'optimum' C4 Temperature ???

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Feb 17, 2006 | 03:01 PM

#21

Nico

Racer

Joined: Oct 2005

Posts: 405

Likes: 0

From: 1984 crossfire, Alhaurin de la Torre Malaga, Spain

Quote:

Originally Posted by Randy93

I believe the crossfire is setup to run in the range I discribed, if it doesn't, clean your radiator out, drain and refill coolant.
If that doesn't do it, I believe your crossfire still had the fans turned on by the coolant sensor, if so get a sensor that kicks the fan on sooner.
If it is turned on by the ECM, you will need to get a chip burned to get the fans on earlier.

Don´t want to hijack guys, only like to answer Randy
The engine did run at normal temperature Randy, the radiator was cleaned and refilled. Because its quite hot here in summer and the fan kicks in at he value of the fan switch approx 110 Degr. C (which happens when I drive slowly in urban areas), I am afraid it will be too high in summer. It already had some problems with fuel boiling in the injector supply an hour after stop. So I tried to find a switch (there is no ECM control for a crossfire) but that was impossible here in Spain. So I made a small electronic circuit that kicks in may fan where ever I want it to do. Now I can set the temperatures at the value you mentioned in order not to overheat in summer or in urban areas.

Feb 17, 2006 | 04:11 PM

#22

96CEwGEARS

Instructor

Joined: Nov 2005

Posts: 151

Likes: 0

From: Chesapeake City, Maryland

Here's a link to an article that seems to explain the difference between running cooler (~160) and running at design temps.

http://vette.ohioracing.com/mods.html

Makes sense to me.

Feb 17, 2006 | 05:07 PM

#23

robertt43

Racer

Joined: Feb 2006

Posts: 462

Likes: 0

From: green valley az

eng temp

I found thatwith a 195 thermo, and a fan switch set for 200=220,my 84 rus real nice. The fan is not on when I am doing cruising,on the interstate,but comes on sometimes around town. With the air on the fan should run all the time. If you have a 160 thermo,after that temp it is open all the time,so you are assuming that the water in the rad.,is cooler than that,or at least keeping it under 225.You must cool the water in the rad first.so it can cool the motor when the thermo opens. Pretty hard to keep it under 160. But,where you live is important also! I live in Az.,so 160 is out of the question .I hope I helped but this is confusing,and has been a discussion for years.

Feb 17, 2006 | 07:49 PM

#24

smacko

Thread Starter

Burning Brakes

Joined: Jul 2003

Posts: 922

Likes: 1

From: Brisbane Queensland, Australia

...OK guys!

It was obvious to me I was talking about coolant temps when I posted the topic, but I guess that was presumptuous of me, so for the record I'm talking about COOLANT temps. I don’t really want this post to go off in tangents about thermostats.

AND in hindsight, I suppose I should also have stated mines an '85.

and thanks for your input.

Feb 17, 2006 | 08:19 PM

#25

RED-85-Z51

Team Owner

Joined: Jul 2003

Posts: 24,650

Likes: 8

Quote:

Originally Posted by smacko

and thanks for your input.

Nice hood ornament!

Hope the mods dont go apechit over it.

I think we pretty much answered you question though right? Every engine is different, depending on mods, and how well it is cared for, and the condition of each component.

Feb 17, 2006 | 08:27 PM

#26

smacko

Thread Starter

Burning Brakes

Joined: Jul 2003

Posts: 922

Likes: 1

From: Brisbane Queensland, Australia

Quote:

Originally Posted by RED-85-Z51

Cheers. Well yes & no; although of course I didn't factor in that there are variances with each different engine like L98 compared to LS-1 etc; I SHOULD have been more specific.

Feb 17, 2006 | 09:24 PM

#27

cv67

Team Owner

Joined: Oct 2004

Posts: 81,241

Likes: 3,062

From: altered state

St. Jude Donor '05

I picked up 10hp and 9 lbs torque on the dyno due to lowering coolant temps from 190 to 170. on the first series of runs.

At the track, comparing 185 coolant temp run to 155-160 I dropped almost 2/10ths

Emissions purposes-Hot as possible
Power-(IMO) 150-170

Feb 18, 2006 | 03:54 AM

#28

sothpaw2

Safety Car

Joined: Sep 2002

Posts: 4,030

Likes: 6

From: Maryland

Quote:

Originally Posted by Alvin

So what makes wear greater at lower temps?

The piston to bore clearance is greater, the metals are harder...

Its a powerplants problem.. nothing more.. nothing less.... GM can get better emmissions and fuel economy by running the engine as hot as possible.

For the racer keeping the heads and intake as cool as possible is going to yeild the most power.. If you don't believe me put a car on the dyno.. the first 4 runs will back each other up +-3/4hp or so (as long as it doens't get into knock on one run) put another 4 runs on it and you'll be down at least 10hp

I talked with the guy who runs the Dynojet for Hendrick motorsports here in concord and he said the same thing.. A street car can't move its heat where it needs to be and keep it from where it doesn't need to be. He said, they run the racecars on the dyno for about 30 minutes then make a certain number of throw away passes.. then 7 test passes.

The nascar guys don't take a pass or two down the drag strip.. they run the cars for hours at a time.. so the learn to use the heat to thier advantage rather than us trying to fight heat out.

BTW.. they told me they shoot for water temps around 230 degrees and the oil temps closer to 300.

You'll start to see heat to hurt a L98 around 195 on the dyno, a LT1 around 185, and a LS1 around 200.

He's got it. For emissions/fuel economy/longevity, you want to be hotter, say in the low 200's on oil in the LT1. But, from experience, the LT1 does a lot better at the 'strip if the motor is cool, say 170 oil. In the last several years, I never even ran the car at the drags without it that cool.

FYI on the dyno, Alvin is right and I have proof. I dyno'd 345 rwhp on my second run. Then told the tech to let the car cool for a while. Oil was cool for last run (170?) and guess what-- 352 rwhp. Nice trick eh?