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Tuning the C20LET - Introduction
This part of the site is dedicated to the tuning and maintenance of Vauxhall's C20LET, the turbocharged version of the highly successful 150bhp 2litre 16valve C20XE.
It is found mainly in Calibra and Cavalier 4x4turbos (but not only)
There is a South African 2WD version, as well as an American, single cam variant.
It has been transplanted into various other engine bays, the most common being Astras and Novas(or Corsas as they're called in other countries) There even are a few minis knocking about with LETs. Even Peugeots find it irresistible!
Here is another site dedicated to the successor, Z20LET
(now covers Water Injection as well!)
Who needs another Vauxhall site, anyway?
Owners of turbocharged Vauxhalls do. They look for a Haynes manual and they can find none. They look for any sort of workshop manual - still nothing. Then they look for experienced dealers or garages: what a joke; it's easier to find a virgin in a cabaret. It's no wonder this page sees an average of 1500 visitors per month.
WHY Optimise?
Manufacturers of mass-produced cars tend to let turboed engines get away with sloppy details because it saves them money. It's not their worth wasting time in the production line optimising minor things, especially in cheap cars like Vauxhalls. They cut corners and fudge their designs a bit, in a desperate effort to keep manufacturing costs low. And when you, the owner, goes ahead to get these details right, the difference in performance can be startling.
OK, maybe you won't be forced by MoT to carry a parachute: Too many people spend big bucks on expensive 'performance mods', while they omit basic optimisations and adjustments that could bring more bhp (almost free!). They spend good money on 'go-faster' bits when the base car isn't performing anywhere near its real potential. Looking closely at the Calibra turbo engine, it seems that the whole thing has been put together a bit sloppily - but then again it's a mass-produced unit, the alternative would be to pay triple the price for some extra attention to detail and (perhaps) an extra 20% power and torque.
This optimisation and TLC we can do ourselves, finishing off where the factory left for a lunch break. It doesn't have to be high-end blueprinting, either, just some attention and optimisation before parts are put back together. It improves both power and fuel economy at the same time.
What about all these specialists and tuners? Why DIY?
I don't know about Germany, but UK tuners? - don't get me started...
In my experience the better-known ones range from the semiliterate to the incompetent, charging a fortune in the process. Even those who do know their stuff (hell, they've been doing the same things day-in, day-out for years!), will be too bored and sloppy when it comes to your car. Sod's law. I've seen and heard so many horror stories that I wouldn't trust them to tie their shoelaces.
For jobs that are non DIY-friendly (dropping the clutch, etc.) then automotive specialists in that field might be much better (and cheaper) than the Vauxhall 'tuners'. Actually that's where the work will be done anyway (if you're lucky), but they'll charge you double for their trouble.
Vauxhall dealerships are the worst - very expensive and seriously incompetent.
They tend to employ inexperienced (but cheap) young people, who will learn the tricks of the trade by botching up your car.
I've watched them, and they were pitiful. Tried a different dealership, it was even worse. Experiences of others tend to agree on this. If it's a rare model like the turbo or the V6 then they'll race it as well. I've seen them "test driving" a (customer's) Calibra turbo and doing handbrake turns as well. They didn't even know that this kills the transfer box - they were toddlers when the car was first introduced. Approach them at your own peril...
It doesn't take the brain of Steven Hawking to realise that these establishments are profit-making entities, not charities, and definitely not enthusiasts' clubs. Therefore commercial reasoning prevails at all times.
Children have to be fed, dressed, sent abroad on holidays, etc.
Someone has to pay for all this:
YOU, the punter
As a result:
Costs will be deliberately underestimated, or else you might not leave the car in their garage in the first place. While it's in pieces, they can always call you and claim that more work is needed...
Corners will be cut, as in worn items may be reused, screws and nuts may be overtightened "just to be safe", sloppy work usually prevails - who's gonna notice anyway - hell, if it fails you'll bring it back for even more work...
Assumptions will be made. Nobody's gonna spend hours inspecting your engine, admiring it and try to adjust it meticulously. They are not enthusiasts, they are making a living out of this. It's a production line.
Look at it this way: It's a tough world out there, they gotta shift so many cars a day, or else they can't pay the rent and are out of business.
When you ask for details, the truth will be stretched
The only way to be 100% certain that work has been done properly is to do it yourself.
Of course this means that you know what you're doing, you've got the manuals, proper tools, workspace and spare parts.
There is no justification in starting half-blind and hacking your way through. In the internet era, there is plethora of forums specialising in these subjects, as well as online manuals and even online parts purchasing. The 'Resources' part of this website is a good starting point. Here is how Dan Willis, a ClubCalibra member, rebuilt his Calibra turbo with a big turbo from the States and re-arranged piping.
If you don't even know what horsepower is, don't worry! Take a look here or here (taken from ITV's motoring column)
If you think that flywheel power is all the rage, take a look here
If you don't know what BOOST is, or even think that Boost is Good, then take a look here
This is the power graph of a stock LET:
Hopefully this website will help guide you in the right way (i.e. move these lines upwards)
Whether you're after monstrous midrange torque or a high-rev screamer, you can do it better than the 'big boys' and much cheaper to boot. Hey, after all a lone amateur
built the Ark. A large group of professionals built the Titanic.
Enjoy the trip!
Here is an enthusiast turned pro trying to dispel some tuning myths. Will anyone listen? of course not!
Here's another voice in the dark: Real Power mods vs Comic Mag mods
Here's a text dump of an interesting MythsUncovered Thread (can't trust external links, they die overnight)
Here is a quick dash through the history of forced asprication from another enthusiast site (local copy here)
