S-Trim numbers
- Thread starter 03SONIC
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The shop the car was done at used a dirty tail pipe sniffer, not very good when you want to see AF for dialing in a car. The base timing was set wrong and nobody ever hooked up all the required equipment to see where boost, fuel, and spark was. The older cars require mad time and for the right equipment to be hooked up to maximize the combo in the tune. It is not like the newer pcm's were all the data is available with just a laptop. Customer was very pleased needless to say. If you look in the video you will see all the data logging things we had hooked up to the car to dial it in the right way. 
The shop the car was done at used a dirty tail pipe sniffer, not very good when you want to see AF for dialing in a car. The base timing was set wrong and nobody ever hooked up all the required equipment to see where boost, fuel, and spark was. The older cars require mad time and for the right equipment to be hooked up to maximize the combo in the tune. It is not like the newer pcm's were all the data is available with just a laptop. Customer was very pleased needless to say. If you look in the video you will see all the data logging things we had hooked up to the car to dial it in the right way.
i don't have any experience with the newer cars, but the fox body computers seem relatively easy to tune (i'm using a tweecer with datalogging feature combined with a permanatly installed wide band) WOT tuning is a breeze and the idle and part load tuning for driveability is not to bad either. what do you tune with?
i've always wondered about auto's on a dyno, with a 4900rpm stall, how do you get accurate torque and hp readings at rpm's below the stall point if the converter is not "locked". from the video it sounds like the pull started prett high in the rpm range.
chris
You can graph the dyno engine speed over time and really dial in peaks of the converter and see where it is lagging, performing, etc. They are not really that easy to tune as you need a bunch of stand alone stuff to monitor things and the PCM speed is much slower than the newer cars. Some just stick a dirty tail pipe sniffer in the exhaust and call it a day. We use dual wide-bands lab grade, boost gauge, fuel pressure gauge, laptop, sct software stand alone. Most the gauges in customers cars this old are off, so you have to have the right equipment to ensure you are giving the best service you can.
Ok, so if I understand correctly, on cars with autos, what you're really graphing there is the torque measured vs. the engine RPM, where the RPM is calculated using the wheelspeed, wheel size, rear gears, etc. which may not necessarily coincide with the actual RPM of the engine, especially in the case where the converter is not locked (in this case below 4900RPM). Or is the RPM really the RPM directly measured off of the dyno's spark sensor?
Reworded differently, on the second plot there I note approximately 180 ft-lbs of torque at 3500RPM. This value seems kind of low (comparatively my car is making 350ft-lbs of torque at 3500RPM with my s-trim pulleyed for a max boost of only 10psig), and seems could be explained with the additional losses that result from the converter operating at an RPM below the 4900RPM stall speed.
For this setup, maybe nobody really cares what the engine performance is below converter stall since you'll never need it but I was just curious how you can truly know the engine's power curve below an auto's stall speed on a chassis dyno.
How much faster are the newer car's PCM than the old Fox body? With the tweecer interface, I'm datalogging with the stock A9L at approximately 10 samples a second, or once every 1/10th of a second. What could I potentially miss in performance tuning not having resolution better than 1/10th of a second? I can even log wideband O2 readings and boost pressure, in conjunction with the engine's sensors so really nothing is stand alone with this setup and it allows for tuning to be conducted on the street in real world conditions. As you know, conditions on the dyno do not necessarily represent the street, especially in this case where this person has an aftercooler, fan or not.
What advantages are available with SCT, PMS, or other stand alone's?
Sorry for all the questions but I'm trying to understand the benefits of conducting chassis dyno tuning, using stand alone PCM's or anything else of that nature, and lab grade widebands, etc. over tuning on the street with available in car datalogging/stock electronics, and whether or not there is potential for more gain in my current combination which has been tuned this way. Reworded differently, do I have 100HP left on the table?
-Chris
Reworded differently, on the second plot there I note approximately 180 ft-lbs of torque at 3500RPM. This value seems kind of low (comparatively my car is making 350ft-lbs of torque at 3500RPM with my s-trim pulleyed for a max boost of only 10psig), and seems could be explained with the additional losses that result from the converter operating at an RPM below the 4900RPM stall speed.
For this setup, maybe nobody really cares what the engine performance is below converter stall since you'll never need it but I was just curious how you can truly know the engine's power curve below an auto's stall speed on a chassis dyno.
How much faster are the newer car's PCM than the old Fox body? With the tweecer interface, I'm datalogging with the stock A9L at approximately 10 samples a second, or once every 1/10th of a second. What could I potentially miss in performance tuning not having resolution better than 1/10th of a second? I can even log wideband O2 readings and boost pressure, in conjunction with the engine's sensors so really nothing is stand alone with this setup and it allows for tuning to be conducted on the street in real world conditions. As you know, conditions on the dyno do not necessarily represent the street, especially in this case where this person has an aftercooler, fan or not.
What advantages are available with SCT, PMS, or other stand alone's?
Sorry for all the questions but I'm trying to understand the benefits of conducting chassis dyno tuning, using stand alone PCM's or anything else of that nature, and lab grade widebands, etc. over tuning on the street with available in car datalogging/stock electronics, and whether or not there is potential for more gain in my current combination which has been tuned this way. Reworded differently, do I have 100HP left on the table?
-Chris
Thanks guys for the compliments, thats my ride or should i say money pit,lol...Thanks to Kevin and Travis for helping me out, especially to Kevin, there isnt a better tuner out there.We went over every little detail, til it was just right...And about that other shop that tried to tune a car with a sniffer,and doing no pre pull checks - yes i paid pull price for that tune that broke alot of expensive parts,lesson learned....And car is for sale,its always for sale for the right price if any one is interested.