Ok. I would like someone to do a little teaching for me.
I use to think exhaust back pressure was the restriction of exhaust flow, out of the truck. The only way to change that was to change turbos, downpipe, echaust itself, ect. To lower the exhaust back pressure you needed to make the system more free flowing.
Now I also understand how the turbo puts backpressure on the motor in relation to boost. More boost more back pressure. You want the most (or right amount) of boost with the lowest back pressure. With in reason.
Now heres where Im lost.
I have been running the Spartan
250 for a little while now. I have been super happy with the tune. It does everything I wanted. EBP from 10-20lbs of boost is around double the boost. From there up the ratio goes down. That seems normal to me.
I decided to try a few other tunes sinse I have soo many there, and with my towing season right around the corner, figured I would try a littel smaller tune so it would be "easier" on the motor.
Loaded up the 210 tune. all around good tune. Ran good, shift well, little sloppy now and then. I did not give it a ton on driving before swapping it out. The EBP was much higher at part throttle than the 250 tune. at 10-20lbs of boost, The EBP was 3 times the boost. Closer to double as the boost went up. This made the motor seem to work much harder and use more throttle just to normally take off from a light. It was also sucking down the gas much faster. I would guess 2-3 mpg less. I did not run a full tank through to check.
I was thinking it was just that tune, I tried the 210 tow tune with the same results, just firmer and quicker (lower rpm) shifts. Which I liked.
So what is really confusing me is how a tune can change the EBP? And if it can, why would they not make all the tunes with lower back pressure? Which tune is really easier on the motor? The 250 tune runs hotter on the exhaust temp, but the 210 tune really seems to work the motor more. So if the 250 tune is cool enough to haul my trailer. It seems that would be the tune to run.
I did also notice the exhuast hiss was much less with the 250 tune with a lot more rumble. Sounds much better.
New Ride 08 F-250 CC SB FX-4 6.4 auto loaded job 1, Spartan 310,RCD 485,525, Erics Xstreet,KEM250 DPF delete,downpipe, intercooler pipe, 4" mbrp, timbrens
04 F-350 6.0,auto,SC,SB, 8ft Fisher X-Blade, Hideaway Strobes, XM Radio,Alpine Head unit, X-codes, Edge Mini spring pack, Edge adjustable track bar, 315/75/16 Toyo A/t,Prodigy brake controler,MBRP 3.5" downpipe,5"stacks, powermaxx turbo, Xrace tuned
Old truck-3/27/03 build F-350,CC,SB,DRW 6.0, Auto, Black on black, Blacked out bumpers/ grill, Moon roof, fifth wheel.
old sick, 1/7/03 build
2003 F-350,SC,SB,6.0, 4" lift 37 MT/R