8-Port EFI - Project Update

Since the first dyno session at Mountune Race engines, and subsequent investigations in finalising an all purpose , single butterfly plenum chamber, development has gone on apace.

Unfortunately getting some sample working castings took longer than we hoped, but it wasn't for lack of effort. The supply time was pretty impressive by normal terms for these things, and it was soon time to go back to the dyno. Now, Dave Mountain is a very busy man and so is his company - being heavily involved in British Touring Cars, the new Zeta Formula Ford engines, and his continued Ford Motor Company associations. Despite every effort on his part, we could not work any dyno time out so it was decided to use the venerable Glyn Swift's services at Swiftune in Kent. Glyn also has a superflow dyno (he loaned us his adaptors and assistance on our maiden dyno session at Mountune) , so comparative test data would not be a problem. A date was set and agreed by those parties needing to attend (Me, Glyn, and of course electronics whiz Jeff Moore of MBE). The day arrived and I assisted in the mounting of the engine on the dyno, Jeff arrived, and we were ready.

A few changes had been made to the engine, so a quick recap of this will set the records straight. The biggest single change was the plenum itself. Now in its cast state to test the design. using a 55mm butterfly, and some clever internal detailing as a result of a conversation between myself and Mike Parry of Race Techniques. The design of the throttle butterfly/ spindle assembly was designed for simplicity. The injector positions were slightly resited and a new fuel rail made. The cylinder head was untouched as we did not want to change too many parameters in one go, the compression ratio was left at 12-1, The only other change was to an MD310 profile applied to an 8 port cam. Oh, yeah, a new pick-up system was used - I'd redesigned this to make fitting more simple, and to ease application to more engines - it will now fit all timing gear/cover configurations. It has also helped the kit price to be kept low.

Following the connection of the electronics. the engine fired up instan tly, and was left to warm up while we all indulged in the excellent coffee percolated at Swiftune. and the beautifuL relaxing rural surroundings. Although Jeff had bemoaned the problems of the journey down (he is based in Cirencester. Gloucestershire) he had to confess it was worth it. By far the most pleasant dyno venue he 'd been to!

OK. time to get on with reprogramming the "chip" - the one used for start up was that produced by the dyno session at Mountune with the supersprint cam. Instead of using a fuel/air mixture ratio sensor, Jeff had brought along his Lamda gauge. This is an extremely accurate and sensitive piece of kit - I was impressed. I wanted one. How much? HOW MUCH? Forget it. I'll stick to my pyrometer. Jeff noticed that the engine was producing more power than the last time by the fuelling alterations he was having to do. The programming is an absolute whiz with the MBE designed system, especially when used in conjunction with Glyn's hi-tech superflow dyno set up. It really has to be seen to be appreciated - total engine control at the touch of a button. Instead of many laborious hours going back and forth with settings. I think it took four hours from start to finish (not including "incidents" - more later).

The results?

Once again I was pretty pleased. and Jeff continually amazed at what these archaic engines are capable of. Even Glyn had his eyes opened at certain points by ignition/fuel requirements. This time, readings at lower rpm levels were possible by the better cam match and plenum efficiency. The readings have been rounded up or down for clarity. Horse power figures include the correction factor for that day.

Comparing these figures to those first obtained with the Supersprint cam (detailed in the Mini T ech News 4) shows a definite step forward giving even more torque over a much broader rpm range. A nett result is an increase in horse power too. I suspect that this would be further enhanced by a higher compression ratio, not to mention a reworked head. Remember the head is untouched and "as sold". Maximum power was actually 114 bhp at 7 ,383 rpm - such is the control of the Superflow dyno. That's 12 bhp more than the other test.

"Incidents" - well does anything go perfectly without any hitches? I was testing a set of the carbon fibre push rods; special long ones for the eight port. Two broke after three minutes of running. Examination showed a problem with the way the end caps were machined. These were replaced. and no more problems were experienced there. Correction of the fault has long since been instigated on the production of all the carbon fibre push rods and absolutely no failures have occurred since. In fact, we have had many glOWing reports (thanks to those concerned).

Then there were the flying bullets. This was a classic case of not getting what you asked for. The pick-up pegs in the crank pulley had not been fitted as I had requested. How did I find out? The first one came out at about 6500 rpm, and punched a bullet hole in the dyno cell wall. It also belted the pick up on its way past. Damn, it was the only pick up I had with me. Doom and gloom. Still, a new pulley was fitted . and the was engine spun over just in case. We were all amazed when it fired first time, I can tell you. About two hours later. another peg did a re-run of the first one - but this time went out through the opposite wall. It also belted the pick-up. This was getting tiresome. Could the pick-up have stood another whack? Glyn did some hurried mods to the pick-up pegs. refitted the pulley, spun the engine over - good grief! It started. Didn't run too well, the air gap between peg and pick-up had got a bit too large. This was reset, and everything was hunky dory again. I had a few unpleasantries to say to the guy who had modified the pulleys. This has, of course, been revised as I had originally requested. That's why it's called "R & 0" I guess.

A few weeks later, we were all back at Swiftune to redyno the engine fitted with an MD296 profile cam as part of the extensive development programme. This time the cam was the only change made. Everything else was left as it was last time. Jeff was quite pleased to return to this rural setting, finding it entirely more agreeable and relaXing than the fraught situations usually experienced in a modem race shop dyno room. Not to mention the exceptional coffee and lunchtime rolls. The results were as follows:-

It was surprising how similar the power output was to that gained with the 310 cam. This confirms my assumption that the 310 was not optimised with regard to compression ratio and port sizing. As previously stated, initial developments are aimed at good torque output; maximising horse power will come later. The MD296 profile was seemingly better suited to the current set up.

Incidents this time? Of course! The engine was fine all day until we were ready to do the final power run with the reprogrammed chip in; just as a double check. A persistent misfire at erratic high rpm points , got us all baffled. Change the rotor arm, still there. Change the dizzy cap. still there , change the leads. plugs, injectors. still there.

Compression check. no problems, Hmm. Out with the Oscilloscope, test the pick-up. then ECU. nO problem. Fuel pump. fuel filter, coil. still it persisted - varying from 6-6500 rpm. Then down to 5500. Swap everything round again, and again. It wouldn't go away. "Tell you what, le1's try increasing the fuel pressure in the rail" says Glyn. "Trouble is, somebody needs to be in there and try to stop the fuel coming out of the return pipe". Yep. be in the dyno cell. next to the engine doing as many rpm we can before the misfire occurs, then press a finger/thumb over the fuel return pipe end (45 psi down a 5/16" pipe). Why do I get all the good jobs? "All in the name of R & D" smiles Glyn. This actually went off without any problems other than me reeking of petrol for the rest of the day, a fair spray comes out of a small pipe at 45 psi with some nutter trying to block the pipe offl Didn't cure the problem.

Out came the plugs once more, Glyn noticed a drop of water in the plug hole, and after examination, in the end of the plug. "Stick the airline on it and pressurise the chamber". Sure enough there was air bubbling up through the cooling tower. Damn, must be a blown head gasket. Still, after nearly 40 hours on the dyno, it might be prudent to do a rebuild. Especially as after the next dyno session to programme for the MD286 profile cam, the engine was to be put in the Mini Spares Project car. So we called it a day. The "epic" will continue in the next issue. when I reveal where the water was coming from and the results gained with the MD286 cam - last stage with the head "as standard".

Keith Calver

Thanks for continued support. patience,
knowledge and general assistance to:-
Glyn & Nick Swift
Swiftune Racing
Longs Corner Farm
Bethersden
Nr Ashford
Kent
Tel: 0233850843

Mike Parry
Race Techniques
Elim Works
Dunalley Parade
St Pauls
Cheltenham, Gloucs
Tel: 0242 245640

Andy Kidby/Dave Mountain
Mountune Race Engines
Unit 3. The Causeway Industrial Unit
The Causeway, Maldon, Essex
Tel: 0261 854029

Jeff Moore
M.BE Ltd
You must be joking - I'm
keeping this under mv hatl