Originally Posted by LS WON

for the info
In plain laymen's terms what is the downside to this "Dyno Tune"? Even something as minor as reduced gas mileage or shorten engine life. There is always a sacrifice and being here in California come smog time will this cause havoc when smog testing time eventually comes up?

Originally Posted by shopdog

The ECM has a series of tables that contain fuel and spark values. These are called maps. The ECM indexes into these tables using RPM, MAF, MAP, IAT, throttle position, etc read in from various engine sensors as indexes. The table value thus indicated is then read and used to control fuel volume and/or spark advance.

The factory maps are conservative, they have to work with rotgut gas, a wide spread of temperatures, a wide spread of atmospheric pressures (different altitudes), etc. So the engine makes less power than it would be capable of making if these values were optimized for performance.

What a tuner does is take a software tuning tool (any of the major tuning tools will do) and change these maps so they are more nearly ideal for performance, given good gas and good air. It isn't unusual to pick up 15-20 hp with a good tune.

There are also other things a tuner can change while poking about in the ECM. He can make the fan come on earlier and harder. He can raise the RPM limiter. He can turn off some emissions and safety related parameters. Etc. Under the right conditions, all of these changes can improve performance.

If you have an automatic transmission, there are a number of parameters a tuner can change which will adjust shift points, adjust shift firmness, etc. These can also improve performance (particularly 1/4 mile performance).

If you have made hardware changes to the engine or drivetrain, it is often necessary to retune the car to take proper advantage of these changes. For example, adding headers can improve cylinder scavenging, and that can make the car run lean. To protect the engine, and to make more power, a tuner needs to go in and make changes to the maps to richen up the mixture at certain RPM and load indexes to compensate for the effect of the headers.

There are a lot of numbers in the ECM maps that can be juggled to achieve various desired effects. It takes a tuner who knows his stuff to get real improvements, and avoid causing driveability problems. The particular tools he uses to achieve results are unimportant, the results are what matter, and that's still a function of the man wielding the tool, and not the brand of tool being used. Just as an old time mechanic wouldn't leave a screwdriver or wrench in your car after he tuned it, a modern tuner will not leave the tool he used to tune your car in the ECM when he is done.

As far as the car is concerned, it doesn't know or care what tool was used to alter the tuning maps in the ECM. For the most part, neither should you. There is only one issue where the tool used can matter. If your tuner uses LS2Edit, it will lock the ECM by default so that no one other than the original tuner can make future changes to your tune. You might need to make changes if you add hardware mods later (see comment on headers, for example). So this is an undesireable situation. HP Tuners software by default does not lock the ECM, so future tunes can be done by anyone, not just the original tuner. This is a more desireable result. Note that a tuner can override the defaults, ie he can unlock a LS2Edit tune, or lock a HP Tuners tune. But generally, tuners tend to go with the defaults of these two tools, and thus a tuner who uses HP Tuners is less likely to create future hassles for you than one who uses LS2Edit. Be sure to talk this over with the tuner you choose. I won't allow someone to hold me captive by locking a tune. Neither should you.

Originally Posted by yell03

$500 is a bit high, but acceptable, but not for 10rwhp

If I knew I would gain 15-20rwhp from a tune it would be well worth it.

My big problem is voiding the warranty for 10rwhp regardless of cost

Howard

Originally Posted by yell03

I don't know?

I'd love to hear from people with minor mods who have done a tune.

Originally Posted by C6 EDDIE

How far are you from Cartek

Originally Posted by JFTaylor

Julio at CARTEK is an ACE. Doubt if he's more than $500. I'm going to Carolina Auto Masters in Durham, NC for Headers & a dyno tune @ $300.

And I don't think a tune will void your warrantee unless he raises your rev limiter to say 7.5k and the engine blows. If that does happen just return to the OEM Tune before taking it to the dealer.

Originally Posted by yell03

I don't know?

I'd love to hear from people with minor mods who have done a tune.

Originally Posted by yell03

Maybe I'll just do a cold air mod to the front fascia for now.

Howard

Originally Posted by Patman

With both my LT1 Firebird and LS1 Corvette, I had them dyno tuned in almost bone stock trim and both times I picked up a noticeable SOTP difference in performance, the midrange and low end torque was noticeably better and throttle response noticeably crisper.

I would expect the same out of an LS2 as well. Automatics will benefit a lot more than manuals too, because the tuning can change the behavior of the automatic trans as well (shortening the shift time and firming up the shifts too, as well as raising the shift points)

Originally Posted by cbrf4i1

not having your timing pull from high iat is almost as good as a tune, considering the ecm could pull as much as 12 degree of timing.