Yes. I sold my softtail not because it was unreliable, but it felt as though everybody was trying to kill me! I still loved polishing it up and looking at it though. And in the end, when I sold it, it paid for the XJS (but I still miss it).

 

Great looking bike, I can not believe u sold it.

 

Bill I sold my 79 Bonneville Special for the same reason, seemed everyone wanted to change lanes into you. When people started texting and driving I said enough is enough and sold it to buy my TR6.

 

We reach a certain age when you realize that riding around in shorts/t-shirt and sunglasses is just plain dumb. So, you buy some leather and a helmet which take away alot of the enjoyment. Then you have a couple of close calls. Then it seems as though (no matter where my travels take me) every time I pick up the local paper, someones been killed on a motorcycle. Then.....we buy something fun with four wheels. I wonder if that's a common story?

 

I agree with you 100%. LOL.

 

I don't find a 20 degree air temperature increase to be either significant or worrisome. Yes, the V12 is great for heating the garage in the winter, which our Honda has never done. The killer or engines is internal heat. Put some thermocouples on the block, I bet that big hunk of iron does not change much at all, other than in a slow downward direction.

As for Mike, piston engines don't see the heat that turbines do, although some turbochargers may come into the same neighborhood. I also know aircraft owners who land, shut down, push into the hangar and immediately install cowl plugs. Just like my cars, I shut down the plane and let it sit and cool on its own. But it ain't no jet, neither.

Driving slowly in traffic is much worse for your engine than parking it in the garage and not opening the hood, a practice I've never seen or heard of until tonight. My car, a 92 5.3, runs the fans for a while after shutting down; opening the hood will completely eliminate the designed airflow over the engine, so if you're worried about cooking your engine when shutting down, you may want to think about this. When did this start?

 

Re traffic: There is at least one person with a Cobra-type car that has demonstrated the opposite. from a post a few back on this thread:
"I also took time to measure another temperature, hood vent air temp. I clipped the sensor right to the middle of my right hood vent grill. Initial idle temperature was 136 F. After 2 minutes driving a 30 mph temp was 85. At a stoplight for 30 seconds temp shot up to 103F, rolled another two blocks temp down to 85F. Then another stoplight 45 seconds, temp went to 146.5F. This pattern was consistent, while driving the air coming out of the hood vents was 85 within 1 F up or down. At each light or intentional idle it would rocket up to over 150F. I stopped at a gas station, engine off for 2 minutes and hood vent air temp was 167.8F. That is a lot of heat escaping from the engine bay.

This demonstrates precisely what an SVT engineer told me personally. Opening the hood vents helps with "heat degas" (removal of heat)"

Next you mentioned:
The high temps persist long after the aux fan has stopped, and the flow from the OEM aux fan is poor. In fact, opening the hood does not, repeat not, "completely eliminate ...airflow over the engine". In fact it greatly improves it, driven as it is by convection throughout the area and volume of the engine bay.

I do completely accept that a heat bath of 100°C might be of no account for longevity of the rubber and PVC parts under the bonnet, but I personally do not believe it. When yuo buy ordinary wiring, for example, it usually has a heat range of 75 or 80°C max. I mean, the insulation cooks to brittle somehow; and the under bonnet temps are much lower on the move, so there must be some benefit - though as Doug pointed out, exactly how much is moot !

Greg

 

FWIW-

The Corvette mentioned above is still in my possession. I've never opened the hood to accelerate cooling. I'd say that 95% of the underhood components are the originals, so they're 41 years old. None of them show any heat related deterioration.

 

With all that heat in engine bay has anyone installed cool air intakes. It seems like you could get better performance from the cool air. I saw one car with air intakes in place of inner headlights , and a couple with small hood scoops. Just a thought. Any ideas?

 

I'm neither an Engineer or a Mechanic, just someone enthralled by his car and trying to understand it a bit better. So correct me if I'm wrong. The small electric aux fan is not meant for after shutdown cooling as there is no coolant flow. And I don't see much airflow benefit during the short time that the fan does run with the engine off (typically under 60 seconds on mine with the hood open). If airflow is wanted after shutdown, then it's either an open bonnet, or louvers.
Anyway, on the one hand, I agree with Greg, that it is possible that venting the engine bay may not help with the longevity of the components. But, I'm not ready to sign off on that yet. I think it's got to make a difference.
On the other hand, I can understand Doug's view that, with improved non-OEM wiring and proactive replacement of rubber parts, venting is a moot point.

Regarding the cold air intakes. The later model cars have just that. By "later" I mean '94 and on (maybe earlier, but as mine is a '94 and it has this change). The intakes have been routed more forward and above the radiator.

 

you are not wrong there.(even though mine is only a 6 I use any excuse to have a look at it.)
Cooling off, I open the bonnet when I get back from a long drive,have a quick look for any fluids where they shouldn't be and leave it open for a bit to let some of the heat out. Can't do any harm




The pics below are what happens when a texting youth doesn't see the lights go red. Although it did make me fell better when I extracted myself from his bonnet to see a destroyed grill,radiator, twisted bonnet and a dimple in his windscreen shaped just like the back of my helmet.
I'm just glad there wasn't a car in front of me. He didn't even brake.
The 4th pic is how the bike was returned to me,better than new!
I find myself driving the XJ6 more than I ride these days,I'm just not so relaxed in the city traffic now. More out of town riding.

 

The rule of thumb is the air entering the engine must decrease by ~11*F in temp to achieve a 1% increase in HP. Without knowing what the stock numbers are it's impossible to say if it's worthwhile.

This was point of my experimenting with the Corvette mentioned above.

 

I had two cents to add, but I spent them on the car,lol. Seems that there is no argument that the softer components under the hood suffer from prolonged heat: hoses, wires, etc. Seems to me the bigger question involves the metal parts. All the discussions about dropped valve seats center on cooling speed differential, ie: are the steel and aluminum parts cooling at a proportional rate that maintains proper fit?
An open hood (plain ole' convection) should release the heat due to thermal mass at a faster rate. Does it affect the internal cooling rate of components -- not a clue. But I open the hood after a run, makes me feel better.

 

without taking time to respond to everyone, ill throw in my 2 cents. I see someone posted the info I was going to mention, where a forum member tested the temps after shut down a while back.


While I believe he used it as a testament to why you should leave the hood open and even set up some sort of cooling fan with a shutoff....my response then and now is that it is only 20 degrees!!
It doesn't hurt but it doesn't really help either. Even over 300,000 miles I doubt you would see any considerable difference in engine life or the life of any other parts in the engine bay. The temps it is constantly running at for much longer periods of time are so similar, 30 minutes at an extra 20 degree isn't going to do anything.

While it doesn't hurt anything, you are sort of going out of your way to not accomplish much. If I told you that you should get some foam blocks and stick them under your wiper arms to relieve the wiper blades and make them last longer you would probably think that sounds ridiculous, but I don't see much of a difference.