GT6 update, rolling road.

Hmm, news on the GT6 is getting a bit out of date, having got the PI system working as it should on the GT6, I wanted to go and do a rolling road run to help further tune the megajolt ignition map, see what sort of power/torque it is producing and get an idea of what further improvements could be made. So we went over to Maynard Ltd in Stroud to have a run up, the results of which are below

Power





Torque




The red run is with the complete exhaust system (GT supplied 6-3-1 onto standard centre pipe and back box), grey is with the rear silencer removed and black is with the middle pipe (from 3-1 collector back) removed. All figures are corrected back to the flywheel.

It seems to suggest at the moment that the back box has minimal effect, but the relatively small 48mm ID middle pipe is holding it back. So one of the next jobs is to get the constricted (48mm) output from the 3-1 collector opened out to 52mm ID

It was a good afternoon out and was interesting to record what the engine is pumping out on what is basically a standard MkII GT6 engine, but with Lucas injection and a proper exhaust manifold. I'm not that bothered about the absolute power figures (though they are a good improvement on the factory figures), more interesting to me is the shape of the torque curve, which is relatively flat compared to other GT6 engines I have seen, with bags of torque from lower engine revs. I'm pleased with the results and that's what matters to me ;)

Tractor time

There has not been much time spent on my cars recently due to work on the Lightweight (more on which another time) and work on my tractor. I've owned this for the past five years or so and has come in really handy when moving engines around or fetching wood for the farm, but the hydraulics, which provide power to lift the front loader or rear implement, have over the years grown weak.
A gear driven pump provides the hydraulic power, but this is hidden away in the back of the tractor behind the gearbox and below the axle. The combined gearbox and rear axle oil was drained and while this was happening, I set about removing any parts which would get in the way.





With all the parts out of the way the rear case came off without any problems, using the two jack-off bolts to separate it and the Massey 35 to hold the weight.






It doesn't look too bad in the rear housing, though there is a bit of silt in the bottom of the case, not too surprising to me for a farm tractor of this age. I shall clean all this out as best I can, then put new oil back in, all 12 gallons of it.

I moved the rear case, with the hydraulic pump, into the workshop to make it easier to work on. Unfortunately there are no obvious signs of failure yet, so I guess a hydraulic pump rebuild could be on the cards.

Up for sale again

After my last post I have been told my old 2000 is back up for sale again after a re-spray. It looks a bit pink to me after the re-spray and I'm not too sure about the plastic hub caps, but it does look better for being in one solid colour again. You can see the full advert here

A departure and some new arrivals

Long time no update again. With the 2000 through it's MOT and a new nose cone fitted I decided it was time to move it on. I've had some good times with this car, the 2008 RBRR being one of the highlights, but it came to a point where it was being used increasingly for daily driving only and I was not getting so much fun out of it, that and the fact that with it's Witor exhaust system it is quite noisy for daily driving. So after the nose cone of the 2000 had a few top coats of paint it went up on a few car for sale websites. The next day I had a call to arrange a viewing and a couple of days later a deposit was put down. The 2000 is now a few more miles West along the M4 with it's new owner, who plans to re-spray it before too long, something I never felt up to.




The GT6 is reliable, but I did not want to have to make it a daily driver, so instead I set about finding a replacement for the 2000. My mind was fairly open about what to get, but my preference was for something rear wheel drive, comfortable, reliable and a bit more modern, without being overladen with electronics.
In the end I decided to plump for a 1983 BMW E21, it has a 1800cc slant-four engine, with a carburettor and a distributor, but fortunately no points. So far I have covered over 1000 trouble-free miles after replacing the fourteen year old tyre and knackered wiper blade it somehow managed to pass a MOT with.




Oh, and the other new arrivals, the farm dog had a litter of puppies about six weeks ago, so we now have seven Welsh Border Collie puppies, all of which, bar one or two, have found homes already.

At a week old




and five weeks

Time for that nose job

I have decided to continue sorting out some of the bodywork on my MkI 2000 and I am part way through a fairly major job, replacing the front nose cone panel. In 2006 the previous owner hit a deer during the CT RBRR, resulting in this.



but when it arrived, the car looked something like this



so I wanged in some metal from a Dolomite door skin to get it roadworthy.



Fortunately when I bought the car, it came with a spares front end, which has already donated parts of it's wings to this car and now has donated the complete nose cone panel



After much deliberation and wielding of the angle grinder, the old nose cane was removed, you can see from the pic below the blue of the old Dolomite door.



After a few hours spent cleaning off both the replacement panel and the car, it was ready for tacking on after a coat of zinc rich primer where I would not be able to paint after welding



And this is where we are tonight, blending in the new panel, removing dents and preparing for paint, which I hope to have done by the weekend

Some shed time

With the MOT out of the way again I set about a few tidying up jobs on the 2000. Around the rear wheel arches, the old underseal has been knocked/peeled off, next job is to get it in primer before giving it a coat of stone chip and a top coat of red to match. The original paint is in surprisingly good condition, but is quite thin.



While waiting for that paint to cure, work has re-started on the front passenger wing. I pulled some dents out and removed some rotten metal from the arches a couple of years ago, but never got round to giving it a top coat.





Up in the wheel arch I could see a bit of rust bubling up



Which cleaned up to look a bit like this



So there's going to be a bit more cutting before some fresh metal goes in.
After the new metal went in it was finished with seam sealant and a few coats of paint, yes I know it is not the right colour, but it is under the carpet.

PI tuning

My initial elation at getting the GT6 running on Pi was dampened somewhat when I realised that the rough running was accompanied by the exhaust from number two cylinder was glowing red. Something was obviously not right, so I gave the supplier of the exhaust manifold and metering unit (Gareth Thomas) a call and described the symptoms to him. He reckoned the timing was out and offered to pop over as he was in the area and check it out.
Later GT turned up and after much checking and re-checking of the camshaft, we had proved that the camshaft was approximately 10deg. too advanced. With the timing cover off, the marks on the cam wheel lined up correctly, but the cam opening were not correct. The cam wheel was a second hand duplex version, bought from eBay some months ago, which I had no reason to think was machined incorrectly, but it turned out that it has never been right when we compared it to another cam wheel I had found.



Eventually, after much checking, the cam wheel was re-fitted rotated round from where it was, along with a second hand chain to give the most accurate timing possible.

So a few hours after starting on the car we had it running something more like properly. No.1 injector needed bleeding, but was soon done and then it was on to the finer settings, once a throttle return spring had been fitted it was much easier to set the idle and then on to balancing the manifolds. A quick run out that evening showed a massive increase in torque and power, with some beautiful sounds coming from the exhaust and a wonderful howl when working hard.

The next day the air box log was fitted, it was much to my surprise that it fitted at all as I had not modified the bulkhead with that in mind. Then it was onto the ignition map, which we made surprising short work of, modified quickly in the shed before going out for a run. The new map cured the un-even idle, a stutter around 2000rpm and having increased the highest rev range, it no longer failed to go over 5500rpm. Out on the run the map was changed while in the petrol station, amid strange looks from other people, further refining it.



I then took to the passenger seat to let GT have a feel of the car, really worthwhile as I had been having some issues with how the car felt, but my lack of experience made it harder to define what the problem is.
One problem, which I knew of, is down to the lack of negative camber on the front, something which I would like to remedy with a pair of top arms from GT6Mike, but for now I shall see if I can get a few more shims in. Another suggestion is to increase the rear track width to make it more stable under braking, as at the moment the front does feel a bit too light and fidgety under heavy breaking.

All of this now gives me a further list of jobs to do, get some more camber on the front, fit a cold air feed to the inlet and seal up the gearbox tunnel.

Oh, and these a the plugs after a good run out.