Mike Brocks..MG Maestro Turbo..web site! Under construction!!

How To Get 200BHP From your...

Maestro

The information I have given on this step by step guide is from my own exsperience, I am no way claiming to be an expert!. All content on this web page is correct to my knowledge, although I will be happy to hear from anyone that may think some info is incorrect. Basically, if you blow your engine, don't come running to me, I will not be held responsible for any damage to your car!. If you are not 100% sure about any of this tuning info given here, then you're best to leave well alone, and seek help from professional engine tuners.

It goes without saying, I know, but, it is highly recommended that you speak to you insurance company first, before any mods are done to your car. As soon as you mention that you're about to tweek your turbo, you will probably find they don't want to know, it pays to tell your insurers everything!,

Make sure your engine is in tip top condition before you start tweeking the turbo!. No point trying to get more power from a sick engine, as this will only highlight other problems. Make sure you change the cam shaft belt to be on the safe side!. The modifications in this page are for a max boost level of only 14PSI, this is the highest you can go, if reliability is the order of the day. The standard cylinder head gasket is weak, any more boost over 14PSI will result in gasket failure in a very sort time! even at this boost pressure, there is no guarentees that the gasket will hold out!. I consider this 14PSI turbo tweek as Stage One tune.

Before you start turning the boost up a word of caution. The more air that's forced into the engine the leaner the A/F ratio will become. This normaly means if you don't re-calibrate more fuel to more boost, there will be a possiblity of engine melt down due to engine running weak. It goes without saying, if your not to sure of what you are doing leave this job to the experts, preferably ones with a rolling road. They will re-profile the needle valve in your SU carburattor to allow more fuel in to more boost accordingly.

Performance air filter is needed to let the engine breathe properly, the one seen above is a Pipercross cone type. This filter is mounted where the standard dust bin cylinder air box normally sites. you will need a bracket to mount the cone air filter, this can be seen on the images above also. Induction roar is very high with this filter, and I found this very difficult to live with, also it draws hot air in due to its close approximatey of filter to engine block. I decided this filter arangement was not ideal, so it was removed in favour of standard arangement, but, with other mods to it.

The standard dust bin air filter arangement acts as a good cold air box, but the air flow feeding into it is not so good. There is a natural opening above intercooler that leads directly to front grill. Obviously this is a high air flow area and air only needs to be channeled to the air box from this. A drain pipe is ideal and costs nothing, with the added benifit of being the right diameter to sleeve over the boss leading into the air box!.

With the front grill removed you can see that I have used an air scoop to funnel all that cool air directly into air box with no restrictions. This air scoop was made from a 10" house gutter, that can be found in any DIY store. It sleeves into the drian pipe perfectly but, don't fix the drian pipe to air scoop with clips, as movement is needed at this joint. A performance foam air fillter is used inside air box to complete modification. Theres a big improvement over cone air filter arrangement and with no induction roare!. The air scoop rams cold air into air filter box and is very effective at higher speeds.

Before the boost is turned up it is recommended that the exhuast system is replaced with a better performance one. The one seen above is a full stainless steel Scorpion system, although the tail pipe is 4" the rest of the system is only 2 1/2" !. Turbochargers don't like exhuast back pressure, the best system would be a 4" full bore system but, unfortunately you will have to make your own. After all the above mods are complete, you will have a good basis for further tuning, your engine will be breathing much more efficiently, and will feel much more responsive on throttle.

Before you start tweeking the turbo boost, you will need a good boost guage. This will allow you to moniter any gains in boost or make sure you don't over boost the engine.

The actuator rod that controls the boost level can be found on the turbocharger. As seen in the jpg above it's the long threaded diagonal rod that controls the wastgate valve. You will see the rod is connected to the wastegate valve by a C clip. Before removing this, first loosen the 10mm nut on the actuator rod, then after C clip is removed,the rod can be pulled off the wastegate valve lever, but be carefull as the actuator arm is under spring tension and will spring off towards the actuator housing.

Now the rod can be shortened by simply screwing into the hollow tube to wastegate end. About every 1- 1/2 turns to 1psi boost gain will be noted, approximately. This is the point where you can be silly and shorten the rod too much, only to discover later that you will need arms like King Kong to pull actuator rod back over wastegate valve lever!. 14 psi is realistically the highest boost level you can go without the need to uprate cylinder head gasket, as I've recently found out!.

Another method for uprating the turbo boost is the bleed off valve kit. This bleed off valve can be mounted inside your car without the need of all that bother of shortening the actuator rod. However, the temptation of just that little extra turn for more boost can be over welming for some!.

After re-boost to 14psi the SU curburattor needle valve will need to be re-profiled to allow more fuel to be burnt. This will involve you having to file a new profile to this needle valve in such a way as to get the right air/fuel ratio balance across the rpm range. Best method is the use of a rolling road tuner, but satisfactory results can be obtained on a DIY basis if you view the colour of your spark plugs. Obviously the colour of the plugs is a good visual indication to what the A/F ratio will be. To do this, you're best to fit new plugs to start with, then find a straight bit of road, prefferably on a hill, then once in fith gear hold throttle open for a few seconds to allow full boost to build then close throttle off. Let the car free wheel to a stop if you can, then check colour/condition of plugs.

On the supject of spark plugs, due to more heat build up within combustion chamber with more turbo boost, I think I can safely say that you will need cooler running plugs. Champion RN7YCC are standard, but a much cooler RN8YCC with gap re-set too 6.5/7.00mm to stop the spark blowing out on high boost. Of course it's really up to the individual what type of plugs work for their car, but, the cooler Champion RN8YCC will give me peace of mind if nothing else.

Uprated Magnicore HT leads work very well with the O series turbo engine. It may be a good idea to fit a new distributor cap and rotor arm to be on the safe side.

The O series turbo engine has it's own dump valve as standard, this can be found in the plenum chamber on carburattor.This work's by reliesing boost pressure on throttle shut off (gear changes) at a predetermint boost level, normaly 12.psi. Remember, the standard maximum boost pressure on open throttle is 10psi, but, this has now been modified to 14psi. This will mean the dump valve has the potential to leak boost on open throttle causing power to fall away. The spring that you see in the picture (3) needs to be modified to allow more tension to push the valve shut against plenum chamber. There are three methods to do this, the first is to stretch the spring (3) not recommended. The second method is to fit washers in between spring (3) to back plate (4) this method will work very well with the added bonus of being able to return to standard if need be. Finally, you can remove standard dump valve componets from plenum, then blank off hole with washer nut/bolt to allow the fitment of after market dump valve kit.

A little comment about plenum dump valve modification, it has to be said I was running over 14psi boost with no modification to this standard dump valve. All was well with no leaks, but other MG Maestro/Montego Turbo owners seem to favour this mod highly, with good reason I bet. My point being, only modified if it's found to be leaking boost.

The images above is an after market group A dump valve with fitting kit. The idea is that the dump valve helps reduce turbo lag inbetween gear changes, however, no difference was noted, but the sound it make's is worth fitting it alone!. Remember, blank off the standard dump valve in plenum chamber after your new dump valve has been fitted for best results.

The standard intercooler will need a little modification done to it for reliability reasons and better air flow for more power. Strapped intercooler img close up. This modification is very easy to do, and will allow over 14PSI of boost, without plastic end caps blowing off. If you look closer at this jpg, you will notice the plastic end caps are simply held together with jubilee clips. Before this little mod was done, I removed the end cap, then removed the temp flap for better flow of air though the intercooler. Plastic moulding was also removed within end cap for flow. On reassembly, I used Silicon sealent, for a better airtight seal.

After all the above modifications are complete, there should be over 200BHP at the flywheel with an estimate of 180BHP at the wheels. To put this into perspective a 4x4 saphire Cosworth only has around 170BHP at the wheels and weighs much more than a Maestro!. 0/60 for the MG Maestro Turbo will be in the low 6 secs and top speed is over 145MPH!. Remember, this is only really a stage one re-boost. Even at this modest engine tune the car is incredibly quick, it truley can out pace most modern high performace cars on the road today. I have deliberately left out information on modification to brakes, clutch, suspension, radiator, as those will be featured else where on my web site soon.