montie98

With all the choices of themostats,fan switches and chips whats the optimum range? Some say too cool is not good. Is this true?

65Z01

That depends on what you mean by "best" temp.
-stock for lowest emissions
-195 for low wear
-160 for best power

jackdaroofer

:cheers: Here we go again :smash:

It's been months since this debate raged here :D

Let me start it :blueangel:

HEAT KILLS!

GM like HEAT, it's good for emission tests.

I prefer to run around 175 at cruising, up to 205 stopped in traffic.

I run all my cars ( 3 with 305's, Camaro Z 28's) cool. Combined they have over 500,000 miles on them and never had the engines out or the heads off. I also change oil about every two thousand miles.

The vette has 106,000 miles, again no problems.

Fuel mileage suffers a little, or so I believe. but fuel is cheaper than metal.

I run a 160 thermo, and a fan switch that comes on at 205

Let the debate begin :D :blueangel:

:seeya

:steering:

vader86

I have some information that i took from a magazine article someone posted, that tested two L98s at different coolant temps, as i recall they pulled the best times when the coolant was right around 160-170F.

Having temps this low allows you to bump up timing and increase fuel pressure, which helps more.

65Z01

I too have noticed the difference from launching at say 155-160 deg F vs say 165-170deg F.

The lower coolant temps always bring a harder launch, lower ET and higher trap speed.

formul89

Yes, only if the plenum/runners/manifold are not heat soaked. That is what kills power more than anything. My '89 Formula 350 runs 3-4 tenths slower when there is any heat in them. A bag of ice on the plenum and an hour or so cool down is the best thing to lower E/T and raise trap speed.

I recommend the SLP 160 degree thermostat or a Robert Shaw thermo w/ two small holes drilled on either side to let bubbles in the coolant passage to flow through and allow the therm to open properly.

TA

L98s definitly like it cool :yesnod:

Vic'89

I need to be at 160 degs at the starting line in order to get my best ET's.

Vic

J Z06

The runs I've made with the car we're with a warm engine. Couldn't tell you exactly what they we're, the '90 car had the idiot gauges 100-260 and no way to tell in between. :rolleyes: :mad

Cooler is better though. I don't typically hammer it as hard as I would in summer as I do in the fall/winter. On a cool day when all is right, it feels SOO much stronger than spring/summer.

BIG JIM 54

Yeah, what Jack said. The cooler the better for HP.

Steel Blue 91

(Said in a Johnny Weismuller stye Tarzan voice)

Cool - good
Heat - Bad

War Machine

I run good when the oil temps are under 170. The coolant is always under 170 unless I'm sitting for a while. After 170 it feels like I tossed an anchor out the window.

KTA1000

dumb question here,,, do you have to change the computer chip with a 160 degree stat ,,, or can you just throw a 160 degree stat in with the stock chip?

thanks
paul

65Z01

formula89, the TB coolant bypass and help to keep plenum temps down; mine now cools very fast even though the valve covers stay hot quite a while longer.

Though tuners say the ECM doesn't look at the MAT signal on MAF L98s, still I moved the MAT sensor into the air filter lid so that the ECM sees a more accurate air temp.

Definitely icing the plenum works, unless you have to sit in line too long.

KTA1000, you can just run a 160 deg stat but your engine will heat up in city traffic because the fans won't come on till stock temps.

You have three choices to bring the fans on earlier with an L98:
-install a lower temp setpoint chip
-install a low temp aux fan switch and wire it to control both fans
-install a manual fan switch so you can turn the fan on when you want



[Modified by 65Z01, 9:22 PM 6/10/2003]

hngacurv

You can buy a Hypertech fan switch/sensor that is plug and go from Autozone for $45. Thermo is a few $ more.

KTA1000

Is this really a noticable gain in performance,,, anybody know HP gains or 1/4 gains from just going with160 degrees. I was thinking a new performace chip with it also for the fans instead of just the switch for a little extra power, or is that a waste of money?

Paul

vader86

You dont gain any HP from just installing the lower temperature thermostat. But, it will allow your engine to stay cool and we see that the harder/quicker launches is proven to be true when the engine is cool. Thats a real benefit in ET's at the track, but shouldnt affect the MPH (mph shows the HP the engine makes)

However, with the engine being cooler, and if your fans are set to come on at or just below 200F, you can advance the timing a couple degrees. This can increase HP just a little with L98s.

gcrouse

Running too cool will cause excessive wear; I would never run coolant below 160* or oil below 185*. Now GM has it set a bit too high at 225* (for emissions). Perfect operating temps all around would be are 180-205.

It's not the coolant temps that help at the dragstrip, but the intake air temps. If you have heatsoak from the heads to the intak, you're screwed anyway- put a bag of dry ice on your plenum.

And I'll say it once more- the thermostat only limits the minimum operating temp. If you have a 180* the engine will not run below that- BUT if you're running at 215* becuase of engine heat energy vs. the cooling system ability to dissipate it, it won't make a damn bit of difference whether the Tstat is 160*, 180*, or 195*.