I'm cool, do you think I'm cool? I think I'm cool. (question on being cool)

[Hink]

@Paveltolz show him your vents!

I can just see them in his avatar... That's exactly what I had in mind. : )> But I'd like to see a better picture.

A cheap and effective way to vent your hood is so simple, it's almost ridiculous, but it works well. Remove the black rubber seal that sits on the crimp atop the firewall. It seals to the underside of the hood. With it removed, you now have a 1/2" air gap that totals almost 24 square inches and is in the LOW pressure area under the cowl, not the high pressure zone a few inches higher up at the base of the windshield., so it actually helps draw air through and out of the engine compartmemt. Idling at temperature with the fan engaged, you can feel the hot air pour out. Another advantage in the winter is that it helped keep the windshield clear and the wiper blades de-iced, too, when driving!

I was eyeballing that as we were contemplating the situation. Good to know it's a known solution.

I should clarify that all the numbers logged above are with the hood on and afterwards with it off, I didn't get numbers but they all improved.

 

[Hink]

I assume by what you mentioned above, you do have the half ton air dam?

Half ton air dam? I don't think that I know what that is. I don't have anything on the hood, just the two air holes in the bumper.

 

[n8in8or]

I can just see them in his avatar... That's exactly what I had in mind. : )> But I'd like to see a better picture.


I was eyeballing that as we were contemplating the situation. Good to know it's a known solution.

I should clarify that all the numbers logged above are with the hood on and afterwards with it off, I didn't get numbers but they all improved.

This is the place he got them from if I recall correctly.

http://hoodlouvers.com/

I thought about doing something cheaper, you can get louvered panels on the Bay, but it's probably one of those things where you get what you pay for so you might as well pay for a known thing. Paveltolz also put vents in his fenders. You should find his thread...

 

[ak diesel driver]

air dam is under the bumper

 

[n8in8or]

Found it.

http://www.thetruckstop.us/forum/threads/getting-the-hot-air-out.23171/

 

[Hink]

Found it.

http://www.thetruckstop.us/forum/threads/getting-the-hot-air-out.23171/

Cool, thanks!

 

[GM Guy]

@Hink The plastic airdam with the cutouts around the tow hook holes, bolts to the underside of the bumper. about 4 inches deep.

IMO it helps direct more air around the vehicle, and less under it, in hopes of lowering the pressure under the vehicle to encourage more flow through the cooling stack. Also same reason I keep the stock rake and never lift the front end.

All a wild theory, just like my use of the factory quick connect in the heater.

 

[Will L.]

I've always thought the lower air dam was for aerodynamics to help mpg.

 

[Hink]

@Hink The plastic airdam with the cutouts around the tow hook holes, bolts to the underside of the bumper. about 4 inches deep.

IMO it helps direct more air around the vehicle, and less under it, in hopes of lowering the pressure under the vehicle to encourage more flow through the cooling stack. Also same reason I keep the stock rake and never lift the front end.

All a wild theory, just like my use of the factory quick connect in the heater.

Gotcha, yup it's there. That's what I had to do the duct tape patch work on and yeah, not much of a change there.

 

[Hink]

I've always thought the lower air dam was for aerodynamics to help mpg.

It's actually plumbed right into the cooling stack so you can see that it would help to direct flow over everything.

 

[GM Guy]

@Hink, I think you might be talking about the plastic scoop that fastens to the underside of the core support and seals the bumper nostrils, that is definitely important, no doubt there.

I am talking about this sucker: what the guy has loose and is installing. I get the hardware out of a junkyard off a half ton or a SUV off a broken one.

 

[Hink]

@Hink, I think you might be talking about the plastic scoop that fastens to the underside of the core support and seals the bumper nostrils, that is definitely important, no doubt there.

I am talking about this sucker: what the guy has loose and is installing. I get the hardware out of a junkyard off a half ton or a SUV off a broken one.

Oh man, gotcha. Nope, don't have that.

 

[n8in8or]

O.K., so I did get some numbers on the return trip but they were so frustratingly inconsistent, I almost wasn't going to even report them here. But I did see one number that could explain things. Again, I know many will say "well, duh!" at it but I just didn't expect that it would make THAT huge of a difference. That is the ambient temp...

The numbers I saw were these;

-65mph
-Flat ground
-Light tail wind
-550 EGT
-205 ECT
-4 PSI boost
This is when I had just started out ( I didn't log ambient), then things went haywire...

-65mph
-Small hills
-No wind
-775 EGT
-215 ECT
-4-5 PSI
-85*-90* ambient temps
Later...

-65mph
-Flat
-Light head wind
-775 EGT
-185-190 ECT
-4 PSI
-71* ambient

Then...
-67 mph
-Small hills
-Heavy head wind
-800 EGT
-190-195 ECT
-5 PSI
-75* ambient

And lastly...
-65mph
-Flat
-Heavy head wind
-700 EGT
-180 ECT
-5 PSI
-39* ambient

So you can see that even with head winds or hills, the ambient was the deciding factor here by a large margin.
Whenever I've read reports about temperature mods and performance, I don't remember reading much about ambient temps which has really screwed up my expectations, I think.
Now having said that, I still think there are things that I need to do which leads me to some more info that I was able to get...

My buddy Jim and I have been trying to think of ways to help the heat issue and one of the things he said racers have asked him to do is to help get the heat out of the engine compartment. We got to really looking and could see that there really is no where for the heat to go except mostly down past the exhaust which is 1- hot, 2- a very small area and 3- likely going against it's more natural tendency to go up.
So we pulled off my hood to leave it with him on my return trip so I can see the difference and if there was one, we were going to design venting that he could put into the hood. I am also going to drill large holes into the fender wells to get air to blow up from there.

Well I can tell you... it did make a big difference. While the ambient temps were pretty low and helped the engine temps stay down, there was still a very large difference in temp performance. The best way I can explain it is "stable". While the rig would still heat up under extreme circumstances (hills, wind, etc.), it was a much slower rise, cooled back down quicker, didn't rise as far and was more controllable with speed/throttle. Getting all that hot air out of there quickly seemed to allow the cooling system to do it's job properly without fighting against itself all the time.
I was able to maintain the 70mph with the temps staying more stable whereas before with decent ambient temps, I could maintain the 70 but I had to really watch the temp fluctuations. The only thing that finally caused me to have to really slow down was when I got back into the Gorge and hit some pretty severe head winds which brought me to 4the gear and about 55-60 mph.

So now my plan is this... Hood vents, side vents sealed to intake to funnel air directly in, 88894035 water pump for balanced flow (the paint is pealing off the passenger side valve covers from the heat), maybe a bigger fan and insulating intake similar to n8in8ors. Then we'll see where we are.

Did you notice much more interior noise when the hood was off? I've been wondering if the interior noise would increase with hood louvers installed in the hood. Of course I would suspect that a full hood removal would be even noisier, but I'm just curious how much the hood blocks the noise. Also, is the sound mat still installed on the underside of your hood?

 

[JayTheCPA]

Paveltolz has some good looking vents on his, and he has a good writeup somewhere too.

From the not knocking, just saying . . . IIRC the hood vents do a great job at letting the heat out, they also let the rain in. So any connector that does not have solid encapsulation (keeping the elements out) wil get water exposure and IIRC even Paveltoz saw the effects of corrosion. So, Yes the vents do look like a good addition, and at the same time am sensing they still need a bit more engineering to address water.

. . . you do have the half ton air dam?

I've always thought the lower air dam was for aerodynamics to help mpg.

Am with Will. My sense was that the air dam was to clean the airflow under the rig and keep the various members from 'dangling' in the wind and creating drag. Nonetheless, I have one and actually wish it went lower.


Toward heat control, am seriously considering wrapping the down pipe with Superwool insulation primarily for pushing the heat further down the exhaust pipe and lessening the heat going to adjacent items (A/C dryer, heat exchanger hoses, intake box, etc . . .). Secondarily to see if it lessens in-cab noise.

 

[n8in8or]

Toward heat control, am seriously considering wrapping the down pipe with Superwool insulation primarily for pushing the heat further down the exhaust pipe and lessening the heat going to adjacent items (A/C dryer, heat exchanger hoses, intake box, etc . . .). Secondarily to see if it lessens in-cab noise.

I would like to try wrapping the downpipe with that as well. If you do it first, let us know how it works.

 

[Hink]

Did you notice much more interior noise when the hood was off?

I didn't really notice anything but I was driving with my window down pretty much the whole way so it was loud just from that. Having said that though, you would think that it would be even louder but nope.
As a matter of fact, after I rolled up the window, I very much noticed how quiet it was! So it's all relative. If you're used to a very quiet cab, it may bother you. Me, I could hear the stereo fine (I don't listen to it very loudly at all), seemed to be able to hear various sounds fine and wasn't bothered by any more noise at all if there was any.

Also, is the sound mat still installed on the underside of your hood?

Yes, the mat is still on the hood and firewall.

 

[Paveltolz]

Sorry, but I've been out of town and not logging in of late. Here's the thread. Hope the pictures are still posted.

 

[Paveltolz]

...and I failed to add the link but, in backtracking, I noticed that N8in8or had already found it and posted. Thanks Amigo.
Anyway, if you want more or better pictures, I've got the louvers off as part of the pseudo-resto I'm doing.
Great thread by the way. Thanks Hink, nice work.

 

[Hink]

Update...

I recently made a trip towing the RV again through Hood River south through Reno, then west to Sacramento for a friends wedding. Afterwards I went west to the coast and up hwy 1 for the return. Lots of variation of terrain. Slow, windy to long uphill straights and everything in between.

Before I left I removed my hood again since I wasn't able to get the vents installed yet. I'm still convinced that it is a good idea.

Moby is still getting hotter than I think she should but really performed very well. She's got more power than she needs at this point for what I need to tow (I've towed ~10,000 lbs), I just need to get this heat issue resolved. To be clear, this isn't really a complete mystery at this point except that I don't have the opportunity to do what I need to really resolve it. (balanced water pump mainly but I also would like to try the Mishimoto radiator some day as a last resort and will get vents on and engine surfaces insulated)

Having said that, I did get hot climbing a long windy mountain at the start and had to pull over a couple times, but after that I was able to get in a better groove to manage. Notice it was my driving habits that changed here. Very similar to this...

Here was what I did to keep temps under control when I climbed long steep (5%+) grades:
> Kick-out the cruise control just at the base of the grade and drove based on EGT & RPM's.
> Manually drop out of OD into direct (3'rd) to get the cooling going.
> Kept the EGT's just under 1K (950 - 990 was good).
> Manually downshifted when the RPM's hit ~2,200 / upshifted around 3,200.

This kept the ECT just under 230 and the TFT in the mid-upper 220's with the A/C 'On'. The fan kiced in-and-out during the climb, but did not worry *too* much as the temps remained in check. Speeds sometimes got down to the 20's in 1'st gear.

I developed the behavior from experience as I learned that:
> EGT's above 800F resulted in heat generation
> EGT's above 1K resulted in ECT wanting to go above 230.

For shorter climbs, I decided whether I wanted to burn the fuel and let the EGT's go above 1K, but definitely held the fuel back on the longer climbs.

Except for the auto trans and cruise, that's what I did and that's about what I saw. Except I drive faster : )>

I'm getting a clearer picture of the affects of ambient temp too. Anything above 75* really causes heat issues. 70* and lower allows me to drive almost without any heat issues at all. Long grades are easily managed and regular road speeds are maintained easily.

At one point I was flying up a very long steep grade in about 65*-70* ambient temps and passed what looked like a mid to late 90s 6.5 towing a similar sized RV as mine and he was doing about 10 mph. I was doing 55-60, buh-by!

Hopefully I'll be able to get the rest of the work done before next summer and report back as to how effective they were.

 

[WarWagon]

Curious as to what fan blade you are running now? Does it come on and scream when things are warming up? What is the history of the radiator and condenser? New, rodded, etc.?

I found smaller precups limit the fuel I can burn before it just turns to smoke, and, the engine MAP pegs it's readings at ~17PSI. Even with a aftermarket gauge installed later I never got over ~18 PSI of boot out of the ATT with the DS4 hybrid 6.2 with military NA precups. Never ran WMI. IMO the small precups may have spiked the EGT as fuel may have still been burning when the exhaust valve opened.

I think you are running more fuel than I ever could by the ATT boost numbers alone. Possible I had more advanced timing than you are running that affects (lowers) boost as well. The only time I lost temp control with a single T-Stat was lugging too much for the grade, or, 115+ degree dry air and grades. The Gearing on the MT is of interest as it may be lugging you vs. a 4L80E aka my experience of being in 4th when I needed the higher RPM of direct. My goal was to maintain and be able to reach the speed limit on grades while towing a bumper pull 24-28' trailer.

You have no auto trans to cause heat issues. Are you running the AC? Next step is to measure the temperature of the coolant going into and coming out of the radiator. This will help decide if you have a lack of airflow, too small a radiator, or a combo of both.