mikmiglia wrote:
Did you ever finish your injection idea, and if so did it make any odds to the performance.
Yes Mike, it's fully functional.
The system consists of: a nos 4 litre 'screen wash bottle meant for an mod truck (£10);
fitted with a low level float switch and warning lamp(£6);
the pump feeds a 70psi fish pond pump (£35) with a 50/50 mix of methanol and distilled water (80p/litre) through high pressure nylon tube (£30);
the pump is connected to a flow control solenoid (£12);
triggered by a micro switch attached to the throttle linkage (£1.99);
the solenoid feeds the mix to a pin hole fogger nozzle (£15);
mounted in the top of my home made aluminium air box (£15 including the K&N filter);
a tee piece (£1.99) mounted between the solenoid and nozzle leads to a second flow control solenoid (£12), which is triggered by the same micro switch to open as the first one closes when you lift off the throttle. This depressurises the nozzle line, stopping the spray from continuing on the overrun (which it does otherwise and would cause problems) and feeding the unused mixture back to the tank so it isn't wasted. Phew!
I can't give you any objective figures about whether it makes a difference to the power and torque yet, as the clutch started slipping with the car on the dyno.
The main benefit, though, is supposed to be raising the octane rating of the fuel so you can run higher compression and/or a more aggressive advance curve without suffering detonation (pinking), which can quickly destroy your engine. That's why it was developed for the Supermarine Spitfires operating on the Russian front - their fuel supply was a pretty ropy mixture for obvious reasons of supply chain disruption.
The Vitesse manual says that you should use 100 octane fuel with the advance set at 13 degrees btdc, but the ignition should be retarded to no more than 7 degrees btdc on anything less than 100 octane (unleaded is 95, super is 97).
When I first started mine with the injection system working I immediately noticed that it had smoothed out the idle and eliminated any smoke from the exhaust. On the road it felt brisk but wouldn't really rev.
I checked the timing and found it was set at about 2 degrees btdc, so the flame front wasn't really developing until the piston was well on it's way back down the bore. I set it to 13 degrees and OMG! it pulled like a train and I'm going to have to fit a rev limiter as the engine tends to take over and charge up the rev scale as if the very Divil himself is in the driving seat (please excuse my rubbish Irish accent on the Satan analogy).
I got no detonation problems and it just felt so
right. Once on the dyno, the engineer chappy commented on how quickly it picked up revs for a Triumph six pot, and asked me if there was any reason why I'd set the advance to
16 degrees btdc when the manual recommended seven?
So, I'd set the ignition timing way in advance of what the engine should comfortably run on 95 octane unleaded and didn't suffer any problems at all. By rights, I should be picking pieces of piston out of the sump and paying Rimmers for a rebuild kit.
I'll have the car back on the dyno next week and I should be able to give some power, torque, acceleration and top speed figures then. It looks promising - when the clutch started slipping it was going well over 100mph with plenty more left
Sorry if that's all a bit detailed but it might just inspire others to have a go themselves...
Oh, and it looks pretty cool too -
