Engine running temperature with mods

[Carbuilder]

I'm just about finished with the mods to my car and have taken it for some short drives. The mods from stock affecting temperature are:

Dale's radiator
Electric pusher fan
A/C added, so a condenser in front of the rad
Engine is a bored/stroked roller cam 302, so 347ci
Engine was dyno'd at 426 HP before I did some mods to tone it down a bit; say 400ish HP now
180F thermostat
Electric fan set to come on at 190F
Temperature being measured with the sensor from the Aces Fuel injection; agrees with temp gauge
One horn hole blocked off (haven't blocked the other one yet)
The hood is NOT on the car yet

Took me a while to get the fuel injection sorted out, but running pretty good now. Yesterday was around 81F-82F so a warm day for a test drive.

Driving around on country roads, about 70kph to 80kph. The car was running very consistent at 185F to 187F, so electric fan not coming on. Stopping at lights and some traffic engine heated up and fan came on. Running a little over 190F. Got home and stopped on the driveway for a while to let it idle. Temperature was steady at 196F to 198F.

I was concerned with those high temperatures, but then looked up data for the Fox Body Mustang 5L engines, which mine more or less is. The factory thermostat is 193F and the engines run at 200F to 210F. So my temperatures are fine, just my mind-set that I'd like it a bit cooler. Since the hood is not on, I don't know how much it will heat up with it back on. I do have the vented hood, but personally don't think that does a lot. It would certainly do some good, but looking at that venting area compared with inlet area....not sure. A good test would be to take it for a drive, then tape up the vents and take it for another drive. Have to try that.

I know the temperature is OK for now, but with the hood back on and higher air temperatures I'm a little concerned. I'm wondering about adding a fan to the engine. Not much room between the rad and the front face of the water pump pulley (maybe 1 1/2" max). Also, it would have a max diameter of 13". Any reason not to do this? Anything else I'm missing?

Thank you,

Rick

 

[Austin Healer]

Rootes specified a 160 thermostat for all of the Tiger variants. I have a mildly built 302 in my Mk2. I have an upgraded radiator core (dimpled tubes) and an LAT cooling fan. I have blocked the horn holes. As I have a Mk2, it has a factory oil cooler. There are other variables that can affect running temps. mixture, ignition timing and type of exhaust. Headers generate a lot of heat....

I built a steel version of the LAT hood and noticed that my engine temps were reduced dramatically as now the air can get out of the engine bay. My temp gauge rarely registers to the mid point. even in triple digit heat, stop and go traffic or climbing mountain passes.

I had a buddy come by and question the effectiveness of the exhaust vents on my hood. I used to have a willow tree and the leaves had fallen into the vents... I started the car and the leaves were blown out of the vents by the force of just the cooling fan (mechanical). The car was stationary in the driveway.... don't underestimate the vents, they work!

The biggest issue with engine cooling on the Tiger is the airflow through the radiator. Because there is so little space in the engine bay once the air hits the radiator it's effectively stopped by all the air trapped in the engine bay. Driving with the hood removed will not give you any kind of real measure of cooling efficiency as you now have a huge hole for the air to escape... I can almost guarantee that your car will run a lot hotter with an unvented hood.

 

[Carbuilder]

Not sure why a 160 thermostat instead of a 180. At my running temps it wouldn't make a difference.

I do have headers that are not wrapped. Too late now to wrap them without a lot of work, so that does put a bunch of heat into the engine area.

I agree that airflow through the rad is very important. That's why I suggested an engine fan in addition to my electric one. The A/C condenser is fairly "fine" and does reduce airflow through the rad. I thought with an additional fan pulling air through it would provide a much better flow through the engine area than I have now. Well, actually what I have now is very good with the hood not on. But with the hood on it is only going to get hotter.

I will be curious to test the hood vents blocked and unblocked. I know you have a lot more experience than I have, but the issue I have with your hood vent example is this. If I had a non-vented hood, drilled a 1/4" diameter hole in it and put some leaves over the hole, when I started the fan the leaves would blow off the vents. But that 1/4" hole would do nothing for cooling. No doubt the vented hood will help (compared with non-vented, not with my no-hood right now) but how much?

I want to charge up the A/C system before putting the hood back on since it is a lot easier to work in that area without the hood on.

 

[sandy]

Yeah, you have to get the air out of the engine compartment, and it's a log jam inside of there. No where for it to go. I added 2 long and large vents on the hood. Started wrapping the headers as well but it will definitely help let the heat out. I also blocked the horn holes and did some knock out holes in the lower radiator support to allow some more air to get to the core which is blocked by the support.

160 T-Stat won't make a difference, will be wide open most all of the time in the Tiger except for those in Icelandic conditions or warming up.

 

[Austin Healer]

Not sure why a 160 thermostat instead of a 180. At my running temps it wouldn't make a difference.

I do have headers that are not wrapped. Too late now to wrap them without a lot of work, so that does put a bunch of heat into the engine area.

I agree that airflow through the rad is very important. That's why I suggested an engine fan in addition to my electric one. The A/C condenser is fairly "fine" and does reduce airflow through the rad. I thought with an additional fan pulling air through it would provide a much better flow through the engine area than I have now. Well, actually what I have now is very good with the hood not on. But with the hood on it is only going to get hotter.

I will be curious to test the hood vents blocked and unblocked. I know you have a lot more experience than I have, but the issue I have with your hood vent example is this. If I had a non-vented hood, drilled a 1/4" diameter hole in it and put some leaves over the hole, when I started the fan the leaves would blow off the vents. But that 1/4" hole would do nothing for cooling. No doubt the vented hood will help (compared with non-vented, not with my no-hood right now) but how much?

I want to charge up the A/C system before putting the hood back on since it is a lot easier to work in that area without the hood on.

This is a copy of the hood I made for my car. it's basically a copy of the LAT hood except mine has a longer and wider scoop for the carb intake. As the exhaust vents are pocketed, forward motion also acts to extract the underhood air (Venturi effect). When I fabricated and installed the vents my engine temps came down by 20 degrees C. On the openings for the exhaust vents I used metal lathe for house stucco that I bought from Home Depot. I had it powder coated black. We have about 6-8 weeks here in the summer when it's in the triple digits and I like to drive when the sun is out!

The 160 thermostat opens quicker and if the cooling system is optimal it makes it so the car doesn't get as hot to start with and makes it easier for the engine to recover if it does get hot. My car rarely ever hits the center of the gauge (70C), and even on the hottest days in traffic or under load, never gets more than 1/8" past gauge center. A 180 or 190 thermostat is designed to keep the engine above those temps. It's not a huge distance from 190 to overheated... I use an 11lb radiator cap, the heater cores really can't stand much more pressure than that.

Aside from airflow, coolant speed is VERY important. You do NOT want to run a high flow water pump. They only move the water so fast that it can't cool in the radiator like it's supposed to. That's also the point of the dimpled tube core, it slows down the water giving it time to actually cool... If the water is flying through the radiator it's going to be nearly as hot coming out as it was when it entered.

When the factory competition cars operated in high heat, they didn't latch the hood completely, this allowed the hot air in the engine bay to escape. The LAT exhaust vents serve the same purpose without looking like you forgot to latch the hood!

Look up the past forum comments on temp control... they offer a lot of the same suggestions

 

[Carbuilder]

I was just making a block-off plate for the right side horn hole. Not easy on mine with an A/C line running through it, and the A/C accumulator very close to it. But I'll get it done.

Since my car was running about 185F+ the other day, the 180F thermostat would have been mostly open. So I don't see that a 160F one would make any difference. It might take longer to get to operating temp, but once it gets there it isn't going to help with an engine running 190F+. And that was not on a particularly hot day. How can you be running a modified engine with the engine temp being under 160F on a hot day stuck in traffic? Mine was running almost 30F hotter on a day that was 10F cooler than you are stating. Is my engine a particularly extreme heat generator or do others run this cool? I have a good rad and cooling system and nothing obvious I can see to change/upgrade.

"Look up the past forum comments on temp control... they offer a lot of the same suggestions" I have, and every one is about how to get the engine to run cooler since even stock ones overheat on hot days.

Having said all that, it isn't a big deal for me to try a cooler thermostat.

Do you mean engine coolant temp when you say "engine temp"? I really have a hard time believing that the hood vents made a 35F engine temperature difference. If you say it did, it did, but doesn't seem possible to me.

Anyone else have temps before and after adding hood vents? I'm really curious how much of a difference they make.

And my idea of adding a fan to the engine won't work. The blades would likely hit the A/C compressor.



I was looking at the front of the car and do see areas I could divert air that goes around the rad to go through it. Not much I can do about a license plate blocking some of it.

I did briefly look into the electric water pumps that vary the flow with engine temp. They go in the lower rad hose. Not sure there is room enough there for it. Think that would help?

I'll keep you guys posted.

 

[Austin Healer]

I was just making a block-off plate for the right side horn hole. Not easy on mine with an A/C line running through it, and the A/C accumulator very close to it. But I'll get it done.

Since my car was running about 185F+ the other day, the 180F thermostat would have been mostly open. So I don't see that a 160F one would make any difference. It might take longer to get to operating temp, but once it gets there it isn't going to help with an engine running 190F+. And that was not on a particularly hot day. How can you be running a modified engine with the engine temp being under 160F on a hot day stuck in traffic? Mine was running almost 30F hotter on a day that was 10F cooler than you are stating. Is my engine a particularly extreme heat generator or do others run this cool? I have a good rad and cooling system and nothing obvious I can see to change/upgrade.

"Look up the past forum comments on temp control... they offer a lot of the same suggestions" I have, and every one is about how to get the engine to run cooler since even stock ones overheat on hot days.

Having said all that, it isn't a big deal for me to try a cooler thermostat.

Do you mean engine coolant temp when you say "engine temp"? I really have a hard time believing that the hood vents made a 35F engine temperature difference. If you say it did, it did, but doesn't seem possible to me.

Anyone else have temps before and after adding hood vents? I'm really curious how much of a difference they make.

And my idea of adding a fan to the engine won't work. The blades would likely hit the A/C compressor.

View attachment 21119

I was looking at the front of the car and do see areas I could divert air that goes around the rad to go through it. Not much I can do about a license plate blocking some of it.

I did briefly look into the electric water pumps that vary the flow with engine temp. They go in the lower rad hose. Not sure there is room enough there for it. Think that would help?

I'll keep you guys posted.

Well, for one I don't have headers! I also have an oil cooler. I'm not a huge fan of alloy radiators either...

I have verified that the temp recorded on the gauge in the car is accurate, both with a laser reader and a candy thermometer in the expansion tank. Before the vents the car ran between 190-200 in heavy traffic and would boil if I got stuck. With the vents, the gauge needle is just to the cool side of center (160F) and will climb to about an 1/8" to the hot side of center (180F) if I get into delays from road destruction... or high speed driving, mountain passes etc.

My engine is not at the level of yours, probably closer to 300-330 HP.

As I said, I'm running a brass OE radiator but with a dimpled tube core. Standard Ford cast iron water pump, LAT fan and one of "Hogheads" Fairmont water pump pulleys. An original fan shroud and horn blanking plates on both sides with the hoses for the oil cooler passing through the LH plate. 11lb rad cap and 160 thermostat. Are you running the factory expansion tank or a good facsimile?? Rootes found that this made a huge difference in running temps when they were developing the car. So did Chevrolet with the Corvette....

As for the electric water pump idea. I doubt it would help, more than likely it would make the problem worse. You don't want to increase flow (volume), you want to slow it down so that the water has a chance to cool in the radiator.

A suggestion... Rootes and Shelby both found that the lower hose could collapse under heavy loads. The currently supplied hose is way too long and can fold all on it's own which obviously reduces flow and causes overheating. I have fit a spring into the lower hose, it was used on the early Mustangs as well for exactly the same reason. I get them from NPD under part #8A286-1A $11 retail.

There have been multiple studies on various cars showing that running w/o an engine cover (the hood) can defeat cooling by altering airflow. Running a standard hood demonstrably does! I did run my car for years with just an air intake for the carb... this provided no cooling benefit as the air can't fight it's way out of the engine bay... unless you drive the car only in reverse!!

My exhaust is OE cast manifolds with 2" i.d. pipes, flowmaster mufflers and straight through resonators behind the rear tires. There is an "H" pipe behind the cruciform. you can see straight through the mufflers and resonators, so no restrictions.

Ignition is by single points and set at 10 BTDC, fuel is Holley 600 CFM 1850 type w/vac. secondaries with manual choke on an Edelbrock F4B intake. I have the idle setting on the slightly rich side. The further the ignition is advanced and the leaner the mixture, the hotter the car is going to run. Idle speed is 900RPM. I found that lower idle speeds didn't generate enough fan speed for cooling. I wanted the ignition and fuel system as simple as possible so I don't have to call for a tow if I break down.

I can see in your photo that you have abandoned the factory remote oil filter assy. I am assuming that you have installed a 90 degree adapter and a short filter (econoline/windstar)... This oil filter set up with headers allows the headers to superheat the oil making the engine run hotter and due to the heat put out by the headers the engine cannot recover. An option would be to locate a remote oil filter head in the LH wheelarch behind the headlight or return to the factory system. I make the factory hoses for both the MK1/MK1a and the Mk2.

Before I welded the exhaust vents in the hood I would regularly overheat if caught in construction zones, or heavy traffic... as I said, the engine temps dropped by 30-35F. just from the exhaust vents in the hood.

An interesting side note... I'm just winding up the restoration of an Aston Martin DB5... it has factory air and as such has an electric pusher fan (thermostatically controlled as well as electrically controlled from the dash), it also has a mechanical fan on the water pump. The condenser is mounted ahead of the radiator. I started the car for the first time Friday and the mechanical fan on the engine was pulling so much air through the radiator and condenser that the electric fan was spinning too.... The Aston has the exhaust vents for the engine bay in the fenders as its engine bay is also tightly packed!

I am absolutely anal about engine temps as it makes it just as uncomfortable to be in the car... 40 years of cooking in Austin Healeys, I guess!! I spent a lot of time making the car as comfortable and reliable as possible as I tend to drive it 5000 miles a year.

As I indicated, the single biggest problem with the Tiger is the hot air not being able to exit the engine bay... it doesn't matter how many fans you run, if the air can't get out, new air cannot pass through the radiator.. The higher the state of tune of the engine, the more heat it's going to generate making it that much more important to be able to evacuate the hot air. The technical term is called "air stacking".

This is precisely why that factory ran the comps cars with the hood open at the rear. If you look at the works Targa Florio car the factory put in fender vents and cut away a huge amount of the body in an effort to aid cooling.... and those cars had nowhere near the power of your engine, probably not mine either. Rootes also thought about louvering the hood and took a car to Morrocco to test the theory... unfortunately,
the ambient temps were lower than expected, so the test was not conclusive. it would have looked like crap anyway.

now you know all my secrets....

i

 

[Carbuilder]

Thank you for all the info!

I've read about water flows being too fast in some cases and not letting the rad cool the fluid sufficiently. I've also read that some radiators, with more passes have a higher pressure drop and the pump needs to pump more (higher pressure or more flow?) to make up for it.

I'm curious to see what the effect will be with the hood (bonnet?) back on. It will be a few weeks until I can get back to working on it.

My car is running a bit rich. I won't play with that yet until I see what the temps are doing.

I do have the oil filter behind the left side headlight.



I do have the factory expansion tank hooked up.

I'm not a fan of adding any more visible air vents to the hood or the fenders. I agree that the air has almost no place to go after going through the rad, which means not as much air is going through the rad as it would with less back-pressure. I do have some ideas that are a bit (?) unorthodox, but I'll wait on those until I see where things stand.

Thank again guys for the help.

 

[Austin Healer]

I would really recommend the spring in the lower hose... cheap insurance! I put these in all the cars I restore. The RHD cars had a cast alloy part where the bend is in the lower hose. Presumably so that the hose wouldn't rub the dog-bone steering shaft connector. It would have been a good idea for Rootes to have fit it to all the cars, regardless of driver position.

 

[Theorangetiger]

FWIW, one more testimonial.

My modifications include dimpled core in stock radiator tanks, Hoghead reduced diameter pulley, six blade Derale fan, modified/extended stock fan shroud & fabricated sheet metal attached to steering rack to direct fan to pull through radiator and not around and underneath it. I don't have an oil cooler but did mount the filter behind the oil sump a la Dan W's idea. All of these mods are borrowed from other owner's ideas. I have a moderately built 289 with Edelbrock aluminum heads.
I know I am in the minority here but I do not agree with blocking off the horn holes. With the modified shroud, I also want cold air to flow through the engine compartment.
I did put louvres in my hood to allow hot air to escape. I believe the open horn holes along with somewhere for the air to exit is beneficial.
I have a 165 degree thermostat and the car runs at 175 all day long, even in traffic. Like the LAT hood vents, the louvres are very effective. After any drive where the engine has gotten up to running temperature, if I put my hands over the louvres, the amount of hot air is exiting is significant and can be felt. Obviously this function will increase significantly at speed, especially with open horn holes. The combined openings of the louvres is greater than that of the LAT hoods.
Sean, I respect your knowledge and followed your advice on the dimpled core and not using a high volume water pump but respectfully disagree that hood louvres would look like crap. I think they look great on e-type Jags and were used on the Coombs modified Mk2 Jags and really set those cars apart. I wanted something unique, functional and period correct looking. I am very happy with the look. Obviously with the color I chose, I wasn't going for a stock look.

 

[0neoffive]

FWIW, one more testimonial.

My modifications include dimpled core in stock radiator tanks, Hoghead reduced diameter pulley, six blade Derale fan, modified/extended stock fan shroud & fabricated sheet metal attached to steering rack to direct fan to pull through radiator and not around and underneath it. I don't have an oil cooler but did mount the filter behind the oil sump a la Dan W's idea. All of these mods are borrowed from other owner's ideas. I have a moderately built 289 with Edelbrock aluminum heads.
I know I am in the minority here but I do not agree with blocking off the horn holes. With the modified shroud, I also want cold air to flow through the engine compartment.
I did put louvres in my hood to allow hot air to escape. I believe the open horn holes along with somewhere for the air to exit is beneficial.
I have a 165 degree thermostat and the car runs at 175 all day long, even in traffic. Like the LAT hood vents, the louvres are very effective. After any drive where the engine has gotten up to running temperature, if I put my hands over the louvres, the amount of hot air is exiting is significant and can be felt. Obviously this function will increase significantly at speed, especially with open horn holes. The combined openings of the louvres is greater than that of the LAT hoods.
Sean, I respect your knowledge and followed your advice on the dimpled core and not using a high volume water pump but respectfully disagree that hood louvres would look like crap. I think they look great on e-type Jags and were used on the Coombs modified Mk2 jags and really set those cars apart. I wanted something unique, functional and period correct looking. I am very happy with the look. Obviously with the color I chose, I wasn't going for a stock look.

View attachment 21144

Looking good subtle louvers install, although I would have move them outboard more.

 

[Theorangetiger]

I placed them as far outboard as I could without having to modify the hood structure underneath. It would be possible but I didn't think it was worth the extra work.

 

[TAH_Tiger]

Recently had my electric 10" pusher fan (strait blades) go bad. The one I replaced it with looked the same and advertised 900cfm, but is nowhere as powerful as the old one. Does anyone have a favorite 10" and/or installed a larger one without much modification.

 

[Austin Healer]

Recently had my electric 10" pusher fan (strait blades) go bad. The one I replaced it with looked the same and advertised 900cfm, but is nowhere as powerful as the old one. Does anyone have a favorite 10" and/or installed a larger one without much modification.

Electric fans only provide cooling below 10MPH. Anything above that and the air entering the engine bay is more than an electric fan will provide. You need to find an LAT fan and set your idle to 900 rpm. that will more than make up for an electric fan.

The biggest problem is radiator efficiency and adequate air flow... the single biggest problem with a Tiger is the inability to get the hot air out of the engine bay....

 

[Carbuilder]

My semi-scientific testing of hood vents.

I finally replaced the hood on my car and did some driving. The ambient temperature was about 75F and all 3 drives were within 1/2 hour.

My hood does have the vents, but there are grills in them that do block some flow area:



So I first removed those. Then I taped up the vents for the first drive.

The drives were the same route and long enough for the temperature to stabilize at a speed of about 47 MPH. Here is what I found:

Hood vents blocked: Engine temperature 189F-190F.

Hood vents unblocked (with grills removed): 189F.

The large vent at the front of the car also has a grill:



For the last test I removed that grill (the other vents were also still open). Engine temperature: 187F.

So I can only conclude that the hood vents do very little for lowering engine temperature.....with my car anyways. This agrees with the detailed testing that was done on the Tiger (Cooling the Sunbeam Tiger). They cut vents in a different area but saw only a 2F temperature drop. Interesting that they concluded that the key is to get more air through the rad and it seemed to find its way out OK.

I will look at improving the flow into the radiator. There is some sealing up I can do and try some deflector plates on the side to direct the air into through rad. I've also thought of making an air dam to direct more air into the rad. Not an easy thing to mount with the modified front suspension setup I have. But some quickly fastened mockup pieces will let me know how effective it is.

As far as hood vents dropping engine temperature by 30F, I still don't believe it. I might be convinced if someone does back to back tests, vents open and vents taped over, one after the other in the same conditions. I've read of the vents helping, but other mods were done at the same time, so that doesn't really prove too much.

It would be a bit of a hassle, but I'm curious how much airflow my A/C condenser blocks, so I may remove it for a test.

Rick

 

[sandy]

Recently had my electric 10" pusher fan (strait blades) go bad. The one I replaced it with looked the same and advertised 900cfm, but is nowhere as powerful as the old one. Does anyone have a favorite 10" and/or installed a larger one without much modification.

The one I have may be 11" straight blade pusher from Spal. It seems really powerful like it could chop your fingers off.