First off, Im sure there will be many people who will post back about how incredibly stupid that is without trying it themselves or even driving their corvette hard enough to realize that the car seems more spunky for the first few minutes after a cold start.

So, Im going to use some references:

page 39 of ' How to Tune and Modify Chevrolet Fuel Injection' mentions unplugging the engine coolant temp sensor and putting a simple 640 ohm resistor across the 2 terminals of the harness.

It claims doing so will allow spark advance to come on sooner and also that it increases the pulse width of the injectors allowing some extra enrichment. The reason why is because it thinks the engine isnt warmed up.

As a caution it mentions that on some applications, the fans only method of turning on is based on engine coolant temperature - and if you were to do this for long periods, the fan wouldnt run and could cause overheating.

I figure:
A. I have a 160 degree t-stat which will help things
B. I run 93 octane gas
C. I have my fans reprogrammed to come on sooner anyways (of course, I dont know what the trigger is for them to come on).

Why not try this for drag runs?

Ive long noticed that it my corvette seems spunkier when I first start it up and drive it (Especially on a hot day). After a while of driving it on a hot day, its less spunky (aka accelerates less hard).

What does C4 Tech think of this?

 

Thats a great book...is it near the same pages or later as they show this mod being used for drag racing only?
I could have sworn there was a section talking about that for drag use,but not to use for driving anywhere else due to other possible problems.

 

your car runs better because the engine IS cold, not because the coolant sensor is telling the computer the engine is cold, when it really isnt...

 

I think that if you want extra timing, why not just add timing? As for fuel, that is moot at WOT right? At WOT the resistor wouldn't give more or less fuel, it goes to max reguardless. The resistor sounds like a good way to always run rich at part throttle.

A cold intake gives more power from not being heat soaked. Really cold air has a similar effect.

 

There are a few flaws in this thinking.

A. Except for while competing in a specific event, a 160° thermostat is too cool for daily use. It doesn't make the engine run any cooler, but it delays the warm up. Also, any improvement seen in performance is due to the intake air temp not coolant temp.
B. What does octane have to do with fooling the engine management about the temp of the engine?
C. Your reprogrammed fans turn on at the temp YOU have set in the prom, which will never be seen, because the resister is feeding false temp info to the ECM. If run long enough, the engine will get red hot, despite the 160° thermostat, and the fans will never budge an inch because the ECM thinks the engine is as cool as a cucumber. You kind of outsmarted yourself on that one.

The engine will be able to produce the best and most efficient power when it is fully warmed up; coolant over 185°, better if over 200°, oil over 200°. The air into the intake should be as cool as possible. If the engine makes more power with more advance and fuel, those items are best addressed in a tune. Unless only as an experiment, to determine if tuning will help, there is nothing to be gained and something to be lost by fooling the engine management as to the conditions. The ECM sees the engine at 160° with 450 ohms resistance, and higher temps with less resistance. With 640 ohms (cooler than 160°), does your car even go into closed loop?

RACE ON!!!

 

So the author of the book is an idiot.

Ive looong noticed that my LT1 seems faster after its been sitting for 3 hours and I drive it. This lasts for about 3-4 minutes.

This is not the case with any other car Ive driven. They seem to retain their performance more.

Ive long concluded that the reason why has to do with the computer retracting something after the engine has warmed up.

Im not advocating driving around with resistors ipo the coolant temp sensor, Im suggesting it might be worthwhile on the 1/4 mile track.

Octane fuel has a lot to do with it. Higher octane fuel means more resistance to detonation. If I run higher octane fuel, I have more leeway where I can screw around with stuff like this.

I dont know what triggers my fans to come on on my car. The author of the book mentions that some lower-model chevrolets use ECT as the only trigger. Leading me to believe that higher model chevrolets (liek the corvette) have a backup sensor to turn on the fans.

Why not give it spark advance like this under all operating conditions? Well, it might be too much for it on that 95 degree day, or if you got 'bad gas'. So stock is safer and normal.

Everyone knows that our C4's werent engineered very well. I can give you lots of examples (ex. optispark). Its likely that the engineers overlooked this.

Since my car gets slower as it warms up, I believe this might work and am willing to try it.

 

Since you have it all figured out, let us know how it works. Post up some time slips.

 

I said no such thing. I am merely trying to apply some common sense to the subject.

My comments on the 160° thermostat aren't intended to include the LTx engines. I missed in your opening post, if it was there, that you have an LTx engine.

I get the latitude you can gain by using higher octane gasoline, I just didn't see where it came into play with running a stock, albeit, a "cold engine" tune. In retrospect, if the ECM is going to advance the timing like the engine is cold, and it really is a 240°, you may well need all the octane you can get.

Your fans are controlled by the same device that controls your engine. If the ECM thinks the engine is cool enough for a "cold engine" tune, it will think the fans aren't needed. 1989 and earlier cars have the auxiliary fan, when so equipped, controlled by a thermal fan switch. In 1990 cars, and up, both fans are controlled by the ECM.

Your engine runs stronger when cool, because of the intake air temp. If this is a "for racing only" modification, why fool the engine into thinking it is cool and risk the damage a "cold engine" tune can do to a not so cool engine, and just make the engine truly cool? Since drag racing first began, racers have spent their time between rounds cooling their engines. Don't fool it into thinking it's cool, make it cool. I'll bet you get better results.

RACE ON!!!