Cheap "rubbish" on eBay.
I hope it doesn’t sound like I am “talking down” to your good selves but I have had a couple of fuel pump failures lately which could have been avoided by doing the obvious. I am talking about fitting a filter in between the fuel supply and the pump. The pump MUST be protected by a filter no matter how new or clean you think your tank is.
Next the eBay demons have struck again. Cheap (for cheap read “rubbish”) fuel pressure regulators, nicely anodised and with a fuel pressure gauge attached, can be had on eBay for very little money. I have seen several now and they all fail to hold a consistent pressure. If you have an engine that you don’t mind falling apart under load then by all means use them - you could save up to £30 and you can put that money towards your engine rebuild.
I mentioned Chris Palmer’s XJS recently and how I had gotten a bit involved in some head porting work. I made the flow bench adapter and did some flow testing and then Chris supplied a head for me to cut up. I could not believe how much metal this head has around the ports.
Once we had established the basic shape, the head went off to CTM (02085 921180). Charlie at CTM did the porting work and skimmed the head to get the compression ratio up. Once it was back on the car I had to re-map to suit and then compare the old and new power curves.
Whilst all the theory said it had to be better, that’s no guarantee that it would be and I was just a tad nervous when I logged the first power runs. Peak was not really any better but the mid-range torque was way up on the previous engine. Last year Chris had been beaten a couple of times where he normally tends to dominate his class. Three wins out of three races made for a pretty good start to the new season!
I had a second XJS in this month from the same race series. All seemed to be going swimmingly until the first power run when it dropped one cylinder. The car went back to base and the head was pulled off in something of a hurry; the first race was only days away. Nothing drastic was found, just some mysterious carbon under two inlet valves. A quick clean up had the valves re-seated and it was back within days on the rolling road.
I had agreed to work late one evening to get the car out for the first race. In the end it wasn’t necessary because someone cancelled and we had a bit of time free. Peak power was actually pretty good for an engine on the standard intake system and the owner/driver (Roger Webster) made the first week-end’s racing in the nick of time. Not a waste of effort either as he came home second in both his races to Chris Palmer.
I have known Steve (Lucky) Butts for about ten years now and his rolling road visits are always good value - in terms of entertainment. We call him Lucky because he is the unluckiest person I know; the first car we mapped for him caught fire and burned out!
For this trip Steve wanted his new engine setting up. This is a 1400cc K Series that he wanted to run in the supercharged class in hill climbs. This engine stated out as a “MG/Rover works special” and Steve had rebuilt it for his Lotus Elise S1. It features all the right bits, steel crank, rods, forged pistons and a supercharger as well as a turbo: quite a mad piece of kit.
The first start up was interesting in that it would not start at all. There were a few encouraging coughs but no real sign of life. We pulled the plugs to check if they were wet with petrol, which they were. A compression check came next. Compression was good but we seemed to have something flying up the plug hole of one cylinder – which looked like paper! To cut a long story short the inlet manifold was pulled off to reveal a lot of blue paper stuffed down the inlet ports! I took a couple of pictures and promised Steve I would never embarrass him by telling anyone – so keep this just between us okay? Hooray it ran, but Steve was soon on his way with a to-do list.
A week later he was back with solid intake hoses and a supercharger-throttled intake system. With race cams and the biggest volume plenum intake in the world the idle was not bad – it was non-existent. The best I could manage was about 2000rpm and lumpy as a lumpy thing. Steve, being a cheerful chap by nature, could not care less, it was running and he wanted boost – lots of boost.
The supercharger appeared to be delivering about 12 psi at very low rpm and the turbo then topped this up. We did a couple of maps, a base line boost and then one with more boost across the rev range. I had my doubts that it would be driveable on anything other than the “girlie” low boost map - it was pretty ferocious.
Lucky managed to get to the first event and had fun trying to get the car off the line with his super-fast idle. Even so, he got his first class win and the time was 0.1 seconds under last year’s class record. The target now is to get under the current course class record and that means finding more driveability and probably more boost. With a project like this you can never expect to get it right first try - it’s called “development” and it takes both time and money.
Like buses that come in pairs I had a second turbo/supercharged car in this month: this time a Renault Five. When Lucky’s supercharger made too much boost on idle the first time around this one made too little. Two psi wasn’t exactly what we wanted and all the boost was coming from the turbo. We messed about all day but you can’t fight the laws of physics - it just wasn’t working without a smaller supercharger pulley or a bigger supercharger. Steve’s engine proves that it can work (sort of) so a bit of head scratching is needed on the Renault. No doubt it will feature here again at a later date.
Boost block vacuum distribution
My mate in Florida, who trades as “Emerald Performance” has come up with a vacuum distribution block which is apparently all the rage in the U.S.A. The idea is that you take one big vacuum from the engine and then use the block to connect everything else to it that needs to see a vacuum signal. I don’t have a need for them but if you do then contact the above.
Richard Johnson is a regular here with his turbo R32 and this month he was back with a four-wheel-drive conversion and a revised exhaust manifold. I can’t give you any detail on the manifold but the result was simply amazing. The boost comes on much, much sooner, faster and holds on at high rpm. This is one of the aspects that many turbo enthusiasts seem to ignore and it’s something we want to investigate if we ever get the Superflow engine dyno up and running.