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Common Modifications - and how useless they can be
When it comes to 'modifying' these cars are no exception to the typical performance car variety. They attract their own share of boy-racers and other misguided individuals. And they all seem to follow the same pattern of spending:
filter->dump valve-> exhaust -> big wheels -> lowering -> spoiler. Some will also 'invest' in Slick50, trick plugs and other cheap'n'cheerful performance upgrades.
So what's wrong with that?
Let's take them one by one:
Air filter.
The idea is that the stock unit is very restrictive for some reason. Take your pick: The manufacturer chose to strangle the car's output to pass emissions tests, keep it in a lower insurance bracket, or they simply aren't sophisticated enough when it comes to designing a decent airfilter.
As a result an aftermarket panel filter, or even better a cone, will allow the engine to breathe easily and unleash a wall of power sitting there just waiting to be unlocked.
The truth is that the filtration quality is typically very inferior and this always leads to accelerated wear. The real power gains are either minimal or negative (due to hot-air inhalation)
Dump valve
This is not a dangerous mod if done properly (some people fail to block the stock recirc valve with the spacer and this leads to slower boost build-up). But the Dump valves do occasionally go wrong, and on stock cars there are no benefits over the stock recirculation valve. Despite the strong 'technical merits' written on the advertisements, it's just spending money on a cosmetic thing. It's mainly the sound that makes people spend their cash on them.
Exhaust
Some try to get away with just a 'sporty' backbox, which is just one step above this ridiculous contraption
Unfortunately the contribution of the backbox is minimal when it comes to unleashing ungodly powers of hidden torque from your beast. The earlier parts of the exhaust are more relevant, but even so their contribution is dwarfed by the greatest restriction of all: the turbine wheel and its casing.
Also beware that a free-flowing decat exhaust may induce smoking at idle and low loads, as it upsets the fine balance of airpressure on either side of the turbo bearing. A double-ring seal on the exhaust side of the turbo can address this issue, but it involves reconditioning it.
No easy plug-and-play power bonanza here then...
Wheels
Hell killjoy, nothing wrong with a fancy set of 18" or even 19" wheels eh? Shows who's the boss!
I've seen people spend over £1000 on a set of large wheels immediately after they've bought the car. Even before the first oil change. So keen are they to make it look kewl.
The problem is that the track rods and the wheel bearings were not designed for such wheels. The extra tyre surface produces extra loads, so after a few thousand miles things start to get wobbly as rubber mounts give up the ghost. These people don't make the connection with the fancy wheels, because the car had already been through a few previous owners, and it's easier (and logical!) to blame them (along with the age of the car, of course!)
This is closely related to suspension 'mods', aka...
Lowering
I've heard that it helps handling too. So all you 'do-gooders' can get lost.
Ah, where do we start...
First of all using shorter springs with stock shocks is a no-no. The shocks are left to operate in a region where they can't do much. Cutting the existing springs is even worse.
Assuming that the 'modifier' is a bit serious, he (or she!) will splash out for a matched set of shocks and springs. This will ensure that ride height and suspension compliance will be spot-on. ....Or will it?
Most of these kits are a bit too generic (say for the 'Calibra') although the weight distribution of the 8v is quite different to that of the V6 or the turbo. So sometimes after the kit has been fitted properly, the car looks funny. Even if this is addressed with adjustable kits, the rear propshaft and the rear differential end up at an uncomfortable angle in relation to the transfer box. The effects of this stress may not be immediate, but it all adds up.
More sophisticated punters go out and buy camber kits, to address some of these stresses on the driveshafts. But that's patching up something that could have been left alone in the first place. As costs escalate and the tyre wear pattern looks dodgy, CV boots start to split, rollbar mounts crack or snap, trackrods play the samba, the tx box builds up psychological pressure and the drops from the steering rack are not tears of joy.
On the upside, the car looks mean. Hitting a pothole (even at low speeds) can damage the delicate ultra-low-profile tyres and even shatter the trick alloy wheels. The cost of replacing these tyres can be 2-3 times the cost of the stock 205/50/16 ones. And on these cars you cannot even change two tyres - they all have to go in a set of 4. Is it worth the aggro?
There is an argument that a lowered car has better aerodynamics, because the frontal area is smaller. This is correct up to a point (the airflow underneath is also very important), but these people more than make up for this advantage with the wider tyres. (Remember that the stock turbo had Cd=0.29 compared to the original Calibra with Cd=0.26. This was mainly down to wider tyres, different wheels and the air intake where the FMIC normally sits)
Then they make the aerodynamic coefficient even worse with the spoilers...
Spoilers
The Calibra's aerodynamics are exceptionally good for a coupe, even by today's standards. 0.29 is pretty damn good, and even the most discrete of aftermarket spoilers will bring it up to 0.31. The large, garish, Fast&Furious spoilers are much worse.
The purpose of a spoiler, when it comes to airflow, is exactly what is says on the tin: to spoil the airflow. This can be done so that an undesirable vortex is minimised at the back of the car (box-shaped hot-hatches are a good example). It can also be done in exchange of downforce at high speeds. These spoilers are like inverted aeroplane wings, and the well-designed ones can typically create 20-30kgs of downforce at high speeds (well over 100mph). Unfortunately they are also retrofitted to cars which cannot even reach those speeds, but they just obstruct the rear view. Some are even totally flat, incapable of creating any downforce at all - they just make the poor car look like a jet fighter in the eyes of the sad owner.
It's all down to personal taste, of course, lets just don't pretend that there are sound technical reasons behind cosmetic botches.
Aftermarket body parts
Quality varies a lot, rarely does it meet factory requirements. Often they fit badly and can be dangerous. This guy's cool bonnet flew off at low speed (local copy here)
Trick plugs and leads
More on these on the ignition pages, as the Splitfire/spitfire/whatever wonders are never as good as good iridium NGK plugs.
Spark enhancers
'Sparkrite' and the like, usually exhibited at motor shows.
They fit between the coil and distributor, claim to make the spark stronger
Total waste of space.
Nothing that can be added onto the path of the high tension leads can ever make the spark stronger.
Normally they are additional gaps that the spark has to jump (with fancy lights sometimes)
Doing an A/B test you see that the spark jumps further with the gizmo, so it must be an improvement, right?
Wrong: The overall energy at the plugs has gone down. Higher voltage but a lot less amps. Just because the spark jumps further doesn't mean it works better under combustion conditions.
Steel gaskets
After having a headgasket failure, many people try to play it safe and opt for super-duper, unbreakable steel headgaskets. If they could get titanium gaskets, they would.
Waste of money in most cases (under 2 bar boost). Gaskets are not conrods. We want the gasket to be the weakest link - we want it to blow under detonation conditions. Because if it doesn't then milliseconds later the pistons will have gapping holes, or even worse, a rod might decide to go shopping through the crankcase. We want the headgasket to act like a fuse, in case we've got our sums wrong and severe detonation is allowed to happen.
The stock gasket, when fitted properly, is good enough for holding over 2 bar boost. This of course stands for an engine where the cylinder pressures have been kept under control, and airflow is in the right direction (exh gases leaving the cylinders and not coming back!)
Non - OEM gaskets (Cometic for example) are also reported to have problems sealing when the mating surfaces are not perfect, with some people even using copper spray to eliminate leaks from brand new gaskets. Having a different composition, they distort in different ways too (creating the sealing!) but somehow it's always assumed that the clamping force needed is always the same as that of the stock gagket. How wise is it to make such assumptions on something so critical that that leave you stranded at the side of the road?
If it blows too easily, then we have to find out why this happens, not weld it down.
Magnetic fuel enhancers
There are several variations of the theme, but this one is my favourite: Harness the power of rare-earth magnets (local copy here)
Apparently fuel has magnetic properties, we learn something new every day...
Here is someone else's take on these miracles of science (local copy here)
Fancy equal length exhaust manifolds
This is the new trend now, for those chasing maximum power figures. They read in colourful magazines (with shiny engine bays and oiled babes) that for proper power you gotta ditch that joke of a turbo and fit a big one.
It sounds logical if you don't know much about engines. Hey, big turbo --> lots of air --> lots of power. Makes sense, innit?
Well, not necessarily.
For starters, an equal-length manifold is a nice to have, not a must have (like it is on n/a engines). There is no tuned-length as such, since the turbine slices all waves into pieces. Equal distance from the turbine is mainly for the benefit of equalising Exhaust Gas Temps among the exhaust valves, or else the ones closer to the turbo will be hotter (cyl #3 in the case of the stock LET manifold)
Secondly, an equal length manifold will inevitably lead to longer runners, meaning less heat for the turbine (less engine power) and more heat in the engine bay (even less engine power).
Thirdly, it will mean more weight, which means more expansion and more cracks in the metal. More weight hanging off the cylinder head studs, too.
Lastly, an equal length manifold with a bigger turbo right in the middle of the block will almost certainly result in ditching the power steering pump and the aircon, both of which are intrusive modifications. You need the power steering pump to operate the 4x4 clutch for example.
So before you decide to ditch the stock manifold, ask yourself if it's worth cutting it up, adding a flange and sticking the bigger turbo there. The simplest ideas are sometimes the best.
Turbo timers
Total waste of space.
Turbo timers are a remnant from days past, when all turbos were aircooled and synthetic oils were not around (or too expensive!)
Switching off immediately after a full-boost run would then cause the oil pump to stop, and the oil remaining in the turbo bearing would carbonise and turn to a form of ash (coking was the term)
Nowadays this cannot happen. The water jacket absorbs all the extra heat from the bearing, and then some. Therefore the oil temps don't exceed 120C even then, and synthetics tend to resist death until over 150C, so there is no benefit from the turbo timer, except unnecessary idling (that does the turbo seals no good, neither the camshafts)
Idle is not good for turbos, water cooled turbos don't need any of this maintenance. Just roll smoothly after a full-boost run, if you're going to switch off immediately, that's all.
ARP rod bolts
This is supposed to be a 'must have' for the discerning engine builder. Sales people (and internet myth) will have you believe that the stock bolts are made of chocolate, totally inadequate to stay in one piece. Once you try to go over 260 (or 300) bhp the stock bolts can suddenly stretch and then your whole block is toast.
...but fear not: specialist firm ARP produce these mega-strong replacement bolts, that can take extreme punishment with no problem whatsoever. Yes, they do cost more (and changing rod bolts is fiddly if you only take off the sump for this purpose) but otherwise you're playing russian roulette with your engine. Can you afford not to change them?
Scare tactics mixed with dodgy data: a recipe guaranteed to work for sales of useless bits.
The reality is that the stock bolts will only fail under extremely high revs - way after the stock redline. But so will the the ARP bolts. In any case, the rods themselves will have failed before the bolts --- we often see snapped rods with the bolts still in place.
The extra stresses of additional engine torque are nowhere as dramatic as the sales literature will let you believe. Furthermore, tuned turbo engines tend to produce the extra torque at midrange and not at the redline, making the claims of the aftermarket suppliers look like scaremongering.There's more: people have lost their engines due to ARP rod bolt failures, and these are more than those losing engines due to stock bolt failures. That's not something that is advertised in internet forums, maybe because it will make fools out of people who believe they are God's gift to mankind (along with K&N filters, Friction eliminators and the like)
Some of the ARP bolt failures were due to faulty installation, either misuse of their grease, or application of the wrong torque procedure - even failing to chamfer the 'seat' as the instructions clearly state. But some failures were due to the bolts themselves failing. I know at least of two instances of mechanics being left with a sheared ARP bolt during torquing (correctly). Another giveaway is people going out in forums asking for a spare bolt!
There is also the suspicion that some stock rod bolts were not properly tightened at the factory. Some people even reuse them (although as stretch bolts, the stock items should always be replaced). So my advice would be to check the torque settings of your existing rod bolts, if you happen to have the sump open for some other reason. But don't bother changing the bolts simply for the 'peace of mind' the name ARP gives you. Just the operation of the swap introduces an extra level of risk, and it's not worth it.
Changing the rods for lighter/stronger items is a whole different story. ARP rod bolts coming with these new rods are welcome (and have to be changed anyway). Being reusable is a bonus. Just don't forget to get the new rods X-rayed for manufacturing faults. They do fail in service and it's not funny.
So how do the 'racers' explain the lack of performance despite all these goodies?
