Notice how I am making 1-2 pounds more boost than back pressure? Does that mean I am past 100% efficient? I had someone mention that my spring was to light but it makes boost really fast / runs cooler than ever / the mileage is mind boggling with this 350 tune........ Notice when I am WOT my back pressure will not increase by more than max 15 pounds of Gauge Pressure which keeps the max EP way down like 65 PSI. I beleive that for a daily driver I hit the spring perfect and there is no need for an expensive AMS controller.
If the cracked piston issue is related to Drive pressure than with my gate kit the problem is solved. People want to see on paper if the wastegate kits work well here it is.
My truck is the Perfect daily driver. Besides the crappy lift there is nothing else I could ask for out of the truck. I obviously need to get a 6.7 but love my 6.4 so much I do not think it is going anywhere. Might take the lame lift and tires off it and go back to factory hieght or lower and use it for hauling our sled trailer in the winter.
At full tilt is where you want the backpressure to come close to boost in order to maximize efficiency for power. On the dyno and dragstrip is where I am concerned with that. IMO part throttle back pressure should be higher because you want the turbo to be snappy at low speeds, thus higher backpressure than boost. At low rpms is where you are more concerned with turbo spool up than max effciency. The turbo can't spool as quick when it has more resistance (boost) than drive (backpressure).
What you aren't looking at in the log is the possible change in VGT duty cycle by opening the gate early. That would make the high pressure charger vanes close down to spin the charger harder to compensate for lack of exhaust psi. Also you have less exhaust now to drive the atmosphere charger because you just dumped in down into the downpipe thus getting the atmosphere charger to light could take more.
I understand this but what blows my mind is that the charger spools as fast or faster than ever. May be I will up one more size and see if I can get it one to one I beleive at 20 Gauge PSI the VTG will already be fully open. I will log turbo duty cyle on the way home tonight to see if it is keeping me consistant
I have to agree. I have tried to keep my BP close to my boost pressure and the truck is a turd. I have found that by only limiting the back pressure limit and allowing as much BP as possible in the lower boost ranges the truck is perfect. I will try to post a lof file for comparison. I am using a higher spring pressure and a regulated boost source to the gate.
I also have to agree about the EGT temps as well. With less BP and the resulting less boost the temps got hot really quick. Probably because of too much fuel and less air. (please correct me if that is inaccurate).
I also have to agree about the EGT temps as well. With less BP and the resulting less boost the temps got hot really quick. Probably because of too much fuel and less air. (please correct me if that is inaccurate).
Here is a log file that I recorded a few months ago. I have since been messing with my configuration and have changed the plumbing (boost reference) several times. I am 99% sure I have it down now and if anyone is interested I will post a more recent log file, once I record one. There will be a slight delay until I get some recent "where there is smoke there is fire" damage/preventative taken care of.
We need to see a log with your data at key on engine off to verify that your map and ebp are similar then go run it up to part throttle and wide open throttle. Looking over the log the numbers aren't looking correct at all.
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