after my DPF delete and fl0-pro 5" install, i've noticed a slight decrease in lower rpm boost. with the tune i have i can still get it wound up, but it takes a little "gettin on it" to get there. i miss the little bit of boost i had from stop lights and what not, or even cruising at 50 with a slight increase in fuel. i don't want to have to have it downshift in order to spool the turbo to get me that slight uptick in power.

i've heard differing opinions - "stock turbos need the 4" for more backpressure" ; "5 inches is great, b/c you could always use a couple extra inches" ; "there's no difference between the two, but you don't NEED a 5 inch until you're at 1k bhp".

i've got the 5" setup on there... that's that. how can i increase the reaction of the turbos? i've read about a wastegate adjustment (tightening), but not sure i'm ready to undertake that in the driveway, and i don't have access to a lift. nor am i sure this will correct my "issue." (i quoted it, b/c it's not really an issue, it's just a personal preference that i'm wanting to adjust to make myself a little more happy with the performance of the truck)

thanks for the help/advice.

 

what tuner are you using and what tune?

 

livewireTS with "performance off" tune selected (DPF is turned off)

other options are tow and race (all have off and on options to tune with or without the dpf system)

 

I'm sorry, but I don't know anything about livewireTS. Have you called them? I know it sounds like such dumb advice, but sometimes talking to the source can save a lot of time. I know with the H&S tunes, I don't experience what you are describing at all, so I think the tuning might be the source of the issue. I know of 3 guys that have 5" and they don't have problems at all. I have 4" dpf delete and then 5" the rest of the way back and I don't have any issues.

 

Do you have other canned tunes with that tuner? Sounds like a tune issue to me, give the other tunes a shot to see if they do the same...???

 

the "race off" tune works like a champ, and i'm still getting "27+ mpg" according to the display. i'll calculate it once i run this tank through it. when i stomp on it, though, from a slight roll, i've seen the boost hit ~40psi, so that's a tad alarming. i'd hate to pop the manifold. :|

 

Wow, the highest I've seen is 35psi

 

My turbo hasn't seen over 32psi and I was not liking that so I started running the current H&S tunes. I think 28 is the highest I've seen with them. 40psi is just a bad idea. As in stop that right now bad idea.

 

yea... i saw it once, and haven't "stomped" it since. i might even loosen the waste gate a bit to avoid anything. or get back with the manuf. for a slightly less aggressive "race" tune. i'll give em a shout on the way home from work today and see if there's a program i can download that can let me adjust my own custom tune. been tuning R6 race bikes for years, i'm sure a big diesel aint HALF as tough. guess we'll see.

 

The engine will take it, but the stock turbo seems to puke after exposure to 35 psi boost and above for a duration. Just my opinion, but it's been reported enough that I took notice

 

oh i believe you... that's why i wanna "dumb it down" a bit, on my own. especially with a stock turbo. i aint ready to drop $2500 on a new aftermarket one right now. especially on a commuter.

 

A 4" circle has an area of 12.6"^2, while the 5" pipe is at 19.6"^2. That works out to a 55% gain in the size of that pipe. I would expect that your new downpipe is causing the turbo to spool up more slowly.

My theory on this is that the speed of the gas flow through the pipe has slowed with all the new volume. Recall that fluids moving through a compressed space gain pressure and speed.

 

Down pipe is the same. And the first pipe after the DP changes from ~4 to the 5". It wasn't exhaust gas causing the lag. It was the tune. With the new tune it's fine. I just need to cap the top of it so I don't ruin my turbo.

 

You're getting 27MPG US? My display indicates 13.3L/100km on highway trips which is 17.7mpg running stock. If you're getting that much gain from a DPF delete then mine is going away real soon.

 

this is the first tank i've put through it, and i drive ~35 miles each way to work - almost exclusively freeway. once i've calculated the numbers, i'll post up. and i'm more than happy to send out any info i can for the source, as i don't wanna ruin a good thing.