This article is sent along by Colyn Firth in the UK, letting us know what can be done for more power while keeping the car mild mannered for street use.

On 10/17/2018, Colyn Firth wrote:
"I have always enjoyed driving my MGA hard and I love how good the car feels when you power it into a bend. My car had a 1850cc 3-bearing MGB engine fitted when I first got it which had a gas flowed head, a stage-1 Piper cam and tubular exhaust manifold which was dynoed at 106 BHP. (With a 5-speed box and a 4.3 diff). It went pretty well but still needed to be revved to get it up the longer Alpine Passes such as the Grand St Bernard in Switzerland, I found that the engine tended to run out of steam in 3rd gear so you had to change down to 2nd gear. Then the car would accelerate again but it would be revving to 5000 rpm and beyond. So I decided to look at ways of giving the car some more easy hill climbing power and it became a bit of a minefield.

My first thought was to fit a supercharger but I realized that the high compression gas flowed head would probably need work to decompress it a little or maybe I would have to replace it completely (Peter Burgess makes a head suitable for superchargers). Then there is the problem of wondering if my 3-brg engines crank would survive long if it was subject to much more BHP. (My friend Stuart Mumby has had two replacement cranks in his 3-brg engine and when broke for the 3rd time a few years ago, he decided to fit a 5-brg block). I asked Peter Burgess about building a supercharged engine or maybe a more powerful normally aspirated engine. Peter suggested a more highly tuned 1860cc 5-bearing engine which he preferred to tune rather than a 3-brg one. However, as a sort of retirement present, I had promised myself a more powerful engine but the problem was that Peter wasn`t able to supply me one for about 18 months as he was so busy.

So I asked around my MGA friends and was recommended to give Cameron Gilmour of Perth in Scotland a call, he builds and tune engines of all makes and he is is very well thought of. (He is also one of the few engineers in the UK who is happy to re-work a MSX crossflow head and get it to perform really well). Well I called him and he asked me what exactly I was looking for, I said half jokingly that I probably needed a turbo diesel as it would suit my style of driving better. I`m a bit cramped in the car and my height and lack of leg room meant that I had to lift my entire left foot off the floor to operate the clutch which become a bit uncomfortable on long journeys. So I tended to be a bit lazy with the gear changes because of this. I suggested an large bore engine with a pair of H6 SUs, a Piper fast road cam and Maniflow manifolds whereas Cameron suggested a 1950cc 5-brg engine with a Newman PH1 cam, a Weber 45 DCOE carb and Maniflow manifolds.

I was concerned that the Weber wouldn't work well at high altitudes like in the Alps and I had never heard of Newman Cams but in the end, it is difficult to ignore the advice of your engine builder. (I checked out the Newman Cams website and found that the PH1 cam would pull between 1500 to 6500 rpm which seemed perfect) Cameron bores out the block and fits cylinder liners to make sure that there is enough cylinder wall thickness. He also supplies his own ported cast iron head with extra large valves. Cameron wouldn't give me exact power figures for his engines but he did assure me that I would be very happy with it. So I decided to go with his advice and confirmed the order.

The engine arrived a few weeks later fully built up and run in and with a simple dyno read out showing over 130 BHP. With the engine out I decided to have the 5-Speed T9 gearbox refurbished and uprated to cope with the extra power, it did need some work as it had begun to jump out of 1st gear on the over-run. I made the decision to have heavy duty bearings fitted and also have higher ratio 1st and 2nd gears fitted which would make 1st gear more useful and also get rid of the larger gap between 2nd and 3rd gears. I have stayed with the 4.3 diff for now. The engine refit went well, I was really delighted to find that fitting the Weber was so easy, you can see and get a spanner onto all the manifold nuts without any of the working blind issues that you get with the SUs. The engine fired upon first pull but at first it would spit-back through the carbs at part throttles and also backfire very loudly, the backfires were so loud that on one occasion, an armed police unit turned up to see where the gunfire was coming from.

After 500 miles of careful running in, I took the car to Peter Burgess to have it set up on his dyno, and after a few runs he managed to get the engine running beautifully, (there is a whole other story to how Peter sorted the Weber out for me which I will gladly let you have if you are interested). He got the power up to over 140 BHP and the end result is awesome, the car has loads of low end torque, so much that it very happily pulls away from 30 mph in 5th gear without pinking or any fuss at all. It will also start easily from a standstill in 2nd gear, I have even pulled away by mistake in 3rd gear a couple of times and the engine just gets on with it without any complaint. Then if you floor the pedal and let the engine rev, it pulls like a monster, so much so that I worry about over revving it. It also now climbs almost any hill in 3rd gear.

To be honest, I didn't expect it to be so drive-able, I thought it would have a lumpy idle with no pulling power until about 3000 rpm but Cameron`s tuning skills have amazed me, he seems to have achieved the impossible (although it did cost me £3500 to do it!). Apparently I could get another 10 BHP if I fitted the next stage PH2 Newman Cam but at the expense of less power under 2000 rpm and the dreaded lumpy idle, but I am very happy with the car as it is. I don't race the car, but if I did, I know who I would go to for the engine".

Cheers, -- Colyn

P.S.
I forgot to mention the only downside of the 1950cc, it isn't particularly economic. It now gives between 22 to 24 mpg (Imperial gallons) compared to around 29 mpg before with the 1850cc with SUs. I once got 29.8 mpg with it but I was whispering along at about 40 mph for about 150 miles, and to be honest, it was really boring and Im not likely to ever repeat it. But I do around 5000 miles per year in it and so I dont think it will break the bank. - Colyn