photos by: the author
Dyno-Tuning an LS1 Trans Am with GEN3 Performance
So your daily ride has just eclipsed its warranty and you’ve added a few bolt-ons or maybe you’ve just switched from nitrous to forced induction for the new race season. Sounds like it’s Dyno time! A dyno tune is a time-honored tradition to both dial-in engine performance and get those all-important horsepower bragging numbers.
In the fuel-injected performance cars of today the on-board computer controls it all. Changes in fuel/air flow, spark, timing events, gearing, etc. must be compensated for through the computer. Additionally, vehicle manufacturers often intentionally limit performance from the factory to improve vehicle longevity and street manners, so tuning alone can often unlock additional performance. Most performance emphasis is put on parts and modifications but without a proper tune and dyno analysis the results may not materialize.
Most TV shows and other media make dyno tuning look easy. Yes from the customer’s perspective someone just sits in the car with a laptop and runs through the gears on the dyno a few times. But that “someone” has likely spent years learning how to tune and honing their skills. While many tuners can work on several different makes and engines, they often specialize in a particular engine/ECM type to focus their efforts. Though the bulk of the dyno tune effort is shouldered by the tuner, it never hurts to be prepared and understand the process.
Gen3Performance and Dyno in Rainbow City Alabama tunes many late model fuel injected vehicles but is most widely known for the GM LS/LT platform we all love. Founded in 2002, Gen3Performance has seen its share of vehicles turn the roller on its Dynojet 224 Chassis Dyno. The owner and lead tuner Scott Culbert was kind enough to let us ask some questions during a dyno session that will hopefully help dyno rookies and veterans alike.
GMEFI: Do you have any tips for how to select a dyno tuner?
Scott: One of the largest requirements for me is experience, and real-world experience at that. In this age of “YouTube tuners” that have very little experience and knowledge with actual vehicles and realistic scenarios, you must be very careful. Some tuners have never even changed the spark plugs in a car, but they are trying to tune them. Someone else’s car shouldn’t be where you are doing your research and development. I’d also be sure to look for someone who owns and maintains the type of vehicles he’s tuning. It’s hard to familiarize yourself with every nuance and characteristic of what is normal and not normal in an application if you have no firsthand knowledge of what is and isn’t normal from that vehicle. So once again, experience and knowledge are key in this aspect.
GMEFI: Should any maintenance be performed before a dyno tune?
Scott: It’s always a good idea to check your engine codes and make sure that there aren’t any that’s not associated with something that the tune should be clearing up. For example, if you have front O2 sensor codes, it would be advantageous to address that before showing up for your tune. After making sure all sensors are working correctly, I’d suggest doing routine maintenance and a tune-up on the car addressing plugs, wires, air filter, fuel filter, and a fresh oil change. It’s always a good idea to have a full tank of the type of fuel you are planning on running from the station you generally buy it from when you show up for the tune.
GMEFI: Are there parts you should wait until after/during a tune to install?
Scott: Generally, if you are changing to larger injectors, it’s a good idea to wait until the time of the tune or have the injectors installed and trailer the vehicle to the tune. Larger injectors will cause the car to run very rich and possibly dilute the engine oil with fuel and or wash down cylinders while damaging piston rings. It’s even possible to hydro lock an engine if the new injectors are very large.
GMEFI: What information should you provide the tuner?
Scott: Besides telling him about all of the vehicle modifications, it’s always a good idea to inform the tuner of what your major performance and driveability concerns are up front. That will allow him to talk to you and see if your expectations are achievable and or let you know what he’s able to accomplish before getting started. Aside from your expectations, you should tell him of any problems the vehicle has had previously that could possibly be tune related and or mechanical that he should be aware of.
GMEFI: What process should someone expect while getting a dyno tune?
Scott: Generally, the tuner will inspect the car for any engine codes, leaks, abnormal tire wear, driveshaft and universal joint abnormalities, and general health of the engine/transmission. Afterwards he will do a short datalog to verify the correct operation of engine sensors if the vehicle is in running condition, if not a base tune may be flashed in first to allow for data acquisition. After initial datalogging, the car may be driven around on the street or in a parking lot if he has some concerns before affixing the vehicle to the chassis dyno.
After the car is on the dyno the tuner will make some part throttle and idle adjustments while beginning to make higher engine load pulls and adjustments. When the tuner is comfortable with the initial idle, part throttle, and mid power adjustments and performance, he will start making wide open throttle pulls to adjust the ignition timing and fueling for the best performance and longevity of the engine. This is a very important process where experience counts. Every application may need a slightly different ignition timing map or fuel map due to the weight of the car and its intended use. Things like this are only learned through experience, youtube cannot help you here.
GMEFI: What information will a tuner likely give you after a dyno tune?
Scott: Besides giving you the horsepower and torque results of your tune, a good, experienced tuner should give you his opinion on if the car is making the power, it should be making for the modifications that are on it. If the car isn’t making the anticipated power, he should be able to give you his opinion on possible issues to address or explore. If the car meets his expectations, he can offer you guidance on suggested modifications that would benefit you in the future. Once again, experience… HANDS ON experience is key.
GMEFI: What should you check/do after getting a dyno tune?
Scott: Before parting ways with the tuner, I would definitely take a test drive and verify that all of my expectations are met. If they aren’t, immediately address them with the tuner before leaving. One of the worst things you can do is know there is an issue when you leave and think that it will rectify itself on its own or that you can learn to “live with it”. A competent tuner will address your concerns with more adjustment or advice to help you achieve your satisfaction.
GMEFI: What are realistic expectations from a dyno tune?
Scott: This is very subjective and is the main reason you should have a discussion of your expectations up front with the tuner. If he’s experienced with your platform and your modifications, he will point blank tell you if your expectations are realistic or not. After those discussions you should expect the end result to be a car that is tuned for all aspects of driving and performance, not just a dyno number.
GMEFI: What’s the strangest or funniest thing you’ve seen happen during a dyno tune?
Scott: The funniest thing was a repo man following a customer to the dyno and repossessing his car after it was tuned! At least he didn’t take the dyno sheet with him! The strangest thing would probably be a large gopher rat running across the floorboard of a car I was doing a wide-open throttle pull on. It was a pretty nasty car!
Here’s some additional observations and takeaways from our session with Gen3Performance:
As you can see Scott has seen it all and understands the customer-tuner relationship. While the penny-pincher in us all wants to price-shop for the cheapest tuner available, building a relationship with a reputable tuner and performance shop will pay dividends if you are serious about performance.
Many dynos are going to require your car to be pulled up onto a ramp to reach the rollers. So if you are ridin’ low or have a low mileage time capsule, you may want to consider putting some painters tape on your lower valence as added protection.
Also, it’s good to be aware that the wide-open-throttle runs to redline are a stress on your vehicle. Any known issues may make themselves known…ask our small power-steering leak turned torrent if you don’t believe us.
As Scott mentioned, a good tuner will do some partial throttle pulls and vary the speed as they tune. So don’t be surprised if it’s on the rollers longer than the one run you see on TV.
After the tuner is confident in the air/fuel ratio data from the partial throttle pulls, a wide-open-throttle run is the main event. Even with a relatively mild car it’s fun to see it strain against the straps and hear it reverberate throughout the room.
Good to his word, Scott provided us with a print-out of the final run. It’s fun to see the hp/tq numbers but that rock solid air/fuel ratio throughout the pull is more important.
A dyno tune is a right-of-passage for many gear-heads and can be a helpful tool in optimizing the performance of your vehicle. If your car leaves running better than it did beforehand you’ve accomplished what you came for regardless of what the power numbers say.
Fascinated with anything on wheels since he could walk, Colby’s obsession quickly narrowed to late-model GM muscle. Modifying, breaking, and fixing project cars over the past 15 years has been his hard knocks education toward a BS degree in Car Guy.
