LT4 Best way to turn on fans early - 1996 LT4?

[froggy47]

I've looked in the catalogs & online but there always seems to be something a little different about the LT4. I know that it is full obdII & I think it has to be "programmed" can't just pull a chip & stick a new one in.

So how do I turn on the fans early (without turning on the a/c)?

It's new (to me) 49k miles & seems VERY strong above 4800 rpm but low end needs help.

I'm putting K&N (not cutting the box - on the 96 it seems pretty open with all those louvers) 160 stat & want to turn on early fans.

Anyone know how?

Thanks!

 

[JT ZR-Won]

Doesn't Mid America sel a $15-$20 fan switch? It's made to do just that.......turn your fans on early.

Jay

 

[froggy47]

It's for 84-91 or 94 & 95

another is 84 - 91 only

There seems to be something different with the 96 lt1 & lt4

Still looking.

Thanks!

 

[warren s]

there are 3 relays on the drivers side of the radiatior shroud, all tghe wires from them run into a wire pack that runs along the inner fender into the car.

If you ground a "light pink, and light green" wire the 2 fans will come on. I did this on a friends 96 LT4, and on my 95 LT1. Same wires. A small toggle switch from radio radio shack for 3 bucks ans some wire was all it took.

I hate to "assume" the wire colors will be the same on other cars so just test.

 

[warren s]

The stock setup runs normal between 195 and 230, and will cycle between those temps. with no air flow while in less than "moving traffic"

Putting in an overide switch will not affect the normal operation of the fans. the computer will still be the "brains". You can just overide when you want. As for the system functioning intellegently, it was designed with emission control in mind, not power and longevity, having the engine run ultra hot (always above 220) helps meet that goal.

Also if you have an A4 trans, keeping the fans on longer also helps keep the trans temp down.

Bottom line -- a 160 therm, TB coolent bypass, overide switch will increase performance all around, track times will decrease and fuel economy will increase. Acooler desnser fuel air mixture will produce more power.

 

[froggy47]

I agree with Warren,

I am more concerned with engine longevity and power and less concerned with helping GM corporate meet some arbitrary emission goal that was crammed down their throat as a result of eco waco's lobbying the wimps in congress.

I'm not for trashing the environment in any way shape or form, I do have some understanding of the politics involved and the tradeoffs between emissions & power/longevity.

It seems like common sense to me that if an engine runs good at 160, 180, 200, or 230, I'll keep it at the low end if I can, thank you very much.

Now I just need to figure it out on the LT4 engine. I'd also like it to happen even if I forget to flip the manual switch - although it may end up coming down to that. It only reaches the 230 degree stuck in traffic on a hot day & comes down as the fans cycle.

Gotta be a way, I searched the archive but not much that's LT4 specific.

Thanks!

PS WhalePirot, it's running within temp specs, I just want it a wee bit cooler, thanks for the post!

 

[LT-4 CE]

Froggy 47,
If you find out, I'd love to know too. I have the 160 thermostat and it is great on the open road, bet creeps to 210 in tight traffic. I would prefer to have the fans kick on around 195-205.

 

[jstkrsn]

I put in a switch that grounds out the 5 volt side of both solinoids. If you ground out the 12 volt side, the switch gets too hot from all the amps running through there to run the fans. The computer hooks up to the 5 volt side. Then you can turn them on or off whenever you want. If your drag racing you don't want the temperature cycling. You want it low when it is time to run. Otherwise it will probably be at the high end when you want it at the low end. My cost was about $3. I had the wire and fittings, all I bought was a switch at Pep Boys.

 

[froggy47]

Does this cause any error codes?

 

[jstkrsn]

Manually switching the fans on doesn't cause any error codes. The computer doesn't know the difference.

 

[timmb001]

froggy47 -

Let me know what you find out about this. I am just south of you in Pt. Loma and would like to do the same sort of mod to my LT4

Captain Burks

 

[froggy47]

Hey jstkrsn,

How do you tell the 12v from the 5v side of the relay? Can you post a dig picture or describe? Thanks!

 

[vettered91]

I had once the same questions-doubts and even problems with the working temps in my C4 vettes and after many questions, research and testing the best and simple advice that I can give you is to put on a 160° Tstat and get a Hypertech Power Programmer (you can get a used one on ebay) and re-program your LT4 OBD II with the coldest options that it gives you to turn on the fans.
Maybe it´s not the cheapest way but it is easy and it has some other options that are going to be very useful for you.
It worked very fine for me, and I know it will do it for your LT4.
By the way ¡Congratulations! I hope my next vette will be an LT4!!!

 

[froggy47]

Hi vettered91,

I follow you re ez & other options.

I gotta wonder about the 160 stat though.

If you think about it:

1) You really don't want any of these engines running at 160,165,170,175 etc. It's too cold, the oils too cold the cats too cold and so on.

2) With a 160 stat (or for that matter with NO stat) you are only delaying/increasing the amount of time it takes to get up to a good operating temp. Say 185 - 195.

I know someone will argue that you make more hp w/ a cooler engine & that's probably true, but engine life may suffer by continuously running a cool engine. Also there's the emissions but I think these late models are plenty clean anyway.


3) I would like to make the LT4 run at a more constant temp (a tighter band width of temps) say 185 to 200 or 205. It just drives me crazy to see the temp go to 225 to 235 before the damn fans come on (without kicking on a/c)

Guess I'll ck out the hyper tech programmer. I'm also looking at something called ls1edit, but it seems very expensive to just turn fans on & not very user friendly, you have to trade data maps with people & each year's different.

Mine's running really good now & don't want to screw it up.

Thanks.

 

[vettered91]

Hi Froggy47,

1.- I have the 160° in the L98 and the LT1. The only time you will see your engine running at 160° is going to be when it is on it´s way to the 185°-198° operating range(with the hypertech). With the 160° Tstat and the coldest option in Hypertech the fans turns on at 192° and off at 185° so don´t worry about running too cold (maybe 175 at high speed). Not the coolant, not the oil.
2.- The warm up time its almost the same (I did not notice any difference at all) and as I said we are talking between 185°-198° in City traffic.
The range we are talking about IS NOT A EXTREME ONE IT IS A DECENT ONE for any engine, the one that can hurt the most (gaskets, oil sensor, heads, hoses, etc.) is the one set at the factory 225°-240° it hurts the engine life the most!
3.- As you can see we are talking about the same goals, the higher temp I have seen in a hot day-heavy traffic in the LT1 is 205° and the cooldest in a long trip at high speed is175°

I was thinking about the LT1-Edit too, but it was a little too much for what I wanted and too sophisticated and + $.

Just for the record:
Before the 160° I had the 180° Stock in The LT1 (it had 28 K original miles) always running: 225°-240° (185° high speed). Same Tstat but with hypertech: 205°-215° (185° high speed)

The Hypertech Programmer is a no-mistake tool with another good options to play with.
You would not believe the problems I had in both cars (91 & 94) and the $ spent thanks to the high factory settins and my brother too (91 & 92).

If any doubts just ask, I will be glad to help if I can!

 

[froggy47]

I went on ebay, & saved the search so I get emailed if a new hypertech goes on auction.

If I snag one I'm going to try the program w/out the 160 stat & see what happens, can't hurt.

Did you do the bypass?

Any roads where you can open it up in Guadalajara? I've traveled more than most but never been there.

See Ya!

 

[vettered91]

froggy47,

It seems to me you are following the same track I did, let us know your temps with the 180° stat & the hypertech (it wont hurt) just do not use the 160° hypertech option.

About the bypass not yet but it is on the list with a 52mm T.B., adjustable fuel pressure regulator, MSD coil & 3.54 rear end.

We have 2 nice highways to the Pacific; one goes to Puerto Vallarta (+- 250 miles) and the other to Mansanillo (+-200 miles), this one crosses a big dry lake.... I am glad Kopvette is a nice friend and is in the other side of the border.:L

The track here opens only Saturdays & Sundays and I only go 5 or 6 times a year. (I need to go test the LT1)

Hope to hear from you and your LT4

 

[Rich96c4ce]

I used the Power Programmer

The HyperTech Power Programmer III inst. manual says: "• You can select between optimizing the cooling fan temperature settings for:
LT1/LT4 Stock Cooling Fan Temperatures:
Fans on/off at: 240°F/225F°

- OPTIMIZED FOR 180°F HYPERTECH POWERSTAT
LT1/LT4 Cooling Fan Temperatures:
Fans on/off at: 213°F/205F°

- OPTIMIZED FOR 160°F HYPERTECH POWERSTAT
LT1/LT4 Cooling Fan Temperatures:
Fans on/off at: 192°F/185F°

I did it along with the 160 thermo, and it runs on the digital readout at about 165 to 175 when driving.

 

[froggy47]

Hi Rich,

Thanks for the detailed post. Your personal data points out what my theory is about the 160 stat. Not just my theory - some others on the forum concur. They think that 165 - 175 is not warmed up enough for this engine. May make more hp/torque but a cool engine (or too hot) wears the engine out faster. Just like cold starts with thick oil.

With the 5-30 Mobil One you may be ok anyway.

Did you do any extensive research on operating temps for lt1/lt4 or just figure cooler is better?

I'm still figuring this one out for mine.

Thanks!

 

[froggy47]

Hi vettered91,

Sounds like your planned mods are along the same lines as mine, not too extreme but a bit more grunt.

From what I've read the first thing (also the most $$$ I guess) to do is the gears. HUGE change in performance depending on what you have now.

I've got 3.45 in the LT4 so that's low enough for now. The rest I'll probably do.

See Ya!