Sylva J15 Build

[NeilEverett]

Had been wondering how you were getting on, thanks for the update, looking good!

[kdempsie]

[/quote] I suspect that you may live to regret the decision to fit a Toyo Sport manifold to the car, especially having had it ceramic coated (which must have been three times the cost of the manifold itsel). I hope I'm wrong....[/quote]

Hi Jeff, fingers crossed on that one. I will be pretty ticked off if the manifold leaks after the cost of the ceramic coating!

Keith.

[jeffw]

Keith, all the Toyo sports ones I've seen have cracked....fingers crossed !

[kdempsie]

We'll folks I have reached the milestone of getting the engine started today, which was fairly undramatic in the end. I did however spend all day yesterday fault finding when it wouldn't go at first!

I was away for a week in the Lake District (really excellent break) when the exhaust was getting made for the car and picked it up on my return. The exhaust has not worked out as I'd hoped and I'm pretty disappointed with it, a combination of not setting my expectations properly and perhaps choosing the wrong garage to do a bespoke system. Anyway, disappointment aside I will modify and sort it to what I want but it was enough to get the car running.

I was ably assisted by my pal Craig and we went through the usual pre-start checks, cranked the engine to build oil pressure without starting, set the fuel pressure approximately right at 50psi, checked the ecu could see the engine turn over, voltage and turn over speed OK etc. Then we connected the coils and injectors and tried to start it but got nothing more than a few pops and a couple of spit backs.

To cut a long procedure short, we tried lots of altering the fuelling and cranking advance to try and get it to run to no avail. So we decided to sleep on it and read a bit of David Walkers book on engine management to make sure we weren't missing anything basic.

I took the book's advice and bought a tin of Easy Start to help fault find if we were looking at a fuel or sparks issue. This confirmed that it was a sparks issue and was very helpful in directing the rest of the fault finding. It didn't take long after that for me to suspect the wiring to the coil pack, a bit of google searching identified the way the coil is set up and allowed us to check the connections, which were reversed. I'd had to change the coil connector on the loom some time ago to suit the latest coil design that was supplied with the engine, I must have had a brain fade and put them the wrong way around

As a quick check we swapped the HT leads and went for a start, it started straight away! I shut it down, put the leads back the right way and swapped the coil pack wiring connector. I put the air filter back on as we had taken it off to spray in the Easy Start and just started it up with no fuss.

I ran the engine up to temp to help get the coolant bled around the circuit and check the fan settings etc. It all worked pretty well, idle is rock solid and engine is very smooth. The smooth running must be mostly attributed to the pre balanced throttle bodies from AT Power. The engine was running pretty rich with some black smoke from the exhaust, rather than adjust the mapping blind, I have simply turned the fuel pressure down to a perhaps more reasonable 40psi. That helped lean it a bit and cleaned the exhaust a little.

My only concern is the flow of coolant around the circuit, the pipes to the radiator got hot but the radiator didn't really. I'm in two minds about this now, earlier I was convinced that the longer pipe runs to the radiator were causing an increase in flow resistance. Perhaps the flow was passing through the lower resistance by pass line and just circulating through the engine and missing out the radiator. I have heard of this on other Duratec installations but maybe I have just jumped to the most complicated possibility. I'm beginning to wonder now if the system just actually has air in it. I think I'll try some more bleeding before I think about trying to equalise the back pressure in the bypass line to prioritise the radiator when the thermostat opens.

Anyone have any experience of this issue on longer cooling runs on Duratecs?

Pretty satisfied for now, on to final sheet metal paneling around the fibreglass (hopefully) and then the body will go for paint.

If anyone has thoughts on the cooling circulation please let me know.

Thanks,

Keith.

[jeffw]

Well done. Your fuel pressure should be around 3bar (43.5 PSI), 40PSI is probable a little low.

[kdempsie]

Hi Folks,

Well I've made a little progress since my last update. I've run the car up to temperature a few times and realised that the system wasn't flowing properly, with a stone cold radiator but the cooling fan running. I read a long blog update on Uphill Racers of a guy with a MK1 Fiesta who was suffering similar problems. I wanted to share some of the issues in case anyone else faces the same problem as I came to a slightly different conclusion than what I had read, it also looks like I have managed to avoid buying an electric pump. I'll keep an eye on it when I get running on the road or on the rolling road.

The Duratec system, I guess like most modern cars, has a warm up bypass loop where the coolant flows through the head and bypasses the radiator. This allows the engine to warm up quickly and helps keep engine temperature stable in general running. As the thermostat opens this progressively closes the bypass loop and mixes hot water in the engine with cooler water coming from the radiator, I guess that is also intended to minimise the risk of thermal shock. The other aspect of the system design that was new to me is that the thermostat is on the inlet side of the system and the header tank bypasses the thermostat at that point.

So I had the system plumbed up in the same way as the Ford original system but with the heater removed. The big difference in the J15 is the length of the pipe work between the engine and radiator. Running the engine the first few times showed that I had flow out of the head through the bypass loop and also back through the small bleed line to the header tank. The system didn't want to flow through the radiator at all. My first suspicion was that all of the flow was passing through the bypass loop, thinking that this was the least path of resistance. I didn't know at that point that that the thermostat closed the bypass progressively as the engine heats up, although it is somewhat obvious now after thinking it through properly.

To 'correct' this I put a flow restriction into the bypass line hoping to balance the resistance and force flow through the radiator. So since the line was already closed this made no difference!

So once I realised that the bypass was not to blame I was still convinced it was a least path of resistance problem. To think it through I drew a schematic diagram of the cooling system and this led me to experimenting with a flow restriction in the header suction line, in order to balance the circuit flow resistance. With the way the circuit operates it was possible that flow was easier from the header tank and back through the small bleed line than the larger radiator lines, since although they are much larger diameter at 32mm they were also much longer.

As it turns out a 5mm orifice, just a hose plug bung with 5mm hole, in the suction line from the header tank was all that was required to balance the flow and prioritise the radiator.

In general a pump suction line does not work best far away from the radiator or restrictions, this promotes cavitation in the line and makes it more difficult to draw the fluid in, even in a closed system like this. I'll just keep an eye on performance in case an electric pump really becomes required in future.

Once running with the 5mm restrictor, after the air bled out and the thermostat opened the radiator warmed up evenly, cooling fans came on, cooled the system quickly and turned off after about 45 seconds. That makes me think the system is working quite effectively now, stationary at least.

I'll upload the cooling schematic later as it might be helpful to support what I've written.

This is the same as many things, takes virtually no time to say now that I have solved it but took about 4 days of head scratching, lots of coolant filling/draining and I seemed to have the taste of coolant in my mouth for all 4 days!

I've also made some more panels and am close to going off for paint, the end is in sight but maybe still using binoculars.

Keith.

[kdempsie]

Well progress has been a little stop start over the last while but I have managed to get the car away to get a proper exhaust made. It just came back today and I'm very pleased with the results. The exhaust builders (Meercat Custom Exhausts in Kilbirnie) took a great deal of trouble to get the 4-2-1 exhaust lengths right. The bends and twists to get the lengths right and fit in the CAT and two silencers are quite amazing - hopefully it makes good power when it's mapped and dyno'd.

I'm not sure if I will get it ceramic coated as I suspect it might be quite expensive since it is a long system but I will need to deal with the heat insulation issues somehow.

So just a few pictures of progress.

[adithorp]

Thats impressive plumbing!

[pigeondave]

That looks so neat, you must be happy with it.

[kdempsie]

Hi Dave,

Yes pretty pleased with it. Just wondering how to insulate the fibreglass body around it now!

Keith