MG British Sports Cars I4 v6 v8 Conversions and Modifications

Written by Jon McCullough

First, lets start off with introductions as I feel it appropriate to do so.  My name is Jon, the younger brother to Brian McCullough (proprietor of BMC British Automobile). Having grown up in a British car family surrounding my every day life observing my dad and brother work on cars since day one, I did not have any interest in cars until I went out and bought my own.  Although I bought the alternate to a British sports car, I did go with a classic Porsche 924.

My automobile passion is the same as my dad and brother: modifying the car, looking under the hood, figuring out what to do next. It's always a pleasure going to car community events and I found that I am welcomed to British car community events even with the lack of Lucas Ignition and SU carbs.

After doing all I could to "that little 4 cylinder that could", I opted for an engine conversion which allows me to share the experience of modifying just about any vehicle as well as observing the pit falls and triumph's (no pun intended) of engine conversions.

Throughout this article I want to share some thoughts I have about any modifications you may consider and be able to get somewhat of a external view to the inside world of modifying your British pride and joy.  Today we will focus on driveline alterations, having a mild focus on any modifications and conversions but will point towards British car community as we continue. Sit back, relax, and enjoy the ride!

 

The Big Conversion and Modification Decision

Converting your sports car's engine and driveline is a fun, yet interesting task. You desire a reliable sports car and perhaps adding a few extra horses under the hood. Some long for the reliability of today's new technology and want to find out more about engine modifications and conversions as an alternate, so we want to break the barriers and do a side by side (as unbiased as you can get) comparison of your options.

The End Goal

Besides continuing to run with the standard engine in your car, either keeping it stock or modifying it until the cows come home lets look at some modifications and conversions. It's fun to think about swapping an engine; perhaps adding a few more cylinders with a drop-in v6 engine, to a full blown supercharged street stalking v8. Really, It comes down to your end goals for your vehicle and the cost/time involved to get to that goal.

What To Evaluate

This is your car. This is your pride and joy. The first thing to question is what do you want to spend for time and money, and if it is worth it. The more aggressive modifications you do to stock components, the more likely you will be spending more time away from family and be spending additional money maintaining components that are above factory specs.  I like to call these issues "hiccups".  From changing spark plugs to adding superchargers: Any and all alterations requires close attention to detail and a quality job so these need to be top priority.

Horsepower: More Then a Simple Number

Isn't it amazing that some of these newer small displacement engines come out with high horsepower figures? We think so. But when you look at it further, they lack the torque to back up that horsepower figure. And as you know, torque is the real number to look at. Torque is what you actually "feel" and what puts you back in your seat when you put the pedal to the metal.

 

Power To Weight

A vehicles weight also dictates how fast you get up to speed. Just because someone installs an engine with 25% more displacement then yours doesn't reflect the percentage distance they will be ahead in a drag race. A simple way to think of it is the total weight of the vehicle and the power it has to back it up. Bigger engines typically bring extra horsepower, but some of that power is lost due to extra weight of the many larger engines.

 

Mileage

It's a sports car. If you chew threw a gallon of gas every 15 miles, that's not so bad, right? We want to remind you: This is your project. The more weight and additional power the closer you might be to a gas-guzzler. Of course this all matters on many law of physics; but this has been the concern of even the weekend driver. Enjoying your ride is the end goal and if your too concerned with going through fuel fast, keep this in mind.

Cost

This is not just dollars and cents. This is blood and sweat. Your time and energy. This is your ride undergoing surgery. Something that can be very personal for some. You need to make a decision on what sort of cost involvement you want to put in and be prepared for the unknown costs of less documented alterations and conversions.

 

What To Watch For

When doing any alteration, or heck, for that matter anything that needs replacement, repair or restoration you need to be cautious about using lower quality products and services.  This is THEE reason any modification get a bad rap.

There are resources out there for most modifications and conversions, so make sure to listen to the expert in their area of specialty.  It's never fun being half way through a project only to be held up because of an incorrect part of procedure that you thought would save you time and money.  The specialists have already found the best way to do the process the right way and are actually saving you time and money when you go directly to the source.

 

Engine Options

Ohh where to start! There are as many options as there are engines out there. We are going to keep it simple and go with the popular options that people have found work successfully (and even not so successfully). This is a HUGE decision and just because a lot of people go one direction or the other doesn't mean you have to be a follower. The three biggest options are:

• Modify the standard engine
• Convert to the GM 60 degree v6
• Convert to the Buick 215 V8

Other popular conversions are:

• Convert to the Ford 302 v8
• Convert to the Miata I4
• Convert to the Honda S2000 I4
• Convert to the Chevrolet LS series V8
• Convert to the Unlisted

Let's go with the most popular options first.

Engine Options: Modify the standard engine

Lets face facts: Most vehicle owners do not convert their vehicles driveline to a different automobile manufacturer. Instead they tinker with the engine that was installed from the factory until the day they pass it on to the next generation (or get frustrated and drive it off a cliff).

Some people are satisfied with the factory horsepower, but you want more; That's why your reading this. That or your bored out of your mind. Modifying an engine with bolt-on modifications can provide a better rev range and give the car some get up but just don't expect it to be significant when you compare it to an engine swap.

Of course drastic changes to the factory engine such as larger bore and stroke, cross flow heads, and superchargers are fun. This usually adds to additional overhead and maintenance. Weak links in the chain are discovered and you need to address them as they come up. This can take away from the experience of your car (read: Ambulance at the bottom of the hill). You can also try to plan ahead and find you will spent far more then you intended for a higher horsepower engine only to be dominated by a drop in engine conversions mileage, power and reliability. The typical rule is when you start to alter the engine beyond what the factory intended issues follow such as mileage, driveability and reliability.

Now of course you can replace old technology with some of today's new technology and drastically improve all of the above.  Doing this of course makes for a very pleasant experience.  Some alterations could be ignition system updates, high torque starters and different fuel pumps.  Whatever it is, older automobiles can be improved with some of today's technology so you can take pride in keeping your sports car a fine road worthy example for years to come.

Now if having significantly more horsepower then the standard engine can reliably produce is your cup of tea, you might want to read on.

 

Engine Options: Convert to the GM 60 degree v6

Simple. Easy. Even a cave man... ohh you get the point. With the least amount of alterations to the body (and for many cars no body alterations) and the cars driveline this is one of the fastest and easiest installs when compared to any other engine conversion. The GM 60 degree engine swap is not only becoming a popular choice, it's one of the top conversion desires for British sports car owners. Horsepower and torque figures are greater then other conversions and engine availability is within minutes from your home.

Drop in engines with no or slight alterations give you the power to merge into traffic with ease and get down the drag strip or race track. Forget the Honda Civics. They aren't an issue. The only issue is wiping the grin off your face with stumped look the person in the other lane has having lost to a 50 year old car. And while everyone else is stopping for fuel at the gas station, your able to go further then your v8 conversion friends.

Not only have you spent the least amount of time/money getting your sports car converted, the average GM 60 degree is neck and neck at lower speeds when compared to the heavier Ford 302 conversions and at higher speeds almost as fast (and by fast we mean close in a drag strip). And depending on the v6 choice, even faster then the same 302 engine of the same generation. Taking the fun further, if you desire more power for the 60 degree engine there are plenty of easy to do upgrades. The exhaust note is excellent, and depending on muffler choice can be as loud or quiet as you desire.

 

Engine Options: Convert to the Buick 215 V8

In stock form the Buick 215 V8 has slightly less power and has a difficult time revving when you compare it to the average v6 conversion; modifying the 215 just a little will get it slightly more. If you get into the 3.9 liter or larger Buick engines you can leave the older v6 conversions in the dust.  The main difference is the Buick engine is old technology compared to the newer GM 60 degree v6 engines.

With the 215's British heritage built into a few thousand factory vehicles you can usually get British automotive support.  Although the costs and availability have slowed the use of this motor as a conversion choice in recent years people are still making this the choice of engine for their sports car.  Don't get it wrong; a good engine conversion such as this deserves a round of applause and if you or your mechanic can support this driveline this might be a good choice if you want to follow what many British sports car conversion owners have done. This is your project.  Take pride in the craftsmanship of your ride!

 

Other Engine Options: Convert to the Ford 302 v8

Displacement usually wins, so if you start down the v8 road you will find you need more installation time and money when compared to the GM 60 degree v6. Depending on your budget and how much time you put into this and the Ford 302 v8 conversion will pull away from the stock GM v6 engine conversion at higher speeds. After the initial installation, the cost per horse is less then the above GM v6, so if you are mad with power, this is the route you may want to go (although if you are insane with power, consider the GM LS series of v8 engines as well as a second job and second mortgage- more on that later).

Although the Ford 302 is heavier then the V6 it is a little faster at higher speeds when compared to the same generation GM v6 conversions. It is recommended to do suspension upgrades to get the power to the ground and so higher speeds won't make you feel like your floating away to go see "The Wizard of Oz". Of course this conversion requires far more time and money when compared to the v6 conversion, but for the strong willed, this can be a good choice. Be prepared to modify your sports car with body alterations depending on how far you go. This conversion is very cool and has a great exhaust note to it no matter the decibel level you chose.

 

Other Engine Options: Convert to the Miata I4

The Miata engine is going to start off being lighter when compared to the MG B engine and have a little more power.  Enough to make the car nimble but nothing spectacular.  Engine reliability will go up drastically compared to the factory British engine and mileage improvements are to be had.  In the end you are looking at the same time and money as the more powerful GM 60 degree v6 conversion.

Engine availability is up there although the costs are higher compared to the other conversion options.  If your goal is an improvement in acceleration, better gas mileage and a car that cranks over every time, this could be an option.

 

Other Engine Options: Convert to the Honda S2000

These engines are a revver!   Your sports car will have some get up and go with a Honda S2000 engine swap, although the torque is not everything in the world you would desire.  It's enough to put a smile on your face, merge intro traffic and run down the drag strip with some excitement in the air!  Engine reliability will go up drastically and mileage improvements are to be had.  With cost and availability of the engine and parts it is not as cheap of a project and process.  There are better engine conversions for the money to be had.

 

Other Engine Options: Convert to the Chevrolet LS Series V8

We saved the best for last.  Also the most expensive.  Forget any GM v8 engine of the past.  The Chevrolet LS Series engines are light weight compared to the past engines and produce great horsepower.  With great power comes great responsibility.  That responsibility means beefier everything.  From suspension to tires to frame; you'll need it.  You want the biggest baddest B on the block?  This is your choice.  Prepare to sell your left kidney, your first born, and buy lots and lots of diamonds for your wife to distract her from the amount of time and money you will be heavily involved in this process - but guaranteed - you will be respected.  Vipers, Corvettes, meh...  See ya later.  But I suppose this also means see ya later to your wallet as you will need a wide body kit to fit the fattest tires possible.  A light car like this will need as much help as it can get.  A modest LS1 with a camshaft upgrade will result in never needing caffeine any more.

 

Other Engine Options: Convert to the Unlisted

It's your car.  Do with it what you wish, but as you enter this unknown world you will need to invent the wheel all over again.  For the adventurous and those that are backyard mechanics who have nothing but time you might like this.  Most have plenty of frustrating moments and the process usually takes significantly longer then what anyone could imagine.  The end result of this conversion is completely up to you.