The V8 Owners Forum -

I ended up putting it in the top hose mainly due to room.. Not a lot of space in the bottom hose. I have used the lower setting and it cuts in and out fine, and is on for around 90 seconds before i switches back off and runs on when the engines off which is good. It doesn't some on while driving as the rad keeps it cool enough, I will have to see how it goes in the summer and when lanning. I can always move it if need be

Cheers Guys

What temp thermostat are you running?

In my 90 the lower range was too low and the fan ran pretty much continuously. Thats with a brand new rad. I am running an 88 deg stat though so the engine would be always running at the temp that the fan wants to trigger at.


Seems fine on the higher range...

I run my RV8 in the bobtail at 84.3c on 79.8c off. IMHO running an RV8 any where over 88c is asking for trouble and 92c + is gonna cook it. I take my temp reading from the coolant sensor which has been calibrated in MegaSquirt so hopefully is as near as correct as possible. The temp guage in the dash is for display purpose and NOT to be trusted.

Just my opinion.

jeff

bobtail84 wrote:I run my RV8 in the bobtail at 84.3c on 79.8c off. IMHO running an RV8 any where over 88c is asking for trouble and 92c + is gonna cook it. I take my temp reading from the coolant sensor which has been calibrated in MegaSquirt so hopefully is as near as correct as possible. The temp guage in the dash is for display purpose and NOT to be trusted.

Just my opinion.

jeff

Oh I don't trust my temperature gauge at all. Especially since it told me everything was hunky dorey whil the engine merrily cvooked itself .

Anyhow I have an 82 degree stat in and so far the fans only come on twice. Once when sat in tesco waiintg for some idiots to park. and then once last night whilst towing a car offf an incredibly steep driveway as all the fuel had sloshed to the front of the tank and it wouldn't start.

Itseems quite happy at the moment and the fan only runs for about 60 seconds now before going off. On tick over it takes ages to get that warm

I always have my manual overide for mud plugging!

Guys,

You will need a water level sensor as well as a temperature sensor to be safe. Temperature sensors only work if immersed in water. In my time with industrial engines I have seen a lot of them cook for just this reason. Temp senders will not work in air!!! It amazes me that more manufacturers didn't fit level sensors as well.


Alan

Yup, I want to filt a coolant level sensor but that again requires dirlling/tapping the rad which I am trying to avoid.

satancom wrote:Yup, I want to filt a coolant level sensor but that again requires drilling/tapping the rad which I am trying to avoid.

IIRC, a simple untapped hole to receive a Rover SD1 rad level sensor and grommet plus the electrical delay unit from Rimmers will suffice. Rover SD1 rads all had them.

You could even have the full SD1 system if you have an expansion tank.

This essay explains.

http://www.vintagemodelairplane.com/pag ... ant02.html

and this is the circuit.

max 80 degrees any thing above that you guys asking for serious
problems
at 95 to 100 degrees you get the block to expand so much that the main caps are no longer firmly in place in the block registers
way to stop main bearing cap fretting problem is to keep temperature at no more than 80 degrees,
any thing above 80 degrees you loose 10 % of power
so if your engine makes 300 bhp at for example 90 degrees at below 80 will make 300 bhp
at the factory blocks got heated up 140-150 degrees so they could slide the liners at room temperature in to position ,they did not press them so y the rover v8 only accepts no more than 3 overheats after that the block no longer can be serviced,
lucas fuel injection don`t switch off last stage off fuel enrichment till 80 degrees so you should switch that off if running at 75 max

cheers
Gil

"at 95 to 100 degrees you get the block to expand so much that the main caps are no longer firmly in place in the block registers "
"way to stop main bearing cap fretting problem is to keep temperature at no more than 80 degrees,"
any thing above 80 degrees you loose 10 % of power
No on two counts
1/ the main cap studs/ bolts are steel, this expands 2.5 X more slowly than ally, and about 1.7 more slowley than the copper/bronze in the bearing shells the net result is that the cap is tightened into place as temperature goes up.
2/ The bottom end of the engine is running at oil temperature, the water cooling system does not extend beyond the swept area of the piston. Changing the thermostat will make no differance to the temperature the main bearings run at.


"any thing above 80 degrees you loose 10 % of power"

This statment is too general to have any meaning, running the bores at a lower temperature than designed will result in a loss of power and more rapid wear of the bores. I agree you want the cylinder head as cool as you can reasonably get it to avoid detonation (if that is a problem on a given engine) but if it is not an issue then taking all the heat of combustion into the cooling system before it has done any work for you just reduces power. Each engine design and combination of C/R ignition advance, fuel type, bore clearances etc are all selected to work at a given temperature. Why doe you think people at the top of motorsport spend so muck on ceramic coatings if the aim is to run the engine cold??
David Vizard did a whole load of work on this on Pintos, SBC and A series and found some very interesting results they certainly weren't "run your engine at 80 deg C"
Best regards
Mike

we are talking about the rover v8 alloy not iron

oh good so was I
As I said the alloy of the block expands faster than the steel of the caps and bolts so tightening up the bearing caps you will notice the threads in the block start below the mating surface. And an over heated alloy engine always siezes its bottom end (fnarh)
Best regards
Mike[/b][/u]

Following on from the points posted by v8man and kiwicar, I'm a great believer in the theory that liner problems on the RV8 is related to high running temperatures.

Running at 95-100 degrees is fine for emissions and economy but when you switch off at this temperature, residual heat can raise the engine temp to about 120 degrees which is getting uncomfortably close to liner install temperature. (The coolant dosen't boil because it's under pressure).
Restarting at this temp could move a liner that is light on interference fit tolerance. This risk occurs probably every time you stop for petrol after a fast run.

It goes without saying, that boiling when running is asking for liner problems.


I like to run my engine at 85-90 degrees as a reasonable compromise on power/wear/economy etc.

On the subject of the effects of temperature on main bearing cap security, I would agree that the vertical location increases with temp rise but side location reduces although this probably dosen't become a problem with crossbolted engines.

Regards Denis

Well assuming that although my gauge does not necessarily give an accurate deflection it does still presumably give the same deflection for any given temp.

Using the higher range on the x-fan switch gives me the same overall running temp as i had with the kenlowe switch.

I have been running my 3.5 at the same temp for over a year, 70 miles a day with no issues.

Perhaps though if it was a larger capacity i would be more worried about running at higher temps, due to the greater risk of liner issues.

Last tank gave 16.5mpg on LPG- so all seems good

Quagmire wrote:Well assuming that although my gauge does not necessarily give an accurate deflection it does still presumably give the same deflection for any given temp.

Using the higher range on the x-fan switch gives me the same overall running temp as i had with the kenlowe switch.

I have been running my 3.5 at the same temp for over a year, 70 miles a day with no issues.

Perhaps though if it was a larger capacity i would be more worried about running at higher temps, due to the greater risk of liner issues.

Last tank gave 16.5mpg on LPG- so all seems good

If I was running a 3.5 I wouldn't be too worried about liner problems.
Although not unheard of in 3.5 blocks, liner problems tend to be associated with 94mm bore later engines.

Regards Denis

have a pic on this one
http://books.google.com/books?id=gmSavy ... 3&dq=block)