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-   -   Daily driving larger single - advice needed (http://www.competitiondiesel.com/forums/showthread.php?t=198321)

SCHMITTY 11-11-2017 04:40 PM

Daily driving larger single - advice needed
 
So I have been adjusting my driving habits after switching from a 64/74/14 to a 71/76/.9 t4.

I have been fighting some bad surge . If I fuel the turbo too much it barks at every shift and can even start bucking when I hit lock up.

One of my buddies sent me a custom stiffer afc spring - it helped.

I put a stock fuel plate in - full forward.it helped but it is slower .

My other buddy cut the mwe groove larger from .140" to .245" It helped with around town driving but it will still buck when I hit od/lock up at wide open throttle. That shift happens around 3000 rpm

I have the afc pretty tight. The turbo is lit at 2500 and starts building boost around 1900 -2100 depending on what gear I'm in. With the afc looser it will
Start spooling well at 1900 rpm but it barks and surges badly so I cut fuel back.

I found that manual at higher Rpm's helps big time.

What am I missing ? 5k springs and higher shift points ? Too much air for the cylinder head?

I'm hitting 50 psi max boost right now. Drive pressure seems to be in the 60s - it flutters a little.

Timing is 19*
Stock stall triple disk
5x16s
7mm dv
3.54 gears and stock tires

Cflanery88 11-11-2017 08:46 PM

Just get a turbosmart blowoff valve and it won’t surge at every shift.

DDually 11-11-2017 10:23 PM

Also more fuel will help the barking between shifts.

jasonc 11-12-2017 07:56 AM

Quote:

Originally Posted by Cflanery88 (Post 2643812)
Just get a turbosmart blowoff valve and it won’t surge at every shift.

A blow off valve should only be used when the throttle is let off quick, not unloading and releasing pressure during shifts, you'll over speed the charger. It just sounds like the comp wheel is to close in size to the turbine to run well as a single. You could go to a larger exhaust housing.

jasonc 11-12-2017 07:57 AM

What charger are you running that's a 71/76?

SCHMITTY 11-12-2017 12:36 PM

K31 with a machined s400 exhaust housing. The way I have it set up now it doesn't bark at every shift- just at lock up/ overdrive. I my tps went out a couple years ago and I replaced it with a pot switch- maybe that's part of the problem. It's the worst when overdrive and lock up happen at exactly the same time. The rpm drop can be 350 rpm and a lot more load. I can draw out the shifts to 3500 or so and the truck does feel faster than the silver 64 I had . The one shift I can't draw out is the 3-4 shift. I'm going to wire up a switch to help keep it out of overdrive and lockup longer. The factory od switch won't let me turn on od when The truck is over 3000 rpm or a certain mph it seems.

I have been thinking about a 1.0 or 1.1 housing.

I'm not giving up on this turbo yet . I'd like to make the power with this thing to get into the 11s. Driving around town and commuting with with the lag doesn't bother me if the power is there when I want to play.

My egts max out at 1300 and 50 psi , cruising is 500-600 and 3-4 psi, once it hits 15 psi it takes off

I'll have more time to play with the afc when I get done with work next week.

SCHMITTY 11-12-2017 12:43 PM

Quote:

Originally Posted by DDually (Post 2643821)
Also more fuel will help the barking between shifts.



That would be great if it does. I'll be pulling the plate next week when I'm
done commuting with the truck. Just in case I break something. With a zero plate set it the middle and a looser afc spring this turbo would start spooling around 1900 and be lit by 2100 and would hit 60 psi. I didn't have my dp gauge hooked up then.

jasonc 11-12-2017 02:03 PM

I remember the thread where he machined that, I think the exhaust housing is alot of your problem. Does ats sell the housing they use seperate?

turbo2387 11-12-2017 02:22 PM

Yes. Its $425. The t3 version is a .85 twin scroll

SCHMITTY 11-12-2017 02:45 PM

If I tried another housing I'd probably pick up another s400 housing for 200$ and have my machinist buddy modify it.

Turbo2387 sent me the afc spring and a pic of the switch wiring.he has also been helping me a bunch with understanding the afc better. I'm going to give that od lock out switch a shot before I try a bigger housing. It almost feels like I'm snuffing the turbo out when it hits lockup/overdrive at the same time. Maybe I'm not fueling it hard enough up top and or the Rpm's are to low to make the shift along with the rpm drop from od and lock up happening at the same time. If I gently hold the brake pedal before it makes the shift into overdrive/lock up and I let off the pedal after the shift , then lock up comes on later and it does not surge

gman99 11-13-2017 09:15 AM

Are you saying that you are shifting from 3rd unlocked to overdrive/locked at the same time?
My truck is smooth but I think even my truck would buck under those circumstances.

turbo2387 11-13-2017 10:20 AM

1 Attachment(s)
I'm gonna elaborate for you a bit while you sleep Mike.

yes. because his TPS is out he has a POT switch installed. after talking with him this weekend we figured out that he is actually skipping a gear. that gear is 3rd lock-up. he is shifting 1,2,3,OD. this is most likely causing his main problem. when he goes race truck mode this 600rpm or so drop is causing the turbo to loose all its drive pressure. Where his smaller turbo use to be able to recover with just a cough this bigger single snuffs.

He will be installing a manual OD switch that allows the truck to shift 1,2,3,3LU then manually shift into OD at whatever RPM he chooses. Me thinks this will solve his problems.

pushlar84 11-13-2017 10:45 AM

What about the BD diverter valve

zstroken 11-13-2017 11:41 AM

Quote:

Originally Posted by turbo2387 (Post 2643964)
I'm gonna elaborate for you a bit while you sleep Mike.

yes. because his TPS is out he has a POT switch installed. after talking with him this weekend we figured out that he is actually skipping a gear. that gear is 3rd lock-up. he is shifting 1,2,3,OD. this is most likely causing his main problem. when he goes race truck mode this 600rpm or so drop is causing the turbo to loose all its drive pressure. Where his smaller turbo use to be able to recover with just a cough this bigger single snuffs.

He will be installing a manual OD switch that allows the truck to shift 1,2,3,3LU then manually shift into OD at whatever RPM he chooses. Me thinks this will solve his problems.


Do you live in Anderson Indiana, as I have been to MOFAB several times!


I agree, as the large RPM drop doesn't allow the CFM produced by the compressor to go anywhere, as well as robbing HP from the exhaust, so you end up with a surge condition

turbo2387 11-13-2017 12:10 PM

Quote:

Originally Posted by zstroken (Post 2643972)
Do you live in Anderson Indiana, as I have been to MOFAB several times!


I agree, as the large RPM drop doesn't allow the CFM produced by the compressor to go anywhere, as well as robbing HP from the exhaust, so you end up with a surge condition



Yep

SCHMITTY 11-13-2017 11:21 PM

Here is a vid. I counted the shifts and I'm pretty sure it went 1-2 2-3 3-od, then lockup. Either way there was 3 shifts and lockup. I stay in it for awhile to give a good example. It's a dog if I let it shift by itself.


K31 surging 12 valve - YouTube

SCHMITTY 11-13-2017 11:39 PM

Here is a vid showing the difference manually shifting. It coughs right at lockup up or over drive which ever one happens last. Shortly after I make the 2-3 shift you can see the tach drop a little again and then the final big drop of the tach happens at the end, it coughs and I lift and it continues to make some noise.

Manually shifting 12 valve 1-2-3 and overdrive / lockup occurs to early I think- k31 surging/buckin - YouTube

SCHMITTY 11-13-2017 11:52 PM

Here's a vid with 2 runs both I've overdrive turned off with the factory switch. I let it shift by itself and it barks at the 2-3 shift . Lockup seems to happen at the same time. I do not lift on the first run in this vid. The 2nd run I manually shift it and it does not bark at all however I did let off the pedal and it barks.

I hit 49-50 psi and 1400* egts.

This setup is much faster if I loosen up the afc and swap plates but it surges even worse.

K31 12 valve overdrive turned off, auto shifting and manual shifting - YouTube

jasonc 11-14-2017 06:33 AM

I only watched the last vid but it sounded like it was even surging over 3k rpm? I had a 362/65/12cm yrs ago that acted just like that. I used the same charger as a secondary in compounds and it worked decent. Man about all you can do is go to a bigger ex housing if in deed it kept surging in the upper rpm's, which I'm sure you know is gonna make it more lazy to spool.

SCHMITTY 11-14-2017 10:30 AM

The 1st and 2nd videos I posted are short. They show the surging at its worst.

I'm happy with the last run in the last video I posted .


Say I did get a 1.0 or 1.1 exhaust housing. If I threw enough fuel at it to get it to spool would it still surge ?


I'm not totally against a ratchet shifter with a switch for od and a switch for lock up.

I'm going to wire up that switch that was posted to keep it out of overdrive longer and also play with the fueling some more. I'll buy a larger exhaust housing last.


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