ABC'S of 80's Cooling Part IV - Hood Vents

[SUMOTOY]

I'd actually like to see some simpler data. Next time you go for an extended drive measure the MPG. 1 way with vents open and the other with them closed.

From my own experience, I saw a measurable increase when I had finally got the engine temps under control. Tools R Us also feels that there was some benefit here as well.

All that other stuff aside I'd prefer data showing the benefit as a final outcome and not individual changes.

Er, not sure I understand. Isn't there already data posted here showing 210F temps as reducing fuel consumption (IIRC 3.1gph at 180F vs 2.80gph at 210F) and engine wear? What then would be your definition of "under control"?

Final outcome? I did Part I-IV as individual changes in an attempt to do these mods in documented stages. All comparable to anyone elses data. The data you and others gather will either support my changes or not support them. When you refer to engine temps, do you mean radiator temps causing changes in engine temps?

What was the increase in mileage Rick? How do you explain that contradicting that fuel consumption decreases with higher engine temps than 180F?

ST

 

[landtank]

Sumotoy,

My mileage increase was around .5 mpg while towing a 3500lb trailer.

My seat of the pants told me the truck drove much better and there was definately less down shifting. And similar improvement in startup and such that you have noticed.

My guess would be along the lines of what Waggoner5 was saying. That the engine itself would warm the incoming air and cause it to lean out. So the cooler running engine basically helped that situation.

It was posted in the "blue clutch mod" thread and I'll have to check these numbers for accuracy.

I'm more of a real world experience kind of guy and not the book type. I don't put a lot of stock in those reports as they seem to be focused on what they are reporting on and over look the overall impact on a system.

Such as a hotter engine might get better fuel economy but with our intake setup that extra heat actually yields poorer performance which costs efficiency. I'm not saying that's the case but that's what's going through my head when I read them.

 

[citadel]

Guys,

Any thoughts on the best tool and technique for cutting the hole in the hood?

 

[syrinxstar]

I'd submit that an IR gun is perfectly acceptable for this level of investigation. The surface temperature will have some lag in change associated with its material properties (heat capacity, for example). Unless Sumo left the hood open for an extended period of time before taking the measurements, they're likely about as accurate as you'll need.

Aside from all that, his results are a significant, if not dramatic, difference that provide some founding for the more subjective data. I agree too that a "proof in the pudding" end result would be nice. However, I've seen enough MPG garbage on this board to uniformly not trust anyone (except CDan with his spreadsheet) - there are just way too many variables coupled with the small number of samples people base their conclusion on.

 

[FirstToy]

Guys,

Any thoughts on the best tool and technique for cutting the hole in the hood?

Wait a month and see if you still want to do it. That technique usually works for all my mods.

 

[landtank]

No doubt that he has lowered his under hood temps. I think most here would have expected that.

Me being skeptical, I can see that since he's opened up his hood it has allowed his shroudless clipped bladed fan to more easily cool the truck and is now seeing the same thing I am.

His truck not being like ours in many ways, gives me pause when considering what he's done.

From what I gather, his shroud is gone, blades are clipped on the fan, the fan clutch had 10k and now I'm not sure what it has and his radiator has had several tubes sealed from damage.

No doubt he is seeing some improvements but can you directly apply those improvements to a truck with good components, I don't think so.

 

[cruiserdan]

I respectfully disagree Rick.

I think of it in this manner:

What is happenning here is underhood ambient temperatures are being lowered, not necessarily engine coolant temperatures. I'm not sure that it matters weather the air passes through a shroud or not, he is just providing a way to get it out as fast as possible.

 

[landtank]

Dan, I don't remember seeing any info on his engine temps other than he was running hot during his ice racing. Since that was in the winter I can only imagine what the temps were during the summer.

 

[landtank]

Just got back from browsing all four ABC threads and while there was a lot of temp data there, there was no mention of the operating temp of the engine. I think that the engine's operating temp could play a role in this. His under hood temps prior to venting where quite a bit higher than mine in similar ambient conditions.

Sumotoy, do you have those readings?

 

[cruiserdan]

My under hood ambient temps are sky-high at idle, parked, A/C on ETC. I have measured, albiet with a crude thermometer, temps over 175 degrees in the area in front of the air cleaner.

 

[landtank]

It must be a SC thing because the highest I ever got was 154*. Do you know your engine temp when you took those readings?

 

[cruiserdan]

It must be a SC thing

EXACTLY! That is the point Scott has been trying to get accross (albeit somewhat under the radar).



"operating temp" as it was before I added my mechanical gauge. I would estimate it at around 200 since it was a hot-soak test.

 

[landtank]

My limited experience with SCs is my dad's Tundra, and he has no issues at all that I'm aware of and he tows a 24' fifth wheel travel trailer all around and even in the mountains.

Maybe I should double check on that as he's 75 and has lost a little, if you know what I mean.

 

[SUMOTOY]

Some more thoughts

Rick et. al.
I exactly ignored engine temps for parts I-IV, because I wasn't addressing them. Put another way, those will vary widely from any specific truck and modifications (or in my case: SC & shroud/fan/rad/ butchery is irrelevent to anyone else). My focus in part I-III was optimizing the A/C system by blowing on the condenser with an Aux Fan. What I noted in Part III was that this mod caused an increase in underhood temps. Again, engine, engine fan, SC at idle, 10kcst fan clutch, all were constants (with varying numbers) in *my* truck. Blowing harder is an option to forced convection (thicker VC fluid), so is blowing the same with less backpressure (hood vents).

What I focused on in Part IV was taking the underhood temps I measured in Part III, and installed hood vents to relieve that heat. Specifically, my concern was/is the air can. What I want with extreme prejudice to task, is my SC inlet temp to be as close to ambient as possible. I will get to and focus strictly on targetting a narrower range of engine temps in Part V, when I do the dual electric fan install.

Regarding your thoughts on engine bay temp causing better mileage because the heat causes it to run leaner... Here's my opinion. My background and experience would tell me that a higher intake air temp will cause a lower intake air density. This in turn would cause a less powerful combustion, put simply volumetric efficiency of the motor goes down for a given rpm. The same as if you take a truck into the mountains of Colorado (see nerdy post regarding Kevin's air filter temps). So you have to put your foot further into the go pedal to get the same torque output = less mileage, not more.

When I see less than 1/2 mile to the gallon, I don't draw any conclusions, you could switch brands of gas and see better than that, or change your tire pressures, have a tail wind, etc. I also believe that the reason the trend is to even equip the bigger trucks with engine temp control fans (on/off mechanical and/or electrics) is fuel economy. It's pretty well accepted automotive theory and application that higher temps yield less fuel consumption. And 100C appears to yield the best benefits.

Whatever you think about the theory, it can't be ignored that more precise control of engine temps yields benefits. Volumetric and Thermal Efficiencies vary greatly with a 180-226F acceptable operating temp Mr. T chose. When they are stabilized (or even narrowed to) at a given temp, the rest of the system can be optimized for that constant.

I'm quite familiar with this theory and application, because Audi started down this path back in the late 80's. And a lot of the SAE articles on cooling come from Audi AG. I have a lot of them in my library, and the application has finally trickled down to the SUV market. Beyond 6speed automatic transmissions, the gains in CAFE are in the 1% range, so that avenue has been tapped. The next logical choice is volumetric efficiency, thermal efficiency and staring hard at the unnecessary engine loads. Rotary A/C compressors are now under 5hp, so the biggest load right now is that mechanical fan with VC.

Not trying to ramble here, only understanding and subscribing to the trends in engine heat management. I've applied a few to my truck with what I consider significant results. Rick, you will get your engine temps in Part V, when I go after electric fans with coolant sensor activation. I won't have any 'before data', but I suspect plenty here can supply that.




SMT

 

[SUMOTOY]

Just got back from browsing all four ABC threads and while there was a lot of temp data there, there was no mention of the operating temp of the engine. I think that the engine's operating temp could play a role in this. His under hood temps prior to venting where quite a bit higher than mine in similar ambient conditions.

Sumotoy, do you have those readings?

I had 1700miles with the 24foot trailer, and the temps were 195-215, high of 220. Ambient temps were 70-100+F. I put a temp guage in (left the sender tho) that flopped around in the coffee bucket for a couple days before I pulled it.

The short answer: No. I figured that was about the most irrelevent data I could post here, and just the thought of the forum sharks swarming... Yikes! Clipped blades, SC, no shroud, and several radiator cores soldered. Generally, I try not to look like a seal on a surfboard

I will say, I have never hit A/C cutoff.

I suspect too, my engine temps are probably lower, for now. Don't really care, since engine temperature has not been my target or focus. It will be soon.

ST

 

[SUMOTOY]

SC thing

EXACTLY! That is the point Scott has been trying to get accross (albeit somewhat under the radar).

It takes one to know one?

I doubt many would agree with under the radar tho dan, I wish!

ST

 

[landtank]

I'm trying to get a handle on what it is your doing and how that might benefit me. And you deliberately not posting some info because you have either deemed it irrelevant or not wanting to deal with the questions raised by it just causes more suspicion from me.

I did find a post where you were running at 250*F and had the tranny temp light coming on during those winter runs on the lake. Seems kind of high to me for a truck running at speed in very cold weather. But again I don't have any SC experience but it would be more palatable for me if your cooling system had a more stock configuration.

During any of my posts I try to be as informative as I can and do my best to present the info unbiased. That can be hard when you put a lot of time into something and get excited about what your seeing as an improvement. Every time I posted my temp numbers whether under the hood or of the engine I made sure that when the AC went down that was included so people could evaluate my experience with their own.

I agree the .5 MPG increase alone isn't a big deal but I only added it to my seat of the pants impression as a package. Just putting as much info out there for all to consider. And to answer your concerns on how relevant, it was 7 days after the first run over the same route in near identical weather with gas from the same vendor but not the same station station.

 

[SUMOTOY]

Rick:
I believe to have clearly addressed my targets and goals in Parts I-IV. I have no real concerns regarding my engine temps. My truck got hot at Steamboat due to boring the radiator with the fan, tho I don't believe I ever experienced a Trans Light. I also was never on a lake either... In addition I saw some pretty high engine temps as my radiator puked it's guts, 6-8 times in fact. On my return trip, I had several clipped fan blades and no radiator shroud, and didn't experience any overheat. I reported that.

Again, I'm not hiding anything, there is no 'secret' witheld data or overheating going on. The only time I actually took engine temps was for 1700miles with a 24 foot camping trailer attached, and I reported those temps above and in prior posts.

It needs to be clear what I'm going after in Part IV, which is better engine performance based on reduction of engine *bay* temperatures I measured in Part III. Specifically, my primary focus and target is the airbox heat. I don't care what my engine temps are, because they certainly appear normal from my dash guage, confirmed with my IR gun and my autometer temporary installed guage in June. And actually, based on them, my target is to manage them better, which will likely result in actually raising the engine operating temp, not lowering it. Specifically, through engine temperature sender and electric fans, precicely narrow and control the engine operating temps closer to 100C

My secondary focus is reducing the backpressure on the electric fans I will be installing in ABC Part V. Right now, I have no doubt that I have reduced the operating temp of my engine using the VC fan, because my guage sits a little lower. I didn't measure any radiator temps, because they have no value to me right now. I certainly will have a boatload of temp data to post as I jump into the relatively untested world of dual electrics on an 80.

The hood vents should reduce the strain on the electric fans by reducing the backpressure. I am proceding into step V with I-IV complete, and IV has the side benefit of helping the electrics backpressure strain in cooling. Because no one has done dual electrics and/or posted up the results, certainly not with an SC attached.

Rick, I believe many here misinterpreted my goal to be reducing engine temps, including you. That *is not* and *has not* been my goal. In fact it's quite the opposite, I plan on controlling and raising the temp. If *reduction* is anyone elses goal, then my data will have a blaring omission of *my* engine temps until Part V.
HTH

SMT

 

[landtank]

Rick, I believe many here misinterpreted my goal to be reducing engine temps, including you. That *is not* and *has not* been my goal. In fact it's quite the opposite, I plan on controlling and raising the temp. If *reduction* is anyone elses goal, then my data will have a blaring omission of *my* engine temps until Part V.

I don't think I am. You are doing this in a step by step operation and all that I'm doing is trying to confirm your conclusions for myself.

Comparing my seat of the pants results with yours it would seem that we're experiencing something similar. The only way I know of to rule this out would be to get your engine temp data if it was available to compare to mine.


Does this make sense?

 

[concretejungle]

gawd this nickle-and-dime stuff is killing the thread. Seems that now instead of determining if cutting holes in the hood do or do not decrease underhood temps to accusing of insufficient testing based on another perspective???