Hood spacers, gave it a try.

[alkaline747trio]

Can't remember the pitch, either M8 or M10, they are the same as most other bolts on your cruiser, but you can ride with one out to match it. I think 150 long is what I went with, it just all depends on how much spacer you add. I need to go get shorter bolts now so I can remove the steel spacer and try it with just the nylon piece, if I get there before you try this I'll tell you what pitch and size I got.

 

[CreeperSleeper]

Perfect, thanks buddy!

 

[Jason Andrews]

It works, but still not good enuf for me. Even with 15 shims (washers) on each bolt Im still overheating with the A/C on in city driving after about 5-10minutes. Yes my fan clutch is locking up and I even have a 14" e fan infront of the condensor. Yikes!!!

 

[slinger5150]

To add another bit of evidence that this doesn't work like one would think is to look at most all the new cars and pick-up trucks with the plastic air-dam hanging down in front. These increase the pressure in front of the plastic air-dam and inversly cause a reduction in pressure on the engine side of the air-dam. This causes the air to move into radiator at a higher pressure (volume) and the reduction side actually draws it into the engine compartment, thus moving more air through the radiator.

Picking the hood up would reduce the temperature under the hood because it removes the air that was heated up by convection. But this is done at the expense of less air moving through the radiator at speed.

If you want to reduce hood temperatures, tack/ glue on some aluminumized radiate barrier on the under side of the hood.

To some degree the warm air being puled off the motor would keep it cooler also the same way cooling fins work on amplifiers. If you're drawing the heat from the engine into the air and then replacing it with cooler air it should run cooler.

 

[wildsmith]

I tried spacers in the hinges and thought it was ok but then I decided to try the scoop Kenlowe do with a 10" fan under it - much better even without the fan running.

 

[alkaline747trio]

Yea, a scoop would be better, but is definitely more work.

 

[elhombre]

It sounds like I may be way off base with my logic . Have any of y'all tried taping the strings on the rear of the lifted hood's edge and driving it at different speeds. It would seem that the "tell-tails" will prove the point either way.

 

[FirstToy]

alkaline747trio,
thanks for posting the info and pics, very informative.
Please do post some followup after you do your adjustments. your results fall in line w/ my friend w/ a turbo 4Runner- runs w/ a slight gap w/ spacers as you have it.

NYC taxi's pop the hood for summer heat so I'm sure it releases alot of trapped heat...

It does work, proven on that turbo'd 4Runner. there is a hood scoop thread somewhere that has more detail on hood aerodynamics and using those pieces of string to see the airflow

the cons are noteworthy, not tried it but it is an interesting subject... I think of doing it maybe removing the weather strip first as a baby step

 

[Atticus]

Well, everyone talks about hood spacers being bad and HVAC problems and "what ifs", so I decided to run with it being the stubborn young gun I am. I am reasonably pleased with the results.

I always thought my truck ran warm, it never overheated according to my needle, but opening the hood it just felt way warmer than anything I have ever driven. That's definately not the case now, I estimate a good 20* drop in average underhood temps. I'll get some numbers once my water temp guage adapter comes in, for more solid results.

Been driving like this for over a month now, and the only problem I have is with the windows down pulling away from a stop I can sometimes catch a whif of "engine smell", same with running fresh air through the vents. No smell at speed, no feelings associated with fumes, passengers haven't commented on it either.

I used a 1" steel spacer and a 1/2" nylon spacer with washers at both ends of the nylon.

Here are some pics, 1" steel spacer, 1/2" nylon spacer, and washers.

That's a sharp look.

 

[Dusty]

i want to make a 10" hole above my turbo and put a fan there to pull hot air out of the motor at low speeds. needs to be a cover for the rain.

if one uses a fan there is no worry about a positive pressure introduced through the vent. the string will always blow out

 

[alkaline747trio]

Even with air being blown in it cools things.

 

[Dusty]

Even with air being blown in it cools things.

true. at low speeds any air movement in or out is probably a help. how about a pair of 14" fans on the hood. you could paint them up like jet intakes for that harier look.

 

[-Spike-]

Even with air being blown in it cools things.

No, if the air is allowed to take a different path than anticipated, it can cool some things, to the detriment of others. For example, air going in through a hole in the hood, cooling the top of the head, and escaping out the bottom of the engine compartment takes the place of air that would normally have come in through the radiator, cooled it, and then exited out the bottom of the engine compartment. If you can guarantee that the scoops, holes, lifted hood edge, whatever, don't interfere with the movement of air through the radiator then you've got something. The best way to cool the engine is through it's cooling system. Cooling the top of the head may help your spark plug wires last longer, but it probably won't help the engine if the coolant is not doing its job.

-Spike

 

[alkaline747trio]

No, if the air is allowed to take a different path than anticipated, it can cool some things, to the detriment of others. For example, air going in through a hole in the hood, cooling the top of the head, and escaping out the bottom of the engine compartment takes the place of air that would normally have come in through the radiator, cooled it, and then exited out the bottom of the engine compartment. If you can guarantee that the scoops, holes, lifted hood edge, whatever, don't interfere with the movement of air through the radiator then you've got something. The best way to cool the engine is through it's cooling system. Cooling the top of the head may help your spark plug wires last longer, but it probably won't help the engine if the coolant is not doing its job.

-Spike

Coolant temps are lower at freeway speeds with the spacers. Thats good enough evidence for me.

 

[zombiekiller]

if you appreciate the cooler underhood temps, perhaps go to a junkyard and find late 80s trans am hood vents. Most yards will sell them to you for $5 or so for the pair. you can mount them in the hood, in the center or sides closest to the cowl and they should reduce underhood temps for you. if you are looking for low speed heat reduction, perhaps try a small exhaust fan attached to the inside of one. turbo lebaron vents work well too. i've used both style of vents in past projects with chevy v8 swaps that had a little too much under hood heat build up sucessfully.

 

[Jason Andrews]

if you appreciate the cooler underhood temps, perhaps go to a junkyard and find late 80s trans am hood vents. Most yards will sell them to you for $5 or so for the pair. you can mount them in the hood, in the center or sides closest to the cowl and they should reduce underhood temps for you. if you are looking for low speed heat reduction, perhaps try a small exhaust fan attached to the inside of one. turbo lebaron vents work well too. i've used both style of vents in past projects with chevy v8 swaps that had a little too much under hood heat build up sucessfully.

This is a seasonal problem tho. Here is Colo I deal with 100* temps and in the winter mountains -10*+ killer windchills. Same in the widwest, no? That is why I like the reversible hood mod.

To add to my earlier post I went from 10washers which was 2/3" to 15washers which raised my hood up 15/16"...what I had it at last year. I sat in 100* heat with the A/C on and finally no movement in the temp gauge. So there is a pretty big gap to get it to work the best. IMHO is works equally well on the highway and in town speeds/idle.

 

[zombiekiller]

This is a seasonal problem tho. Here is Colo I deal with 100* temps and in the winter mountains -10*+ killer windchills. Same in the widwest, no? That is why I like the reversible hood mod.

To add to my earlier post I went from 10washers which was 2/3" to 15washers which raised my hood up 15/16"...what I had it at last year. I sat in 100* heat with the A/C on and finally no movement in the temp gauge. So there is a pretty big gap to get it to work the best. IMHO is works equally well on the highway and in town speeds/idle.

the way the trans am vents are designed, you could definately make some thin sheetmetal block off plates for the winter time and attach them through the "screen " that runs underneath the actual hood vents. i'd guess that once you fit the vents into the hood and made the block off plates, it'd take 5 minutes total to remove/put on the " block of plates" ... food for thought i guess.

 

[wildsmith]

This is a seasonal problem tho. Here is Colo I deal with 100* temps and in the winter mountains -10*+ killer windchills. Same in the widwest, no? That is why I like the reversible hood mod.

The Kenlowe vent could easily be blocked off and the fan switched off in winter.

To add to my earlier post I went from 10washers which was 2/3" to 15washers which raised my hood up 15/16"...what I had it at last year. I sat in 100* heat with the A/C on and finally no movement in the temp gauge. So there is a pretty big gap to get it to work the best. IMHO is works equally well on the highway and in town speeds/idle.

Although the vent works well without the fan running, when the fan does switch on the amount of heat it pumps out is amazing.