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MG MGB Technical - Why no Turbo?

I know that the turbos work a heck of a lot better with todays fuel injected engines. Now that Moss has an FI kit for the B. Anyone put a turbo on it?

Is there a way to turbo a carburetted engine? I know that would be difficult with the twin SU's but what about with one of the aftermarket single carp manifolds?
Bruce-C

Single carp, no, you would be better off using one fit for porpoise and make sure you use a good seal. Mammals breath better!
PHIL

Post in the super charge section. I saw photos of one person who did it.
If you hunt around the how it was doen articles you'll find it eventualy
http://www.britishv8.org/index.htm


I suspect that in order to make the engine even remotly reliable you'd have to do a high performance rebuild. This is an old design motor keep in mind, '50's tollerances. At that point a V8 swap starts to be competitive cost wise, and there's no way a turbo can compete with the huge torque and feel of the V8.
Peter

I'm no expert on turbos but no doubt it would be possible - in the B I guess it's just easier and probably cheaper to go the well-troden V8 route. The 1275cc A-series was used in turbocharged form in the MG Metro Turbo and the B-series isn't a million miles away in design.

See: http://www.mgownersclub.co.uk/mg-metro-turbo.html

Extract:

"The engine was fitted with a Garrett T3 turbo on a specially designed and cast exhaust manifold. Compressed air was delivered to the single carburettor that was specially modified to run with pressurised air by having special sealing and a variable rate fuel pressure delivery to ensure a constant positive 4psi fuel delivery pressure whatever the operating pressure was. The engine was also significantly strengthened with materials and processes common to competition engines with many Turbo only parts such as the cylinder head, pistons crankshaft, block, sodium filled exhaust valves, etc. This was a pretty unique engine yet when fitted into the car it didn’t look that different.

The Achilles heel for the Turbo was the 4 speed gearbox as the engine was in simple terms too powerful for it. To try and compensate for the weakness Austin rover developed a two stage electronic control for boost to try and soften the impact. The problem was that peak torque with even low levels of boost would damage the gearbox so boost was set on the wastegate at a low 4 psi. However, at 4000rpm or higher an electronic module would allow a controlled leak from the sensor hose going to the wastegate and would allow air to ‘leak’, so that the wastegate actuator would see a lower pressure and would not lift the wastegate valve off its seat. That allowed the boost pressure to rise and only when it reached 7psi would the module then close off the ‘leak’ and allow the wastegate to move. It would then modulate the leak to maintain this raised boost pressure until rpms dropped below 4000rpm."

Cheers,
Tim
T Jenner

The turbo set up from any of an MG Metro Turbo, MG Maestro Turbo or MG Montego Turbo could be addapted with suitable manifolds. They all used special single SU carbs. I guess the Montego or Maestro equipment would be better as it was a 2000cc engine and the Metro was only 1275cc. The MGB exhaust valve and exhaust port would benefit from being openned up in the same way Peter Burgess does for those using the Moss supercharger. If I was doing this I would also go for mapped ignition such as Megajolt or Megaspark if you want to keep the distributor.

I have almost talked myself into it! I have some low comp pistons on the bench out of my ex California car.

Bruce, you main problem will be that the MGs with turbos never crossed the atlantic.

David
David Witham

"but what about with one of the aftermarket single carp manifolds? "

Try one of these - http://mk1-performance-conversions.co.uk/images/reece_1.jpg
Paul Hunt

injected,turboed, but hrg cylinder head
regards


mw michel

I believe there was a special purchase of the last of the UK MGB's that were turbo'd. Can't exactly recall who did it - it may have been Tickford. I've seen pictures. Turbo's are notorious in that they need very high amounts of proper engineering to get right, what with detonation, pop-off valves, ignition advances, etc.

Carbureted engines have been turbo'd via "blow-through" and "suck through" configurations. Blow-throughs must be encapsulated the carb in order to maintain the seal (see Pete from Southampton's remark). Suck-through's are simpler and more ofen used - although some systems from the 50's and 60's used the sealed carb - I believe both Studebaker and Ford used them, albeit in supercharger installations. (I'm working from memory here - feel free to amend as necessary.)
John Z

There were a couple of turbocharged Spridgets at the 50th this summer, one used the Metro system and another was a home brew using a throttle body off of a late model car and controlled by a Megasquirt system. For a B you could use the later single carb manifold if you wanted or adapt to a dual carb as well or build you own as the Spridget owner did. The intake side would be a lot easier to configure with a TBI system, that way you wouldn't need to modify the intake manifold for injectors or a fuel rail. Getting the fuel maping right is another matter, takes some trial and error, perhaps expensive error, before you get it dialed in. The guy with the Megasquirt system drove to Missouri from Oregon IIRC and didn't have any problem with mixture even through the mountains. Photo of installation by Gryf Ketcherside:


Bill Young

Wow Michel,

Très impressionant!
Is it yours, how much hp? :-)


Alex
Alexander M

Oh no, the thought of an MG making that god awful 'psssshhhHHHHHHH!' pop off sound make me cringe :)

I have always liked the idea of supercharging though and once event went to the trouble of working out how to do it out using a Toyota SC12 supercharger and a single 2 inch SU.

Still have the 2 inch SU just in case!

Simon
Simon Jansen

Well done Paul, I forgot about the Reece, what a pilchard!
phil

Moss US offered a turbo kit for the B once upon a time. It's probably got to be about 20 years ago now. I've never seen one in the flesh, but do remember it in the catalog. IIRC it was a draw through.

I asked my sales contact there a few years before they offered the SC why they stopped selling it. He told me that too many people put them on clapped out engines to bring the power back up instead of doing a rebuild. A lot of those engines lived VERY short lives after that.

Tom
Tom Sotomayor

Just looked over the installation instructions for the Moss FI. This uses the intake manifold from the 75-80 MGB.

Was discussing this with a frend who has a racing shop for Mitsubishi's. He does not see why it would be hard to adapt a throttle body and FI system from something like the eclips to the MGB. With the FI, putting a turbo on it would not be hard.

Going to see if I can come up with a B motor that we can play with.

My friend says the electronics are not an issue. A lot of after market systems that are fully adjustable. You run the motor with a computer attached and tweek it to get the best power range.

Could be in interesting winter project.
Bruce-C

Bruce,

a turobo charger can be abbebd to a B-Series engine, but it will not be as efficiant as on a modern engine that was built to be run with a charger.
The B-Series does not have oil jets to cool the inside face of the pistons, it does not have adequate exhaust valves and might suffer badly from detonation. Lots of detail work on the manifolds, chambers and ports will have to be done too. Balancing and new bearings are essential...
You can also get a modern turbo charged engine at low costs from a donor car and place it into a B or stage tune the carb engine to equal power outputs as with a reyable turbo B, i think.

Ralph
Ralph

Alexander,
no, it's not mine, shot picked up on the web, I own a 1950 and it's well enough for me.
Regards
michel

"I believe there was a special purchase of the last of the UK MGB's that were turbo'd"

Personally never come across turbo'd MGBs that weren't done relatively recently with replacement engines as one-offs. Tickford did the Maestro turbo in the mid-80s.
Paul Hunt

A lot of misinformation going around here. A turbo isn't any different in principal than a supercharger, it is simply a compressor driven by the exhaust gas rather than by a pulley.

There is no problem using a turbo on a B series engine, and the same parameters apply as they do to supercharging - you can only go so high in boost with stock internals, after which you need to look at forged pistons etc.

It is actually easier to turbo a non-crossflow engine - did you look at that bloody long intake tract on the HRG headed turbo?

Just as for supercharging, you have a choice of blow through or suck through and the latter is much easier to implement. A 2" SU would work just fine.

With a supercharger you have belts and pulleys to worry about; with a turbo, you have to take care to keep everything vital shielded from the added heat coming from the turbo unit. Six of one....

The supercharger gives power from very low down in the RPM range, while a turbo tends to come in around 2000 RPM, but a properly designed system comes in smoothly - the turbo lag is a thing of the past unless your system is badly designed.

I'm sure Moss or another vendor could easily come up with a turbo kit for the MGB, but I expect that the supercharger has more appeal for the traditionalist, harking back as it does to prewar MG exploits.

I use a turbo on my V6 engine and it functions very well!
Bill Spohn

Bill,

as long as the engine is designed to be run with a Turbo or a SC you are right.
Remember those days of the upcoming chargers on the A and later on the B and think about the efficency they made, campare these figures with modern charged designs and with the possible gains of power of a well prepared ralley/race B-series engine or even a cheap 215-V8 swap, the charged engine is not that powerfull but will end up costy. A lot of detail work on the components has to be done to make it meet the results that the other choices will bring you.
With turbo charging the B, there is another problem still left: you will need very high quality of engine oil for it's bearings to keep it working and you have to cool it down when the engine is stoped or make use of a water cooled charger as Alfa Romeo did on the 75 with the 1800 dohc engine (~140 Bhp).
BTW, many official turbo engines have a seperate booster pump for the oil to cool down the bearings and it's packing after the engine is stopped.
I think, that it will not be that easy to find an engine oil that is adequate for the old B-series engine but 'High-Tech' enough to prevent damage to the bearings of the charger.

I still remember the BMW 2000 turbo in the early 1970's. Very powerful (170 DIN-HP) but they stopped production after 2000 cars made as it was a real problem to drive it. Without modern engine management, as it is usual today, the engine was not able to give a continious increas of power but the turbo kicked in suddenly. The behaviour of an SC engine is different to that. They still have one thing in common: poor mpg figures compared with modern layouts or the other alternative engines that can be used in a B.

Bruce is searching for a solution that works troublefree, i think, so old school stage tuning seems the way to go... as discribed in Abingdons Special Tuning Manual or in the BMC MGB Huffacker Tuning Manual.

Ralph

Ralphl

Hi to all!
I have been playing with turbocharged Bs for a long time and my results are really good. the most simple system is a blowtrough 32/36 weber.

right now i have a crossflow B with two 45mm webers in a blowthrough configuration with really great results, also i have made another one with programmable injection.

you need to take care o basic issues like colder plugs, pressure sensitive fuel regulators with efi type fuel pumps, never exceed 10psi and you need syntetic engine oil.

I dont know how to attach a picture here but i have some pictures to share with you guys.
at this moment i have a turbo manifold for sale since i had to fabricate a new one for my crossflow configuration. the efi engine made more than 180hp and almost 200 f/pound of torque at only 5000 rpm cause clutch was slipping.

Thanks
luis rodriguez

Tickford did the bodykits on the Maestros, not the turbo installation. The Maestro Turbo was the same as the Montego Turbo, and I had one of those. The engine was rubbish, leaked oil from new and blew the head gasket at 50k. Always ran hot. Aluminium head on a steel block - not good. And the bottom end was the same as the diesel, so it only revved to 5500rpm. Car was very fast in a straight line but cornering and stopping were a bit hair-raising.

Neil
Neil

luis,
souds good,
like to see the photos.
You need to log in. Top RHS.
Then up coes the attach option.
Do remember to tick the "don't show email" otherwise these mad Africans will bombard you with messages that you've mysteriously aquired millions of dollars and all you have to do is tell them all your bank account details.
peter

"Tickford did the bodykits on the Maestros, not the turbo installation"

Installation, yes, but they were involved with engine development and suspension tuning, see http://www.maestroturbo.org.uk/tickford.php. Ironically it was Austin Rover that designed the bodykits.
Paul Hunt

Sorry to be picky Paul, but the engine already existed - my Montego Turbo was a 1985 E reg and that was the 'second generation' installation with reduced turbo lag and torque steer. The first generation must have been exceptionally bad! According to the link, Tickford were engaged to see if the Maestro 'chassis' could handle the Turbo. But as the Maestro was near enough identical to the Montego then I'm not sure this was a tricky job. Although the answer should have been "no"...!

Neil
:-)
Neil

Better tell the owners of that web site then!
Paul Hunt

Ralph, peaky turbo engines that kick in suddenly went out with modern knowledge about turbo sizing etc. It is simply no longer a problem, and turbos come in quite smoothly.

The issues of reliability on the early units on Volvos etc. without water cooled centre bearings is also long gone.

As for oiling, of course these engines need clean oil, but then so should any engine. The ashing issue when you shut off the engine doesn't require a separate pump. It can be dealt with very simply and elegantly by placing a one way valve and a T in the oil line to the turbo bearing, and connecting a small canister (most use essentially an empty propane or fire extinguisher sized light weight cylindrical tank) to the T. When the engine is running, it pushes oil into the bottle. If you shut off after running hard without allowing the turbo to cool, it won't matter as the extra litre of oil that was pushed into the bottle will now be forced slowly (through a small orifice) through the turbo bearing, cooling it for perhaps 5 minutes. Normal oil (GTX etc.) is just fine for turbo use - been running it in my street turbo engine for the last 15 years).

The engine doesn't know whether it is being fed from a turbo or a supercharger - pressure is pressure. As I stated, with stock engine internals, you can't exceed a certain pressure, while with better pistons, higher boost pressures are possible.

There is nothing special about these old engines that makes them unsuitable for positive pressure enhancement, and in fact they are excellent candidates given the basically poor flow of the cast iron heads. The turbo or blower basically forces air and fuel into the engine, overcoming the shortcomings of the original design.
Bill Spohn

In considering a 'performance' engine rebuild, be careful what you tell the parts guys - be sure to use a LOW compression ratio on the engine. Blown/turbo'd engines are happy around 8.x:1, it allows higher boost before detonation. If you run high compression you won't be able to run much boost.
Sam

I have a running turbo MGB as well with a bored, cam'd and ported alloy head on a early 18V. She runs on the megasquirt efi system with the Extra code and EDIS plus an intercooler. Currently at 6.5psi. Went 9.91 @ 71mph in the 1/8 mile this past spring.

http://5700ccmgb.atspace.com/Roadster/runtime/runtime.html

Louis, what sort of connecting rod did you run in your 180bhp engine? Mine are stock 18v rods. I am wondering when to expect failure! I would love to turn the boost up to 12psi.
Rob

Hi Rob!

Send to me PM to my email, i wan to share some pictures and thoughts related to turbo MGB
luis rodriguez

This thread was discussed between 04/11/2008 and 19/11/2008

MG MGB Technical index

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