decision to pursue a custom option rather than an off-the-shelf product was based not on cost but on my wish to have the noise of the finished exhaust system tuned to my liking.
CUSTOM SET-UP FROM UNDERNEATH
CUMBERSOME OEM MID-SECTION
SUSPENSION
The stock suspension of the GranSport is 10mm lower than the standard 4200. I have had my GranSport lowered by a further 30mm, and I have replaced the OEM springs with Formula Dynamics performance springs. The new springs allied with the lowering reduces body roll a little and enhances handling, as well as lowering the overall centre of gravity of the car. The results are very noticeable: the car sits lower, feels very 'planted', and is less 'floaty' than standard. The ride is slightly harsher, but not to the point of shaking out one's fillings. Skyhook helps here, since if the ride feels overly harsh in some conditions then you can simply select 'Normal' rather than 'Sport' mode to soften out the ride.
Altering the suspension characteristics is arguably the single most noticeable change you can make to the performance of your car, and one I would highly recommend. It is also reasonably cheap to do.
There is always the worry of tyre rub into the arch, but I have never experienced this personally.
I did not fit spacers, although this is a common addendum to the abovementioned changes.
AFTER LOWERING - 3/4 VIEW
SIDE VIEW
BEFORE LOWERING
ECU/ECM
As you are probably aware, it is feasible to alter the standard ECU signature of the 4200 and GranSport. This is achievable in different ways. For instance, it is possible to reflash the stock ECU itself. My set-up consists of an auxiliary engine control module, wired in series with the standard ECU. This extra control unit alters timing and the air/fuel mixture.
I purchased it from Formula Dynamics. It is tailor-made to my specification, with the custom signature providing enhanced torque around the 3K RPM range.
The standard GranSport for me has great top-end power, but after moving to a GS from a 3200GT I did miss the rush of acceleration from the turbo boost. I should point out finally that the ECM is calibrated for use with 100 RON fuel, which I always purchase on the premise that every slight improvement to performance is worth taking when offered.
DRIVE-BY-WIRE
It is possible to modify the characteristics both of the throttle response of the 4200/GranSport and also the speed of the CambioCorsa (CC) changes. To achieve this, I have had the Formula Dynamics Drive-by-Wire Enhancement module fitted. As with the ECM from FD, this unit can be tailored to one's individual needs, although the difference is that one chooses from presets. My module has a switch offering two modes: 'aggressive' and 'very aggressive'. I always drive the car in 'very aggressive' mode. This makes the throttle response instantaneous, but can be a bit much for some, and does require a little care at times, e.g. when parking in a narrow garage like mine!
The same 'very aggressive' mode also sharpens up the gearbox changes: 'Normal' mode is no longer sluggish, whilst 'Sport' mode becomes exceedingly quick - perhaps too quick for some. The choice here really depends on driving style. But the fact is that it is difficult to go back to the original gear change settings once you have experienced the enhancement.
It is worth noting that speeding up the CC change can theoretically enhance the longevity of the clutch - the sluggish, protracted changes in 'Normal' mode arguably wear down the clutch rather more than is necessary - however I suspect that too many fast, aggressive changes without easing off the gas pedal could also compromise the lifetime of the CC clutch.
Since I like an aggressive gear change, I also had the PIS setting on the clutch reduced (currently 4.97), and the paddles tighted - I pay attention to detail!. But this would not be to everyone's taste.
INSTALLED FD MODULE (WITH SWITCH VISIBLE)
Total Effect
The total effect of all these modifications is quite noticeable. In terms of measurable performance, I have not dyno'ed the car, but I would expect it to show around 420-450BHP and probably 350-370 lb/ft of torque. The car generally feels a lot faster, more Ferrari-esque, if that description makes sense to you. I will not embark on a Clarkson-esque ramble about how I enjoy all the extra 'powwwerrrr', but the changes I have made, to my mind, really make the GranSport complete. I imagine the mods would work equally well on the 4200, probably producing a car very similar to this one.
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