6 replies to this topic

[Pavel]

Okay I just bought me a MG lump (apparently rebuilt, but I dunno how well ;p). Has a new oil pump and was checked so I'm assuming it's fine since I know the guy that I bought it off!

Gonna run a compression test on it next week, and then start removing it from the car.

Incidentally I just acquired a bunch of turbo parts off ebay, and am considering turboing this engine and driving it till it goes (100 pounds for the whole car isn't bad at all i think). That also means that I can use the MG carb/inlet on my current engine

I'm assuming the MG unit has a compression of around 9.4:1 so would it be okay to turbo this using the standard turbo gear?

Ill be rebuilding a brand new engine from my GT block throughout next year, but I want to try out forced induction as soon as possible...

Is it just a matter of dropping the turbo stuff onto the engine after modifying the bulkhead, running a return fuel line to the tank, uprating the existing fuel pipe, inserting a fuel pump and regulator?

Expected power from this lump?? (it's the big valve head MG version, not the unleaded one).

Cheers

[Dan]

As far as I understand there are several differences between the standard MG mill and the Turbo, including the shape of the combustion chamber and the oil pump.
If you want a motor that will last any time then it's best to build one with the turbo in mind I think. But if you just want to try it out it might work for a while, although it won't give you a fair assesment of what the turbo can do at its best. If you do go for it, at least change the pump to make sure the compressor gets enough oil or you'll knacker that and have to get another one.

[Turbo Phil]

The normally aspirated MG lump has a compression of 10.5-1, the Turbo lump has 9.4-1.
You will ideally need to lower the compression if you are using the normally aspirated engine, to at least that of the Turbo engine, or lower depending what kind of boost you plan to run.
The shape and size of the combustion chamber is the same, measuring around the 21.4cc mark, so whichever head you use, Turbo/non Turbo, you'll still end up with the same compression. So to lower it you'll either need to use lower compression pistons. enlarge the chambers in the head or a combination of both depending what you're trying to achieve.
You'll also need to use the Turbo dizzy, or have yours modified to suit, as the advance curves differ.
Here's a list of other things you'll need to do - turbo-mini.com

Hope this helps.
Phil. :grin:

[Pavel]

Can I run 4psi at standard compression?

And how bad is it to run with the standard MG dizzy? because I'll have a hard time finding a turbo dizzy around here :S

[Turbo Phil]

Can I run 4psi at standard compression?

It's one of those try it and see what happens situations, but personally i wouldn't run a Turbo engine with a compression ratio that high. Why not just spend some time working the chambers to drop the compression to a safer level ?

And how bad is it to run with the standard MG dizzy? because I'll have a hard time finding a turbo dizzy around here :S

The normal MG dizzy will give a greater total advance than the Turbo one, if you run this you'll be asking for trouble. You need to limit your total advance, you can do this by modifying the dizzy yourself. Somthing like 25degrees at 5,000rpm is usually safe, but may not give the best power. Can you get it to a rolling road ?

Phil.

[Pavel]

No rolling roads around here

What about strapping it on a regular HC metro engine? 9.5 compression as far as I know...

[Dan]

Oh, I thought that turbo heads had a small area of the valve shroud removed between the valves giving less of a cardioid combustion chamber to avoid this area burning off? But I only heard that from someone and you know turbos better than I.