Oldbald1

David Lutsi @ Liberty 1 in Ft Myers FL just completed an install and tune for me. 302rwhp 184 lbs tq Added a Vortech SC and cooler, 550 injectors, AEM EMS and a few gauges. Took him a little while but it was because my TDC sensor was cracked and sending random signals plus a couple other subtle problems that I unknowingly brought to him. I have scanned the dyno run into my PC. Now I have to figure out how to attach it to the next message.

mase1

I love this thread, its about time there was an informative thread like this

however, there is no reason to tune so rich, it was stated 11.5:1. you're surely losing power there.

gilbertg

mase1,

Sean (TorqueFreaks) has massive amounts of experience in tuning engines. Most engines have peak power output with an AFR somewhere between 12:1 and 13:1, however the ignition needs to be so retarded due to the increased heat generated over a period of time at this output level negating any positive effect that the AFR might have. Going richer enables the supplied fuel to have a cooling quality in the cyclinder thus helping to reduce knock. Not all of the fuel will be burned also helping to reduce knock but it will be good balance of power (from advance) and safety (from cooling). Safety and longevity of our engines (Chris and myself) was our #1 goal and exactly the reason why we went with the EMS. In Chris' case 11.5:1 is ideal because he tracks his car a lot and so can produce some pretty high temperatures. A little richer helps him. Trust Sean - he knows what he is doing :-)

cbender

Mase1, in truth, the *only* way to know the precise tradeoff between air-fuel and power is through empricial testing. We've been there. We've done it, and I'm confident that what power I'm giving up by running a bit richer than the gospel -- so often cited by those who heard it from someone else who heard it from someone else, who decided is must Be True, etc. -- is modest, while the reduction is knock is appreciable (and appreciated). My dyno charts and AEM logs -- as well as Giles' -- prove it.

CB

HorsepowerFreak

It's also important to note where the A:F ratio is retrieved from. If you dyno tune and the dyno wide-band monitoring is done in the tail pipe, it will read at minimum 1/2 point leaner than it really is. The best A:F ratio also depends on the application. For drag racing (very short bursts) you can often get away with a 13:1 A:F, however, at the higher power levels it is best even in drag racing to lower this amount to a more conservative 12:1 A:F. Some of it also depends on how resistant the motor is to pre-ignition. Some motors have a lot less hot spots than others. Some motors come with ceramic coated pistons from the factory which can also help. It also depends on the spark plug heat range. If you run a colder plug you can get away with a leaner mixture and more aggressive timing. Driveability will sometimes be sacrificed if you go too cold, and colder plugs are easier to foul.

We test out different kinds of fuel as well. Some fuels take much longer to burn, others burn really fast and will result in a much leaner mixture. We've tried everything from 130 octane which burns very very slow and results in an overly rich mixture, to C-16 which burns very fast and runs at minimum 2 points leaner than the 130. We've also tried 104 unleaded, 100 leaded and 92 octane unleaded which have somewhat similar characteristics depending on the brand of fuel. So if you tune with one fuel, be very careful if you switch fuels.

I'm off to Sema.... I'll talk with you guys next week.

Take care,
Chris.
www.horsepowerfreaks.com

3ngin33r1

You guys never answered my PM...

HorsepowerFreak

I didn't realize I had any. I just turned email notification on for PM's. I replied to all of the PM's I had. If you have any other questions, you can email me directly at chris@horsepowerfreaks.com or our tuner at sean@torquefreaks.com. I'll be out this week at Sema but I'll be back in the office again on Monday.

Take care,
Chris.

TorqueFreaks

PM? Can you resend it? Or just shoot me an email - sean@torquefreaks.com.

As far as AFR, while it is true that 11.5:1 is on the conservative side, there is definitely a reason for it. On a high compression motor with boost added to it, it is absolutely necessary to keep things cool. Running proper timing with a rich AFR accomplishes this nicely and makes for a long lasting, reliable engine. Chris and Giles told me several times that their goal was to have a car that is reliable and fun. They are not concerned with dyno numbers; rather, they want a car that will last and last, track day after track day. I believe they are tuned perfectly for their goals.

Just a data point - we also tried leaning it out and running more advanced timing. The knock was audible.

If I tune a car to be a 1/4 mile racer or a dyno queen, things are definitely more aggressive

Take care!!

gilbertg

[QUOTE]Originally posted by TorqueFreaks
Just a data point - we also tried leaning it out and running more advanced timing.

KYS2000

Hello Chris, I just bought the EMS. Currently I'm using the AVC-R for boost controlling but I want the EMS to monitor and control boost, what solenoid and where do I need to purchase. Also, other than the wideband is there anything else i need to purchase for correct operation of the system?