So just to confirm
When idling it takes 15/20 minutes for the rad fan to switch in and even with it running continuously the car continues to get hot and over heats.
Are you sure the fan is running the right way?
The air off the rad is red hot ?
The Polo rad although small did not give me any issues at all with a 155BHP Zetec and people are running 200+ BHP XE's and Zetecs with them without issue as well as RV8's so the rad should be able to keep it cool when idling with no more then 20BHP so I do not think that the rad is the problem - it obviously cannot be.
Ideally the header tank should be fitted near the rad bottom hose but I would think that that return on the pump should be OK
A smaller pump pulley is however not a good move - this should be larger so the pump runs slower to reduce the chance of pump cavitation at higher RPM.
Andrew
Rover V8 Cooling Advice Needed
Moderator: phpBB2 - Administrators
Not 100% convinced by that - I would have thought that as its a heat engine a higher efficiency would mean more heat produced from a given a fuel value not less.
Besides that as I stated at idle the rad and fan should cool it as little heat is actually being produced if it only over heated at high power outputs then accepted the rad may well be an issue.
Andrew
Besides that as I stated at idle the rad and fan should cool it as little heat is actually being produced if it only over heated at high power outputs then accepted the rad may well be an issue.
Andrew
4.5L V8 Ginetta G27
In my experience, idle temperature control is just as hard as driving. Electric fans are rubbish compared to an engine driven fan.
But at the end of the day, some science will sort it, either via temporarily fitting a bigger rad, or measuring bottom hose temp.
I wonder if the RV8 water pump is relatively poor as well.....
Chris.
But at the end of the day, some science will sort it, either via temporarily fitting a bigger rad, or measuring bottom hose temp.
I wonder if the RV8 water pump is relatively poor as well.....
Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8
Hi guys,
Sorry for the delay in replying, I didn't realise I had missed so many posts...
Taking the replies in turn:
Chris, it may well be radiator size but in the mode I am driving the car I am hardly using any power. Think of it as a quick squirt up to 50-60MPH and then a cruise for 0.5 miles to a roundabout. Then repeat a few times. My average BHP output is probably 20BHP or so as Darkspeed says so my cooling requirements should be minimal. I would completely understand your argument if I was having problems with overheating at a track day. I don't currently have a means to measure bottom hose temp while driving although I did buy an infra red temp gun so I can measure the various temps when stationary.
Ian, I have ducted my nosecone inlet to my radiator as you suggest and this has had little effect. Worth doing all the same I agree.
Darkspeed, the fan can keep the car at around 100C when stationary but has no margin for hot days as it needs to run continuously. I will replace this with either a large single fan or twin slimline fans as I also intend to duct the hot air out of the nosecone like on the westfield SEight V8. The fan is definitely running the right way - it is the Polo fan to go with the Polo rad and sucks air in from the front. Yes, I have heard of people using the Polo rad on more powerful cars which is why I bought it. With respect, I disagree about running a smaller water pump pulley as this is recommended in David Hardcastle's Rover V8 book and Des Hammill's book as well. I am only running it at something like 1.05 times crank speed instead of 0.9 times crank speed so cavitation at 5500RPM is not a problem I don't think. They pulley in question can be found here:
http://cgi.ebay.co.uk/Water-Pump-Pulley ... 2066wt_985
ChrisJC, you are correct, I found an article recently which talked quite authoritatively (IMO) about cooling. Here is the link - it is well worth reading:
http://www.arrowheadradiator.com/14_rul ... obiles.htm
The rule in this article is that 1/3rd of fuel energy goes to exhaust, 1/3rd goes to drivetrain and 1/3rd goes to cooling system. So, you need as much cooling capacity as you have engine BHP. In my case 155BHP or so. Darkspeed, I would agree with ChrisJC that the RV8 is less efficient than a modern multivalve EFI engine and will dump more fuel energy into the cooling system. For one thing there are twice the frictional losses in the cylinders. Also, I'm not sure if it is fair to say that at idle the radiator should be able to cope with the (eg) 20BHP because the water pump is only turning at 800 RPM or so not 5800RPM which it would be at full power.
ChrisJC, yes the P6 water pump I am using is supposed to worse than the SD1 pump which is why I opted for the smaller pulley but many people use it so it should be capable.
I think I am going to try simplifying my bleed hose arrangement and I will try to get a better thermostat housing from Dave at V8 Dev. I will make a better top hose and then see what improvement that yields. I still think the Polo rad should do the job on the road if not on the track but I am prepared to be proven wrong...
Thanks to everyone for valuable input,
Craig.
Sorry for the delay in replying, I didn't realise I had missed so many posts...
Taking the replies in turn:
Chris, it may well be radiator size but in the mode I am driving the car I am hardly using any power. Think of it as a quick squirt up to 50-60MPH and then a cruise for 0.5 miles to a roundabout. Then repeat a few times. My average BHP output is probably 20BHP or so as Darkspeed says so my cooling requirements should be minimal. I would completely understand your argument if I was having problems with overheating at a track day. I don't currently have a means to measure bottom hose temp while driving although I did buy an infra red temp gun so I can measure the various temps when stationary.
Ian, I have ducted my nosecone inlet to my radiator as you suggest and this has had little effect. Worth doing all the same I agree.
Darkspeed, the fan can keep the car at around 100C when stationary but has no margin for hot days as it needs to run continuously. I will replace this with either a large single fan or twin slimline fans as I also intend to duct the hot air out of the nosecone like on the westfield SEight V8. The fan is definitely running the right way - it is the Polo fan to go with the Polo rad and sucks air in from the front. Yes, I have heard of people using the Polo rad on more powerful cars which is why I bought it. With respect, I disagree about running a smaller water pump pulley as this is recommended in David Hardcastle's Rover V8 book and Des Hammill's book as well. I am only running it at something like 1.05 times crank speed instead of 0.9 times crank speed so cavitation at 5500RPM is not a problem I don't think. They pulley in question can be found here:
http://cgi.ebay.co.uk/Water-Pump-Pulley ... 2066wt_985
ChrisJC, you are correct, I found an article recently which talked quite authoritatively (IMO) about cooling. Here is the link - it is well worth reading:
http://www.arrowheadradiator.com/14_rul ... obiles.htm
The rule in this article is that 1/3rd of fuel energy goes to exhaust, 1/3rd goes to drivetrain and 1/3rd goes to cooling system. So, you need as much cooling capacity as you have engine BHP. In my case 155BHP or so. Darkspeed, I would agree with ChrisJC that the RV8 is less efficient than a modern multivalve EFI engine and will dump more fuel energy into the cooling system. For one thing there are twice the frictional losses in the cylinders. Also, I'm not sure if it is fair to say that at idle the radiator should be able to cope with the (eg) 20BHP because the water pump is only turning at 800 RPM or so not 5800RPM which it would be at full power.
ChrisJC, yes the P6 water pump I am using is supposed to worse than the SD1 pump which is why I opted for the smaller pulley but many people use it so it should be capable.
I think I am going to try simplifying my bleed hose arrangement and I will try to get a better thermostat housing from Dave at V8 Dev. I will make a better top hose and then see what improvement that yields. I still think the Polo rad should do the job on the road if not on the track but I am prepared to be proven wrong...
Thanks to everyone for valuable input,
Craig.
Hi,
Just to let you know, I got a new thermostat housing from Dave at V8 Dev and hope to fit it tomorrow. I'll make a top hose up from a piece of flexible radiator hose from Halfords (Vulcoflex I think it's called) - this is what I use for my bottom hose already.
Thinking about it, does anyone have any experience with these flexible hoses? They are the type with a steel spring down the middle which prevents the hose collapsing when you bend it. The thing which worries me a bit is the fact the internal diameter of the hose is quite small and the spring is visible which might cause turbulent and thus inefficient flow.
Cheers,
Craig.
Just to let you know, I got a new thermostat housing from Dave at V8 Dev and hope to fit it tomorrow. I'll make a top hose up from a piece of flexible radiator hose from Halfords (Vulcoflex I think it's called) - this is what I use for my bottom hose already.
Thinking about it, does anyone have any experience with these flexible hoses? They are the type with a steel spring down the middle which prevents the hose collapsing when you bend it. The thing which worries me a bit is the fact the internal diameter of the hose is quite small and the spring is visible which might cause turbulent and thus inefficient flow.
Cheers,
Craig.
Hi guys,
I have now revised my top hose by incorporating the straighter thermostat housing recommended by Chris and supplied by Dave from V8 dev. Thanks to both for your help.
As you can see on my gallery here in the last four photo's posted, the result is much lower, cleaner and simpler. I have retained the top hose bleed for filling purposes but it is only for manual bleeding now and is not routed to the header tank. I have also removed the radiator bleed pipe as I think it should bleed just fine via the upward sloping top hose.
I have also removed the mess of t-pieces and replaced it with a single bleed pipe from the inlet manifold bleed pipe to the header tank upper inlet. This should keep the inlet manifold and cylinder heads bled of any air or steam which is naturally released.
Finally, and perhaps most importantly, when refitting the thermostat housing I decided to test my thermostat before refitting. Despite testing it before original fitment, I found it to be faulty!!! I tested it alongside the 82C thermostat which I had fitted originally and in a pan of boiling water the 82C was wide open and the 74C was completely closed. I used my infra red thermometer to determine that the 82C 'stat is fully open by 86C which seems about right. I just fitted the 82C for now until I can source a good quality, ideally large bore 74C 'stat. I don't know what caused the 'stat to fail as I never let the temperature of the engine exceed 110C and never let it boil.
Anyway, lesson learned - never trust a thermostat!!
I've not had a chance to run the car yet but hope to do so tomorrow evening if the weather is dry. I'll let you all know how it goes.
Thanks to everyone for your help and advice,
Craig.
I have now revised my top hose by incorporating the straighter thermostat housing recommended by Chris and supplied by Dave from V8 dev. Thanks to both for your help.
As you can see on my gallery here in the last four photo's posted, the result is much lower, cleaner and simpler. I have retained the top hose bleed for filling purposes but it is only for manual bleeding now and is not routed to the header tank. I have also removed the radiator bleed pipe as I think it should bleed just fine via the upward sloping top hose.
I have also removed the mess of t-pieces and replaced it with a single bleed pipe from the inlet manifold bleed pipe to the header tank upper inlet. This should keep the inlet manifold and cylinder heads bled of any air or steam which is naturally released.
Finally, and perhaps most importantly, when refitting the thermostat housing I decided to test my thermostat before refitting. Despite testing it before original fitment, I found it to be faulty!!! I tested it alongside the 82C thermostat which I had fitted originally and in a pan of boiling water the 82C was wide open and the 74C was completely closed. I used my infra red thermometer to determine that the 82C 'stat is fully open by 86C which seems about right. I just fitted the 82C for now until I can source a good quality, ideally large bore 74C 'stat. I don't know what caused the 'stat to fail as I never let the temperature of the engine exceed 110C and never let it boil.
Anyway, lesson learned - never trust a thermostat!!
I've not had a chance to run the car yet but hope to do so tomorrow evening if the weather is dry. I'll let you all know how it goes.
Thanks to everyone for your help and advice,
Craig.
Guess what???
It stays cool!!
Took it out for a quick blast tonight and the temperature came up briskly to the 85 degree mark and then stopped rising. Over the course of the next 10 minutes it rose slightly higher but still below 90C. Then when slowly driving through the residential roads on the way home it rose to just over 90C and then the fan switch came on and took it back down below 90 again where it stayed while idling stationary.
I think I still fancy a cooler thermostat and fan switch just to keep the under bonnet temperature as low as practical and since my silencers are getting barely warm to the touch I will get some manifold wrapping tape and wrap up the manifolds. I might go for a bigger radiator fan as well as I suspect the existing one will struggle in the hotter weather.
Anyway, looks like the problem was mainly a dodgy thermostat which is a bit annoying as it was tested before installation and was brand new. At least it prompted me to sort out my inefficient and ugly top hose so now I can think about getting rid of my bonnet bulge and perhaps even getting the car painted at some point...
Thanks again everyone,
Craig.
It stays cool!!
Took it out for a quick blast tonight and the temperature came up briskly to the 85 degree mark and then stopped rising. Over the course of the next 10 minutes it rose slightly higher but still below 90C. Then when slowly driving through the residential roads on the way home it rose to just over 90C and then the fan switch came on and took it back down below 90 again where it stayed while idling stationary.
I think I still fancy a cooler thermostat and fan switch just to keep the under bonnet temperature as low as practical and since my silencers are getting barely warm to the touch I will get some manifold wrapping tape and wrap up the manifolds. I might go for a bigger radiator fan as well as I suspect the existing one will struggle in the hotter weather.
Anyway, looks like the problem was mainly a dodgy thermostat which is a bit annoying as it was tested before installation and was brand new. At least it prompted me to sort out my inefficient and ugly top hose so now I can think about getting rid of my bonnet bulge and perhaps even getting the car painted at some point...
Thanks again everyone,
Craig.
-
CastleMGBV8
- Top Dog
- Posts: 2334
- Joined: Sat Aug 18, 2007 5:09 pm
- Location: Sidcup, Kent, UK
Craig,
Glad to hear the problems solved, although you had a stat problem I think it was also a combination of the other issues and getting the circulation properly sorted, has also contributed to getting more efficient cooling.
Just to clarify where the stat cover came from, it was V8 Conversions not V8 developments.
Kevin.
Glad to hear the problems solved, although you had a stat problem I think it was also a combination of the other issues and getting the circulation properly sorted, has also contributed to getting more efficient cooling.
Just to clarify where the stat cover came from, it was V8 Conversions not V8 developments.
Kevin.
Hi Kevin,
I am really sorry, not only did I get V8 Dev and V8 Conversions mixed up but I also got you and Chris mixed up as well with regards to who it was who pointed me in the direction of V8 Conversions in the first place...
Obviously I am still grateful to Chris for his advice but a special thank you goes out to your good self for pointing me at V8 Conversions and their modified thermostat housing.
Sorry again for the mix-up,
Craig.
I am really sorry, not only did I get V8 Dev and V8 Conversions mixed up but I also got you and Chris mixed up as well with regards to who it was who pointed me in the direction of V8 Conversions in the first place...
Obviously I am still grateful to Chris for his advice but a special thank you goes out to your good self for pointing me at V8 Conversions and their modified thermostat housing.
Sorry again for the mix-up,
Craig.
