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Northwest Chapter
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I'm no tuning expert, but the clutch fan operation was explained to me in the following way:

"In any case the fan will always drag at 20% lockup as this is the min lockup with the EV clutch. (80% max) Design limits of viscous fan clutch."

So if I just had a little black fooler box I could just plug in, eliminate fan drag for about a 1/4 mile and have no ses light, then plug the fan back in and go home.
Never heard they couldnt be commanded 0% lockup, know for a FACT the one in my 02 can command 0% lockup and I cannot spin it by hand.

Yes this design would work but I do not believe it would be worth the money. If you're going to spend this much might as well save and buy efans too. Then get a tune if you're not already, never have to think about it again.

You didnt answer my question, are you tuned or not?
 

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2007 chevy trailblazer_ss_1ss
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42 Posts
Sorry, got it tuned at Vector, see my sig. I just don't know enough about how everything works tuning wise. I have a feeling (since I can stop the fan with my hand while unplugged and even very cold after running a few minutes can not) that even when commanded to 0% the clutch still stays 20% engaged. Funny thing is I bought this thing to drive and not have to think about little things like I am now thinking about. I just thought for $50 that ecm "fooler" would be a good track and Friday/Sat. night mod. I have a race tcm also that gets swapped out at the track.
 

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Northwest Chapter
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Sorry, got it tuned at Vector, see my sig. I just don't know enough about how everything works tuning wise. I have a feeling (since I can stop the fan with my hand while unplugged and even very cold after running a few minutes can not) that even when commanded to 0% the clutch still stays 20% engaged. Funny thing is I bought this thing to drive and not have to think about little things like I am now thinking about. I just thought for $50 that ecm "fooler" would be a good track and Friday/Sat. night mod. I have a race tcm also that gets swapped out at the track.
Im pretty dang sure Vector has the fans come on earlier than the factory. I wont be near my SS til Thanksgiving I dont think so I cant check until then.

Its up to you with trying this out, I wouldnt touch it unless I was bothering to do efans as you still have that 10lb mass on the motor. I just dont think you'll see any improvement in time, what happens when you unplug the harness and rev the engine? Does it rev faster? Im betting not, so why would you get a better E.T. or better throttle response at the track with the fooler installed?
 

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2007 chevy trailblazer_ss_1ss
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42 Posts
My theory in unplugging the fan is to eliminate the resistance of having to spin the 10 lb mass at any speed. With the fan unplugged it basically free wheels and the engine doesn't have to work extra to spin that mass. Basically a poor mans way of getting the temporary benefit of e-fans.
 

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Northwest Chapter
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My theory in unplugging the fan is to eliminate the resistance of having to spin the 10 lb mass at any speed. With the fan unplugged it basically free wheels and the engine doesn't have to work extra to spin that mass. Basically a poor mans way of getting the temporary benefit of e-fans.
How I ask? The fan clutch is STILL BOLTED to the engine and therefore the engine MUST spin the mass. Just because you unplug the wiring doesnt mean the clutch isnt spinning once you turn your truck on, it is. Only way to not have it spin is to remove it or never turn your truck on. Yes there wont be any resistance to spinning it but I really dont believe thats the problem. My I6 wasnt any faster when I unplugged the fan last summer to test EFILives 02-05 I6 efans stuff.

Im going to try it again today just because this is bugging me. Will be the exact same tune just with the fan clutch turned off.
 

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2007 chevy trailblazer_ss_1ss
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The mass isn't really bolted to the engine, there is a clutch between the engine and mass so the engine doesn't have to spin it when the fan is unplugged. There is less/no resistance when unplugged. I look at it this way, with the fan unplugged, I can stop it with my bare finger easily, meaning the engine isn't using much energy if any if I can stop the fan, even if it were a 100 lb weight, there just isn't any resistance with the fan unplugged. However, with the fan plugged in, even at it's lowest engagement level, it can not be stopped by hand (at least by me), telling me that the engine is using some amount of power to spin that mass, no matter how much it weighs. How much power I have no idea. That's just my theory though, and I could be wrong.

I guess one could think of it like pushing a car. Now granted a car weighs alot, but imagine how hard it is to push a stick shift car while in gear, it would be impossible almost. However, if one were to disengage the clutch (push the clutch pedal in or put the car in neut) it would be much easier to push the car.
 

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Northwest Chapter
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The mass is indeed bolted to the engine, the mass is on there. The clutch disengages the fan part from the engine but the mass is on the engine not the fan. Unless you unbolt and physically remove the clutch you still have to spin the mass whether you think it will or not, it must.

You said it yourself, the engine is using some power to spin the clutch with it plugged in. Please tell me how simply unplugging an electrical connection magically makes this 10lb rotating mass go away?

If you order this and make it work let us know but when you go to the strip take one pass normal then hook the fooler up. Pretty sure you're not going to see any noticeable difference.
 

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2007 chevy trailblazer_ss_1ss
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42 Posts
OK, on my 07 TBSS, if I spin the fan with the engine off, the whole fan and clutch asm. spins, and, with the engine running and the fan unplugged I can stop the entire fan asm, clutch and all. Not just the fan, but I stop the entire mass. Now there maybe some internal portion of the asm that is still spinning, but that would have to be minimal. So yes the mass is bolted to the engine, but with the fan unplugged there is nothing engaging the mass to the engine, IT SPINS FREELY and can be stopped easily. Only some internal friction is keeping the fan asm moving, and this can be overcome by such a small force as my finger. I'm not denying the mass isn't bolted to the engine, just that the engine doesn't have to use any power to spin the mass when the clutch is totaly disengaged or unplugged. I don't know how much horsepower is wasted with the fan asm not engaged, but I bet if it was even one horsepower I wouldn't be able to stop the entire fan assembly with my finger. Now, I know the fans are different somehow on the 08-09 TBSS's than the 06-07's and I see you have an 08. Maybe the clutch fan asm is diff somehow on yours and mine thats why there is a discrepency in our views.
 

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2007 chevy trailblazer_ss_1ss
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42 Posts
Something just dawned on me. Something may be being overlooked. I'm not trying to make 10 lbs disappear, I'm trying to convert it from a rotating weight to a hanging weight. For example, wheels and tires. A set of wheels and tires that weigh 15 lbs each effects the vehicle performance more than just adding 60 lbs (15 x 4), it effects it exponentially more because they are rotating, unfortunately I don't know the formula. So what I am trying to accomplish is the engine to not have to work to spin that 10 lb mass, not to eliminate it.
 

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Northwest Chapter
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Something just dawned on me too, how Ive been thinking about how the clutch works is wrong. For some reason I was thinking the disconnected the fan blades from the clutch and the clutch was bolted straight to the engine but I think the fan/clutch are bolted together and the clutch disengages on the motor.

I see your point, I know what you're trying to do I just simply dont think you'll get any gains from it. My 02 I6 and your 07 SS clutch are identical, no differences at all. When I unplug it and drive around with it unplugged there is NO difference in acceleration. Right there this makes me believe you will not see any gains.

Prove me wrong and show me time slips of plugged in and not, then Ill believe you but until then I believe we need to part ways on this.
 

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2007 chevy trailblazer_ss_1ss
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42 Posts
I'm not claiming it will work, just hoping.:worried: Wether it works or not I'll let you know.

It's nice chatting with someone with a differant view/opinion and keeping it civil. Many times that's not the case. Thanks.
 

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Northwest Chapter
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11,917 Posts
I'm not claiming it will work, just hoping.:worried: Wether it works or not I'll let you know.

It's nice chatting with someone with a differant view/opinion and keeping it civil. Many times that's not the case. Thanks.
And now you've got me thinking about it in another way too, thanks! I agree, lots of times people just flame on when others dont respect their view, not good.
 
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