|
| Online Projects |
| |
| MGB V8 4.6 Power Upgrade. |
|
A Classic MG Roadster, Traveled in from
Germany
After so many weeks of deciding an
exact power upgrade for this 4.2 MG Roadster, It would seem our better judgment
prevailed once again.
Before it came over, it only had 132 BHP (4.2Ltr) No wonder the owner was not
impressed. So I new we could do loads to help, but It was not until it arrived
and we got deeper into its actual status, that I really new what.
|
 |
|
|
|
 Piston
bores are contaminated, The raised area of the engine numbers is required to be
removed to facilitate the fitting of approprate Headers.
|
Careful Measuring the bores,
however reveals that the stroke of this engine is that of a standard 3.5 or 3.9
so with the 94mm Pistons we now know it is only a 3.9. |
The contamination on the original
engine's surface is also very bad for such a low mileage engine.
This is a very unhappy engine, |
| Hands on, The customer finds out the worst
for himself, |
|
This M.G. Roadster 4.2 , as you can see,
turned out to be only a 3.9, also the plenum mods carried out by, Its no wonder
this engine produced no more than 135bhp.
Before the engine had been seen, the original plan (plan A) was to
improve the injection system (as with all stock EFi V8's and tweak the 4.2 with
new stage 3 heads and Piper 285 cam. (obviously this was not going to happen,
so nothing left for it but to resort to plan B)
Plan B. Take it all out, fit a stage 3 4.6 with A Weber 500 and Mallory
ignition.>
We soon realized that it would not cost much more to put a whole new 4.6 stage
3 in, Run it on the Weber Carb. system ( Plan B) and there it was, up to 270bhp engine and a very very happy customer. The
above & following pictures, show some of the problems with the original
3.9/4.2?. engine. we have many more pictures that should appear soon.
|
|
|
| By this time he had nearly had enough!!. |
The owner, Hands on. |
Very Weak Mixtures. |
Now its better |
| The results of preceding mods to the
injection system, show clearly how weak this engine has been running, The
Valves in the Heads show it all. |
And close up shows center Cyl's are weaker
still, it's lucky the unequal combustion of this engine has not already caused
a complete failure. at best it has been running very
inefficiently. |
Anyway once the Rpi 4.6 engine is in then
nothing else matters, and all things before it are just another learning
experience, not only for the customer but for ourselves too., Who knows what
will turn up next?. |
 |
Now its all over, The engine you can see here Is a complete replacement RPi 4.6
Stage 3 With Weber 500 and Mallory ignition, and considering what the customer
has been through with his previous engine. He is now a very very happy Man.
With at least an extra 100Bhp on tap, and improved fuel economy, It just shows
that a happy engine is an efficient engine." The
Owner, Looking Very pleased, as you would expect".
|
|
 |
Happy Now ?? he certainly
looks it., You
bet. There is nothing to match the character of a 60's sports Car (MGB
Roadster) with the immense torque and drive-ability of a 4.6 V8,
It's so unstressed an engine this car could be used as shopping trolly In
Tesco's, or a "Street racer" to rival anything on the
road.
But the ultimate is That "Big Big" sound of
a Large V8. coming ever closer.
|
|
|
Prices do not
include local EU.Tax.(VAT).
Prices & stock are subject to change without notice. Information and
advice, as always, is free.
|
|
|
|
