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I have a 87 irocz L-98 350 w/Ls1 fans.(fans are wired together/come on at the same time) I am running a 170* thermostat with hypertech 2026 on at 176* off at 166* fans never shut off. I was looking at the hypertech 2028 and the GM switch 3053190 On at 190*. Any suggestions/info is greatly appreciated! Thanks.
There is a best cruising temperature, perhaps 212 to 220*F, and newer vehicles run the coolant around this temperature for this reason to achieve better engine life and/or economy. Compare injector duty cycle logs to find lowest duty cycle and highest engine vacuum. Wrap the exhaust, or get it coated, and add a turbocharger for even more of this fundamental concept to improve economy. The more well contained the energy of the exhaust, and with the help of the turbine, the more performance oriented the engine will be and achieve higher economy.
In WOT applications, obviously fuel economy is of no concern, and for those situations we use enough fuel to keep the reaction cool and can monitor the EGT easily and make sure nothing is overheating. If we wish max performance using turbochargers, sometimes the temperature is being excessive due to boost, and two great solutions are methanol/water and E85 will help bring back down the temperature with small fuss. Many would agree 500-600bhp is possible with 93 octane using meth/water in a surpluss of modern/recent V8 OEM engine applications.
I mainly just wanted to make sure everyone is aware that colder is not necessarily good for an engine. Cold engine temperatures are associated with shorter engine life, increased wear and tear. I really think this has more to do with the temp of the oil than the coolant, I believe that as long as you are getting the oil to warm up quickly to 188-205*F and get it thinned out before making max performance runs it will help with the engine longevity. Sometimes we want a cold coolant to help control the IAT (the exhaust coating/wrapping goes a long way towards achieving this same goal) and together we have a colder intake package. while keeping the oil hot enough to boil out water (literally, if you never warm an engine oil up, it will gradually collect water and need changing just because of that alone, the crankcase of an engine is not sealed off, but rather has ducting that leads from the filter-intake path directly to the crankcase for pcv actions)
Alright ima bump this into the Trump era as I got a very similar question. L98 stock dual fans/stock rad (and stock prom). In an effort to not be staring at this
all summer when in traffic, I decided on the 170 thermo as well. TPIS seems to have a good one but anyone plz lemme know if this is just a rebranded generic or POS generally. https://www.tpis.com/parts/view/217
However to accompany it TPiS recommends a 160 switch(?) From my reading on this topic I got the sense you want the fans coming on 10/20F later than the thermo so the thermo is around fully open, no?
I was thinking 185-on for the switch or maybe even ~200-on as I don't need the fans spinning (and shortening their already questionable lives) a half hour after I'm already on the highway or etc. Thoughts?
That's funny you mention that as after learning about near every damn thing I was just browsing the Last Frontier: DIY PROM. I'm at stage 1: "this looks daunting." lol
There is a scaler tunerpro rt, $6e mask. It’s easy to set the fans on and offs.
You would need a moates.net g1 and burn 2 and a few sst27sf512 EePROMs.
Wowza- thanks bro. Going to 3.45 gears, 3k stall and dana's shift kit was my main motivation for investigating DIY tuning but all the better. Tho I'm guessing you still need a new fan switch for the secondary fan given
Stock 220/222 (104/106C) first fan (d-side) via ECM (via CTS) then 238 (114C) secondary fan (p-side) via thermostatic fan switch
?
There's some threads where some dudes tried wiring the sec. fan to the ECM but it didn't seem to work great in alotta cases.
Looking at the programming there is a setting for primary and secondary fan on and offs.
I don’t know which output the ecm controls for a secondary fan relay on the 165 ecm.
Factory the ecm controls the primary fan. A/c command or the cylinder head temp switch for the secondary fan.wiring a secondary relay off the ecms ground control wire might fry the ecm.
Yeah I scrapped that idea fast. I pulled some of the better of the other members' guidance from aaall the threads on this to try to have a fulsome understanding of the whole setup and consider all possible solutions. For instance one dude explained how his new lower sec. fan switch just turned on the prim. fan as well which seems to run a little counter to the stock routing of the two fans I posted earlier (but overall good to observe). Other members encountered trouble trying to skip the earlier-on-fan switch change by just using the A/C as a kind of sec fan switch itself, which was an easy remedy I was initially hoping to use but clearly not reliable in all driving conditions:
I have a 200(93C)/185(85C) fan switch on the passenger side. At the moment, I have the stock GM chip in the car. Now in this situation, you would think that the passenger fan would come on before the ECM controlled driver side fan. But they both turn on at 200° (93C) So it appears that the passenger won't come on without kicking on the driver side if it's not already on.
In '89, the A/C would cause both fans to run. (a/c doesn't turn on second fan for a guy) =your engine needs a certain temperature before the addition of the A/C can create sufficient pressure for the switch to close.
When the ecm detects a "high A/C pressure", the A/C is on, your vehicle speed is less than a specified speed AND your temperature is above a specified amount; the second fan will come on.
There were other solutions I ultimately discarded for my application, like the in-dash on/of fan switch and the thermochip that accompanies the hypertech switch, which got mixed reviews. (This is probably just a piggyback simple change into the ecm vs the customability of what you're suggesting.)
So just to be clear, going this tuning route you'd snag a 160/170 thermo but wouldn't need to change any switches? ie any switch would be getting on/off commands at any custom temps one tuned into their ecu?
Yeah my shop guy swears by 160 but he races a Mopar xxxxxhp madmaxmobile (luckily he also has a framed IROC behind his desk, lol). I originally thought 180, but saw so many guys do 180 winter/160 summer. Emissions-testing in my jurisdiction, leaning up on 160 and somewhere on here a dude mentions Lingenfelter himself preferred 170 settled it for me. The odd cold October evening right before it's put away all winter as well. Also Ill be doing TB coolant bypass which I think factors in.
The thermostat sets the minimum operating temperature, not the maximum - if you're having an overheating problem, switching to a 160 deg 'stat is not going to solve it. As stated above, a 160 thermostat is too cold and will cause drivability issues in a computerized car and will also shorten engine life. For performance you want an engine operating in the factory temperature range with a cool intake charge.
Good point on factory specs- many dudes advise don't sweat traffic in/near the red. At the same rate, many wanna fix it anyway as they find it anxiety provoking. (NB I'm going 170 not 160).
However I think the issue w the factory specs ie the inordinately high second fan+195 stock thermo is it was a lot more about GM grappling with new strict emissions standards and trying to burn off every last atom than anything to do with decreasing engine wear. There's a small argument to be made about fan(s) life I suppose but overall was about emissions. That's my read on it anyway... As for performance I think you'll find a lot of pushback on hotter being faster, particularly given this context.
