Where for a new K series

[robin]

True. And in my experience you need to fettle the fuel filter bracket to avoid the tang on the bracket from fretting the silicone downpipe. If you've got the time then several trial fittings are called for and possibly shortening the metal pipe at the gearbox end of the engine to make the silicone pipe bend a little bit better fit.

Cheers,
Robin

[woody]

True. And in my experience you need to fettle the fuel filter bracket to avoid the tang on the bracket from fretting the silicone downpipe. If you've got the time then several trial fittings are called for and possibly shortening the metal pipe at the gearbox end of the engine to make the silicone pipe bend a little bit better fit.

Cheers,
Robin

It's fine on an S1, but I think Geary is looking at doing an S2 specific design to fix this.

[kerryxeg]

I'm no expert but here's what I think I've learned

The 82 deg thermostat was originally fitted to the VHPD when they did the upgrade to the 190. At that time they weren't fitting a PRT or any other form of bypass kit.

Taking advice on making sure I minimise the risk of HGF, I fitted the QED remote thermostat with an 78 deg thermostat. With the result that the temp stuggled to get the car out of warm up mode. The QED remote thermostat seems to be a bit more extreme than the more standard PRT kit. The standard ECU wasn't happy with the low temp and 190 ecu was even worse. I changed the stat to an 82deg version and got the emerald fitted which can be set to be less sensitive to temp. Now all is well but standard running temp is typically 74.

So in short I think the PRT is a good idea - negates some of the issues of having the rad so far from the engine but not sure about fitting a lower stat, you might get much lower temps than expected.

[GilesM]

I think I'll give the PRT a go, the details in the description that Robin posted seemed to make sense, and I will have time and space in the engine bay for plenty of attempts to get it right.

Cheers

Giles

[robin]

Remote stats don't really change the problem, unfortunately. They change some of the operating points but the loop as a whole remains unstable in the face of fast transient load changes.

When the engine is warm and the rad is cold (normal cruising on motorway stuff) if you then drop a gear and floor the accelerator you'll increase the pump output hugely and thus the flow through whatever aperture the stat is presenting to the coolant (more pressure, same hole size = more flow). This will cause the engine to cool, starting at the front where the coolant goes in and finishing at the coolant elbow where the water comes out. Effectively you get a "wave" of cold water spreading across the engine. Meanwhile the car is accelerating so the airflow over the radiator is increasing thus making the water even colder. Eventually the cold water finds its way into the bypass loop which jets water over the stat bulb and the stat will close up in response (probably it will shut completely if you did a really good job of flooring it). The stat movement is deliberately damped so that it can only open/close at a certain rate of change. The more damped the stat, the more the temperature will drop before the stat finally closes.

The reverse is then also true. If you now pop it into 5th and go to light throttle the coolant flow reduces a lot and the stat is not open enough so the temperature in the engine will rise (latent heat from just being thrashed plus normal combustion heat). Eventually the temperature in the bypass loop reaches the point where the stat starts to open and this allows cool water back into the engine to resume normal operation.

This behaviour is more or less inevitable for any control loop that uses only a wax bulb thermostat + bypass circuit. The killer is the high speed throttle opening. Now I know nothing about metallurgy, engine design, etc., so I cannot comment on why the K seems to be more sensitive to this fluctuating temperature gradient, but it does appear to be true. In particular its not absolute temperature that matters but rather the changing gradient across the engine. So whether you have a 78,82 or 88 degree stat won't change what I described above, it will instead just change the average temperature at steady state.

The PRT stat advantage is not its remoteness (it would be fine if it were installed right where the OEM stat lives I believe) but rather it's ability to sense pressure in the radiator loop and respond to it. Thus it can "cancel out" flow rate changes that would result simply from engine speed changes and instead focus on moderating the rate of change of temperature of the engine in response to actual load. In the end though the data shows that it's just better at doing this, not perfect. So I bet that some people will still suffer from HGF despite having a PRT fitted.

On the subject of absolute temperature for a predominately road car I think you want a higher temperature because this is best for efficiency and engine longevity - i.e. 88C stat is most appropriate. For a race engine where everything else is just so much hotter (you wouldn't believe how hot the engine bay gets in a race where you are on full throttle, full revs for 70% of 20-30 minutes) it perhaps makes sense to lower the target temperature because this increases the amount of heat you take out of the engine oil and you don't really care whether or not the engine makes 100,000 miles before the pistons wear out.

Cheers,
Robin

[campbell]

So it's the pressure feature of the PRT which is the key, not the fact that it's remote?

That's also a useful cautionary tale about how pure driving style could be used to hasten...or lessen...the likelihood of HGF.

Thinking of how I drive the Elise, I am unlikely to be on an m-way cruise but then instantly nail it with high revs for a period. However I am almost certainly quite likely to have nailed some high revs for a period on backroads then settled back down to a real steady cruise (whether through a long town street, perhaps, or when joining the A9!!).

I think you are saying that either scenario can develop "thermal shock" for the engine?

So what's the answer?

In my case, perhaps when transitioning from a revvy x-country blast to a period of cruising, using one lower gear on the cruise might be of value for a few minutes? This keeps the revs higher, reduces the rate at which temps fall (especially if you've entered a 30 or 40 zone when rad airflow will be quite poor) and presumably helps the stat cope with the temp change a bit better?

As for the cruise into revvy mode, sounds very like building up gradually as you would when starting from cold?

Or is this all poppycock...

[robin]

The effect is much more localised (in time) than that campbell. Warming the engine up before thrashing is obviously a good idea. However whenever you're driving in a full-throttle/no-throttle style you're always at risk of this issue arising. Just taking the car on track, for example, will do this. Down the back straight to the hairpin you're running at full throttle and say 80mph average over that stretch. Then you break down to 40ish and no revs/no throttle for a moment so the temperature will quickly rise and the stat will open while you're rounding the hairpin. Then you nail it to max revs all the way up the pit straight and the stat has to shut - while it's not shut the cool water from the radiator floods into the engine.

As I say, this is the way most cars have worked for ever so it's not necessarily a disaster, but the K does seem to be a sensitive to it.

Cheers,
Robin

[GilesM]

Cylinder head packed up and waiting collection to head off to Sabre heads for a bit of re-adjustment.

Just looking at the water pumps, Elise Parts one is approx half the price of the OE one from DeRoure, for many parts I plan to stick with OE, but the OE water pump seems such a horrible design, anybody any thoughts.

Elise parts pump:
http://www.eliseparts.com/products/show ... ater-pump/

[campbell]

Dig about for some KingK posts on water pump ideas. Doubt you'll find a "commercially available" version in line with his recommendations / designs (point of debate elsewhere!) but might help you evaluate the EliseParts design.

Or maybe Stu Pollock can fabricate your own improved design

[GilesM]

Dig about for some KingK posts on water pump ideas. Doubt you'll find a "commercially available" version in line with his recommendations / designs (point of debate elsewhere!) but might help you evaluate the EliseParts design.

Or maybe Stu Pollock can fabricate your own improved design

I'll have a look through some of the older posts, but I think KingK's thoughts are more along the lines of the OE one being horrible, and not really up to the job for a wonderfully tuned K-series with extra huge amounts BHP, looking at the pump I've just taken out, I have to agree with him. My re-built engine won't be hugely powerful, I just want it to work when I need it to. With the Elise parts water pump, I was just wondering if anybody had tried one, and did it work, has it been running for the last 50k miles, or did it fail instantly type of thoughts.

As for getting Stuart to fabricate one, I think that would be a very good idea, but I'm not sure you could get a decent pump in the space there is available, I think a remote electric one may be better, but that's for cleverer people (Cleverer than me) with some available time to sort out.

[GilesM]

Things are moving slowly, engine now in many bits, and crankshaft looks okay, thanks to Stuart and his knowledge of this sort of stuff, new bits about to be ordered, off on hols for a couple of weeks, so hope to start putting things back together when I get back, and a visit to Stuart's for sorting out the stand proud on the cylinder liners.
The head is being looked at by Sabre heads, that seems to be progressing nicely, so hopefully I may have the car back together and tested in time for Achmelvic in September.

Quick question for those that know, what would people suggest for holding the cylinder liners in place when I re-build the engine, I see there is a recommended Rover tool, but I can't find these anywhere.

Thanks

Giles

[Shug]

Old longbolts, bits of pipe and large washers. Tough to explain, but simple when you see a pic... Anyone got a pic?

[woody]

Old longbolts, bits of pipe and large washers. Tough to explain, but simple when you see a pic... Anyone got a pic?

It's in the manual /standard work answer.

[GilesM]

Old longbolts, bits of pipe and large washers. Tough to explain, but simple when you see a pic... Anyone got a pic?

Thanks, I understand from that, will a bit of 15mm plastic pipe do, or do you think I need a bit more force than that.

[steve_weegie]

Old longbolts, bits of pipe and large washers. Tough to explain, but simple when you see a pic... Anyone got a pic?

Thanks, I understand from that, will a bit of 15mm plastic pipe do, or do you think I need a bit more force than that.

That will do fine - you dont need too much force to clamp them, especially if you make sure you're always pushing the piston downwards, towards the crank when you're connecting up the bearing caps. The blue hylomar sealant for the liner bottoms doesnt set solidly either, so isn't mega sensitive to movement during assembly.