Running without thermostat

[kiwicar]

Hi John
can't say directly for the rover v8, but from my mini days, you would never removed the stat completely what you did was either buy a high flow stat like the one I posted up a link to earlier, perforated the body of the stat full of holes, it allowed lots more water through but made it very turbulent, in the theory the turbulent flow brought more water in contact with the hot bits of the engine (I was always a bit dubious about this one) and still kept up the back pressure on the pump. Finally some people replaced the stat with an insert with a 1" hole in the middle, abouy 1 1/2" long and a 3/16 bolt across it to make the flow turbulent again.
There is a theme here! you don't want the flow too smooth and you want to keep up some back pressure (It was said to stop the pump cavitating as well as improve heat transfer to the water).
Best regards
Mike

[mgbv8]

The area to calculate for running without a stat is the free area of the opening of the stat when fully open. So you measure the distance between the stat flange and the face of the disk on the stat. Then measure the circumference of the opening in the stat flange. This gives you a length and a width. From this you can calculate the free area of the opening when the stat is fully open. In my case. This equates to the same area +/- 5% as the opening in my JE stat cover. So I'm happy that I can run without a stat fitted and still be sure that I have the right resistance to water flow at all times while still retaining full flow of water...

[topcatcustom]

I'd just like 5 or so knocked off my temp.

What stat are you running? I run a 74 degree stat and my stage III 4.6 runs at around 78 degrees.

I'm running a 75deg stat, they didnt have a 74 in stock.

My gauge reads about 85-88, infrared heat gun read about 78 on the thermostat housing, which is painted black and the hottest part of the engine I could find with the guns readings! Not sure of its accuracy (or the gauges as numbers are close together) but for peace of mind I would like it slightly cooler, less chance of liner slip and I dont have to worry about emissions as the car is pre test. I think I will get a 74deg stat and use that, it may make some difference and only a few £.

[adamnreeves]

Okay I have installed the JE straight out thermostat cover but before I did I looked it at closely. Obviously the straight out hose is the obvious difference. The other difference is that is not like the standard item which is kind of bowl shaped, this one is cylinderical, the I.D of the bore is almost exactly the same size as the bore of the thermostat when open. I've therefore cut out the middle of the thermostat knowing that the restriction to the flow is going to be marginally less when compared to an open stat. I also noted that this thermostat cover might not be compatible with the later thermostats that have a hole in the flag with a float type ball as this would foul the cover indeed my hole that I drilled into the thermostat flange would also be obscured adding to justification to remove the bulb and spring.

So I started up my car in the cold garage which indicated a coolant temp of 12celius. By the time I pulled the car out of the garage and got my helmet on and buckled up it was showing 34celius. Drove off and by the time I had driven 0.5 mile it was reading 60celius. Crusing at 60 down a dual carriage way the temperature seem to settle at 80-82celius. However as soon as I drove through a town with traffic doing less than 20mph it climbed quite quickly to 100celius, seem to just about hold it there with the fan on. As soon as I cleared the town it started to drop almost as quickly as it raised. until it got to 89celius and then it seem to take five miles to get to 85celius, by which time I was home.

So mixed results, cruising is ideal, warm-up seems to be fine. Traffic seems to be worse. I am going to let it cool down and check the coolant level as some air might have bleed through. Also going to squeeze the hoses. But now I do not have a 180degree bend in an upward position only one 90 out of the thermostat housing, no heater matrix, no closed thermostat, no many places for air to hide.

edit: I am also going to check my belt tension.

Thoughts???

[adamnreeves]

Went for another run today. This time I took some ECU logging. The ECU temperature sensor requires no calibration unlike the digital dash.

Started logging at 103seconds after engine start and the coolant temperature was 37celius

at 170seconds temperature had reached 45celius which is when I pulled of my drive.

Temperature raising at a steady pace to 73celius by 391seconds

At 524seconds it had levelled off at 80celius stayed here until I got to traffic lights which were red at 794seconds. I was to wait at the lights until 847seconds by this time the temperature reached 88. A bit of traffic and some stop starts mean temperature only started to drop 911seconds to 85.

Some time later it dropped to 81. Highest temperature it reached was 93 when I just left it idling for ages at home to see what max temperature it reached on the fan. The dash at this point said 100. It seems the dash temperature gets further and further out the higher the temperature which gives the illusion that the temperature is raising quickly however its all relative and it does seem the temperature raises more quickly when stop than it used to do with a thermostat in. Would the restriction imposed by a thermostat help with slowing temperature increase at stand still. Thoughts anyone?

[zim]

I've got a 4.2 in an offroad landrover. The radiator is a pretty big aluminium one behind the seats. I'm running a 74 degree stat, and it will run all day at 82 - 88C. My first fan kicks in at about 84 and am yet to have my second fan kick in (about 92 i think).

I can spend a long time sat not moving whilst winching (hydraulic pump run off the engine) and the temp is always happy

Gordon

[jetskijase]

Adam
cracking build there mate! wish i had more funds to finish my robin hood to your standard!!

but i have gone for the rv8 and i'am running it in at the moment and i'am always around 90 on the gauge( i reckon it is around 2-3 degrees high on the gauge as i had to fit a resistor to match sensor and gauge) with the fan always on though.
in traffic it climbs to 100 on gauge, the engine bay is really hot and you cant touch any hoses, is this right??
i have just fitted a header tank and bleed in the top hose.
my last chance to get the temp down is timing( hopefully)
i'am on the second mark before tdc, is this 4 degrees advance at idle??? and considering the realibililty of the pulley i might not have any advance.

So ( sorry for highjacking the thread, i will start a new one if needed) will advancing the ignitionto at least 10-12 ( tuning books say 14 for a 3.5) will this drop the temperature down??????
any ideas please???? got to get it to lemans in 2 weeks time!!!!!!!!aaaaaaaaaaahhhhhhhh

it also gets upto 90 in around 3-4 mins.

thanks everyone and hope it is good news!!!!!!

jason

[adamnreeves]

Jason,

Thanks for the positive comments. Also I took five years to build and finance mine including downgrading my daily drive for 2 years to pay for it all. Water temperature at 100 I would try and touch the hoses to be honest especially as I have an infra-red temperature probe anyway. I connected my bleed to the top of the header tank. 4 degrees at idle according to my book is bang in the middle of the factory setting but then it does say that most engines response well to this being increased between 10-16. I am running 9. I might play with my idle advance. I think you're right advancing timing does reduce temperature. Of course if the fuel mixture is too lean this will also increase temperature, at idle I am running around 1:13.5 AFR which is what the RV8 likes.

[TVRleigh]

Well I run without a stat, just the outside bit, due to having a 4.6 front cover, but not the remote housing or heater matrix.
Can was on the Dyno for 5 hours on Saturday, and never went over 100
was running about 80 most of the time, with a max of about 95.

I did think in the past I was running too hot, but they used some infered temp sensors and turns out my sensors are over reading, so will need to re-calibrate them.

I'm running an emerald with sensors I got from them which was told did not need calibrating, but look likes will have to program them manually.

[adamnreeves]

Yeah mine was well behaved on the dyno it was on for three hours. but it did have a fan simulating 70mph. Might be more to do with idling, what you got your static advance set to?

Well I run without a stat, just the outside bit, due to having a 4.6 front cover, but not the remote housing or heater matrix.
Can was on the Dyno for 5 hours on Saturday, and never went over 100
was running about 80 most of the time, with a max of about 95.

I did think in the past I was running too hot, but they used some infered temp sensors and turns out my sensors are over reading, so will need to re-calibrate them.

I'm running an emerald with sensors I got from them which was told did not need calibrating, but look likes will have to program them manually.

[SuperV8]

A few of my thoughts:

Jason:
Re timing, you should first check (if you haven't already) the timing mark on the pulley lines up with the pointer (TDC piston 1 = 0degs). It is only a bent bit of steel, they are quite renown for not being acurate. Only then can you correctly set your timing.

Re: thermostats, not sure why you'd want to remove them (leaving a restictor in place) (appart from risk of a stuck shut stat in a racing engine) There is more going on in heat transfer than just flow. If there is too much flow then there isn't time for the heat to transfer from the block into the coolant, also with no thermostat there in no control of the coolant temp going into the engine, if you cruise on a motorway with very little load and high wind speed you may get overcooling. The thermostat is there to provide a consistent engine temp and try and minimise thermal gradients across the block.

Adam:
If it only over heats when you're in traffic it suggests to me you haven't got enough air flow through the rad, how big is your fan?

If you want to run a little cooler the limit is the size of your rad and airflow through it. If the rad can only lower the water temp to 90degs then fitting a 74degs sat or restrictor will do nothing.

Would be interesting to also measure the temp of the water before and after the rad to see how effective it is?

Tom.

[jetskijase]

hi Tom

Thanks for advice, thats on my list of jobs for today! tdc, timing and mixture settings.

what rad are you using in your dax tom?? any website for pictures? would be interested to see the supercharger in a 7 type kcar!!!

[adamnreeves]

Good points well made. To be honest I haven't a clue what the radiator or fan specs are other than its a high efficiency ali radiator provided by Westfield for Rover V8 installation. Likewise for the fan although I know it makes a racket or you can real feel the air moving and it is protecgted by a 20Amp fuse. I'll have to call them to find out I guess. My nose cone is the ducted type which ensure that all air entering the front of the car has to go through the rad. when driving along I can feel the heat coming out of the duct after the radiator over my aeroscreen so I know its doing something. I have tried to read the rad temperature but its very difficult as it is completely enclosed at the rear and sides, the gaps in the drill are not wide enough to get my heat probe in there.

A few of my thoughts:

Jason:
Re timing, you should first check (if you haven't already) the timing mark on the pulley lines up with the pointer (TDC piston 1 = 0degs). It is only a bent bit of steel, they are quite renown for not being acurate. Only then can you correctly set your timing.

Re: thermostats, not sure why you'd want to remove them (leaving a restictor in place) (appart from risk of a stuck shut stat in a racing engine) There is more going on in heat transfer than just flow. If there is too much flow then there isn't time for the heat to transfer from the block into the coolant, also with no thermostat there in no control of the coolant temp going into the engine, if you cruise on a motorway with very little load and high wind speed you may get overcooling. The thermostat is there to provide a consistent engine temp and try and minimise thermal gradients across the block.

Adam:
If it only over heats when you're in traffic it suggests to me you haven't got enough air flow through the rad, how big is your fan?

If you want to run a little cooler the limit is the size of your rad and airflow through it. If the rad can only lower the water temp to 90degs then fitting a 74degs sat or restrictor will do nothing.

Would be interesting to also measure the temp of the water before and after the rad to see how effective it is?

Tom.

[TVRleigh]

I've fitted a hose joiner with a hole for a sensor, I've fitted this in the outlet of the Radiator, this way I can measure rad temp as well as engine temp

[SuperV8]

Hi Jason, i'm using an ali rad supplied by Dax.

My issue sounds similar the the westfield mentioned earlier, coolant temps were fine when driving but when in traffic & ambient temps were higher than 20oC the fan struggled to keep the coolant temp below 97 - 100oC. Going to try and fit the biggest fan I can, or might try two fans?

Some pics of my car can be seen here:
http://forum.daxsportingclub.com/phpBB3 ... =35&t=4305

Tom.