twin turbo truck power drops @4500rpm

[jarrah]

hi guys,

I had a truck the other day on dyno with twin turbo kit and cam I have tuned several similar setups with good luck making 700whp, whoever with this particular truck something is weird it feels as if it hits a wall @4500 rpm and power drops throttle doesn't close at all I tried several things advancing cam and retarding with same results.

954850_10154218497033682_5265592839540021245_n.jpg

dyno log never mind the AFR at low speeds it has 4.5 inch exhaust and AFR is in the back
rev.1.hpl

[GHuggins]

When I see this it's usually boost related? Just a thought. Is the boost dropping at this point?

[jarrah]

Boost is not dropping i am getting 10psi all the way it has a boost controller

[Ben Charles]

What is fuel rail pressure, fuel pressure, actual fuel look like in the problem area?
Since your getting 100 throttle desired AND actual what does timing look like??

[jarrah]

What is fuel rail pressure, fuel pressure, actual fuel look like in the problem area?
Since your getting 100 throttle desired AND actual what does timing look like??

Check the log I posted i am getting comanded fuel pressure and timing is 14deg still does it i also thought cld be cam was over advance maybe installed i tried retarding in the tune and still same issue it still drops at same rpm similar setup i get 700whp on this truck its making 540ftlb at 4500rpm and the cam in it shld be good for 6800rpm no issues i still believe it shld make in higher 600s but still dnt get wats happening

[Redline MS]

When I see this it's usually boost related? Just a thought. Is the boost dropping at this point?

Zaid, we talked about this....I have seen boost stay stable but lbs/min drop due to the design of the system....kinda like a airflow stall.... if fueling and timing is good and blade is staying open then its either bottle necking airflow or the trans is pissed..

[Ranger6202]

Had same issue with my Vmaxx turbo setup. Mine mine falls off at 4800. Exhaust back pressure has been my theory.....i'm thinking that my turbo exhaust housing is too small (my exhaust is 3.5" to 4" all the way to tail pipe). My boost would stay a full 10#'s throughout RPM to 5800 (eliminating boost or compressor issues), and my afr would match commanded (eliminating fuel injector sizing or pump sizing). My thoughts were that i couldn't get the exhaust out fast enough, thus slowing lbs/min like Redline was saying above. Timing might be an issue since the only way we can set further boosted territory with the enhancement is only with the last row @ 100 kpa. Mine was @ 13 degrees.

[GHuggins]

Typically you can back the boost off or if possible change the boost ramp of the turbo's all together to fix this. If possible have boost max later in the power band... I've been seeing turbine housings choke them out... Haven't looked at the log yet, but the MAF is usually the big give away - it should be stopping and dropping in air flow at your trouble area if it's a choke problem...

[GHuggins]

Just looked at the log - watch your MAF at the trouble area - going up then drops back down and slowly goes back up - it's choking...

If you've got a boost controller with programmable stages, set it up to ramp in after the bad area and see how it does.

[jarrah]

Just looked at the log - watch your MAF at the trouble area - going up then drops back down and slowly goes back up - it's choking...

If you've got a boost controller with programmable stages, set it up to ramp in after the bad area and see how it does.

Wats chocking exactly it does the same watever settings it ison bc

[SinistiR]

What is before the turbo inlet? Is there a hose that could be collapsing?

[GHuggins]

Is this

What is before the turbo inlet? Is there a hose that could be collapsing?

Is this using the same turbos as the other installs you've done?

[jarrah]

Is this

Is this using the same turbos as the other installs you've done?

I am using twin pte 6266 I checked nothing is collapsing

[GHuggins]

But are they the same as your other setups? Looking like the turbine housing is choking it out... You usually see this on smaller turbo's. I'm not familiar with the 6266's...

[GHuggins]

Just looked it up. Smaller turbine housing for spoiling, but still shouldn't be choking out on 4 cylinders? You did say it was a twin setup - yes? Where is your wastegate setup located - just wondering if it's screwing with airflow somehow? Still have cats? Are they still flowing and far enough from the turbine?

[jarrah]

Just looked it up. Smaller turbine housing for spoiling, but still shouldn't be choking out on 4 cylinders? You did say it was a twin setup - yes? Where is your wastegate setup located - just wondering if it's screwing with airflow somehow? Still have cats? Are they still flowing and far enough from the turbine?

Yes its a twin turbo setup exact same setup made 700whp the wg r in the collectors no cats downpipe to from each turbo goes into a varex 4 inch out dual