VX Engine in a 4/4 - Independent Road Test

A General Motors Engine in a Morgan 4/4? Sacrilege or Brilliance?
It all started a week or so back with a phone call. "Kevin Vernon has evolved a high-performance engine conversion for a 4/4. Will you test drive it and let us know what you think?" Naturally, I had to think carefully about this, so it was probably as much as 3 or even 4 microseconds before I agreed.

Today, I took the car out for the promised test drive, and in the process I discovered something about myself and about the nature of prejudice. Driving Hamwich, my 1986 CVH-powered 4/4 2-seater up the M5 towards the Tudor Motor Bodies premises, I was absolutely determined not to like this car. Fancy new-fangled electronickery, too much power, a Vauxhall engine. What's to like? If one was going to go down this route, why not buy a new Duratec-engined car from the factory? Or buy a Cosworth Duratec from Burton's or Raceline? Surely it would be better to do something (anything!) oneself rather than end up with a Vauxhall engine from an Astra (yuk!) in one's beloved Morgan?

Arriving at the Tudor premises in Market Drayton, Kevin and I started with a discussion on the choice of engine. Kevin was interested in why I didn't like the selection. Which I summed up as:
1. I didn't think that modern engines were amenable to being worked on by the average home mechanic (anti-electronics prejudice)
2. I didn't like Vauxhalls, because I used to own an Astra diesel van that was utter shite (brand prejudice based on a tiny sample as evidence)
3. I felt that the right amount of power for a 4/4 was about 130bhp - so a 175bhp option was far too much (power prejudice)

Kevin agreed with the power opinion (he too felt that 130bhp was a good target for a 4/4), and questioned if it really bothered me were the engine to have a Vauxhall badge. I confessed that well yes, actually, it did. And started to wonder why...

[ Computer Input ]
On the electronics options, I agreed that in wanting to get the spanners out myself, actually I was probably in somewhat of a minority - and in fact most owners probably would readily trade the ability to fiddle for the eco-friendly advantages of a Euro 4 compliant engine. Kevin then pointed out that far from having a sealed factory management system, they had selected a bespoke solution which was capable of being tuned via a laptop. Realising that this opens up a whole new opportunity for fiddling (sorry, "improving") the engine oneself, I sensed Prejudice Number 1 starting to melt away.

Let's take a look at the car. The only outward clues that something is different are the right-hand exhaust, the different gearshift, and a couple of extra warning lights on the dash. Under the bonnet, the 1.8 VVTI Sport engine looks like it's right at home, sitting on some new engine mounting brackets. But then would we expect anything less from Kevin? Of course not.

By far the best thing from my point of view is that:
(a) it looks like a proper engine, and
(b) it doesn't say 'Vauxhall' anywhere.
Prejudice number 2 not to like this car is now crossed off.

The installation is pretty neat - there's a induction box sat above the radiator, the plumbing is all nicely integrated with the stock setup, and the exhaust system wraps neatly under the engine and exits down the right side of the car. There's a hydraulic clutch instead of the cable version on the CVH engine, and the ECU, together with a distribution panel, are tucked up away under the dash. A high pressure in-tank fuel pump is also needed to keep the injectors happy.

[ Neat under the bonnet ]

Prejudice number 3 was destroyed over the next hour in an orgy of revs, speed, and excitement - but more on that later.

A bit of background first. The whole project was initiated by the serendipitous confluence of a number of factors:
Firstly, there was the notion that there are lots of 4/4 owners out there who have an emotional attachment ot their cars, but would like more performance.
Secondly there was the availability of emissions-compliant engines in affordable form from GM, and
thirdly the desire to produce a kit to enable these transverse engines to be mounted in longitudinal format to enable a range of kit-car installations.

Couple these to the growing need to start offering an engine solution that will provide an environmentally-responsible installation, and a plan emerges. Accordingly, a 1984 4/4 was purchased, and a 1.8 DOHC Variable valve-timed engine rated at 175bhp was mated to a 5-speed Omega gearbox and dropped into place. Brakes were uprated with High-Spec twin piston alloy calipers to keep pace with the massive power increase over a stock 4/4, and the master cylinder seals were renewed.

[ Rolling Road 147bhp !]
Off to the rolling road for tuning, and an impressive 147bhp at the wheels was measured. The setup still isn't perfect: the cold start system isn't quite right, and the electronic throttle "takes a bit of getting used to" according to Kevin.

So: out for a test drive.

For the first few moments, I took things extremely gently, Kevin's warning about the fly-by-wire throttle still ringing in my ears. What is this car going to be like? I had brought a dictaphone to record my thoughts as I drove. The voice recorder tape is somewhat revealing, you can hear 3 voices - me, Jane, and the car.
Me: "Quite a long clutch travel, it bites about half way up"
Car: "Bwaaa" (rising revs)
Me: "He He!" Car: "BWAAA" (right on the cam)
Me: "'kin 'ell" Jane: "Steady!"
Me: "Jesus wept, this thing accelerates like a missile!"
The rest of the tape is a rather entertaining mixture of engine sounds, me cackling with glee, and the occasional excited squeal from Jane. Jeez, but this thing is good.

I already have the High-Spec brake calipers on my tired old 1986 CVH car, so I was not expecting the vast improvement in the brakes. I have decent shocks and springs too, so my car handes pretty well too. The difference, and by golly it's a big difference, is the engine. Prod the throttle in 2nd, and it's just instant violence. None of the relaxed unstoppable steady torquey rush of a Plus 8 as it hurls itself towards the horizon, this thing kicks like a stinger missile, sharp and concentrated, precisely targeted. It's a 2-ounce espresso compared to the Plus 8's half-pint of Americano - not so much of it, but so much more concentrated - it hits the spot, and is ultimately just as satisfying (if not more so!) than the larger quantity delivery from the V8 car.

Blasting down a twisty 'B' road, flipping between 3rd and 4th, flinging the thing into bends, chasing the vanishing point, catching the tail as it steps out, booting the throttle just for the thrill of listening to the way the revs spin up. Does life get any better than this? I think not. The 4/4 steering box gives high-geared but light steering with 1 and a half turns lock to lock. This, coupled with the narrowness of the car and its light weight means you are dueling with an epee rather than a sabre. And on twisty narrow roads, there are few better weapons to use.

Onto the dual carriageway. Let's see what it can do. Yee Haa! I've never seen the speedo needle so far round the dial on a 4/4. Alright, the speedo hasn't yet been calibrated to suit the drive from the Omega 5-speed box, and there's no way I'm really doing 130mph plus. But then again the 60mph mark painted onto the dial by Kevin as a guide is way way behind, not much more than halfway round the needle's arc. And we're still gathering speed! But fortunately for my licence, we run out of space, and a return to more sensible speeds is required.

Has this car got too much power? No. Not quite. Prejudice number 3 is swept away. So. The car accelerates with a rush, handles beautifully, stops well, and cruises over the ton with no sweat.

Surely there must be some downsides? Well, yes. The induction roar is quite frankly tinny sounding. The exhaust is too quiet. Most annoyingly, the revs spin up fast like a racer, but hang on the way back down. I wondered if a lighter flywheel might help, but Kevin thinks it could be improved thorugh adjusting the fueling map. And if you go for the Omega 5 speed box, you'd better have small feet - or at least not the desert-boots I was wearing - there's really not much room in the pedal box. Kevin also reckons the Omega gearbox is whiny, but to be frank, I didn't notice it. But hey, this is the first car, the development mule.

Next up will be a conversion using a Type 9 5-speed box (like in the later 4/4s), then hopefully a left-hand drive version. Various exhaust options will be explored, maybe with a larger-diamter pipe. Meanwhile there will be more work done on the ignition map, and various other tweaks and improvements, based on the feedback Kevin's getting from the people who are driving the test car.

Shortly after that, accountant willing, Kevin will be converting my own car. I have confronted my prejudices, and found them wanting. The car, I have not. If you too have a 4/4 with a tired engine, but like me you don't want to get rid of your beloved, then you could do much worse than to beat a path to Market Drayton. The team at Tudor Motor Bodies will be only too happy to put a big smile on your face.

by Tim Harris