K series engine tuning page

My dry-sumped VHPD before installation

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Background

The Rover K is an all aluminium engine with compact dimensions and lightweight. It is eminently tunable and is very reliable. Caterham Cars have an excellent relationship with Rover and it is this that has ensured the longevity of supply of the engine for use in the 7.

Available initially in 1991 and designed primarily for the new Metro range the K is now over ten years old and has developed considerably. The first motors were 1.4 litres and had physically smaller pistons and liners along with a short stroke crankshaft. This means that the crank doesn’t pull the piston down the bore as far on rotation thus keeping the effective cylinder volume down and hence only 1400cc capacity.

When people originally tried the 1.4 K in a 7, they were absolutely amazed at the improved handling created by the lack of weight and improved weight distribution. The performance with the 100bhp was lively and the only area of concern was the 5 speed Ford gearbox which has ratios that were miles to long. The development of the 6 speed box solved this issue and the 1.4k Supersport with its improved grunt and 6 speed gearbox was the thinking man’s choice.

The 1600K was created by increasing the bore size. The good news is that if you have an old 1.4 it is easy to change the liners and create a 1.6! The block is the same. One problem is the cylinder head, which is poor on early 1.4 engines. Dave Andrews details how to spot a “low port” cylinder head. Since power is essentially developed in the head it is a good idea to source the best one you can.

Technically speaking, the 1.6 engine with its still short stroke is a smoother unit than the longstroke 1.8 because it is more “square” in configuration ie the bore width is more similar to the crank stroke. The lower capacity also makes the motor more revvy and the 1.6 can be tuned effectively. There are many reasons why people choose to tune the 1.6 of which more later.

The 1800k was created by changing the crankshaft for a longstroke item. In itself, the action of increasing the capacity on an otherwise standard 1600 only adds a few bhp (from 115bhp to 122bhp) but there are useful increases in torque and of course, if you are serious about tuning, the 1800 will have to work less hard in terms of specific output than an equivalent 1600.

Cylinder head choice

The original 1.4 head had small valves and badly designed ports and is not ideal as a basis from which to tune.

The later 1.6/1.8 heads used bigger valves than the 1.4 and it is possible to upgrade the valve sizes in these to dimensions more suitable for a performance engine, but the ability to do this is restricted somewhat by the physical casting.

The VVC engine has a super cylinder head. It has bigger valves and a superior combustion chamber shape along with better designed porting. If you are using one of these on your engine you will have to obtain a “VVC blanking plate” which blocks off the extra aperture in the head provided for the VVC gubbins. This will cost about 100GBP. In addition, the VVC head will need different cams (the bearings are different) and these are that bit dearer than standard upgraded ones (about 350GBP instead of 150GBP, in fact!!) Also, Dave Andrews makes the point that the VVC head suffers from some degree of oil retention in the head. I suggest that this will be not such an important issue as long as the oil system is allowed to breathe properly and something like an anti cav tank is used.

The VHPD head is 1300GBP brand new from QED (www.qednet.demon.co.uk) but if you can find one from a written off Exige or Elise190 then great! This has the standard bearing sizes so cams are cheaper and you don’t need a blanking plate. The oil retention issue is solved too. The standard casting still isn’t perfect but it’s a great place to start.

Tuning

Decide how much power you want. If you can’t decide, I suggest you go out in different cars until you find the one you like the best. This might sound unrealistic but there is nothing worse than “gradually” doing something only to find that you end up throwing away most of the components you’ve bought!

If you are buying a new car and can’t decide whether to order a 1.6 or 1.8 then I suggest you start with a basic 1.6 engine and tune it until you need a stronger bottom end and more capacity. Paying extra to get the standard 1.8 bottom end is great if you are happy with about 190bhp and 7500rpm but if you want 220bhp then sooner or later the pistons will come through the bonnet with those standard rods!

Uprated piston fastened to its rod – Still 1600cc

You can get 180bhp from the 1600 and still have reliability so it is not like you have a handicap by going this route but be warned that most tuners disagree with this view, saying that it is better to start 1800. As I said, this is fine if you are tuning only mildly but be warned that it is very addictive!

ECU

First step in my opinion. The Rover MEMS ECU is non user programmable, so it is not practical to change the setup of the engine within the computer. This is necessary to optimise the motor to whatever change you make to its physical specification and this optimisation will be needed whenever you upgrade something. You need to find a system that your preferred tuner is comfortable with in terms of setup.

Lotus 7 people seem to go for the Emerald ECU a lot. This was plug compatible with K series until the new EU3 engine loom. Now you’ll have to chop of the plugs and hardwire the rascal but many tuners love this system and know how to get the best from it.

Here you can see what the Emerald system looks like:

The DTA system sold by QED is also great and if you are going to use them for further work I suggest you go DTA because they have a great knowledge of this system. Sadly QED won’t rolling road your car; they only work on engines out of the chassis so maybe go this route if you are sending QED your entire engine and a fist full of money! As an aside, QED offer a facility to find a donor engine and build it up for you to their “trackday” spec 180bhp for about 4000GBP. This is good value because it includes the DTA system, throttle bodies, cams etc and all the labour. You would need to get Caterham to erase the engine from your order (they should knock off about 4000GBP if you look at the engine prices in their starter kit brochure but I could only get them to shave the price by 2700GBP.)

Throttle Bodies

The standard induction is pants. Throw it all away and fit a pair of throttle bodies. Jenvey make nice ones (above) and QED have some form of deal with them, offering a multitude of different types. Lumenition also do some now too – I think they even do a set of roller barrels like the R500! You could buy some roller barrels from Caterham for 1600GBP if you like! Yikes! You’ll spend about 700GBP here and will get better engine response at high speed as well as increased flow for more bhp!

Exhaust System

The standard Caterham 4 into 1 exhaust that has the little single pipe coming out of the side of the body is very poor.

There is an ongoing war between advocates of 4 into 1 race systems and 4 into 2 into 1 systems. Dave Andrews reckons the latter is a better choice, as does QED, because they say that the better mid range torque it produces is worth the few bhp it costs at the very top end. My friend Richard Hackney, from JP Exhausts in Macclesfield – www.jpexhausts.co.uk , is an absolute expert on the design and construction of stainless steel exhausts and he tells me that in his opinion a 4 into 1 system, if properly designed and built, will gain a significant amount of power at the top in return for a minimal loss in the middle. His opinion also (and not hard to agree with) is that in a six speed sportscar weighing less than 500kgs it should not be too much of a chore to keep the engine in the powerband (!)

Roger King of the excellent 7 Workshop also is an advocate of the 4 into 1 system. Caterham’s R500 uses one too and develops 230bhp.

Cams and Head

The 1600 motor likes cams, and will give about 165bhp with the ECU, Throttle bodies and a pair of Piper (www.pipercams.co.uk) cams. If you want more then get the head ported and specify more aggressive cams still and you’ll realise 175bhp!

Don’t get the head ported if you are going for only a mild upgrade on the cams because it has been proven by Dave Walker from CCC magazine that this actually has a detrimental effect on power!

If you can find one, fit a VVC or VHPD head with the big valves and you should produce about 180bhp with a fatter torque curve.

Bear in mind that the ECU will need constant tweaking to get the best from these upgrades and beware any tuner that says “Don’t worry about that.” The last thing you want is a lean condition at 7500rpm held for 5 seconds down a long straight! (Hello pistons again!)

Pistons and Bottom end

Very nice new forged pistons about to go into Rich Ellis’ 7! Note deep recesses that allow valve lift the size of a JCB !!

At this point, you are about as far as you can go by just removing the head and now you are back to what I said initially; be careful buying parts you might have to change later. Now you’ve got to make a decision as to where the engine is going. It is possible to extract a few more horses by specifying forged pistons with deeper cutouts and then using an even more aggressive set of cams but of course you are now pushing the standard rods and crank!

For engine bottom end upgrades, look to Doug Kiddie for Billet steel cranks, and Arrow Precision engineering for uprated rods. Peter Carmichael, (owner of the 250bhp K powered monster 7) informs me that these two companies often work together to ensure compatibility of components, which is absolutely essential when you are spending anywhere from 2-4 grand on your motor depending on exactly how far you go! A set of forged pistons weigh in at 600GBP a set and there is a point to note that the R500 uses interference fit gudgeon pins in the pistons. This is a technique of securing the pivot pins that connect the pistons to the connecting rods. It has been critisised by several tuners I have spoken with who insist that a thoughtfully designed engine at this level should have removable circlips to aid easy removal when the engine is due for an inevitable “refresh.”

As a note, now is the time to ask your crankshaft man to sell you the crank as a 1.8 litre engine (no extra cost now, you see!)

Refreshes

Depending on who you speak to, a highly tuned K series will need a refresh (rings, head work etc) every 3000 miles. This sounds terrible but I think it to be a consequence of the varied use a 7 can get in terms of its propensity to become involved in “motorsport”!

I think common sense should dictate that assuming that service schedules are carefully adhered to, a road engine used occasionally on the circuit in the form of a trackday, and driven to sensible, self imposed limits, will last a very long time and not be subject to the loads that can wreck a race engine in 20 laps.

Conversely, the customer that buys a new R500 and bounces it off the rev limiter from stone cold every morning will soon be spending a never ending flow of money.

There are people out there without an ounce of mechanical sympathy and it is, in my opinion, these people, who seem forever to be blowing something up.

Oil Choice

The official choice of Caterham for the K series is “Comma” Semi Synthetic Caterham oil. Rover specify 10w40 for the K series in whatever form you like. Minister Power also recommend “Comma” as above but have no problem with customers using Mobil 1 Motorsport 15W50 oil. Valvoline make an absolute cracker called Synpower that I personally have used in many high performance cars and never had an issue with – it is 5W40 rated, so just a tad thicker than Mobil 1 0w40 that some people use in the K, but has Rover’s recommended 40 viscosity at high temperature.

The thinner oils are apparently better in K’s with hydraulic tappets – the VHPD one has mechanical valve actuation so doesn’t need the lifters pumping up in a morning. The downside is that it sounds like a sack of spanners at low RPM!

Conclusion

There we go! Not the best or most comprehensive guide to tuning a “K” but I’ll update it regularly as I go along and hopefully it is of some use to you as a simple set of guidelines or ideas to work from.

The best place to look for much more technical help tuning your K series is Dave Andrew’s almost legendary website.

http://members.aol.com/_ht_a/DVandrews/kengine.htm

Here, Dave talks at length about methods, techniques and practical results gained from hours of personal tinkering and observing. I can’t match this level of expertise but I do feel that his page is centered around doing the work physically yourself as opposed to paying someone else to do it like most of us would have to!

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