OK, back in my younger days... I had a cool yellow 87 Formula Firebird (loved that car)... Even though it was "only" and LG4/305... I changed exhaust and added a Chip.

Honestly, I don't remember the chip really doing anything to help my car out. But I do remember it had to now run 93 octane...


Anyway, now I'm old and forgetful....

I am curious, what does the chip control on the LG4... Timing? Carb? Trans?
I won't add one , to my 85 z28 (don't know if they are even available anymore for the LG4).

 

The chip, and I would assume it was a Hypertech as they were the originators of the drop in "chip" movement, altered timing and fuel curves very slightly. Understand that the ECM was already tuned for best overall performance and efficiency at the factory during many hours of dyno tuning the engine before production.

There is very little that can be done, without basic mechanical modifications to the engine itself, to improve performance on any naturally aspirated factory engine. One thing I do remember with the Hypertech chips in the TPI engines was their tendency to run the engine lean at cruise.

The real limit to engine power in any factory GM engine is the cylinder heads. All the bolt ons and chip tuning in the world will never make real power through those crummy stock heads. Any real power upgrade has to at least start there, if not with a complete engine upgrade. Once the heads are addressed, then power can be made by combining CR, cam, intake and exhaust to arrive at the target power level.

The only vehicles that see any real power improvement with ECM tuning is supercharged applications(turbo diesel trucks?) as increased boost pressure is an easy way to increase power. Of course engine longevity is another story.

 

Makes sense
Thanks

 

If I may add to what the Doc described, the ECM is only capable of altering fuel mixture in a very narrow band in the E4ME carbed applications. The limits of the idle air bleed and enrichment solenoid travel are fairly tight and really only affect mixture at idle and low-end part throttle angles. Once the primaries are opened beyond the idle transfer circuit control range and certainly once the secondaries are opened, the ECM is just along for the ride and mixture relies upon fixed jetting.

The largest changes could be accomplished through ignition advance curves, but those are still dependent upon the base timing setting and are quickly retarded as soon as the knock sensor became active. In reality there was little if any operational benefit from drop-in PROMs which could not be accomplished by adjusting what the factory provided out of the box.

The product was successful, however, in accomplishing its primary goal of complete separation of a driver who wanted additional performance from his money. That is still occurring today as many vendors offer ALDL plug-in tuners or PCM piggybacks for the same purpose (separating cash from a customer).

You are far better off modifying a stock tune and making the associated necessary changes to the fuel and ignition adjustments, and as suggested, improve the head flow to support more power.

 

thanks

over my head, kind of stuff... but good to know.

Never going to expect a POWER HOUSE out of the LG4...
the topic had come up in a discussion the other day and I was not sure.

thanks again.

 

The short answer is that if the carb is clean, functioning, and is properly adjusted and the base timing is set correctly it will run its best. You can always toy with the base timing and try to get as much as 6-8° more total advance so long as preignition does not become a problem. It is a little more forgiving now that many of our pump fuels in Ill-Noise have at least 10% ethanol and run a bit cooler and with less tendency to preignite. If it doesn't work for you the timing can be set back closer to the 0° spec and all is forgiven. You can also "cheat" just a little by dropping to a 180°F thermostat since the factory ECM tuning should tolerate it without problems. It would also be good to have the original style cold air induction system in place. Those chromed open element air cleaners might look pretty, but can actually be a huge detriment.

 

I must admit, I wasn't paying careful attention when I first replied to this thread. I was thinking of EFI, not CCC(LG4). However, the same applies to either. Little can be done to increase power output from the stock engine, aside from optimizing the tune, as explained by Vader. At the same time, either the E4ME carb or EFI can be upgraded to support higher output for those who do decide to build up the engine.