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MG MGB GT V8 Factory Originals Technical - Big Engines or Little Engines?

Depends on what you want in the end, but there are things to be said for both schools of thought.

The problems with using a large displacement engine in a small car (and I'm really addressing this not to the Rover V8 crowd, for that is sort of a medium sized engine, but to the SBC and Ford advocates) are that they produce prodigious amounts of torque low down and if you want to get any of that to the road, you need to resort to things like big wheels, big sticky tires, and body mods that make the end result perhaps a bit different than you may have intended (or perhaps exactly what some people had intended!)

A friend was in the business of installing new Ford V8 engines into Miatas for some years, and did road test the result. The 0 - 60 figures weren't far off what the same engine would do in a Mustang - all because there was no way to get the power to the road without changing the car so that it looked like some sort of transformer toy.

The other main school is to use a more moderate 4 or 6 cylinder engine, whether from an American car or an import. Some of the Miata and Toyota conversions are very pleasant cars to drive with power that is more or less up to date with what is on the road. I heard of one Lexus MGB that sounded particularly interesting.

A third avenue is the high tech small engine transplant. This usually means a 4 or six cylinder engine that produces lots of power, but less torque low down that the large displacement swaps. A bit busier to drive, but with less off the line problem and less driveline breakage - but that also depends on your driving style.

I am not a drag race sort of guy (I have been a road racer for over 30 years), and don't often indulge in stop-light grand prix because I am the guy that has to replace the clutches. For that reason, the idea of some of this last class of car intrigues me.

I seriously thought of using a Honda S2000 driveline in my Jamaican MGA swap, but just couldn't find one.

I like the idea of MGBs with a nice little Ecotech with 200 BHP at the wheels, and I become positively excited when thinking about a nice space frame chassis with an MG body (MGB or MGA, pick your flavour) covering a 4WD Subaru WRX driveline......

It should be interesting as people increasingly explore some of the new high tech engine options.
Bill Spohn

Amazing how people like to make things so....complicated.


Bill, You are quite right - high power MG V8's have a traction problem - especially if you pin the throttle in first or second without wide or sticky tires. But most owners are not trying to build 0-60 dragsters - you could buy a motorcycle for a fraction of the cost that would just disappear into the distance.
What I wanted to improve was the lack of torque in mid-range driving on a windy road. The MGB/C have such good inherent stability and manners that they practically cry out for a bit more grunt at crucial moments. And that is what the V8 provides - instant urge without a six-speed gearbox and/or a short diff.
Just keeping the rear tires on the edge of adhesion on your favorite hill is possible so easily with a torquey V8 and is not nearly as much fun with a "screamer" with a narrow torque band. Not to mention relaxed driving on longer trips!
But each to his own. Possibly a narrow angle V6 is the "best" compromise as the engine is so small- makes a very easy fit in the bay with lots of room for good cooling but still provides the power of the smaller V8's.
Clutches probably have an easier time on the V8 engines as they were generally designed for heavier cars.
I still wait for an M-3 engine to turn up at the Wreckers! Bob Elwin MG 302
Bob Elwin

All I can say is, once you've had it you *will* miss it. So if you *want* to be happy with something reasonable or practical, for God's sake don't be tempted to put in more. This is from personal experience. Having first started out with a screamer Buick 215, when I broke a piston skirt and spun a rod bearing I had to fit the backup engine, a low powered 2bbl Olds. And it just wasn't enough. Actually, it *was* enough, it was more than enough. But you see I'd already been spoiled. So the Olds got a turbo, which made it unpredictable in the corners, and then it got replaced by the torque monster blown, intercooled and injected Olds. And this beast exceeds the performance of the old Buick by a pretty wide margin, so now I'm spoiled once more. But you are right, traction is an issue. Even with wide tires, even in high gear, and even at freeway speeds. Do I care? Only in the sense that throttle induced oversteer is never more than a step away, anytime, anyplace. Would I go back? Oh God, Please, NO!

Jim Blackwood

I say "Speak softly and carry a big stick and you will go far", or was that said by Teddy Roosevelt?

Doesn't matter, what I find as a good compromise is to put in the most powerful engine you can and if you can't get traction gear it down a bit.

My 269 ci 62 Olds Turbo Block "stroker" engine, built by Dan of D&D with a 225 HP shot of Nitrous and World Class T5 could smoke the tires through all 5 gears with a 3.9 or 3.55 to one rear but with a 3.0 it is actually a little on the tame side out of the hole if I don't floor it (but then I'm used to riding motorcycles).

As a side benefit at 80 mph I'm only turning the engine at less than 2500 rpm.
Michael S. Domanowski

Bob - as you mention an M3, take a look at this:

Yes, I like the 60 degree V6 as it fits more easily and will give the same power as the larger 215.

And I get what you guys are saying about torque, but that isn't all there is, you know.

I have a Jensen with over 450 ft-lbs. of torque, and I also have a Lamborghini that weighs a similar amount and 'only' has 290 ft-lbs. I enjoy each one, and wouldn't want to give up either, as the experiences are quite different.

My point is that there is scope for both in MG swaps as well - an S2000 engine in an MG would be more fun than Miss January in a tub of grease......
Bill Spohn


There's been no mention of perceived speed yet. I would prefer the feel of a 3.5 litre engine at 6000rpm, producing 225bhp, to a 4.6 at 4,800, producing the same power level.

You don't quite get that 'Days of thunder' feel at the lower rpms.
J E G Eastwood 1

Well said Jim.
Even if you could get the traction on a short wheel base MGB it would go in every direction but straigt, just like a gas alter.(use to race one witha 427)
I have a 74 B with 225 hp 200 lb of torque 3.4 V6 and is plenty to keep up with about just anyone in the fwy and stop to stop light fun stuff, it's also fun to drive anytime.

Putting a S2000 engine in a B would be going backwards, it would be best to keep the S2000 as it
it's and enjoy the balance of the car. If I want hot performance I would be looking at other options were high power is mathced with the chassis. But you can build a hot MGB with a tube frame etc. so that the high output engine is useable. But hey! it's always nice to have something different.
Bill Guzman

Bill - great idea!

Now we just need to find a wrecked S2000 and a source of plastic MGB outer body panels to graft on so we have a completely updated MGB!!

I like it! Saves creating a tube frame!

I'd be inclined to disagree with you a bit more if we were talking about a chassis that was a bit more advanced than the cart sprung MG, though. MY recently departed 1963 TVR with all independent suspension would have taken much more interesting drivelines without needing nearly as much updating to suit.
Bill Spohn

I'm toying with the idea of putting a Ford ZTEC engine in a MGB. Used engines and performance parts are readily available. The 2.0L SVT version is rated at 170HP @ 7000RPM. And there's always that Caterham Supersport version at 200HP...
CDD Dewey


I had the 170PS Zetec engine in a Focus ST170, it's capable high reving engine, and would have sounded even better through an after market exhaust system.

You'd also probably get close to 40mpg, as I was managing 33-34 in a vehicle 20% heavier than a B GT.

J E G Eastwood 1

This thread was discussed between 29/10/2005 and 05/11/2005

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