Timing tips
So I recently swapped the old MSD Hemi 6 off my 5.7 and upgraded my Megasquirt setup to an MS3X to run full sequential and spark control in a single box. Generally speaking things are running pretty well, but I'm having some issues working out some reduced power over my old setup and a really bad shake at highway speed in 6th gear (0.5:1 overdrive with a 3.55 rear end in my case, around 1600 rpm).
To start with, I put the factory timing tables that have been posted online in as my base timing settings. I have a tableswitch set up to run the "closed loop/cruise" table normally, and then swap over to the "open loop/WOT" table when my TPS goes over 90%. Cruising around town and idling the car is awesome and a noticeable improvement over the old setup. However, full throttle hits even in first feel pretty lackluster to me. The old setup would blow the tires off or at least chirp them, but the new tuning just feels really lazy until maybe 5000 rpm when it picks up again. Trying to cruise 70 in 6th is near impossible as the car will just shake hard and have a hard time keeping the speed.
For reference, I'm running a 5.7 with an Inertia Motorsports SRT Max Plus cam with a little tighter LSA (I think it's something like 107 or 109), stock 6.1 exhaust springs, an Indy ModMan intake, TTI headers, all backed up by a Viper T56. I know the ModMan isn't a great intake and my system as a whole may not be super well matched, but I loved the sound of the cam in videos I'd seen and this is just where I am today.
I have a feeling I need more timing in both cases, but wanted to get some opinions and see if anyone else had a setup even remotely similar to mine. Looking at the stock WOT timing table there is a massive crater from ~3000-5000 rpm where the timing drops 5 degrees before working its way back up (picture below).
This seems to correspond to what I'm feeling in the seat of my pants, and I'm thinking maybe my cam and intake don't need the same kind of timing dip as the stock setup due to the different runner dynamics and cam timings. I'm planning to try flattening that out to see if it brings any life back. The high gear cruising problem I'm less sure about. I have a feeling it's a similar problem of not enough timing, but that one is a little harder for me to figure out. I'm running close to 80-85% load, but super low rpm. The factory table has me around 15-18 degrees of timing at this point while lean cruising at 14.7 AFR. I know lean cruise can take a lot more timing than full power, but I wouldn't have thought I'd be way off of factory numbers for this. Ideally I'd sit in the passenger seat and feed it timing a degree at a time while someone else is driving to see if it smooths out, but I haven't had a chance to try that yet. Looking for any ideas or datalogs people have done though to try to get a better idea of what is out there before I mess with timing too much.
So I recently swapped the old MSD Hemi 6 off my 5.7 and upgraded my Megasquirt setup to an MS3X to run full sequential and spark control in a single box. Generally speaking things are running pretty well, but I'm having some issues working out some reduced power over my old setup and a really bad shake at highway speed in 6th gear (0.5:1 overdrive with a 3.55 rear end in my case, around 1600 rpm).
To start with, I put the factory timing tables that have been posted online in as my base timing settings. I have a tableswitch set up to run the "closed loop/cruise" table normally, and then swap over to the "open loop/WOT" table when my TPS goes over 90%. Cruising around town and idling the car is awesome and a noticeable improvement over the old setup. However, full throttle hits even in first feel pretty lackluster to me. The old setup would blow the tires off or at least chirp them, but the new tuning just feels really lazy until maybe 5000 rpm when it picks up again. Trying to cruise 70 in 6th is near impossible as the car will just shake hard and have a hard time keeping the speed.
For reference, I'm running a 5.7 with an Inertia Motorsports SRT Max Plus cam with a little tighter LSA (I think it's something like 107 or 109), stock 6.1 exhaust springs, an Indy ModMan intake, TTI headers, all backed up by a Viper T56. I know the ModMan isn't a great intake and my system as a whole may not be super well matched, but I loved the sound of the cam in videos I'd seen and this is just where I am today.
I have a feeling I need more timing in both cases, but wanted to get some opinions and see if anyone else had a setup even remotely similar to mine. Looking at the stock WOT timing table there is a massive crater from ~3000-5000 rpm where the timing drops 5 degrees before working its way back up (picture below).
This seems to correspond to what I'm feeling in the seat of my pants, and I'm thinking maybe my cam and intake don't need the same kind of timing dip as the stock setup due to the different runner dynamics and cam timings. I'm planning to try flattening that out to see if it brings any life back. The high gear cruising problem I'm less sure about. I have a feeling it's a similar problem of not enough timing, but that one is a little harder for me to figure out. I'm running close to 80-85% load, but super low rpm. The factory table has me around 15-18 degrees of timing at this point while lean cruising at 14.7 AFR. I know lean cruise can take a lot more timing than full power, but I wouldn't have thought I'd be way off of factory numbers for this. Ideally I'd sit in the passenger seat and feed it timing a degree at a time while someone else is driving to see if it smooths out, but I haven't had a chance to try that yet. Looking for any ideas or datalogs people have done though to try to get a better idea of what is out there before I mess with timing too much.
